Solar Air Conditioning System Research Articles

Design and analysis of a medium-temperature, concentrated solar thermal collector for air-conditioning applications

Solar thermal energy is considered as a promising source to drive air-conditioning applications due to the good correlation between supply and demand. The present work examines the feasibility of a novel, low-profile concentrated solar thermal collector to provide medium-temperature heat to commercial buildings for both heating and cooling purposes, aiming to reduce their non-renewable energy consumption levels. To the best of the authors’ knowledge, the semi-passive tracking/concentrating platform employed in this collector represents a significant improvement for ‘stationary’ (internal tracking, the module itself remains fixed) solar concentrating technology. To investigate the real-world viability of this collector design for solar heating and cooling, a system-level techno-economic performance analysis is conducted using a validated TRNSYS model. The solar heating and cooling (SHC) system includes the proposed solar thermal collectors, an auxiliary heater, and a double-effect absorption chiller. In this study, the proposed solar collectors are employed to supply thermal energy to the chiller to offset the building cooling demand or the thermal energy can also be used directly to satisfy the building’s heating demand. When sufficient solar energy is not available, the auxiliary heater provides the rest of the heating and cooling demand. The annual solar fraction and economic metrics (e.g. total levelized costs) were used as the selection criteria among design options. The simulation results demonstrate that a specific collector area of 2.4m2 per kW cooling and an optimal storage tank specific volume of 40L/m2 are sufficient to cover 50% of the load requirement of the building. The economic analysis indicates that a levelized cost of cooling energy (LCOC) of ∼0.6$/kW-h can be derived from this solar air-conditioning system.

The Research on Solar Photovoltaic Direct-driven Air Conditioning System in Hot-humid Regions

This research presents a design method of photovoltaic direct-drive air conditioning system, and arranges the photovoltaic direct-drive air conditioning system in an office building in hot-humid regions, the system mainly includes photovoltaic array, storage battery, confluence unit, PWM controller, and air conditioner. Through the test, we found that photovoltaic direct cur-rent air conditioning system is still able to better meet the indoor thermal environment needs even in hot weather. Besides, in the test day, the amount of photovoltaic power generation apart from meeting the demand for air conditioning and there are remaining. The excessively power generation is stored in the battery, it can be self-sufficient for the system, no municipal power grid supplement and energy efficiency is more significant.

Solar Heating and Cooling in Buildings – How Sustainable?

Conventional heating and cooling systems are responsible for large amounts of carbon dioxide release to the environment, as well as for the use of harmful refrigerants regarding the greenhouse effect and the ozone depletion potential. Solar radiation is a clean form of energy, which is required for almost all natural processes on earth. In South Africa, the majority of produced electricity is generated from fossil fuels and the potential of renewable energy sources is vast, solar radiation in particular is in abundance. The upper limit for Global Horizontal Irradiance (GHI) in South Africa can be as high as 2 300 kWh/m2/a, whereas the Direct Normal Irradiance (DNI) value attains a maximum of 2 900 kWh/m2/a, which is significantly higher than it is in other regions worldwide. The global air conditioning systems market has been estimated to reach 78.8 million units by 2015 due to increasing living standards, comfort expectations and global warming. South Africa is not the best performer regarding renewable energy use among African countries and there is a long way to go to achieve a sustainable environment. This paper seeks to investigate the feasibility and the sustainability of solar driven air conditioning system in South Africa based on meteological weather data. Currently, renewable energy is a topic of interest in South Africa after the 2008 energy emergency when power outages were rolled out due to inadequate maximum load planning. Solar air conditioning technology remains an untapped technology in South Africa.

Increasing the share of renewables through adsorption solar cooling: A validated case study

Tools and experience on solar thermal cooling system sizing and design are still limited, as less than one thousand plants have been built until now. In this paper, a design tool for mid-size thermal solar cooling systems is presented. The tool consists of a model realised in TRNSYS and validated using the data of a real solar air conditioning system installed in the green building of Shanghai Research Institute of Building Science. Characteristic features of the system are the use of adsorption chillers driven by low-temperature solar heat from U-type and heat pipe evacuated solar collectors. The model has subsequently been employed for a technical analysis: the most relevant parameters have been varied and figures of merit calculated. An energy analysis has been performed for 6 reference cities, differing for climates and latitudes, highlighting the possibility to use only renewable energy for cooling purposes. Eventually, the systems have been compared with reference ones. Comparison highlighted that considerable savings in primary energy and CO2 emissions can be achieved: 0.97 MWh per installed square meter of solar collectors and up to 22 tons of CO2 annually, thus indicating a great potential for increasing energy efficiency and reduce CO2 emissions.

