Armando C. Oliveira

• PhD
• Professor at University of Porto

This study investigates the implementation of passive design strategies to improve the thermal environment in the extremely hot climates of Brazil, Portugal, and Turkey. Given the rising cooling demands due to climate change, optimizing energy efficiency in buildings is essential. Using the Trace 3D Plus v6.00.106 software, typical residential buil...

Building integrated photovoltaics (BIPVs) consist of PV panels that are integrated into a building as part of its construction. This technology has advantages such as the production of electricity without necessitating additional land area. This paper provides a literature review on recent developments in urban building energy modelling, including...

Most heat transfer problems are complex, in the sense that in most cases there are no analytical (exact) solutions to obtain temperature fields or heat transfer rates/coefficients. Thermal energy systems, and in general energy systems, involve heat transfer processes and, therefore, also require approximate solutions. The approximate solution to no...

Mathematical models can be successfully applied to predict the multi-effect distillation system integrated with thermal vapour compression unit (MED-TVC) performance under different operating conditions. In this work, a one-dimensional (1-D) mathematical model was developed to perform the theoretical analysis of a small-scale parallel feed MED-TVC...

In this paper, the experimental results of the thermal sub-system of a reliable and cost-effective polygeneration solar system are presented. This polygeneration system produces heating, cooling, and electricity from solar energy, which is used in an existing test building. Heat is generated in four evacuated tube solar collectors (ETCs). The heat...

In this paper, the experimental results of the thermal sub-system of a reliable and cost-effective polygeneration solar system are presented. This polygeneration system produces heating, cooling and electricity from solar energy, which are used in an existing test-building. Heat is generated in four evacuated tube solar collectors (ETC). The heat m...

Este livro resulta da experiência letiva e pedagógica do seu autor, como docente da Faculdade de Engenharia da Universidade do Porto ao longo de mais de 40 anos, nas áreas da Transferência de Calor (fundamental e aplicada). Dessa experiência constatou o autor que, com muita frequência, os estudantes são levados a procurar “a equação”, ou conjunto d...

Agriculture plays a significant role in the labor force and GDP of Mozambique. Nonetheless, the energy source massively used for water pumping in irrigation purposes is based on fossil fuels (diesel oil). Despite the water availability and fertile soils in Moamba, Mozambique, farmers struggle with the high cost of fuels used in the pumping systems....

Nowadays, desalination is the primary alternative to increase water supply for domestic, agriculture and industrial use. Energy demanding desalination could be a sustainable solution in places where renewable energy resources are abundant. Multi-effect thermal vapour compression desalination is widely applied; however, its integration with solar en...

Concentrated Solar Power techno-economic value has been proven due to the ability to dispatch energy with thermal energy storage integration. Though, additional technical and cost-effective solutions may result from the strategic combination with other energy sources (i.e. hybridisation), as in Shams 1 where CSP and natural gas are combined. Analog...

A significant share of the world energy consumption is related to the industrial sector energy demand. E.g. in the European Union, about 50% of the energy consumption is for heat and cooling; of which 37% are related to the industrial sector. In order to attain the ambitious greenhouse gas and fossil fuel consumption reduction, it is crucial to adv...

Freshwater demand on our planet is monotonously increasing, due to population growth and increasing living standards. The United Nations predicts that two-thirds of the world's population will suffer water shortages by 2025. Although seawater desalination is energy-intensive, it is one of the potential solutions to deal with water shortages. Curren...

The building sector is growing at a rapid pace and has become the third largest consumer of fossil energy, after industry and transportation. To achieve a significant reduction in building energy consumption, aiming a sustainable development, passive methods are not enough: renewable energy technologies should be integrated with passive building co...

A renewable electricity system hybrid concentrated solar power/biomass power plant in Tunisia has been assessed. Life Cycle Assessment (LCA) and the Input-Output Analysis (IOA) methodologies have been performed to assess the environmental and socioeconomic impacts of this technology in the Tunisian context. Application of these methodologies allowe...

Building Integrated Photovoltaic (BIPV) systems have been increasingly used as a means to generate electricity on-site, and their diffusion will increase in the near future. The objective of this article is to carry out a sustainability assessment of a BIPV system installed in Turkey regarding the three pillars: environmental, economic and social p...

Hotels hold an important role in the energy efficiency policies of the European Union (EU), as they are typically ranked among the top energy consumers in the non-residential sector. However, a significant amount of the energy used in hotels is wasted, leaving ample room for enhancing energy-efficiency and resource conservation. Indeed, energy refu...

