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Chillers energy consumption, energy savings and emission analysis in an institutional buildings
... The speed of the motors, pumps, compressors and fans can be modulated by variable speed drives (VSDs). It provides continuous control, matching motor speed depending on the specific requirement, which may reduce the cost of energy [16,58]. ...
... In this case, VSD can be used to control the speed of the motor for the pump or fan according to their load demand. Since the power requirement of a fan or pump is proportionate to the cube of their speed, and energy can be saved by fitting the speed of the motor to the requirements of load using VSD to improve the overall system efficiency [58]. The advantages of using VSD in fan and pump applications include [59]: ...
... Typically, the appropriate design of VSD systems can save 20 to 70% of energy use compared to the conventional motor. By using VSD, the energy saving by a motor can be predicted as follows [16,58,61,62]: ...
Automation, modernization, economic development and global progress depends on efficient extraction and utilization of energy. Power generation by burning fossil fuels makes various adverse impacts on the environment. Additionally, the worldwide fossil fuel reserve is limited and depleting very fast. Hence, efficient energy usage and savings are crucial to address the environmental issues to ensure sustainable development. Buildings, both commercial and residential, represent a major energy consumption sector. Approximately 40% of the total energy is reportedly consumed in the building sector. Worldwide building energy consumption, performance measuring systems and best practices, energy-saving techniques and policies are reviewed and summarized in this article. Underfloor air distribution, double-glazed windows, use of highly efficient electric motors and variable speed drives may play a great role in reducing building energy consumption. In the UK, the application of double-glazed windows in commercial buildings can save 39–53% energy. The proper maintenance of a building’s central heating system can save up to 11% energy. The automatic HVAC control system can reduce up to 20% of the building’s total heating load. Proper utilization of a VSD system in motor and building performance optimization by an ANOVA tool also proved instrumental in saving energy. Apart from this, the building codes of different countries also help to improve building performance by reducing energy consumption. This study will help building researchers and policymakers to make a framework for sustainable, green building.
... Bill savings and payback period are also calculated and reported. [16] Energy management strategies for a governmental building in Oman were investigated. The collected data were calibrated and re-simulated to match the real-time energy consumption. ...
... Energies 2023,16, 7145 ...
In the domain of energy consumption in restaurant-type commercial buildings, traditional energy audits tend to concentrate mainly on electrical loads, often neglecting the specifics of the restaurant sector, especially regarding liquified petroleum gas fuel consumption. This research employs a comprehensive energy audit framework specifically designed for the commercial building restaurant sector. Using energy data from 130 restaurants, we computed the building energy index that ranged in between 650 and 1000 kWh/m²/year. Using linear regression, we assessed the relationship between building energy index and restaurant area, uncovering a low R² value, suggesting the unsuitability of the building energy index as an exclusive measure for restaurants. Concurrently, our detailed comparative study showed that liquified petroleum gas-fueled equipment uses about 38% more energy than electric fueled equipment but is 0.5% cheaper and significantly less polluting. Investigating renewable energy potentials, we found solar PV application as a viable option for restaurants. The results showed that solar PV installation could produce approximately 11,064,898 kWh, translating to utility savings of RM 7,381,929 and reductions of 7,108,327 kgCO2, 68,959 kgSO2, and 31,823 kgCO emissions. Conclusively, our findings underline the need for a diversified energy assessment in restaurants and the tangible benefits of renewable energy integration.
... Mathematical analyses were performed for the energy-saving strategies, including payback year. [14] A walk-through energy audit was conducted in an institutional building. Mathematical analyses were performed for the energy-saving strategies, including payback year. ...
... Tables 2-4 show the details of the summary data, type, quantity, and running hours of energy-consuming equipment in the restaurant. Using the energy assessment data collected from the fast-food restaurant, the energy consumption by air-conditioning, lighting, and other equipment can be calculated using Equation (1) as below [14,15]: ...
Commercial buildings in Malaysia contribute to 35% of the total electricity demand. During the recent COVID-19 pandemic, the global economy faced a challenging situation that forced many businesses to shut down. However, fast-food restaurants with drive-through features managed to get through this pandemic phase without much effect from the economic impact. Since COVID-19, the operational guidelines have changed for restaurants. However, from an energy perspective, fast–food restaurants are high energy consumers in the retail sector. This paper analyses the load profile of fast-food restaurants and the potential strategies that can be adopted in a free-standing fast-food restaurant. From analysis, it is calculated that a total of RM 97,365.9 of utility savings can be obtained in a year. A total of 91,392.1 kg CO2, 881.8 kg SO2 and 385.5 kg CO pollutant emissions can be reduced. The BEI for the restaurant was reduced to 856.4 kWh/m²/year. By converting to energy-saving strategies, the return on investment was 27.3% and 3.7 years, which is a very short period of time and is attractive for businesses of this nature.
... result of fossil fuels burning, greenhouse gases (i.e., CO2, SO2, NO;^) are emitted(Saidur et al., 2011;Qandil et al., 2019). Carbon dioxide is considered one of the major harmful gases to the environment and the community; reduction of energy consumption in motors and lights leads to a huge reduction in CO2 emis sions(Zhang and Cai, 2018). ...
... To make the calculations more con venient, those different fuels are treated as one fuel, which is a blend of different percentages of the original fuels. Using Eq. (6)(Saidur et al., 2010a(Saidur et al., , 2011Mahlia, 2002), the total amount of the emission (in tons) associated with energy savings can be calculated based on fuel type, percentage of electricity generated by the specific fuel, and the emission factor of fuels to produce the electricity. The emission fac tor per unit electricity generation for various fuels has been taken from Congres sional Research Service (2019) and shown inTable 4:EM, = EP, (PE,"' X Emp' + PE,^ x Emp+ PE,^ X Emp^ + ... PE;" X Emp"), ...
The key of this study is to explore the primary energy consumers in wastewater treatment plants, which is considered as one of the major energy consumers, and introduces the best solution to save energy and reduce emissions in these facilities. This study is based on the energy assessment and analyses of eleven wastewater treatment plants. Through the investigation, it was found that plants can save up to 44,158 MWh of the energy consumption which is 47% from the total electricity consumption with a 17% reduction in the total utility bills and that about 2.5 million dollars cost savings after reviewing the currently facilitated energy system. An average of five years’ payback period resulted in most energy-saving recommendations. A vast potential of greenhouse gas emissions can be reduced with a total range reduction between 13 to 35 mil-lion kg of CO2 based on the speed reduction percentage.
... However, these systems have always been known for consuming huge amounts of energy, resulting in high operating costs and carbon footprint. For example, past studies on an office building (Saidur 2009) and educational institution (Saidur et al. 2011) have shown the significant effects of using HVAC systems, as shown in Fig. 1. These observations, along with the ever-changing climate conditions amplified by human activities, highlight the need to improve the energy efficiency of HVAC systems. ...
Heating, ventilation, and air conditioning systems are known for their high energy consumption, and the operation of parallel chillers is an important way to increase the energy efficiency of these systems. In the field of optimal chiller loading, algorithms are used to find the best loading combinations of chillers for different systems. Existing studies assume that all chillers in a case study are available and included for optimization. Furthermore, due to the iterative nature of stochastic algorithms used for optimal chiller loading, they can present huge variations between results, leading to suboptimal performance. This study aims to solve these problems by modifying an existing optimization algorithm, which is the barnacle mating optimizer. By allowing manual overriding of the on and off statuses of each chiller, these modifications improve practical applications in cases of chiller maintenance or breakdown. Furthermore, optimization precision was increased by introducing continuous cycles in each optimization procedure, followed by filtering and sorting of the best loading distributions. With numerical testing, the proposed continuous barnacles mating optimizer performed on par with its native counterpart at high cooling loads while providing up to 11% energy savings and reliably following optimization constraints at lower loads. Manual chiller switching functions of the modified algorithm also demonstrated good stability despite having fewer chillers during high-load situations. This study encourages improvements other than power consumption in the optimal chiller loading field to improve their feasibility in practical applications while addressing the 11th goal of the Sustainable Development Goals, prompting another step towards more sustainable buildings and cities.
... Chillers consume more than 40% of the total energy usage of heating, ventilation, and air-conditioning (HVAC) systems in commercial and industrial buildings [1]. Building automation systems (BASs) are usually installed in these buildings to record the building operation data for control purposes. ...