Performance Evaluation of Photovoltaic Solar Air Conditioning

Abstract Information on the electrical-driven solar air conditioning (SAC) is rather scanty. A considerable body of technical data mostly concerns large-scale photo-voltaic solar air conditioning (PV-SAC) systems. Reliable information about the energy output has arisen only in recent years; however, it is still not easily accessible, and sometimes its sources are closed. Despite these facts, solar energy researchers, observers and designers devote special attention to this type of SAC systems. In this study, performance evaluation is performed for the PV-SAC technology, in which low-power (up to 15 kWp of cooling power on average) systems are used. Such a system contains a PV electric-driven compression chiller with cold and heat sensible thermal storage capacities, and a rejected energy unit used for preheating domestic hot water (DHW). In a non-cooling season, it is possible to partly employ the system in the reverse mode for DHW production. In this mode, the ambient air serves as a heat source. Besides, free cooling is integrated in the PV-SAC concept.

PERFORMANCE OF SOLAR-ASSISTED ABSORPTION CYCLE AIR CONDITIONING SYSTEM

A study of the efficiency of the cycle of solar assisted absorption air conditioning system has been carried out. The absorption cycle system has been in operation in Malaysia, but only in large buildings such as the KL International Airport, government buildings in Putrajaya and KLCC buildings. This study focuses on a small-scale lithium-bromide (LiBr) absorption cycle air conditioning system for residential application. The important component of the system has been designed with the capacity of 3.517 kW cooling load suitable for small-capacity application. Generator, condenser, evaporator and absorber have been designed, fabricated, assembled and tested in the laboratory. A total of ninety-pieces of evacuated tube solar collectors have been installed to produce hot water to be used as a heat source to separate the absorbent and refrigerant. Lithium bromide-water pair was used in this experiment. With the concentration of lithium bromide of 33%, the average coefficient of performance (COP) obtained was 0.446, 0.438 and 0.431 for category A, category B and category C respectively. This study shows that the cycle of solar absorption air conditioning system in small scale can be used in Malaysia and tropical climate countries. 

Modeling, Simulation and Optimization of a Solar Absorption Air Conditioning System for an Office Block in Zaria, Nigeria

In this study, a solar absorption air conditioning system has been modeled simulated and optimized for an office block covering a total floor area of 90[Formula: see text]m2using the TRNSYS 16 software. Meteorological data over a period of a typical year for Zaria in Nigeria where the office block is located was used in the simulation and optimization. The hourly cooling energy demand of the office block for the whole year was simulated using the TRNSYS sub program TRNbuild. The peak cooling energy demand was used to size the components of the solar absorption air conditioning system. Based on the initial sizes, a TRNSYS model of the air conditioning system was developed. The simulation and optimization process was done by employing a monthly average data approach in which the TRNSYS software was combined with Microsoft excel. The simulation was done on an hourly time step, optimization was done by studying effect of varying system component sizes on performance indices: coefficient of performance (COP), solar coefficient of performance (SCOP) and solar fraction (SF). Results indicate that the system is capable of attaining an average annual SF of 0.79 in the given location.

The Effect of Ground Conditions under a Solar Pond on the Performance of a Solar Air-conditioning System

Heat loss through the bottom of a salt gradient solar pond is significant if the bottom of the pond is non-insulated. This loss has an impact on the thermal performance of the solar pond and the solar air conditioning system connected to it. In this paper, a coupled simulation between a transient model of the solar pond and the ground underneath it in MATLAB and of an absorption chiller, air conditioning system and building in TRNSYS is used to investigate the effect of ground conditions on the performance of the complete system. Four factors have been studied for soil underneath the solar pond: moisture content, soil type, sandy soil texture and the depth of the water table. It was found that dry, fine sandy soil with low thermal conductivity is best and that the deeper the water table, the better for system performance.

Optimization of Standalone Solar Heat Fired Absorption Chiller for Typical Australian Homes