The trend towards decentralised electricity generation and combined heat and power (CHP) is continuously increasing. The transition towards a decentralised power system relies on small-scale and often intermittent generation, bringing new challenges such as matching the demand with supply. A possible solution is the use of renewable energy technolo...

Direct Steam Generation in parabolic trough solar collectors is one of the most promising alternatives for replacing the use of thermal oil in solar power plants and process heat. The main advantages are: elimination of steam generator heat exchangers; use of a non-toxic fluid; operation with power cycle higher temperatures, therefore with higher e...

Novel renewable energy technologies in the Middle East and North Africa (MENA) region can be developed through microgeneration systems aiming to supply local energy demands in a sustainable way. In this study, we carried out a sustainability assessment combining two reputable methodologies which have been applied to a facility comprising a hybrid s...

This paper presents an experimental study of the influence of a variable geometry ejector (VGE) design on the performance of a small-scale, 1.5 kW nominal capacity solar heat driven ejector air-conditioning system under real-life working conditions. Under variable operating conditions (e.g. solar radiation, ambient temperature) fixed geometry eject...

The hotel sector is one of the most energy- and resource-intensive branches of the tourism business. Improving the performance of the hotel building stock, especially in the 4- and 5-star segment, is critical in order to reach the nearly zero energy building (nZEB) status imposed by the European Union's 2020 and 2030 targets, and also to meet the l...

Buildings are responsible for a large portion of the energy consumption and harmful emissions to the environment. To change this situation, the European Performance of Buildings Directive requires new buildings to be nearly Zero Energy Buildings. To achieve this goal, energy saving measures combined with large use of renewables on-site must be appl...

A study was carried out to predict the long-term energy performance of swimming pool solar heating systems for four Brazilian cities using the utilizability method. The chosen cities were Brasília, Fortaleza, Porto Alegre and São Luís. The pool area was kept constant and both glazed and unglazed solar thermal collectors were considered for the diff...

In this work, an educational tool to be used in solar energy courses is proposed. It consists of software, named Softsun, with educational purposes, which allows performing some tasks applicable to solar thermal and photovoltaic systems. Among other things, this software allows: obtaining the I–V curve of diode models using data from manufacturers,...

In this paper, a reliable and cost-effective polygeneration system for an existing test building, able to provide electricity, cooling and heating needs is presented, modelled and assessed. The system relies on solar energy as the primary source (PV and solar thermal collectors). Building cooling demand is achieved with a variable geometry ejector...

This paper presents a detailed energy analysis of a 37-year-old house, located near Porto, Portugal. The current situation leads to overheating in the Summer and low temperatures during the Winter, causing high levels of discomfort to the occupants. With the aim to improve the overall comfort, several passive/active solar systems were proposed, and...

The present work is elaborated in the framework of the REELCOOP research project. A mini hybrid (solar/biomass) power plant was installed and is under testing at ENIT (Ecole Nationale d`Ingénieurs de Tunis), Tunisia. The power plant relies on Parabolic Trough Collectors (PTC) operating with Direct Steam Generation (DSG), an Organic Rankine Cycle (O...

The value of renewable energy systems is undeniable since they rely on a free source that will not run out. However, they depend on meteorological conditions, leading to uncertainty on the instantaneous energy supply. An interesting concept consists on the strategic combination. In this article, two 1-MWel concentrated solar power/biomass hybrid po...

Concentrated Solar Power (CSP) has proven to be a reliable and economical solution due to the easiness to dispatch energy with thermal energy storage (TES) integration. On the other hand, valuable concepts such as Direct Steam Generation (DSG) have been hindered by latent heat storage technical challenges. An interesting concept is renewable energy...

In this work, the evaluation of the performance of a small-size photovoltaic plant, with 15 kWp of capacity, is made and some proposals for its optimization are presented. The plant consists of a grid-connected centralized system, where the output power is consumed in the same building. The PV plant production data of the last couple of years are a...

The present work is elaborated in the framework of the REELCOOP research project. A mini hybrid (solar/biomass) power plant was installed and is under testing at ENIT (Ecole Nationale d’Ingénieurs de Tunis), Tunisia. The power plant relies on Parabolic Trough Collectors (PTC) operating with Direct Steam Generation (DSG), an Organic Rankine Cycle (O...

In this chapter, we considered a building-integrated photovoltaic (BIPV) system, which was installed at Yasar University in Izmir, Turkey, within the framework of an EU/FP7-funded project and has been successfully operated since February 8, 2016. The BIPV system consists of 48 crystalline silicon (c-Si) modules in 4 rows and 12 columns, and the tot...