The development of data-driven prediction models of energy performance of HVAC equipment, such as chillers, depends on the quality and quantity of measurement data for the model training. The practical applications always struggle with the credibility of results when the training dataset of an existing chiller is relatively small. Moreover, when the energy analyst needs to develop a reliable predictive model of a new chiller, the manufacturer’s proprietary data are not always available. The transfer learning method can soften these constraints and can help in the development of a predictive model that captures the knowledge from the available chiller, called the source chiller, using a small dataset, and apply it to a new chiller, called the target chiller. The paper presents the successful application of transfer learning strategies by using grey-box models and DNN models for the prediction of chillers performance, when measurement data are recorded at 15 min time intervals by the building automation system (BAS) and used for training and testing. The paper confirms the initial hypothesis that both the grey-box models and DNN models of the source chiller from July 2013 predict well the energy performance of the target chiller with measurement datasets from 2016. The DNN models perform slightly better than the grey-box models. The pre-trained grey-box models and DNN models, respectively, are transferred to the target chiller using three strategies: SelfL, TLS0, and TLS1, and the results are compared. SelfL strategy trains and tests the models only with the target data. TLS0 strategy directly transfers the models from the source chiller to the target chiller. TLS1 strategy transfers the models, pre-trained with an extended dataset that is composed of training dataset of Ds and training dataset of Dt. Finally, the models are tested with another set of testing data. The difference in computation times of these two types of models is not significant for preventing the use of DNN models for the applications within the BAS, when compared with grey-box models.
... The energy consumption and emissions related to the operation of a chiller and other chiller plant components installed in a university building powered by fossil fuels were examined by Saidur et al. [14]. The authors estimated the emissions and energy savings associated with incorporating variable speed drives (VSDs) into chillers and motors in their study. ...
In standard district cooling (DC) plants, central chillers produce cold energy for space cooling throughout the district network. In recent times, the integration of the vapor compression system, which includes the functionalities of vapor compression chillers (VCC), and thermal energy storage (TES) tanks in the DC setup, has gained more implementation across the globe. This is due to the possibility of load shifting by using the VCC to produce chilled water for charging the TES tanks during off peak periods. Since the environmental implications of various energy intensive systems are largely determined by the amount of material and energy consumed throughout their life cycle, it is critical to conduct a sustainability assessment of these systems in terms of environmental contributions, and suggest design options to reduce these impacts. A cradle to grave life cycle assessment (LCA) model is created in response to these issues and in order to meet the project’s objectives. The life cycle impact assessment (LCIA) results of the analysis reveal that the carbon footprint per 1 RTh of the produced chilled water is estimated at 0.72 kg CO2 eq/RTh. The operation phase of the system’s life cycle accounted for the most impact, about 98%, with other life cycle phases having negligible contributions. In substantiating the study’s investigation, the environmental performance based on several design options were discussed and compared to the case study. Among the several scenarios considered, incorporating the Sweden mix technology provided the case study with the most significant environmental savings, of about 94%.
... Air conditioning systems are the major energy consumers in office building, hotel, central library, hospital, shopping mall, residential and others building. Many literatures reported that in commercial building, air conditioning systems account almost half of the total power consumption, and being the single biggest consumers [1][2][3][4][5][6]. It is also found that another building consumes more than 50%-70% for HVAC (Heating, Ventilating, and Air Conditioning) of total electrical energy use [7][8][9]. ...
Split air conditioning systems produce reasonable amount of condensate which is usually not utilized and thrown away to the environment. On the other hand, it consumes a lot of energy during operation. The aim of this study is to investigate the improvement of air conditioning systems performance utilizing condensate. A direct evaporative cooling using condensate is incorporated on a 0.74 ton-cooling capacity of split air conditioning to decrease the air temperature before entering the condenser. Performances of the split air conditioning with and without direct evaporative cooling are compared and presented in this paper. The results show that the use of direct evaporative cooling using condensate into the air before passing through the condenser reduces the compressor discharge pressure. The decrease of the condenser pressure led to 4.7% and 7% reduction of power consumption for air conditioner without cooling load and air conditioner with 2000 W cooling load, respectively. The cooling effect and coefficient of performance (COP) increase with the decrease of compressor power. The use of direct evaporative cooling with condensate into the air before entering the condensing system can enhance the system performance and protect the environment.
... Indoor electricity demand for cooling may be reduced by up to 67%, if chillers are used efficiently (Bannister, 2009;Piper, 2003;Xue, Wang, Yan, & Cui, 2015, p. 86). Literature suggests active systems are not working as effectively as they could be, which is due to chillers not being sequenced and operated correctly (Chen, Chang, & Chan, 2014;Piper, 2003;Saidur, Hasanuzzaman, Mahlia, Rahim, & Mohammed, 2011;Sun, Wang, Cui, & Yim, 2013;Wei, Xu, & Kusiak, 2014;Xue et al., 2015;Yu, Chan, Yang, & Sit, 2015;Yu & Chan, 2012). ...
The application of western comfort standards to buildings in the Arabian Gulf has resulted in mass-use air-conditioning. Buildings are cooled to temperatures that are excessive compared to historic expectations in Abu Dhabi. This thesis raises the question of whether these thermal conditions are appropriate. If not, is there scope for adjustment of indoor standards to reduce energy use whilst retaining thermally satisfied occupants.
The thesis investigates the entrance lobby, a form of transitional zone. Transitional zones are communal spaces that include areas where occupants would typically transition through and are characterised by their location in bridging the indoor and outdoor environment; their occupancy time and use; their volume as a percentage of the whole building; architectural/engineering features and, for the purpose of this section, the methods used to analyse their thermal comfort. They are cooled identically to occupied zones (also known as steady-states) that provide occupants with a bridge between external and internal environments. If transitional zones have different comfort conditions to steady state environments, they may allow occupants to acclimatize before reaching their destination inside the building. Occupant evaluation of indoor comfort may provide insights for Abu Dhabi’s challenge to reduce energy demand.
In 2012, twenty, existing, mixed-use case study buildings were tested to trial an increase in temperature of the entrance-lobby using a 1oC intervention. Quantitative and qualitative data were measured alongside occupant feedback. The results were compared to a base case taken the year before. The thesis results of the intervention show there are some changes in buildings that can be associated to the intervention of broadening of thermal comfort parameters in transitional zones. A change in the temperature setpoint may lead to a reduction in cooling without a negative impact on occupant satisfaction. A dynamic simulation was conducted to verify these findings. This resulted in an energy saving averaging 0.62% per 1oC reduction of cooling for the whole building. The finds are valuable to countries like the UAE where there is a drive to reduce domestic energy use and diversify the economy away from oil.
... Generally, the cooling system and air conditioning system are not only the most used energy in hospitals but also in other buildings. A study conducted on institutional buildings yielded a similar result in which refrigeration systems and accessories primarily account for about 51% of total building energy use [48]. While almost every building owner chooses to replace or upgrade their cooling system to a more energy efficient system through retrofit methods, it does not guarantee the best investment solution due to its high cost and long return. ...
The tropical climate with its high average temperatures throughout the year affects the thermal comfort of buildings, especially for naturally ventilated spaces. The government’s move to turn hospitals into green buildings is seen in line with the global commitment to conserve the environment and the country’s current policy of supporting sustainable development. To achieve this goal, energy efficiency and thermal comfort need to be given priority in the focus on hospital planning and implementation for a better quality of the indoor environment. This literature review has led to the need to improve thermal comfort in natural ventilated wards in government hospitals. Some wards are built without air conditioning to save on construction costs, reduce utility costs through low energy consumption, as well as the need for infection control and airborne infections. However, current climate change requires a special study of thermal comfort in wards that use natural ventilation. An innovative solution is proposed to solve the problem statement identified in the reviewed literature through the application of solar PV/T systems and heat pumps. This hybrid system re-uses the heat energy (cogeneration) generated from solar PV panels to be cooled by heat pumps and is then pumped into the ward for cooling purposes. The proposed system has the potential to improve thermal comfort in natural ventilation wards and increase efficiency of the solar PV system for optimal electricity generation as well as improve the overall energy performance of buildings through low-energy cooling systems. It is not only solving the thermal comfort issue but also avoid the use of extra energy for cooling by optimizing the renewable energy.
... Saidur et al. [15] examined the energy consumption and emissions related to the operation of the chiller and other chiller plant components installed in a university powered by fossil fuel-generated electricity. They estimated the emissions and energy savings resulting from incorporating the chillers and motors with variable speed drives (VSDs). ...