The increased penetration of residential air-conditioners (AC); specifically vapor compression types, is regarded as one of the foremost causes of a dramatic rise in critical peak electricity demands requiring corresponding upgrades of electricity infrastructures. These upgrades requires heavy investments, consequently, driving up electricity prices. Solar air-conditioning systems can reduce this trend, but current vapor-compression air-conditioners (VCACs) needs very large investments in both photovoltaic system and battery storage. Alternatively solar heat-driven absorption chillers need less expensive solar collectors and thermal storage, drawing only small amounts of electricity to overcome parasitic power. There are ample studies conducted previously on either the technical and/or economic feasibility of solar heat driven absorption chillers. But these studies are only focused on supplementing solar heat energy with an auxiliary heater. This study, examines the option of running the absorption chiller by solely relying on solar heat energy. It focuses on minimizing the life cycle cost of a solar heat driven absorption chiller through optimizing the size of all of its main components. The system is named the standalone solar heat fired absorption chiller (SA-SHF-ABS-CH) sized to sufficiently meet the space conditioning demands, both heating and cooling, of a typical Australian 6 star home. For the aims of this research, TRNSYS17 software was used in modelling and dynamically simulating the integrated system, while GenOpt software was used to carry out the optimization. The economic assessment on the most optimally sized system component configuration shows, firstly, the twenty-year lifecycle cost of the system with the most minimized cost is AU$ 53,387 in Brisbane, AU$ 51,639 in Adelaide and AU$ 32,816 in Melbourne. These investment costs in each of these cities appear higher than those incurred if the householder were to instead install a standard efficient inverter, ducted, reverse cycle air conditioner (IRC-AA-HP) powered by grid electricity; as follows: Brisbane at 77%, Adelaide at 58% and Melbourne at 28%. Secondly, the payback period was found to be longer than the twenty-year system service- life, which is far too long to justify the investment on such solar air-conditioner. However, when compared with IRC-AA-HP, in Adelaide and Melbourne, SA-SHF-ABS-CH consumed at least 50% less power, meaning it offsets half of the carbon dioxide emissions, furthermore, it draws 75% lesser critical peak kWp power, which means it has strong potential to obviate the need for heavy investments in electrical infrastructures, ultimately contributing to mitigating rapid electricity price rises.

TRNSYS Simulation of a Solar Cooling System for the Hot Climate of Pakistan

Cooling is a basic need for buildings in hot and sunny climates. In most countries the major source of cooling is electrical power based. During summer in hot climates there is an increase in electricity consumption due to cooling load. Pakistan is facing an electricity shortage crisis, which becomes worse in summer due to the high demand for cooling. The annual average insolation for Pakistan is 5-6 kWh/m2/day, reaching 6-8 kWh/m2/day in summer with sunshine of 10-13hours a day, which gives suitable conditions for solar powered cooling system operation. TRNSYS software provides the possibility to simulate a complete solar air conditioning system integrated with a building. In this study, TRNSYS is used to model an absorption chiller operated by hot water from an evacuated tube collector. It is found that, with a hot water storage tank, a collector area of 12 m2 is sufficient to maintain the temperature in a room in a typical house at or below 26°C during the cooling season.

Life cycle Cost of Standalone Solar Photovoltaic System Powering Evaporative Cooler and Heat Pump Water Heater for Australian Remote Homes

Deploying standalone solar air-conditioning systems in residential buildings forms a radical demand-side energy management solution for eliminating the peak electricity demand from residential air-conditioning. For existing grids to meet this demand a correspondingly major investment is required to extend the capacity of the infrastructure. For any standalone solar air-conditioner to become acceptable to individual residents, it needs to be cost competitive with buying electricity from the grid. For dry climate regions such as South Australia, evaporative coolers (EVAP-C) can handle the building space cooling load sufficiently and require only small amounts of power to operate. Thus, the need here is for a small capacity standalone photovoltaic system (SPVS), and corresponding less investment. Since evaporative coolers switch off in winter and SPVSs have massive excess power, a significant amount of the SPVS's power is dumped. To augment the SPVS's economic feasibility with a little oversizing, the SPVSs can also power a domestic heat-pump water heater (HP-WH) throughout the year, which in return benefits householders by obviating the need to purchase hot-water heating energy. This study, aims to techno-economically optimize the size of the components comprising an SPVS powering EVAP-C and HP-WH to meet the demand of a typical Australian house model, and for two widely different climates. The study was performed with modelling and simulation using TRNSYS then coupled with GenOpt to carry out system optimization. A comprehensive economic evaluation of the most optimized system size revealed that, for an on-grid house, taking into account current purchase costs of components and cost of power in Australia, even for a low energy consumption air-conditioner such as an EVAP-C, even when coupled with HP-WH, a SPVS is still not cost competitive to the cost of purchased the same amount of power from the grid. However, for future off-grid houses, not presently, wherever SPVS's are up taken, they will obviate the equivalent resulting charges for augmenting the capacity of the grid infrastructure. Optimized SPVSs have the potential to become gradually grid cost competitive while electricity prices continue to rise and component costs drop. How soon this will occur, depends on the electricity price inflation rate in Australia, our economic evaluation has forecasted this to be around the twenty year mark.

