Article

Use of condensate drain to precool the inlet air to the condensers: A technique to improve the performance of split air-conditioning units

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Abstract

In hot ambient conditions, split air-conditioning (AC) systems experience a drop in their coefficient of performance and an increase in power consumption due to the direct relationship between the condensation temperature of the unit and the prevailing ambient temperature. In this work, the enhancement in the COP and the reduction in power consumption for a split AC unit are evaluated when a direct water spray evaporative cooling system is used. The study focuses on minimizing the amount of water needed to cool the condenser by utilizing the wasted water from the condensate drain, synchronizing the water injection with ON–OFF compressor operation, and determining the optimal hourly periods for the injection system to achieve a reduction in energy consumption. The objectives of this work are threefold. The first objective is to conduct experiments inside an environmental chamber to determine the effectiveness of the evaporative cooling system at different ambient conditions and to derive correlations that predict the outlet air conditions and the water consumption. The second objective is to develop an integrated mathematical model to simulate the performance of the evaporatively cooled split AC system in a controlled space under certain operational conditions (using steady-state performance data supplied by the manufacturer and taking into account the transient effect during the ON–OFF compressor cycling) and to experimentally validate this model. The third and final objective is to evaluate the model under “real environment conditions” for a case study where the thermal conditions and energy demand of a typical office space in Beirut during three months (June, August, and October) are investigated and where the “sufficiency” of drain water is the limiting factor. The simulation results have shown that the drain water would be sufficient in October only, resulting in 5.3% energy saving throughout the whole day. On the other hand, the synchronized spray of water is found to last for six operating hours in a June day and eight hours in August; this results in a total daily reduction in the consumed energy of 5% in June and 4.5% in August.

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... Sumeru et al. [9] classified 4 methods under the sub-cooling method, as in Figure 2. There are a few numbers of studies that investigate the use of waste condensate water to improve the performance of air conditioning (AC) system [10][11][12]. Sawant et al. [10] utilized an evaporative cooling method using waste condensate water to decrease the air temperature that enters the condenser of a residential air conditioner. ...
... Their results showed a decrease in energy consumption of up to 10%. Sawant et al. [11] conducted an experimental study on the effect of evaporative cooling for condenser air inlet temperature of a split air conditioner in Beirut. They concluded that their method decreased energy consumption by 5% and 4.5% in June and August, respectively. ...
... The decrease in these temperatures helps the condenser in removing heat to the ambient air in a more efficient way. Consequently, the system generates better sub-cooling effects, which lead to an increase in cooling capacity and improved in performance of the system [10][11]14]. ...
Article
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This paper experimentally investigates the effect of condensate water on the performance of automotive air conditioning (AAC) system under difference evaporator air inlet temperature. An experimental test rig was fabricated using the actual component of AAC system used for Proton Wira passenger car. During experimental work, the volume flow rate of condensate water was manipulated at 0, 140 and 340 ml/min. The evaporator air inlet temperature was also varied at 28, 32 and 36°C. The other parameters of compressor speed, condensate water temperature and condenser air inlet temperature were kept constant at 1550 rpm, 29 ± 1°C and 32 ± 1°C, respectively. The study showed that the coefficient of performance (COP) of the AAC system increases when the volume flow rate of condensate water increased from 0 to 140 ml/min. It was due to a dominant decrease in compressor work, as compared to the drop in cooling capacity. In addition, the highest increment in COP occurred at evaporator air inlet temperature of 36°C (9.8%), followed by evaporator air inlet temperature of 28°C (2.8%) and 32°C (0.4%). The highest COP is 3.66, occurred at evaporator air inlet temperature of 32°C and volume flow rate of condensate water of around 140 ml/min.
... At the time of writing of paper, the authors have not found references that discuss the use of condensate water as a compressor discharge cooler. Some topics that discussed the utilization of [11], Sawant et al. [12], Britto and Vasanthanathan [13], Sawan et al. [14], Tissot et al. [15] and Ibrahim et al. [16]. ...
... Sawan et al. [14] employed evaporative cooling using condensate water as media for absorbing heat from the air before entering the condenser on a split-type A/C in Beirut. The results showed that the power consumption reduction on June and August are slightly difference, that is 5% and 4.5%, respectively. ...