District cooling (DC) systems have recently proven to be more economically and environmentally viable as compared to conventional cooling techniques. In most DC setups, electric centrifugal chillers (ECCs) are installed to provide chilled water (CW) to charge the thermal energy storage (TES) tank or for direct CW supply to the DC network. The operation of these ECC systems consumes most of the electrical power supplied to the entire DC plant; this therefore strengthens the need to conduct a comprehensive environmental assessment in order to quantify the indirect ecological impact resulting from the energy consumed in the ECC system operation. In order to achieve this, a case study was conducted of four ECC systems with a use-life of 25 years installed in a large DC plant in Malaysia. A gate-to-gate life cycle assessment (LCA) methodology was adopted to analyze the environmental performance of the system setup. The result of the study year reveals that April and June account for the highest and lowest environmental impact, respectively. The influence of climatic temperature conditions on the monthly cooling and environmental load distribution was also observed from the results. Finally, in substantiating the study’s investigation, environmental performance based on the composition of two different electricity fuel mixes is discussed and compared. The results revealed a drastic decrease in environmental load as the ratio of non-renewable energy sources decreased in the composition of the mix, thereby reducing the contribution of the overall environmental impact of the ECC systems’ use phase.
... Nowadays, it represents more than 20% of global energy consumption in developed countries [40]. Most of that energy consumption is due to the air conditioning systems, which consume up to 44% of the total energy consumption in commercial and industrial buildings [43,47]. The main element of those systems is the chiller, which is in charge of removing heat from inside the buildings by means of electric power. ...
Intensive use of heating, ventilation and air conditioning systems in buildings entails monitoring their efficiency. Moreover, cooling systems are key facilities in large buildings and can account up to 44% of the energy consumption. Therefore, monitoring efficiency in chillers is crucial and, for that reason, a sensor to measure the cooling production is required. However, manufacturers rarely install it in the chiller due to its cost. In this paper, we propose a methodology to build a soft sensor that provides an estimation of cooling production and enables monitoring the chiller efficiency. The proposed soft sensor uses independent variables (internal states of the chiller and electric power) and can take advantage of current or past observations of those independent variables. Six methods (from linear approaches to deep learning ones) are proposed to develop the model for the soft sensor, capturing relevant features on the structure of data (involving time, thermodynamic and electric variables and the number of refrigeration circuits). Our approach has been tested on two different chillers (large water-cooled and smaller air-cooled chillers) installed at the Hospital of León. The methods to implement the soft sensor are assessed according to three metrics (MAE, MAPE and ). In addition to the comparison of methods, the results also include the estimation of cooling production (and the comparison of the true and estimated values) and monitoring the COP indicator for a period of several days and for both chillers.
... Water chillers produce domestic water and space cooling, and often represent the highest energy users in buildings [343]; chillers account for 40% of the total airconditioning energy load [344]. Lee [345], using second law analyses, determined that compressors had the largest opportunity to improve energy efficiency, followed by the condenser and the evaporator, respectively. ...
Engineering innovations - including those in heat and mass transfer - are needed to provide food, water, and power to a growing population (i.e., projected to be 9.8 billion by 2050) with limited resources. The interweaving of these resources is embodied in the food, energy, and water nexus. This review paper focuses on heat and mass transfer applications which involve at least two aspects of the food, energy, and water nexus. Energy and water topics include energy extraction of natural gas hydrates and shale gas; power production (e.g., nuclear and solar); power plant cooling (e.g., wet, dry, and hybrid cooling); water desalination and purification; and building energy/water use, including heating, ventilation, air conditioning, and refrigeration technology. Subsequently, this review considers agricultural thermal fluids applications, such as the food and water nexus (e.g., evapotranspiration and evaporation) and the food, energy, and water nexus (e.g., greenhouses and food storage, including granaries and freezing/drying). As part of this review, over 100 review papers on thermal and fluid topics relevant to the food, energy, and water nexus were tabulated and over 350 research journal articles were discussed. Each section discusses previous research and highlights future opportunities regarding heat and mass transfer research. Several cross-cutting themes emerged from the literature and represent future directions for thermal fluids research: the need for fundamental, thermal fluids knowledge; scaling up from the laboratory to large-scale, integrated systems; increasing economic viability; and increasing efficiency when utilizing resources, especially using waste products.
... Heating, ventilation, and air conditioning (HVAC), which maintain comfortable and healthy indoor thermal environments, is an important part of public and private buildings [2]. As an important part of central air conditioning systems, the chiller is the major energy consumer [3]. Hence, it is of vital importance to have a fault detection and diagnosis (FDD) method to maintain optimal operation for chiller systems. ...
Sensor fault detection and diagnosis (FDD) has great significance for ensuring the energy saving and normal operation of the air conditioning system. Chiller systems serving as an important part of central air conditioning systems are the major energy consumer in commercial and industrial buildings. In order to ensure the normal operation of the chiller system, virtual sensors have been proposed to detect and diagnose sensor faults. However, the performance of virtual sensors could be easily impacted by abnormal data. To solve this problem, virtual sensors combined with the maximal information coefficient (MIC) and a long short-term memory (LSTM) network is proposed for chiller sensor fault diagnosis. Firstly, MIC, which has the ability to quantify the degree of relevance in a data set, is applied to examine all potentially interesting relationships between sensors. Subsequently, sensors with high correlation are divided into several groups by the grouping thresholds. Two virtual sensors, which are constructed in each group by LSTM with different input sensors and corresponding to the same physical sensor, could have the ability to predict the value of physical sensors. High correlation sensors in each group improve the fitting effect of virtual sensors. Finally, sensor faults can be diagnosed by the absolute deviation which is generated by comparing the virtual sensors’ output with the actual value measured from the air-cooled chiller. The performance of the proposed method is evaluated by using a real data set. Experimental results indicate that virtual sensors can be well constructed and the proposed method achieves a significant performance along with a low false alarm rate.
... Obviously, these machines play an essential part in the energy efficiency and consumption demand of the whole facility [3]. Therefore, any optimization in the efficiency of control systems or fault detection entails a great enhancement in facility operation [4]. ...
Chillers are commonly used for thermal regulation to maintain indoor comfort in medium and large buildings. However, inefficiencies in this process produce significant losses, and optimization tasks are limited because of accessibility to the system. Data analysis techniques transform measurements coming from several sensors into useful information. Recent deep learning approaches have achieved excellent results in many applications. These techniques can be used for computing new data representations that provide comprehensive information from the device. This allows real-time monitoring, where information can be checked with current working operation to detect any type of anomaly in the process. In this work, a model based on a 1D convolutional neural network is proposed for fusing data in order to predict four different control stages of a screw compressor in a chiller. The evaluation of the method was performed using real data from a chiller in a hospital building. Results show a satisfactory performance and acceptable training time in comparison with other recent methods. In addition, the model is capable of predicting control states of other screw compressors different than the one used in the training. Furthermore, two failure cases are simulated, providing an early alarm detection when a continuous wrong classification is performed by the model.
Commercial restaurant buildings stand out as significant consumers of energy. In Malaysia, commercial restaurant buildings have access to both cooking fuel types: liquified petroleum gas and electricity. This paper analyses the potential for an energy transition for commercial restaurants by analyzing the energy, economic, and environmental impact of liquified petroleum gas-fuelled and electric-fuelled equipment. It is found that liquified petroleum gas equipment has approximately 38% higher energy consumption but only 0.8% higher energy cost compared to electric. Liquified petroleum gas equipment efficiency is 66%, while electric equipment performance scores 97% using the water boiling test. The life-cycle cost analysis reveals that electric fuel equipment could save up to USD 63,045.20 in cost while reducing greenhouse gas emissions with applied strategies. Hence, a new energy policy is proposed to create a strategic energy transition for Malaysia's electricity generation mix to accelerate the Nation's carbon emission reduction goal by 2030.