This paper presents an integrated bottom-up approach aimed at helping those dealing with strategical analysis of installation of Building Integrated Photo Voltaic (BIPV) to estimate the electricity production potential along with the energy needs of urban buildings at the district scale. On the demand side, hourly energy profiles are generated usin...

This paper deals with both energetic and exergetic performance assessments of two combined systems as a whole. The first one is a Building Integrated Photovoltaic (BIPV) system while the second one is a wastewater (WW) Source Heat Pump (WWSHP) system. Both systems were installed at Yasar University, Izmir, Turkey within the framework of EU/FP7 and...

Computational fluid dynamic tools have been widely used for the design and improvement of ejectors for cooling and other engineering applications over the last two decades. Most published works are based on the solution of the compressible RANS equations using commercially available codes. These codes provide a number of different turbulence models...

The fundamental benefit of using renewable energy systems is undeniable since they rely on a source that will not run out. Nevertheless, they strongly depend on meteorological conditions (solar, wind, etc.), leading to uncertainty on the instantaneous energy supply and consequently to grid connection issues. An interesting alternative concept is re...

The fundamental benefit of using renewable energy systems is undeniable since they rely on a source that will not run out. Nevertheless, they strongly depend on meteorological conditions (solar, wind, etc.), leading to uncertainty of instantaneous energy supply and consequently to grid connection issues. An interesting concept is renewable hybridis...

Renewable and sustainable energy generation technologies have been in the forefront due to concerns related to environment, energy independence, and high fossil fuel costs. As part of the EU’s 2020 targets, it is aimed to reach a 20% share of renewable energy sources in final energy consumption by 2020, according to EU’s renewable energy directive....

The first experimental results with a small scale solar driven ejector cooling system installed in Porto, Portugal are reported. The system is constituted by three sub-systems: solar collector field, cooling cycle and thermal energy distribution sub-systems. The novelty in the cooling cycle is a 1.5 kW nominal capacity variable geometry ejector usi...

In this paper, the development of a TRNSYS model, for the simulation of a solar driven ejector cooling system with an integrated PCM cold storage is presented. The simulations were carried out with the aim of satisfying the cooling needs of a 140 m3 space during the summer season in Tunis, Tunisia. The system is composed of three main subsystems, w...

This paper presents a holistic approach to assess the energy performance of a naturally ventilated PV façade system. A rigorous combined experimental and numerical approach is established. The real energy performance of the system has been evaluated through a long-term high resolution monitoring of a typical ventilated PV façade system. A numerical...

The European Directive on Energy Performance of Buildings has established a target of Nearly Zero-Energy Buildings (nZEB) for a sustainable future. For this target, hotels take a special interest, as shown in the neZEH project (Nearly Zero Energy Hotels project) (neZEH, 2016), (Tsoutsos et al., 2013). In this work, a hotel located in Tenerife (Cana...

Renewable energy sources such as solar energy are characterised by a high degree of intermittence, sometimes leading to inability to meet the demand of a power system. Hybridisation with more stable renewable sources, such as biomass, represents a resourceful way of meeting energy demands uninterruptedly. In this paper, a hybrid renewable electrici...

A computational fluid dynamics (CFD) model was developed for the simulation of a phase change thermal energy storage process in a 100 l cylindrical tank, horizontally placed. The model is validated with experimental data obtained for the same configuration. The cold storage unit was charged using water as the heat transfer medium, flowing inside a...

In this work, the performance of a photovoltaic (PV) installation is assessed. The plant consists of a grid-connected centralized system, where the supplied power is not associated with a particular electricity customer. Operational data from this PV plant, ground-mounted and located in the north of Portugal, are now available for a period of 3 yea...

A novel concept for a building façade is presented. The façade uses solar energy to generate electricity, heating or cooling, by combining photovoltaic solar cells with a solar air collector and thermoelectric (TE) heat pumps, into a compact building envelope solution. The generated electricity may be partially or totally used to provide heating or...

Ejector refrigeration is a promising technology for the integration into solar driven cooling systems because of its relative simplicity and low initial cost. The major drawback of such a system is associated with its relatively low coefficient of performance (COP) under variable operating conditions. In order to overcome this problem, an advanced...

The REELCOOP project funded by the European Union aims at developing and demonstrating three small scale solar electricity generating units with two of them using thermal power cycles and one using PV. The system described here includes parabolic trough collectors and an organic Rankine cycle (ORC), enhanced by a biogas boiler and a thermal storage...