... They reported that for hot and dry weather conditions, that is RH = 19.7% and T = 35 o C, the COP of a heat pump system increased by 28.9%. Similar to the Sawan et al. [14], Ibrahim et al. [16] performed an experimental investigation on a split-type A/C with cooling capacity of 1.5 ton refrigeration. Based on their experiment, the air temperature before entering the condenser reduced by 4 o C. The decrease in air temperature resulted in the decrease in discharge pressure. ...
Article
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In residential sector, air conditioning (A/C) system contributes the largest power consumption. As a result, several methods have been developed to improve the system performance. Subcooling is a method to improve the performance of A/C by increasing the cooling capacity. Because R32 has much lower global warming potential (GWP) than that of R22 and R410A, this refrigerant is projected as a substitute of R22 and R410A. This study investigates the performance improvement of residential (A/C) using condensate water as a compressor discharge cooler to generate subcooling. In present study, the experiment was carried out on a split-type A/C using R32 as working fluid. During the experiment, the indoor and outdoor temperatures were controlled at 20°C and 33°C, respectively. The experimental results showed that the average decrease in refrigerant temperature at the condenser outlet was 4.5°C. The decrease in temperature at the condenser outlet indicated that the subcooling occurred on the system. The subcooling on the condenser outlet resulted in increase in cooling capacity by 12.1%. In addition, the use of condensate water as a compressor discharge cooler increased the COP by 21.7%.
... Therefore, it can be utilized to decrease the condenser air face temperature and compressor discharge temperature. The decrease in the condenser air face temperature and compressor discharge temperature can lead to the improved performance of the air conditioning system [29][30][31]. Figure 14 shows the direct effect of condensate water as a cooler that causes a decrease in the discharge temperature from point 2 to 2. It shows that the temperature of point 2 is lower than point 2, which resulting a significant reduction in the power consumption of the compressor. ...
... According to Eq. (30), to obtain optimum , the numerator (ℎ 1 − ℎ 4 ) must be as high as possible, whereas the denominator (ℎ 2 − ℎ 1 ) must be as low as possible. However, to increase the degree of the subcooling from point 3 to 3 for higher (ℎ 1 − ℎ 4 ), the point 1 tends to move on the left side of point 1 (decreasing ℎ). ...
... In short, a dominant decrease of point 2 from 2, as opposed to a decline of point 1 to 1, as well as a prominent decrease of point 3 from 3, rather than a decline in point 1 to 1, lead to the improvement of . The use of condensate water to lower condenser air face temperature for AC performance improvement has been investigated by several researchers [29][30][31][32]. In general, the authors agreed that the use of condensate assisted sub-cooling method provides huge advantage when the condensate water is abundant and water pump input power is relatively small as compared to compressor input power. ...
Article
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Vapor compression refrigeration cycle (VCRC) is widely used in refrigeration and air conditioning (R&A) systems. Sub-cooling is used to improve the coefficient of performance (COP) of the R&A system by enhancing the cooling capacity. This paper presents various sub-cooling methods, which have been established and applied to enhance the performance of the VCRC. In a simple cycle of VCRC, the exit of the condenser is at saturated liquid line. Further cooling of the exit condenser to the sub-cooled region can result in an increase in the cooling capacity due to low vapor quality refrigerant entering the evaporator. As a result, the refrigerant absorbs more heat in the evaporator. The lower the quality of the refrigerant entering the evaporator, the higher the cooling capacity that is produced by the evaporator. This cooling capacity improvement results in an increase in the COP. In the present study, four sub-cooling methods are reviewed, which are liquid-suction heat exchanger, dedicated mechanical sub-cooling, integrated mechanical sub-cooling and condensate assisted sub-cooling. The advantages and drawbacks of each method, as well as future research direction in this research domain were discussed in detail.
... Therefore, it can be utilized to decrease the condenser air face temperature and compressor discharge temperature. The decrease in the condenser air face temperature and compressor discharge temperature can lead to the improved performance of the air conditioning system [29][30][31]. Figure 14 shows the direct effect of condensate water as a cooler that causes a decrease in the discharge temperature from point 2 to 2. It shows that the temperature of point 2 is lower than point 2, which resulting a significant reduction in the power consumption of the compressor. ...