Over the past few years, a growing emphasis has been placed on providing sustainable energies to reduce carbon emissions and promote energy efficiency. This paper delved into energy, exergy, exergoeconomic, and exergoenvironmental investigation for a system that combines the Kalina cycle, a double-effect absorption chiller with a vapor compression refrigeration system coupled with an air handling unit driven by a geothermal renewable energy resource. This innovative system generated four distinct outputs: electricity, potable water, cooling load, and hot water. Key system performance variables, such as net power output, coefficient of performance, sum unit cost of the product, energy and exergy efficiencies, the temperature of supply air to the cold store, and potable water production in the base mode, are measured at 63.45 kW, 0.83, 56.74 $/GJ, 62.28 %, 45.67 %, 268.7 K and 20.82 lit/h, respectively. This research explored the impact of various parameters on the output variables, the exergy destruction and environmental impact rate of all components, and the net percent value of the proposed system. The multi-objective optimization significantly improved energy and exergy efficiencies by 6.83 % and 1.8 % from its base mode. Exergy and exergoenvironmental analysis revealed that the highest exergy destruction occurs in Re-injection, and the highest environmental impact rate associated with exergy belongs to the HPG component. Moreover, the geothermal section has the largest share of exergy destruction, approximately 58.5 % of the total exergy destruction of the system
Một mô hình tham số đặc tính chính xác sẽ có vai trò then chốt trong việc nâng cao tỷ lệ chính xác của quá trình phát hiện và chẩn đoán lỗi trong hệ thống chiller. Vì vậy trong nghiên cứu này đã thực hiện so sánh đánh giá 3 phương pháp MLR, GRNN và RBFNN đóng vai trò là mô hình tham số để mô hình hóa các đặc tính hoạt động của chiller. Hai chỉ số thống kê là R2 và RMSE được sử dụng là tiêu chí đánh giá mô hình ở giai đoạn huấn luyện mô hình. Sau đó, kết hợp với phương pháp t-test cùng với quy luật chẩn đoán để nghiên cứu khảo sát và đánh giá khả năng phát hiện chẩn đoán của 3 mô hình. Bộ dữ liệu thực nghiệm thường được sử dụng hầu hết cho hướng nghiên cứu phát hiện chẩn đoán sự cố trong hệ thống chiller của ASHRAE RP-1043 đã được sử dụng trong nghiên cứu này. Nghiên cứu tiến hành khảo sát đánh giá 3 mô hình với 3 trường hợp tiêu biểu là “Chiller hoạt động bình thường” và 2 sự cố thường xuất hiện trong hệ thống chiller “Thiếu môi chất lạnh”, “Tắc thiết bị ngưng tụ”. Kết quả của nghiên cứu cho thấy rằng, RBFNN và GRNN là một chiến lược rất thiết thực và có độ chính xác cao.
Multi-source looped district cooling (MLDC) systems exhibit promising application potential owing to their ability to utilize various renewable energy resources. The load dispatch for multiple sources is considered a critical factor during operation owing to its effects on the energy and hydraulic performance. However, few studies have investigated the behavior of energy and hydraulic performance under different load dispatch ratios (LDRs). In addition, straightforward methods for determining the optimal load dispatch of MLDC systems have not been introduced. This study investigated the relationship between the load dispatch and operating performance and proposed a fundamental method to achieve optimal load dispatch for MLDC systems and overcome the existing challenges. A double-source looped district cooling system was selected as the case study, and its Modelica model was developed. Subsequently, we investigated the relationship between the LDRs and operating performance, and verified the existence of an optimal LDR (LDRopt), which achieves the best hydraulic performance and lowest energy consumption. Finally, a dataset constructed using a hybrid optimization algorithm was employed to develop a multi-variable data-driven model for predicting LDRopt under various load conditions. This study provides a valuable framework and recommendations for further investigation of the optimal control of MLDC systems.
The resultful energy saving of central air-conditioning (CAC) plays a key role in the overall energy saving of large public buildings. And the optimization of air conditioning energy consumption first needs an accurate energy consumption prediction model. A CAC system of a shopping mall is taken as the object of study in this paper. Considering the correlation of the air conditioning system's coolers, refrigeration pumps, cooling pumps and cooling towers, multiple data of the four devices are preprocessed. Extreme Gradient Boost (XGBoost) and Random Forest (RF) fusion algorithm is applied to select the feature subset of energy consumption optimization. The clustering algorithm of Density-Based Spatial Clustering of Applications with Noise (DBSCAN) is devoted to detect and remove outliers. A comprehensive data model of CAC system is established by means of the Deep Residual Network (DRN), and the energy efficiency ratio (EER) of the system is predicted in real time. Compared with the Back Propagation Neural Network (BPNN) and the Long Short Temp Memory (LSTM) network, it is found that DRN has the highest prediction accuracy and the lowest error, which provides a reference for the energy efficiency analysis and control optimization of CAC.
The fault detection and isolation (FDI) of centrifugal chiller system is essential for improving energy efficiency and reducing energy consumption. Considering the non-Gaussianity of chiller measurement, this paper proposes an effective non-Gaussian chiller FDI method based on independent component analysis (ICA) and k-nearest neighbor (KNN) classifier. First of all, an enhanced fault detection method is developed by combining exponentially weighted moving average and ICA (EWICA). The exponentially weighted moving average is employed to develop a dynamic threshold scheme, which reduces the false alarm rate (FAR) and improves the fault detection rate (FDR) of chiller faults. Then, based on the KNN with cosine similarity metric, a novel fault isolation method using the direction of the residual vector is presented to isolate the chiller faults. To further improve the isolation performance, the number of neighbors (k) is optimized by 10-fold cross validation. Finally, the proposed FDI method is validated by using a data set from the ASHRAE Research Project 1043 (RP-1043). The FDI performance of the proposed method is comprehensively analyzed and compared with six state-of-the-art methods. Both of detection and isolation results suggest that the EWICA-based method delivers superior performance for chiller FDI.
In this paper, we propose a global self-optimizing control (SOC) approach, where nonlinear dynamic model is obtained from historical data of plant operation via the framework of sparse identification for nonlinear dynamics (SINDy) combined with regularized regression. With the nonlinear static input-output map obtained by forcing steady-state operation, the globally optimal solutions of controlled variables can be found by tracking the necessary conditions of optimality (NCO) in an analytical fashion. After validation with a numerical example, the proposed method is evaluated using a Modelica-based dynamic model of a chilled water plant. The economic objective for chiller plant operation is to minimize the total power of compressor, condenser water pump and cooling tower fan, while the cooling tower fan speed and condenser water mass flow rate are used as manipulated inputs. The operating data are generated based on realistic ambient and load conditions and a best-practice rule-based strategy for chiller operation. The control structure with the SOC method yields a total power consumption close to the global optimum and substantially smaller than that of a best-practice rule-based chiller plant control strategy. The proposed method promises a global SOC solution using dynamic operation data, for cost-effective and adaptive control structure optimization.
Hospital buildings are the main energy users among government facilities which require substantial energy reduction to save its annual operational costs. At the same time, the Ministry of Health Malaysia has set a policy for all hospitals to achieve green building certification, which in line with its global commitment to conserve the environment. Energy efficiency is an important component in every green building rating tool because of its high potential on point scoring. Thus, there is a need to find the most appropriate method to explore energy saving opportunities as much as possible. The overall aim of this article is to evaluate the potential for energy saving in public hospital using a systematic approach. Three methods are applied in this approach which involved energy audit, empirical evidence and simulation works. Energy audit predicts that the chiller system provides the highest energy saving amount of 1,535,175.40 kWh/year (45.54 %) with discounted payback period of 7.15 years. A chiller retrofit measure was implemented as pilot project and the predicted energy savings were validated by empirical evidence. The actual energy saving of 1,688,347.02 kWh/year (50.08 %) was obtained from the chiller system retrofit and slightly higher than what was predicted with discounted payback period of 6.29 years. Apart from active measures, many more energy saving potentials can still be explored through passive strategies. Simulation method is used to establish energy baseline as the basis for predicting energy saving potential for passive strategies that cannot not be measured through energy audit. The combination of these methods is essential to optimize the potential of energy saving through active and passive strategies that have so far has never been implemented in any public hospital in Malaysia.
Wastewater treatment is one of the main problems of industrialized societies. Decreasing availability of freshwater creates a need for finding new, better and more efficient ways of pollution elimination. Lately, static mixers are more often used in wastewater treatment. Variety of possible shapes and sizes of static mixers opens up the way for finding new technical solutions. In this paper the review of static mixer application as multifunctional reactors for wastewater treatment is presented. The following processes were discussed: photocatalysis, ozonation, coagulation, flocculation and membrane filtration. In each case the application of static mixers significantly enhanced the efficiency of treatment process. The huge variety of possibilities in design of static mixers makes these multifunctional reactors a very interesting and promising alternative for wastewater treatment technology.