Central receiver systems (CRS) are a promising concentrated solar power (CSP) technology for dispatchable electricity generation. The CRS levelized cost of electricity (LCOE) is usually increased by low power-block capacity factors or by high thermal storage costs. The economical turnover is still positive for the Portuguese case but depends on the...

Experimental results with the first laboratory scale variable geometry ejector (VGE) using isobutane (R600a) are presented. Two geometrical factors, the area ratio and the nozzle exit position, can be actively controlled. The control of the area ratio is achieved by a movable spindle installed in the primary nozzle. The influence of the spindle pos...

Micro-cogeneration systems are an efficient way of meeting energy demands in buildings. They achieve the goal of distributed electricity generation, combined with useful heat, with a high global efficiency. Organic Rankine Cycle (ORC) systems are an interesting solution in cases where the heat demand is significantly larger than electricity needs,...

Portugal has a high potential for concentrated solar power and namely for atmospheric air volumetric central receiver systems (CRS). The solar multiple and storage capacity have a significant impact on the power plant levelized electricity cost (LEC) and their optimization and adequate control strategy can save significant capital for the investors...

This work focuses on the performance analysis of a photovoltaic (PV)–thermal collector, regarding parameters like number and location of PV cells, inlet fluid temperature, irradiation level and ambient temperature. This is accomplished through the numerical solving of a developed 2D mathematical model of the collector. A hybrid flat plate and tube...

A number of factors influence the performance of an ejector, e.g. working fluid, geometry and operating conditions. In the present work, six low-environmental-impact working fluids were evaluated for their use in an ejector cooling system running on low-temperature thermal energy. The numerical analysis was based on a model applying the 1D constant...

In the present paper, the numerical results for two 1 kW cooling capacity ejectors with variable primary nozzle geometry are presented using R152a and R600a as working fluids. Working fluids were selected based on the criteria of low environmental impact and good performance in the range of operating conditions adequate for using solar thermal ener...

Noise can be considered as one of the strongest health problems for seafarers. In the present paper, we present the major flaws in standards related to maritime transport, which should be resolved, and the precarious state due to its anachronism or its suitability in application at the national level of Spain. Finally, based on a practical case stu...

This paper analyses the Brayton cooling cycle for the reliquefaction of the boil off on liquefied natural gas (LNG) vessels. By performing a thermodynamic study, we analysed and evaluated the conditions, parameters and energy consumption required in the process, including the influence of the choice and variation of diverse factors on the operating...

The aim of this chapter is to show the main standards applicable to evaluate indoor environments at international level. These standards show us the mean values and limiting conditions, as well as models for indoor environments. Following a methodic enumeration of standards, they are classified into general thermal comfort, local thermal comfort an...

In the past few years, permeable external coverings and impermeable internal coverings of plastic emulsion paints have not been recommended by architects and engineers. This is related to the fact that partial vapour pressure inside the building, which is higher than outdoors, may drive water vapour through walls and condense in some zones damaging...

General thermal comfort is related to the general conditions of an environment. However, in this environment, we usually find parameters out of the thermal comfort range. Hence, it is necessary to study the localised effect of the thermal comfort variables over human thermoregulation to evaluate thermal comfort. On the other hand, it is possible to...

Concentrated solar power (CSP) plants generate an almost continuous flow of fully dispatchable “renewable” electricity and can replace the present fossil fuel power plants for base load electricity generation. Nevertheless, actual CSP plants have moderate electricity costs, in most cases quite low capacity factors and transient problems due to high...

The climate of Iberia (Spain and Portugal) has adequate conditions for wind power generation during the winter and spring seasons, whereas in the summer, the low wind velocity and the moist air density reduce the possibility of energy conversion. To solve this problem, low speed wind turbines employing a wind concentrator were assessed during the l...

Energy consumption has emerged as one of the most important factors to be considered in the design of new buildings, as well as in building retrofitting. Several software resources are available to estimate building energy consumption during a whole year, including different standards for building energy certification. However, adhering to one of t...

Nowadays, it can be stated that climate change will alter weather conditions, and that regarding wind power production, values out of wind turbine design conditions will occur. In this article, a wind concentrator and a wind farm were designed and modeled to predict changes in local power production. The results showed the feasibility of low speed...

At present, engineering students must learn an adequate programming language that allows them to easily automate typical problems. This result is more important when we require an adequate graphical representation of the problem, as is usually done in engineering. This study presents an optimal programming language for quality control analysis. The...

Located in the northwest coast of Spain, A Coruna has a mild climate where humidity is relatively high throughout most of the year, due to the effect of the Atlantic Ocean winds. This high relative humidity is related with mould exposure and allergy history, although it is difficult or impossible to determine health risks with current assessment me...