... According to Eq. (30), to obtain optimum , the numerator (ℎ 1 − ℎ 4 ) must be as high as possible, whereas the denominator (ℎ 2 − ℎ 1 ) must be as low as possible. However, to increase the degree of the subcooling from point 3 to 3 for higher (ℎ 1 − ℎ 4 ), the point 1 tends to move on the left side of point 1 (decreasing ℎ). ...
... In short, a dominant decrease of point 2 from 2, as opposed to a decline of point 1 to 1, as well as a prominent decrease of point 3 from 3, rather than a decline in point 1 to 1, lead to the improvement of . The use of condensate water to lower condenser air face temperature for AC performance improvement has been investigated by several researchers [29][30][31][32]. In general, the authors agreed that the use of condensate assisted sub-cooling method provides huge advantage when the condensate water is abundant and water pump input power is relatively small as compared to compressor input power. ...
Article
Full-text available
Vapor compression refrigeration cycle (VCRC) is widely used in refrigeration and air conditioning (R&A) systems. Sub-cooling is used to improve the coefficient of performance (COP) of the R&A system by enhancing the cooling capacity. This paper presents various sub-cooling methods, which have been established and applied to enhance the performance of the VCRC. In a simple cycle of VCRC, the exit of the condenser is at saturated liquid line. Further cooling of the exit condenser to the sub-cooled region can result in an increase in the cooling capacity due to low vapor quality refrigerant entering the evaporator. As a result, the refrigerant absorbs more heat in the evaporator. The lower the quality of the refrigerant entering the evaporator, the higher the cooling capacity that is produced by the evaporator. This cooling capacity improvement results in an increase in the COP. In the present study, four sub-cooling methods are reviewed, which are liquid-suction heat exchanger, dedicated mechanical sub-cooling, integrated mechanical sub-cooling and condensate assisted sub-cooling. The advantages and drawbacks of each method, as well as future research direction in this research domain were discussed in detail.
... The condensed water usually wets the building walls and adjacent ground surface if not handled properly, creating a good living environment for pathogens and other bacteria that are detrimental to human life. Investigations on the collection and utilization of the condensate for performance improvement of airconditioning systems as well as additional water source have been reported earlier by several authors (Al-Farayedhi et al. 2014;Habeebullah 2009;Mahvi et al. 2013;Sawan et al. 2012;Sawant et al. 2011). ...
... There are few experimental studies on the use of condensate to improve the performance of vapor compression systems. This includes the work of Sawan et al. (2012) where they used condensate in an evaporative cooler to pre-cool the air entering the condenser of a split air conditioner. They reported a 5.3% energy reduction in the month of October. ...
... In their studies Sawant et al. (2011) and Sawan et al. (2012) focused on pre-cooling the air entering the condensers by condensate for enhancing the performance of vapor compression systems. Based on the previous literature survey and to the best of the author's knowledge, no study had been conducted on utilizing condensate to pre-cool the air entering the evaporator. ...
Article
Full-text available
Air conditioning systems consume large amount of energy and generate considerable amount of condensate when operated in hot and humid climates. This study considers utilizing the generated condensate to pre-cool the air entering evaporators to improve systems performance. Experimental and analytical investigations are carried out by using an air-conditioning system of 4.75 kW (16207 BTU/h) cooling capacity incorporated with an air pre-cooler and a condensate tank that acts as a thermal storage. During the pre-cooling-on period, the air inlet temperature of the evaporator is decreased by 5.7°C (10.3°F) and the compressor power consumption is reduced by 5.1% because of the decrease in discharge pressure. The coefficient of performance increases by 30.7% and second law efficiency by 24.2%. The air pre-cooling is practical for 4–5 hours daily during the daytime if a 450–1000 kg of condensate cold thermal storage is employed. The deviation is 6.7% between the analytical and experimental results.
... The use of condensate water to lower air temperature before entering the condenser to improve the AC performance has been investigated by several researchers [12][13][14]. Sawant et al. [12] employed condensate water to lower the air temperature before entering to the condenser of a window air conditioner. ...