Early detection and diagnosis of the chiller sensor drift fault are crucial to maintain normal operation for energy saving. Due to the complex physical structure and operation conditions, sensor drift fault in the chiller system is difficult to discover. To improve the energy efficiency and operation reliability of the chiller system, this paper proposes a novel chiller sensor drift fault diagnosis method using deep recurrent canonical correlation analysis and k-nearest neighbor (KNN) classifier. A deep bidirectional long short-term memory recurrent neural network-based deep recurrent canonical correlation analysis (BLCCA) model is developed, which can automatically extract the nonlinear and temporal features from raw operation data in the chiller system. Based on the proposed BLCCA model, a residual generator is designed to generate the directional residual vector. The cumulative residual vector method is employed to improve the detectability of the sensor drift fault. An efficient KNN-based method is applied to classify the residual vector and judge the faulty sensor. Different distance measures and neighbor numbers are further analyzed to optimize the fault diagnosis performance. The proposed fault detection and diagnosis (FDD) method is validated by using a data set which has been collected from an actual chiller system. Three different state-of-the-art fault diagnosis methods are used for comparison with the proposed method. The comparisons of the experimental results demonstrate that this method achieves significant fault diagnosis performance in terms of diagnosis accuracy, recall, and F measure (F1 score).
Chiller plants are the most energy consuming system during summer season in residential, commercial and hospital buildings. The highly variable cooling demand of the buildings connected to a hybrid chiller plant included absorption and vapor compression chillers to achieve higher energy efficiencies is one of the important issues. Cooling load sharing strategies and apply the variable water flow system in chiller plant have a significant impact on energy consumption and consequently with more productivity and environmentally protected. This paper examines the behavior and pattern of energy consumption in a hybrid chiller plant that includes a combination of two air-cooled screw vapor compression and three single effect absorption chillers. In order to properly understand the pattern of energy consumption, an existing mechanical room in a hospital in Tehran has been studied for five months, and its energy consumption has been compared with the optimized model. The results indicate that the sequence of the chiller function and the way in which they are placed in the circuit during a partial load, is in highest importance in view point of energy saving also by Applying of variable water flow system for optimized chiller loading the more energy saving is achieved for hybrid absorption and vapor compression chiller plant.
The great expansion of industries in Ethiopia has significantly increased the demand for the limited energy source of the country. Hence, effective and efficient way of utilizing the available energy is a crucial issue in all industries. This study investigates the energy consumption performance and possible energy saving potentials of Pasta and Macaroni Factory-a case of Africa PLC which is located in Adama city. It is the biggest pasta and macaroni producing factory in the city and consuming a very large amount of energy. The thermal and electrical energy consumption of the factory has been analyzed based on the actual data measured. The thermal performances of the two boilers (steam generators) are analyzed using an indirect method (i.e., calculating the different losses) and the typical boiler efficiency obtained are 81% and 80% for boiler #1 and #2 respectively. It is found that the major heat loss from the boilers is due to the dry exhaust gas. Similarly, water chiller, air compressor, electrical motors, pumps and lighting system equipment energy utilization have been analyzed. The various energy saving measures are analyzed and it is found that the industry can save 2,301 GJ/year of electrical energy by using high efficient motors instead of the existing normal standard motors, 782.6 GJ/year of heat energy can be recovered from the dry exhaust gas by using air preheater and 1,221 GJ/year of heat energy can be recovered by controlling the air to fuel ratio which is a significant energy saving potential. Finally this study reveals that the total possible annual bill saving potential of the factory is 1,676,871 ETB.
NZEBs concept has received incrementing attention especially since European Union Parliament are progressively moving towards regulation in which all new buildings to be “nearly Zero-Energy” Buildings by 2020. Even though this concept delivers promising benefits, previous studies found that the benefit of NZEB is still in vague to the Malaysian construction industry, mostly for healthcare buildings. The NZEBs concept implementation is critical in healthcare building as it seen as a key part of the needed transition towards sustainable development. This paper aims to define benefits of NZEBs practices through initial investigation among architects. Several existing energies works of literature and pilot studies by using semi-structured interviews were conducted. The findings divulge that, although the term ‘NZEBs design strategies’ is not being used largely across construction industry in Malaysia, some sustainable practices related to the design stage of construction has been implemented. The findings are also promising in growing awareness, practices and implementation of NZEBs design strategies by the practitioner in Malaysia. It is foreseen that the paper will provide a straightforward knowledge for future research in NZEBs design strategies practices for healthcare buildings construction in Malaysia.
A low cost methodology of chiller analysis and forecasting was developed to compete with Climacheck, currently the most used equipment on the market. This methodology comprises two types of analysis, internal and external. The internal method analyzes the several chiller elements and evaluates their behavior. The external analysis predicts the equipment’s behavior for different load levels and climatic conditions through a previous selected model.
In order to assess this new methodology, the obtained results are compared with the ones from Climacheck. First, they are applied to a laboratory case and later to two field cases.
With the proposed methodology, it is possible to obtain efficiency values and internal parameters of the refrigeration cycle quite accurately, making it possible to do a system diagnosis.
Intending to contribute to the discourse about industrial energy efficiency and barriers to its improvement, deep insight into the scope and methodology and achievements of an energy audit on a Catalytic Naphtha Reforming Unit are provided. The audit of this particular unit was a part of the audit of the whole SLOVNAFT refinery in 2010–2012. The audit itself is the preparation of saving proposals’ implementation and post-implementation monitoring and targeting that lasted until spring 2016 covered in retrospective as the auditors were involved in all post-auditing phases as well. Several saving ideas emerging from the performed audit were rejected or have still not been implemented due to either technical issues or non-technical factors. Implemented proposals included improvement in the condensates’ management system, boiler feedwater preparation, and increased exploitation of the cogeneration potential. A cumulative 3-year benefit of over 600 k€ is reported which is close to the targeted value. The post-audit cooperation of auditors with the refinery’s staff enabled to define the non-technical barriers to saving proposals’ adoption that are of general nature. These included (1) short payback period requirement, (2) possibility of implementation of changes during the turnaround/general revisions, (3) conflicting relationships between local micro-economies of production units and the net-economy of the whole refinery, (4) internal processes and communication, and (5) personnel policy. Long-term cooperation, winning the trust and support of the staff and managers, and regular monitoring and targeting of implemented measures are seen as essential parts of sustainable industrial energy efficiency improvement in any industrial energy auditing.
In the air-cooled chiller system, sensor fault diagnosis has great significance for ensuring normal operation. However, according to the operating mechanism of the chiller system, sensors’ readings exhibit dynamical data-temporal dependencies and are easily affected by external factors and control parameters. To further capture the data characteristics existed in the sensors time series, in this paper, we propose a novel data-temporal attention network (DAN) for the chiller sensor fault diagnosis. Based on the conventional encoder-decoder network (EDN), the proposed DAN model is firstly built by adding three novel parts: the first one is a data attention mechanism embedded in the encoder, which is used to capture the dynamic data correlation between different sensors; the second part is a temporal attention mechanism, which is employed in the decoder to model the dynamic time-dependencies among the sensors time series; considering the influence of external factors and control parameters, the third part is a fusion module to incorporate these influential factors from different domains. Thereafter, we design a specific chiller sensor fault diagnosis strategy using the proposed DAN model. The sensor fault diagnosis strategy uses only normal sequences for training and learns to reconstruct normal time series behaviors, and then determines the fault threshold of each chiller sensor, and finally identifies the specific sensor fault by comparing the absolute reconstruction error vector with the fault threshold vector. In the end, the experiments which adopt data sets from a real air-cooled chiller platform are conducted, and detailed comparisons are made. Various magnitudes of fixed biases are introduced into eleven sensors for validation. Experimental results reveal that the sensor fault diagnosis strategy with the proposed DAN model achieves the best training and fault diagnosis performance compared with its variants and the traditional EDN model. Especially for the sensor fault diagnosis performance, comparison results demonstrate that the proposed DAN model is more sensitive to the small biases than the other contrast models and has better robustness for impacts on fault sensor in the reconstruction of the fault-free sensors.
The sustainability of the mining industry is contingent on the industry's ability to improve upon the status quo of operational efficiency. The advancement of energy efficient technologies coupled with modern strategies have resulted in large industrial energy efficiency improvements, lowering emissions and wastage. Mine ventilation fans in South Africa were identified as large energy consumers with potential for efficiency improvements, with the installation of medium voltage variable speed drive technologies. An extensive energy audit was conducted on ten mine ventilation networks to calculate the feasibility inter alia cost savings, energy savings and greenhouse gas emission reductions under varying airflow conditions. Two ventilation-on-demand applications were considered namely, constant speed reduction- and dynamic applications. The financial indicators revealed it is economically viable for the implementation of medium voltage variable speed drives as part of the ventilation-on-demand applications. The energy audit revealed that a total annual electrical energy saving of 179 421 MWh could be achieved with the implementation of the ventilation-on-demand applications. The resulting cost saving is estimated at US$11.57-million with an average payback period of 9 months. The average greenhouse gas emission reduction is calculated as 53% per annum. The feasibility of installing medium voltage variable speed drives on South African mine ventilation fans as part of ventilation-on-demand applications to improve efficiency and lower emissions was proven. The results emphasise the importance of such audits to illustrate the underutilised resources available to increase mine sustainability and subsequently profitability.