Energy consumption in Spanish school buildings is higher during spring seasons. Thermal inertia of buildings can help to reduce such consumption, improve comfort, and even replace HVAC systems. This thermal inertia is usually associated to heavy wall construction, but the truth is there are other parameters that can have a significant effect on thi...

Objective This paper aims to show a practical case study of safety assessment concerning possible injuries and fire occurring in the engine room on-board a merchant ship, due to fatigue. Methods The methodology was centred in literature hazard identification, measurements in real ships and heat stress indices definition. Results Some corrections ar...

Based on earlier studies, new research work must be developed in the next few years. For example, some easy modifications on HVAC systems must be considered, such as changing the set-point temperature during the winter season in office buildings with permeable coverings. Hence, this chapter includes different sections in accordance with the differe...

Indoor environments were simulated as a function of weather conditions with HAM tools software. At the first stage of the research, real measurements of indoor temperature and relative humidity for a year allow an adjustment of the simulation software. After air change rates, infiltrations and orientation were adjusted, a good agreement between rea...

In this chapter, the main parameters considered for designing and analysing an indoor environment are described. These parameters are typically classified in relation to energy saving, thermal comfort, preservation of materials, hygiene and health effects. A good understanding of the relationship between parameters will help us optimise previous an...

In this work, a micro-tri-generation system integrated with a solar system is studied. A basic micro-cogeneration technology [micro-CHP (combined heat and power) system] integrating solar collectors, storage tank, micro-turbine and a thermodynamic cycle based on the organic Rankine cycle (ORC) is combined with an absorption chiller. The heat reject...

A low cost, black nickel solar absorber coating used in thermal solar collectors on nanostructured high thermal conductor copper was analyzed using XPS (X-ray photoelectron spectroscopy) and MFM (magnetic force microscopy) techniques. Copper substrate nanostructuration was realized by electrochemical polishing to improve MFM analysis. Black nickel...

In the present paper, experimental and CFD results for a 5 kW capacity steam ejector with variable primary nozzle geometry are presented and compared. The variable geometry was achieved by applying a movable spindle at the primary nozzle inlet. Operating conditions were considered in a range that would be suitable for an air-conditioning applicatio...

Energy saving methods can be employed to reduce energy consumption in buildings, or improve indoor thermal conditions. An example of those methods is the use of permeable coverings, but there are other important parameters like thermal inertia. To understand and predict these energy saving procedures, one may employ different software resources. In...

In recent years, European electrical consumption in buildings is experiencing a marked increase, rising to values above design conditions. Consequently, power cuts occur in different periods, such as during the early morning hours in winter and the last hours of occupation in summer. To solve this problem, passive methods could help to reduce energ...

The advantages of numerical modelling compared with experimental studies (e.g. reduced cost, easy control of the variables, high yield etc.) are well known. Theoretical studies where experimental validation is also presented provide an important added value to numerical investigations. In the present paper, experimental and computational fluid dyna...

For a long time, the following are considered to be related to the sick building syndrome (SBS) in buildings: mechanical ventilation, air-conditioning systems, wall internal coverings with textile materials, bad quality of construction materials and air tight buildings with reduced air exchange. Recent studies showed that permeable coverings are a...

In buildings with heating, ventilation, and air-conditioning (HVAC), the Predicted Mean Vote index (PMV) was successful at predicting comfort conditions, whereas in naturally ventilated buildings, only adaptive models provide accurate predictions. On the other hand, permeable coverings can be considered as a passive control method of indoor conditi...

A low-cost, black nickel solar absorber coating, to be used in thermal solar collectors on nanostructured highly thermal conductor copper, was analyzed using the thermoanalytical flash method at 293 K and Cernuschi's two-layer models, to identify the thermal properties of the blackening layers and the energy losses connecting different parameters s...

A solar collector is an apparatus that collects the sunlight energy then alters this energy into a more usable or storable energy form. The absorber surface used in thermal solar collectors requires high absorptance in the solar spectrum and low emittance. Several techniques, such as vacuum techniques, are currently used to produce solar absorber s...

Indoor space cooling represents a large potential for solar energy use due to the relative coincidence between energy availability and cooling demand. Solar-assisted air conditioning (AC) applications emerged with the development of high efficiency solar collectors. Energy storage (hot or cold) must be implemented for solar-assisted AC applications...

Today's world suffers from an increasing dependence on fossil fuels, either for electricity production, transportation or reagent for the chemical industry. A technological revolution in hydrogen and electricity production is important to support the future needs and lead the world towards a better future. For that, technological and economical bar...