... Their results showed that the evaporative cooling using condensate water decreased power consumption of the AC up to 10%. Another experimental investigation about the use of condensate water on the evaporative cooling to lower the air temperature of condenser was carried out by Sawan et al. in Beirut [13]. The experiment to reduce power consumption was performed on a split type air conditioning unit on June and August and the results were 5% and 4,5%, respectively. ...
Article
Full-text available
The experimental investigation of subcooling effects on system COP was carried out on a residential air conditioning using R410A as working fluid, with a compressor capacity of about 0.75 kW. In the experiment, the indoor and outdoor temperatures were controlled at 24°C and 32°C. The results showed that the use of condensate water lowers the refrigerant temperature in the condenser outlet by 2.7°C. By lowering the refrigerant temperature, the cooling capacity of the air conditioning can be enhanced. The decrease in of refrigerant temperature results in COP improvement 16.4%. Besides increasing the COP, the condensate water also decreases the discharge compressor temperature by 7.6°C. The decrease in of the discharge compressor temperature resulted in the decrease in power consumption of the air conditioning system by 5.9%.
... There is limited number of studies on the use of condensate to improve the performance of air-cooled vapor compression systems. One of the related studies is the work of Sawan et al. [21], where they used condensate to precool air by evaporative cooler before entering the condenser of split-type air conditioner. The results show that the condensate would be sufficient for air pre-cooling during the month of October, resulting in 5.3% energy saving. ...
... Based on the above literature study, it is clear that the authors [21,22] focused on evaporative cooling using condensate to precool the air entering the condenser. In the present study, the authors considers dry cooling technique for air pre-cooling before entering the condenser of a vapor compression air conditioning system using condensate. ...
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Full-text available
Air conditioning systems contribute to the largest share of energy consumption in building sector. On the other hand, the systems produce reasonable amount of condensate, especially when operating in humid climates. The aim of this study is to minimize the energy consumption and improve the performance of air conditioning systems utilizing condensate. Experimental investigation has been carried out to improve the performance of an air-cooled vapor compression system by pre-cooling air entering the condenser using condensate. A pre-cooler is incorporated on a 1.5 ton-cooling capacity split-type air conditioning system to lower the air temperature entering the condenser sensibly. Performances of the air conditioning system with and without air pre-cooling are compared and reported in this paper. The results show that pre-cooling the air by about 4°C before entering the condenser lowers the compressor discharge pressure. The decrease in the discharge pressure resulted in the decrease in compressor power consumption by 6.1% and the cooling effect of the system is enhanced. The combined effect of the increase in the cooling effect and decrease in compressor power resulted in an increase in the coefficient of performance (COP) and second law efficiency of the system by about 21.4 and 20.5%, respectively.
... When humidity is increased other evaporative cooling configurations can be a viable solution. More configurations [149][150][151][152][153][154][155][156][157][158] and applications [159][160][161][162][163][164][165][166][167][168] are described in next sections and tabulated in Tables 4 and 5. ...
... Improved cpmfort by IEC versus DEC [163] Demo building Shihezi, China IEC 40% reduction in electricity. [164] Office Beirut, Lebanon DEC with split air conditioning system Total daily reduction in the consumed energy of 5% in June and 4.5% in August. [165] Office Sydney, Australia Hybrid evaporative cooling coupled with HVAC 52% power savings can be obtained by this system while maintaining the predicted mean vote (PMV) between −1 to +1 for most of summer time [166] Office Xinjiang, China radiant air conditioning based on evaporative cooling 43% energy savings [167] Residential US Retrofitting the air conditioning condenser with a media pad evaporative cooler. ...