Intensive use of heating, ventilation and air conditioning (HVAC) systems in buildings entails an analysis and monitoring of their efficiency. Cooling systems are key facilities in large buildings, and particularly critical in hospitals, where chilled water production is needed as an auxiliary resource for a large number of devices. A chiller plant is often composed of several HVAC units running at the same time, being impossible to assess the individual cooling production and efficiency, since a sensor is seldom installed due to the high cost. We propose a virtual sensor that provides an estimation of the cooling production, based on a deep learning architecture that features a 2D CNN (Convolutional Neural Network) to capture relevant features on two-way matrix arrangements of chiller data involving thermodynamic variables and the refrigeration circuits of the chiller unit. Our approach has been tested on an air-cooled chiller in the chiller plant at a hospital, and compared to other state-of-the-art methods using 10-fold cross-validation. Our results report the lowest errors among the tested methods and include a comparison of the true and estimated cooling production and efficiency for a period of several days.
On site application of the fault diagnosis (FD) techniques is beneficial to reduce energy use and to extend life of the equipment. Considering the following aspects, a practical chiller FD method is proposed by introducing discretization to Bayesian network (BN) in this study. Firstly, most real-world domains involve continuous variables which are not easy to handle, and the gaussian hypothesis is not always realistic. Secondly, BN is easier to be dealt with discrete variables, but the traditional discrete FD method based on chiller experts is time-consuming and inefficient. The proposed method makes no assumptions concerning the distribution of the input features, and can quickly determine the parameters of BN without experts, thus it is more efficient and has strong robustness in practical applications of FD. Using the experimental data from ASHRAE RP-1043 to evaluate the proposed method, the results show that the proposed method is very effective for chiller FD.
Various types of faults occur in building energy systems throughout their life-cycles. Some faults grow gradually causing system energy penalty and performance degradation. Hence, it is crucial to implement an efficient fault diagnosis strategy and maintain optimal operations for systems. Recently, data-driven methods have got increasing interests due to the model flexibility and data availability. The fast development of data science has provided advanced data analytics to tackle data classification problems in a more convenient and efficient way. This paper attempts to investigate the potential of a promising data analysis technique, i.e., deep neural network, in classifying and diagnosing faults in a building energy system, i.e., centrifugal chiller plant. This study exploits the deep neural network based method in both supervised and unsupervised manners, and compares the fault diagnosis accuracy. Centrifugal chiller experimental data from the ASHRAE Research Project 1043(RP-1043) are used to validate the proposed method. Results show that the method can correctly diagnoses the fault data for seven typical chiller faults.
As China’s rapid urbanization continues and urban dwellers become more affluent, energy use in buildings is expected to grow. To understand how this growth can be slowed, we explore four scenarios for Chinese buildings, ranging from a high-energy-demand scenario with no new energy policies to lowest energy demand under a techno-economic-potential scenario that assumes full deployment of cost-effective efficient and renewable technologies by 2050. We show that, in the high energy demand scenario, building energy demand has an average annual growth rate of about 2.8%, with slower growth rates in the other three scenarios. In all scenarios, CO2 emissions grow slower than energy, with building CO2 peaking around 2045 in the high energy demand scenario, and as early as 2030 in the techno-economic-potential scenario. We show that although various technological solutions, systems and practices can be very effective in minimizing building energy use, rigorous policies are needed to overcome multiple implementation barriers. © 2018, The Author(s), under exclusive licence to Springer Nature Limited.
The appropriate application of advanced control strategies in Heating, Ventilation, and Air-conditioning (HVAC) systems is key to improving the energy efficiency of buildings. Significant advances have been made in the past decades on model development to provide better control over the energy consumption of system components while simultaneously ensuring a satisfactory indoor environment in terms of thermal comfort and indoor air quality. Yet it is an ongoing challenge to select and implement the best-suited modeling technique for improving the control strategy of HVAC systems. For the development of modeling research it is important that the building research community is informed about the role, application, merits, shortcomings and outcomes of different modeling techniques used in HVAC systems. Even though several review articles have been published on modeling techniques, the weaknesses and strengths of these modeling techniques, along with performances of developed models associated with research studies, have rarely been identified. This study presents a critical review of current modeling techniques used in HVAC systems regarding their applicability and ease of acceptance in practice and summarizes the strengths, weaknesses, applications and performance of these modeling techniques. Additionally, the performance and outcome of some of the developed models used in real world HVAC systems have been discussed. From the extensive critical review it is evident that almost every model has a major/minor shortcoming generated from assumptions, unmeasured disturbances or uncertainties in some system properties. This review aims at highlighting the shortcomings of existing application-based research on HVAC systems, and accordingly, recommendations are presented to improve the performance of building HVAC systems.
Due to constant toughening of requirements to technical and economic indicators of transport refrigeration units, the condensers cooling method influence of the refrigerating machines on their characteristics is considered. Refrigeration units of marine vessels are operated in a wide temperature range of the cooling air and water. To assess the degree and scope of a water and air cooling in this temperature range, as well as the use of natural circulation schemes of refrigeration units, numerical analysis was carried out by known methods of calculation. The results of the calculation determined the most appropriate application spheres of one or the other refrigeration unit scheme, and also the need for additional research in the condensation node combined cooling sphere was identified, because such a scheme is able to combine the water cooling, air cooling and refrigeration unit cycle with natural refrigerant circulation advantages.
The industrial sector is the largest user of energy in Malaysia. Industrial motors account for a major segment of total industrial energy use. Since motors are the principle energy users, different energy savings strategies have been applied to reduce their energy consumption and associated emissions released into the atmosphere. These strategies include using highly efficient motors, variable speed drive (VSD), and capacitor banks to improve the power factor. It has been estimated that there can be a total energy savings of 1765, 2703 and 3605 MWh by utilizing energy-efficient motors for 50%, 75% and 100% loads, respectively. It was also found that for different motor loads, an estimated US230,693 can be saved in anticipated energy costs. Similarly, it is hypothesized that a significant amount of energy can be saved using VSD and capacitor banks to reduce speed and improve the power factor, thus cutting energy costs. Moreover, a substantial reduction in the amount of emissions can be effected together with the associated energy savings for different energy savings strategies. In addition, the payback period for different energy savings strategies has been found to be reasonable in some cases.
Cited By (since 1996): 12, Export Date: 28 April 2012, Source: Scopus
A comparison was conducted between ON–OFF and variable frequency drive (VFD) systems to control ventilation fans of greenhouses and poultry houses. The study aimed to determine the effect of each system on the energy consumption and resulting microclimate within the houses. The experiments were carried out in a commercial-size greenhouse in which pepper was grown and in commercial poultry houses. Reducing the fan speed with the VFD system resulted in reductions in the airflow rate through the houses and energy consumption, the latter being much more significant. The study showed that VFD control can reduce electricity consumption compared with ON–OFF operation. In the present study, the average energy consumption with the VFD control system was about 0.64 and 0.75 of that with an ON–OFF system in the greenhouse and poultry houses, respectively. The average greenhouse daily air temperatures and humidity ratios obtained with each control system between 07:00 and 18:00 were nearly equal. The results obtained in the greenhouse further showed that the VFD system has a greater potential than the ON–OFF, to reduce the range of amplitude variations in the air temperature and humidity ratio within the greenhouse. The average air temperatures over day and night, in the poultry houses, with each control system were nearly equal. The relative humidity, however, was slightly lower with VFD than with ON–OFF. Reductions in the range of amplitude variations of the air temperature and humidity were also observed in the poultry houses.
The industrial sector is the largest user of energy in Malaysia. Industrial motors account for a major segment of total industrial energy use. Since motors are the principle energy users, different energy savings strategies have been applied to reduce their energy consumption and associated emissions released into the atmosphere. These strategies include using highly efficient motors, variable speed drive (VSD), and capacitor banks to improve the power factor. It has been estimated that there can be a total energy savings of 1765, 2703 and 3605 MWh by utilizing energy-efficient motors for 50%, 75% and 100% loads, respectively. It was also found that for different motor loads, an estimated US173,019 and US$230,693 can be saved in anticipated energy costs. Similarly, it is hypothesized that a significant amount of energy can be saved using VSD and capacitor banks to reduce speed and improve the power factor, thus cutting energy costs. Moreover, a substantial reduction in the amount of emissions can be effected together with the associated energy savings for different energy savings strategies. In addition, the payback period for different energy savings strategies has been found to be reasonable in some cases.