Article
Passive cooling in the built environment is now reaching is phase of maturity. Passive cooling is achieved by the use of techniques for solar and heat control, heat amortization and heat dissipation. Modulation of heat gain deals with the thermal storage capacity of the building structure, while heat dissipation techniques deal with the potential for disposal of excess heat of the building to an environmental sink of lower temperature, like the ground, water, and ambient air or sky. The aim of the present paper is to underline and review the recent state of the art technologies for passive cooling dissipation techniques in the built environment and their contribution in the improvement of the indoor environmental quality as well as in the reduction of cooling needs. The paper starts with a short introduction in passive cooling and continues with the analysis of advanced heat dissipation techniques such as ground cooling, evaporative cooling, and night ventilation in the built environment. The various technologies are compared versus their contribution to energy efficiency and users’ comfort. Future trends and prospects are discussed.
... Whereas there was limited number of studies on the use of condensate to improve the performance of air-cooled vapor compression systems. R. Sawan and Al-Hindi (2012) used condensate water to pre-cool the inlet airflow to the condensers. The simulation results showed that the condensate water would be sufficient in October only, resulting in 5.3% energy saving throughout the whole day. ...
Article
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A method of using condensate water to reduce the airflow temperature around the air conditioner condenser and improve the performance of air conditioner is presented in this study. The structure of traditional split air conditioner is adjusted by changing the installation direction of fan and adding disk-type atomization cooling element (ACE) in the outdoor unit. The performance of the air conditioner under four modes is tested in different environment temperatures. Four modes were named, i.e. the original unit without ACE, original unit with ACE, blowing mode without condensate water and blowing mode with condensate water. The blowing mode with condensate water is used to pre-cool the incoming airflow, and the maximum temperature reduction at the air outlet surface of the condenser is up to 2.2 °C in 35 °C. With the environment temperature increasing, the refrigerating capacity of four modes decreased, and the power consumption increased, leading to the decrease of EER. However, owing to the cooling effect of condensate water, the performance of blowing mode with condensate water was greatly improved compared with the original unit without ACE. The variation rates of refrigerating capacity, power consumption and EER at environment temperature of 43 °C were 8.1%, -9.5% and 20%, respectively. The unit with condensate water could greatly improve the performance of air conditioning in high environment temperatures.
... It was estimated that using optimal mist control with condensing temperature control could achieve a 19.84% reduction in the annual electricity consumption of chillers operating for the office building. Sawan et al. [14] Experimental and Analytical Investigation Split air conditioner drain have been used to precool the inlet air to the condenser. ...
... Por otro lado, R. Sawan [15], utilizando condensado, obtiene en un aparato tipo Split ahorros de entre un 4,5 % y un 5,3% dependiendo del mes. ...
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El crecimiento sustancial en la industria de refrigeración y aire acondicionado tiene un impacto significativo en el consumo de energía. Existe una necesidad urgente de desarrollar tecnologías rentables y mejorar la eficiencia de los sistemas de enfriamiento. La presión del condensador es uno de los parámetros críticos en la operación eficiente de sistemas de refrigeración y aire acondicionado. El condensador enfriado por evaporación de agua ha sido una de las soluciones en la búsqueda del uso eficiente de millones de sistemas de refrigeración en todo el mundo. Los brotes de Legionella sp. han condicionado su uso y ha dado lugar al desarrollo de nuevos equipos. En esta revisión del estado del arte se analizarán diferentes sistemas de condensación, los diseños que los investigadores han presentado dirigidos a su utilización en equipos del sector comercial y residencial y, en último lugar, los estudios publicados sobre el uso del condensado para el enfriamiento.
... Sawan et al. [12] and Sawant et al. [13] used condensate to pre-cool air by evaporative cooling in split type and window type air conditioners respectively. The results reported by Sawan et al. (Sawan, Ghali, and Al-Hindi 2012) showed that a maximum power saving of 5.3% could be achieved within the month of October by using condensate water for evaporative cooling of the air conditioner's condenser unit. Similarly Sawant et al. (Sawant, Agrawal, and Nanda 2012) showed that condensate water from the cooling coil could be used to enhance the energy performance of a window type air conditioner by 13% in addition to raising the device's COP by 18%. ...
Conference Paper
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Shading is a technique used to reduce the cooling demand in buildings and save energy. This paper investigates the possibility of reducing the electrical demand and saving energy by shading the condensers of air-conditioning (A/C) equipment. A limiting analysis compares the performance of several A/C systems with ideal shade to those with ideal solar heat gain. The comparison is based on a theoretical model and data from equipment catalogs. The results show that the theoretical increase in the coefficient of performance (COP) due to shading is within 2.5%. Furthermore, this small improvement in ideal efficiency decreases at higher ambient temperatures, when enhancements to efficiency are more needed. A sensitivity analysis shows that the small COP enhancement is not significantly affected by assumed variables. The actual efficiency improvement due to shading is not expected to exceed 1%, and the daily energy savings will be lower. The findings indicate that condenser shading alone, without evapo-transpiration, is not an effective measure to improve efficiency or save energy.
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Energy conservation and increase in performance of air-conditioning systems could be achieved by pre-cooling the air intake of the condensers. This paper experiments three different methods of pre-cooling the condenser air; the cooling pad (CP) setup, the cooling mesh (CM) setup and the shading setup. The CP and CM setups are two different methods of evaporatively cooling the air. The three methods have been applied to three identical, 2.8 tons, split air-conditioning units during the peak summer time period in Kuwait, under ambient temperatures ranging from 39 to 45°C. The results yielded a drop in the power consumption ranging from 8.1 to 20.5% and an increase in the cooling load ranging from 6.4 to 7.8% by using the CP and CM setups, which, in turn, resulted in an increase in the coefficient of performance (COP) of the units by 36–59%. The shading setup has resulted in an increase of power consumption due to air trapped below the shaded area, which resulted in heat being generated. Copyright © 2005 John Wiley & Sons, Ltd.
Article
Energy conservation measures on buildings have a significant role to play in reducing the burden of the energy bill on the Lebanese economy. The residential sector is one of various sectors that energy measures can be applied to. Such measures include the use of insulation materials, double-glazed windows, shading, efficient air-conditioning systems, economical lighting and reduction of infiltration rates. It is demonstrated through detailed energy analysis of typical residential and office buildings that strict conservation is benificial on the micro- and macro-economic levels. A code of practice is suggested to establish acceptable standards for energy use in residential buildings and ranking is done of energy measures based on economical indices. © 1998 John Wiley & Sons, Ltd.
Article
This paper analyses how to apply mist pre-cooling coupled with condensing temperature control to enhance the coefficient of performance (COP) of an air-cooled chiller system and hence achieve electricity savings. A modified DOE-2.1E chiller model was developed to predict the change of chiller COP due to various set points of condensing temperature and pre-cooling of air stream entering the condenser. The model was calibrated by using manufacturer's data and used to estimate the annual electricity consumption of a chiller system serving an office building under four operating schemes: traditional head pressure control (HPC); HPC with a fixed mist generation rate; condensing temperature control (CTC) with a fixed mist generation rate; CTC with an optimal mist generation rate. It was estimated that using optimal mist control with CTC could achieve a 19.84% reduction in the annual electricity consumption of the system. Considerations when using mist pre-cooling to maximize electricity savings have been discussed.
Article
Water-cooled air-conditioning systems (WACS) are widely used in the commercial sector for energy efficiency, but not in the domestic sector. It has been found that there are no mathematical models and energy simulation programs to enable detailed investigation and evaluation into the energy performance of water-cooled air-conditioners. To improve the applicability of water-cooled air-conditioners in the domestic sector, the development of a prediction model for energy performance analysis is needed. This paper addresses the development of an empirical model for predicting the operational performance and energy consumption for the use of water-cooled air-conditioners. The model consists of four sub-models which has taken into account the energy consumption of the condenser water system. A prototype WACS was set up and tested in an environmental chamber to validate the resultant model. The overall COP of the WACS was found to be greater than 3 at 90% rated capacity. The predictions from the model compared well with the experimental results, with RMS error within 11%.
Article
Reduction of energy consumption is a major concern in the vapor compression refrigeration cycle especially in the area with very hot weather conditions (about 50 °C), where window-air-conditioners are usually used to cool homes. In this weather condition performance of air condenser window-air-conditioners decrease sharply and electrical power consumption increase considerably. These problems have activated the research programs in order to improve the performance of window-air-conditioners by enhancing heat transfer rate in the condenser. In this article, a new design with high commercialization potential for incorporating of evaporative cooling in the condenser of window-air-conditioner is introduced and experimentally investigated. A real air conditioner is used to test the innovation by putting two cooling pads in both sides of the air conditioner and injecting water on them in order to cool down the air before it passing over the condenser. The experimental results show that thermodynamic characteristics of new system are considerably improved and power consumption decreases by about 16% and the coefficient of performance increases by about 55%.