Controls logic and design conditions can be used to optimize chiller, cooling tower and condenser pump system performance. A system model of hour-by-hour energy use for a typical office building in three cities demonstrates the effect of different cooling seasons and wet-bulb profiles. The model is based on a 160,000 ft2, eight-story office building with variable air volume (VAV) HVAC system that includes two centrifugal chillers in a variable primary flow configuration. It uses induced draft-type cooling towers and constant flow condenser pumps that are dedicated to each chiller.
ABB's Jukka Tolvanen, energy efficiency market manager, introduces life cycle cost (LCC) analysis and shows how efficient motors and AC drives can often be used to minimize lifetime costs, especially in high usage pump and fan systems.
Air-cooled centrifugal chillers are commonly used in commercial buildings but their performance analysis is lacking. This paper investigates the part load performance of the chillers via a thermodynamic model. The model was validated using a wide range of operating data from an existing chiller with specific settings of outdoor temperature and condensing pressure in controlling the condensing temperature. The validated model was developed specifically to ascertain the maximum coefficient of performance of chiller (COP) together with the strategy for optimizing the condensing temperature under various operating conditions. It is found that the highest COP occurs at a part load ratio (PLR) of 0.71–0.84, depending on the outdoor temperature and the control of condensing temperature, rather than at full load. Yet the chillers operating at such part load conditions will cause extra energy used for the early staging of chilled water pumps. To minimize the overall chiller plant energy consumption, it is still preferable to implement chiller sequencing based on the full load condition than on the aforementioned PLRs. The results of this paper present criteria for implementing low-energy strategies for operating air-cooled chillers satisfying a given building cooling load profile.
Corrosion behavior of TP316L was investigated with simulated atmosphere and ash deposition for the superheater in biomass boiler. Corrosion dynamic curves were plotted by mass gain. The results showed that the corrosion was dependent on temperature and was greatly accelerated by ash deposition. The mass gain was distinctly reduced in the presence of SO2 with and without ash deposition on the specimens. Corrosion rates with ash deposit at different temperatures were calculated. Two feasible methods were provided to avoid serious high-temperature corrosion in the biomass boiler.
Using a variable speed drive is one of the most effective ways to save energy, argues ABB's Jukka Tolvanen. While other energy-saving methods may shave singular percentage points off the overall consumption, a variable speed drive frequently can save 50% or more of the energy in applications that use pumps and fans.
This paper considers how to apply optimum condensing temperature control and variable chilled water flow to increase the coefficient of performance (COP) of air cooled centrifugal chillers. A thermodynamic model for the chillers was developed and validated using a wide range of operating data and specifications. The model considers real process phenomena, including capacity control by the inlet guide vanes of the compressor and an algorithm to determine the number and speed of condenser fans staged based on a set point of condensing temperature. Based on the validated model, it was found that optimizing the control of condensing temperature and varying the evaporator’s chilled water flow rate enable the COP to increase by 0.8–191.7%, depending on the load and ambient conditions. A cooling load profile of an office building in a subtropical climate was considered to assess the potential electricity savings resulting from the increased chiller COP and optimum staging of chillers and pumps. There is 16.3–21.0% reduction in the annual electricity consumption of the building’s chiller plant. The results of this paper provide useful information on how to implement a low energy chiller plant.
This book presents an overview on energy management. Chapters include energy management systems; energy audits; economic evaluation; energy bills; lighting; HVAC systems; industrial wastes; steam generation; control systems; maintenance; insulation; process energy management; and renewable resources and water management. Individual chapters were processed separately for the databases.
The industrial sector is the largest users of energy around the world. Industrial motor uses a major fraction of total industrial energy uses. This paper describes a comprehensive literature review about electric motor energy analysis. This paper compiles latest literatures in terms of thesis (MS and PhD), journal articles, conference proceedings, web materials, reports, books, handbooks on electrical motor energy use, losses, efficiency, energy savings strategies. Different types of losses that occur in a motor have been identified and ways to overcome these losses explained. An energy audit that helps to identify motor energy wastages have been discussed extensively. As motors are the major energy users, different energy savings strategies such as use of high-efficient motor, variable speed drive (VSD), and capacitor bank to improve the power factor to reduce their energy uses have reviewed. Different policy measures (i.e. regulatory, voluntary and incentives based) to save motor energy use have been reviewed and presented in this paper. In this review, computer tools that can be used to analyze electric motors energy used has been discussed. Cost parameters to carry out economic analysis have been shown as well. Moreover, payback period for different energy savings strategies have been identified.
Compressed-air systems account for about 10% of total industrial-energy use for few selected countries as found in literatures. Compressed air is typically one of the most expensive utilities in an industrial facility. This paper describes a comprehensive literature review about compressed air energy use, savings, and payback period of energy efficient strategies. This paper compiles latest literatures in terms of thesis (MS and PhD), journal articles, conference proceedings, web materials, reports, books, handbooks on compressed air energy use, efficiency, energy savings strategies. Computer tools for compressed air analysis have been reviewed and presented in this paper. Various energy-saving measures, such as use of highly efficient motors, VSD, leak prevention, use of outside intake air, reducing pressure drop, recovering waste heat, use of efficient nozzle, and use of variable displacement compressor to save compressed-air energy have been reviewed. Based on review results, it has been found that for an electric motor used in a compressed-air system, a sizeable amount of electric energy and utility bill can be saved using high efficient motors and applying VSDs in matching speed requirements. Also, significant amounts of energy and emission are reducible through various energy-saving strategies. Payback periods for different energy savings measures have been identified and found to be economically viable in most cases.
Electric motors consume 30-80% of total industrial energy around the world. This study estimates the economic viability of replacing rewound and standard motors with high efficiency motors (HEMs) in the industrial sector. The efficiency of a motor is degraded when it is rewound and it is better to rewind a larger motor compared with a smaller motor. It was found that a HEM can save on average 5.5% of energy compared with a standard motor. In addition, the payback period was found to be reasonable when a motor is operated at a 50% load. HEMs will also save a sizeable amount of energy and reduce emissions. It was estimated that 67,868 MWh/year energy and US$ 4,343,531 per year could be saved by introducing HEMs. By contrast, 44,582 tons of CO2, 333 tons of SO2 and 122 tons of NOx emissions could be reduced through the aforementioned energy savings. This study found that rewound motors of a larger size and HEMs are economically viable.
Chillers consume a major share of total air conditioning energy use in commercial and industrial buildings for space conditioning to get thermal comfort for a country. Experiences from other countries show that government intervention in the form of regulations such as mandatory and voluntary approaches can save huge amount of energy along with the reduction of emissions associated with energy have been quantified and presented. Emission reductions associated with the energy savings has been estimated and presented as well. Study also estimated the amount of avoided emissions along with the cost of avoided carbon. From the data analysis, it has been observed that energy efficient chillers can save huge amount of energy and utility bills. Based on review of international test standards, it has been found that ARI550/590 can be used for testing and rating of chillers energy performance. However, energy guide label is not suitable for information dissemination for chillers. Study estimated that 1688 MWh of energy and US$108,040 bill can be saved for using energy efficient chillers.
In this paper, ''energy efficiency" studies, done in a big industrial facility's pumps, are reported. For this purpose; the flow rate, pres-sure and temperature have been measured for each pump in different operating conditions and at maximum load. In addition, the elec-trical power drawn by the electric motor has been measured. The efficiencies of the existing pumps and electric motor have been calculated by using the measured data. Potential energy saving opportunities have been studied by taking into account the results of the calculations for each pump and elec-tric motor. As a conclusion, improvements should be made each system. The required investment costs for these improvements have been determined, and simple payback periods have been calculated. The main energy saving opportunities result from: replacements of the existing low efficiency pumps, maintenance of the pumps whose efficiencies start to decline at certain range, replacements of high power electric motors with electric motors that have suitable power, usage of high efficiency electric motors and elimination of cavitation problems.