Article
In this paper, the performance of an innovative evaporatively cooled condenser is compared with that of a conventional air-cooled condenser for a split heat pump system. The system was tested in an environmentally controlled test chamber that was able to simulate test conditions as specified by ASHRAE Standard 116. Tests to optimize refrigerant charge and short tube restrictor size were conducted using refrigerant HCFC-22. The wheel rotation speed of the evaporative condenser was also optimized experimentally to maximize the coefficient of performance. Using these optimum parameters, steady state and cyclic performance tests were conducted. The experimental results showed that the evaporative condenser has a higher capacity than the air-cooled condenser by 1.8 to 8.1%, a higher COP by 11.1 to 21.6%, and a higher SEER by 14.5%.RésuméDans cette communication, on examine la performance d'un nouveau condenseur refroidi par évaporation ; on compare sa performance à celle d'un condenseur refroidi par air classique utilisé dans un système split de pompe à chaleur. On a testé ce système dans une chambre à environnement contrôlé afin d'obtenir des conditions d'essai requises par la norme ASHRAE 116. On a réalisé des essais destinés à optimiser la charge en frigorigène et les détendeurs pour HCFC22. On a optimisé de façon expérimentale la vitesse du moteur de rotation du condenseur évaporatif afin d'augmenter le coefficient de performance le plus possible. A partir de ces paramètres optimaux, on a effectué des essais en régime permanent et sur la performance du cycle. Les résultats expérimentaux montrent que le condenseur évaporatif a une puissance supérieure à celle du condenseur refroidi par air (de 1,8 à 8,1 %), un COP de 11,1 à 21,6 % supérieur, et un SEER* de 14,5 % supérieur.* SEER (Seasonal Energy Efficiency Ratio) = Rapport d'efficacité énergétique saisonnier
Article
This paper presents a steady state simulation model to predict the performance of a small split type air conditioner with integrated water heater. The mathematical model consists of submodels of system components such as evaporator, condenser, compressor, capillary tube, receiver and water heater. These submodels were built based on fundamental principles of heat transfer, thermodynamics, fluid mechanics, empirical relationships and manufacturer’s data as necessary. The model was coded into a simulation program and used to predict system parameters of interest such as hot water temperature, condenser exit air temperature, evaporator exit air temperature, mass flow rate of refrigerant, heat rejection in the condenser and cooling capacity of the system. The simulation results were compared with experimental data obtained from an experimental rig built for validating the mathematical model. It was found that the experimental and simulation results are in good agreement.
Article
The objective of this study is to conduct a realistic prediction of the potential energy saving for using water cooled air conditioners in residential buildings in Hong Kong. A split type air conditioner with air cooled (AAC) and water cooled (WAC) options was set up for experimental study at different indoor and outdoor conditions. The cooling output, power consumption and coefficient of performance (COP) of the two options were measured and calculated for comparison. The experimental results showed that the COP of the WAC is, on average, 17.4% higher than that of the AAC. The results were used to validate the mathematical models formulated for predicting the performance of WACs and AACs at different operating conditions and load characteristics. While the development of the mathematical models for WACs was reported in an earlier paper, this paper focuses on the experimental works for the AAC. The mathematical models were further used to predict the potential energy saving for application of WACs in residential buildings in Hong Kong. The predictions were based on actual building developments and realistic operating characteristics. The overall energy savings were estimated to be around 8.7% of the total electricity consumption for residential buildings in Hong Kong. Wider use of WACs in subtropical cities is, therefore, recommended.
Use of general models with a small number of parameters: Part 1: Theoretical analysis
  • L Laret
Laret, L. 1980. Use of general models with a small number of parameters: Part 1: Theoretical analysis. Proceedings of 7th International Congress of Heating and Air Conditioning CLIMA 2000, September 17-19, Budapest.