Compressed-air systems account for about 10% of total industrial-energy use for few selected countries as found in literatures. Compressed air is typically one of the most expensive utilities in an industrial facility. This paper describes a comprehensive literature review about compressed air energy use, savings, and payback period of energy efficient strategies. This paper compiles latest literatures in terms of thesis (MS and PhD), journal articles, conference proceedings, web materials, reports, books, handbooks on compressed air energy use, efficiency, energy savings strategies. Computer tools for compressed air analysis have been reviewed and presented in this paper. Various energy-saving measures, such as use of highly efficient motors, VSD, leak prevention, use of outside intake air, reducing pressure drop, recovering waste heat, use of efficient nozzle, and use of variable displacement compressor to save compressed-air energy have been reviewed. Based on review results, it has been found that for an electric motor used in a compressed-air system, a sizeable amount of electric energy and utility bill can be saved using high efficient motors and applying VSDs in matching speed requirements. Also, significant amounts of energy and emission are reducible through various energy-saving strategies. Payback periods for different energy savings measures have been identified and found to be economically viable in most cases.
Cited By (since 1996): 1, Export Date: 28 April 2012, Source: Scopus
The commercial sector consumes 8–50% of the total energy consumption for a few selected countries around the world. An energy audit was conducted in a Malaysian public hospital to identify energy using equipment and their energy consumption breakdown. Different energy saving measures have been identified and applied for electrical motors used in this hospital. It was estimated that this hospital consumed about 19,311 MW h for the year 2008. It was also estimated that about 212 MW h, 250 MW h and 317 MW h of annual energy can be saved using energy-efficient motors at 50%, 75% and 100% loads, respectively. In addition, use of variable speed drives are expected to save 1735 MW h, 4048 MW h and 6361 MW h of annual energy consumption for 20%, 40% and 60% speed reductions, respectively. It was found that the payback period for using high efficiency motors at different loads is less than a year which is economically very viable. However, the use of variable speed drives was found to be economically viable for larger motors for higher speed reductions. The study also found that a sizeable amount of emissions can be reduced for the different energy savings measures applied for electrical motors.
There are increasing views on implementing all-variable speed chiller plants in place of conventional constant speed plants. Supporters of these views claim that all-variable speed chiller systems can operate much more efficiently at part load in response to changes in building cooling load. This paper introduces load-based speed control for all-variable speed plants to optimize their environmental performance. Thermodynamic-behaviour chiller system models were developed to perform environmental assessment (in terms of annual electricity and water consumption) for typical constant speed and all-variable speed chiller systems operating for the cooling load profile of a local office building. Operating cost differences between the two systems were calculated and compared in an economic analysis. Applying load-based speed control to the variable speed chiller plant can decrease the annual total electricity use by 19.7% and annual water use by 15.9% relative to the corresponding constant speed plant. The significance of this study is to provide more insights into how to make chiller systems more sustainable.
This paper presents a review of the application of variable-speed capacity control to refrigeration systems. The aim is to put together diversified information in a single source and to appraise recent advances in variable-speed technology. The review reveals that although variable-speed drives based on inverters have been applied successfully to control the capacity of rotodynamic machines, such as pumps and fans, their application to positive displacement machines, such as compressors, has so far been restricted to small-capacity air-conditioning units. There has been only a very small uptake of the technology in the medium-range capacity units, due to a number of problems, such as insufficient development and integration of components, poor reliability, high capital cost and the failure of demonstration installations to produce the expected energy savings. Although inverter-based variablespeed compressor technology offers the potential for energy savings, considerable research work is still required for the development of optimised and cost-effective systems.
This paper presents the results of investigations into the performance of positive-displacement refrigeration compressors for variable-speed capacity control applications. Compressors tested include an open-type reciprocating, a semi-hermetic reciprocating and an open-type rotary vane. All three compressors were tested under constant and variable head-pressure operating conditions. The results indicate that all three compressors were designed for maximum efficiency at nominal speed. At constant head-pressure only the open-type compressor exhibited an improvement in the COP at reduced speeds. With variable head pressure-control all three compressors showed an increase in the COP with a reduction in speed. The results of an energy analysis carried out based on the experimental results and weather conditions for two locations representing temperate and warm weather conditions showed that all three compressors when operated at variable speed offer energy savings compared to their fixed-speed counterparts. The analysis has shown the open-type reciprocating compressor to be the most efficient system offering 12% savings when operating in a temperate climate and 24% savings when operating in a warm climate.
Emissions in the process utilization produce adverse effects on the environment that influence human health, organism growth, climatic changes and so on. The Kyoto protocol, produced by the United Nations Framework Convention on Climate change (UNFCC) in December 1997, prescribed a legally binding greenhouse gas emission target about 5% below their 1990 level. About 160 countries including Malaysia now adopt this protocol. Electricity generation is one of the main contributors to emissions in the country. In order to calculate the potential emissions produced by this activity, the type of fuel use should be identified. Malaysia hopes to gradually change fuel use from 70% gas, 15% coal, 10% hydro, and 5% petroleum in the year 2000 to 40% gas, 30% hydro, 29% coal, and only 1% petroleum by the year 2020. The changes in fuel type have changed the pattern of emission production. This study attempts to predict the pattern of emissions from 2002 to 2020 due to the changes in fuel use. The calculation is based on emissions for unit electricity generated and the percentages of fuel use for electricity generation. The study found that the electricity generation company has produced huge emissions from their power plants in this country.
The commercial sector consumes 8e50% of the total energy consumption for a few selected countries
around the world. An energy audit was conducted in a Malaysian public hospital to identify energy using
equipment and their energy consumption breakdown. Different energy saving measures have been
identified and applied for electrical motors used in this hospital. It was estimated that this hospital
consumed about 19,311 MW h for the year 2008. It was also estimated that about 212 MW h, 250 MW h
and 317 MW h of annual energy can be saved using energy-efficient motors at 50%, 75% and 100% loads,
respectively. In addition, use of variable speed drives are expected to save 1735 MW h, 4048 MW h and
6361 MW h of annual energy consumption for 20%, 40% and 60% speed reductions, respectively. It was
found that the payback period for using high efficiency motors at different loads is less than a year which
is economically very viable. However, the use of variable speed drives was found to be economically
viable for larger motors for higher speed reductions. The study also found that a sizeable amount of
emissions can be reduced for the different energy savings measures applied for electrical motors.
This paper is concerned with the estimation of energy use in office buildings in Malaysia and with the energy use of major equipment. Energy intensity (EI) - a measure of a building's energy performance - is estimated for Malaysia and compared with a number of selected countries. Air conditioners are shown to be the major energy users (57%) in office buildings, followed by lighting (19%), lifts and pumps (18%) and other equipment (6%). It is estimated that 77,569Â MWh of energy can be saved and a huge reduction of emissions achieved through the application of advance glazing, compact fluorescent lamps (CFL), insulation, housekeeping, and by raising thermostat set point temperature of air conditioners, and reducing EI. It is also estimated that a very substantial amount of energy can be saved by making use of energy-efficient motors in building systems with different motor loading percentages. Finally, it can be shown that the use of variable speed drives (VSDs) and energy-efficient motors leads to substantial energy savings and an enormous reduction in emissions.
Under the supervision of Professor John Mitchell; 189pp. The objective of the work is to develop methods for minimizing the energy costs of chilled water systems through optimal control. The general approach includes the following tasks: 1) proposing a system of parametric models that represent the real chilled water system, 2) determining model parameters from measured data, and 3) subjecting the system of parametric models to an optimization algorithm. A comprehensive approach for determining the optimal control for any general chilled water system is developed. The general system presents a difficult problem for parameter estimation and optimization because of discontinuous variables and nonlinear relationships between input and output variables. Various methods for parametric estimation and control optimization are pre- sented and demonstrated on simulated and actual plant models. The actual plant model consists of interconnected component models, including an electric motor driven chiller, a steam turbine driven chiller and associated steam condenser, and a multi- cell cooling tower. Different parameter estimation methods using measured plant data are applied and compared. Optimal supervisory control is determined through application of the simulated annealing method to the model. The dependence of optimal control settings upon independent variables (e.g. chilled water return temperature and ambient wet bulb temperature) is investi- gated. Cost savings of optimal over conventional control strategies are calculated and compared.
Energy effficiency building systems: green strategies for operation and maintenance
- L Jayamaha
Jayamaha L. Energy effficiency building systems: green strategies for operation and maintenance. 7th ed. McGraw-Hill; 2007.
Power quality and cost analysis of industrial electrical distribution systems with adjustable speed drives
- L Abbott
Abbott, L., Power quality and cost analysis of industrial electrical distribution
systems with adjustable speed drives, MS thesis, California State University,
USA. 2006.
Energy efficient heating, in energy management and conservation. Oxford: Butterworth-Heinemann
- Dc Beggs
Beggs DC. Energy efficient heating, in energy management and conservation.
Oxford: Butterworth-Heinemann; 2002. pp. 117e147.