Performance evaluation for solar liquid desiccant air dehumidification system

In this paper, a solar liquid desiccant air conditioning (SLDAC) system has been studied. The effect of changing evacuated tube collector area on the performance of the SLDAC system was fulfillment. This inquest was done over all a year in Borg Al-Arab city located in the Northern region of Egypt. Meteorological data, such as hourly average solar radiations and temperatures, were needed to achieve this research. The hourly cooling loads were determined by using Hourly Analysis Program (HAP) 4.7. These loads are wall, illumination, people, and equipment loads. Then, the hourly differences of different parameters such as amount of water absorbed in conditioner, amount of water desorbed in regenerator, hot water temperature and coefficient of the performance were calculated.In addition, the maximum solar thermal energy was determined to meet the regeneration demand according to the hourly average solar radiation data. For 220m2 evacuated tube collector area, the maximum required heat energy is obtained as 38,286kWh on December, while using solar energy, will save energy by 30.28% annual value.

Solar Air-conditioning System in University of Indonesia

Solar Air-conditioning System in University of Indonesia

Solar driven air conditioning and refrigeration systems corresponding to various heating source temperatures

Solar driven air conditioning systems can cope with solar collectors working in a wide range of temperatures. Sorption systems, including absorption and adsorption refrigeration systems, are among the best choices for solar cooling. Five systems including modular silica gel–water adsorption chiller, single/double effect LiBr–water absorption chiller, 1.n effect LiBr–water absorption chiller, CaCl2/AC (activated carbon)–ammonia adsorption refrigerator, and the water–ammonia absorption ice maker with better internal heat recovery were presented. The above five sorption chillers/refrigerators work under various driven temperatures and fulfill different refrigeration demands. The thermodynamic design and system development of the systems were shown. All these systems have improvements in comparison with existing systems and may offer good options for high efficient solar cooling in the near future.

DESIGN a solar hybrid air conditioning compressor system

This thesis presents the investigation into the feasibility of solar assisted vapour compression air conditioning system in providing thermal comfort in Malaysia. Conventional vapour compression air conditioning system consumes large amount of energy which is a clear disadvantage considering the high fuel price and electric tariff. Therefore, this research was intended to develop and integrate solar hybrid system into conventional air conditioning system which provides the same cooling load with considerably less electricity demand. In addition, Microsoft Excel spreadsheet is also prepared to facilitate the calculation of refrigerant temperature and energy saving of the system. DC compressor and evacuated tube solar compressor is introduced to assist the electric compressor in compressing the refrigerant, effectively reducing the air conditioning electricity consumption by up to 45%. Meanwhile, during night time, energy saving is only contributed by the DC compressor which reduces electricity consumption by up to 25%. The development and utilization of solar energy reduces the dependency on energy generation from fossil fuel which emits greenhouse gases and worsen the global warming while also pushing Malaysia one step closer to their aim in reducing CO₂ emissions and harnessing renewable energy. Malaysia as a tropical country with average solar radiation of 4500Wh/m² per day, has endless potential in solar energy (Borhanazad, 2013). This project provides technical overview which involves the study of solar energy conversion system and viability of solar hybrid vapour compression air conditioning system under Malaysia climate.

A review on the recent development of solar absorption and vapour compression based hybrid air conditioning with low temperature storage

Conventional air conditioners or vapour compression systems are main contributors to energy consumption in modern buildings. There are common environmental issues emanating from vapour compression system such as greenhouse gas emission and heat wastage. These problems can be reduced by adaptation of solar energy components to vapour compression system. However, intermittence input of daily solar radiation was the main issue of solar energy system. This paper presents the recent studies on hybrid air conditioning system. In addition, the basic vapour compression system and components involved in the solar air conditioning system are discussed. Introduction of low temperature storage can be an interactive solution and improved economically which portray different modes of operating strategies. Yet, very few studies have examined on optimal operating strategies of the hybrid system. Finally, the findings of this review will help suggest optimization of solar absorption and vapour compression based hybrid air conditioning system for future work while considering both economic and environmental factors.

Design of direct solar PV driven air conditioner

Solar air conditioning system directly driven by stand-alone solar PV is studied. The air conditioning system will suffer from loss of power if the solar PV power generation is not high enough. It requires a proper system design to match the power consumption of air conditioning system with a proper PV size. Six solar air conditioners with different sizes of PV panel and air conditioners were built and tested outdoors to experimentally investigate the running probabilities of air conditioning at various solar irradiations. It is shown that the instantaneous operation probability (OPB) and the runtime fraction (RF) of the air conditioner are mainly affected by the design parameter rpL (ratio of maximum PV power to load power). The measured OPB is found to be greater than 0.98 at instantaneous solar irradiation IT > 600 W m−2 if rpL > 1.71. RF approaches 1.0 (the air conditioner is run in 100% with solar power) at daily-total solar radiation higher than 13 MJ m−2 day−1, if rpL > 3.

Energy and Greenhouse Gas Emission Assessment of Conventional and Solar Assisted Air Conditioning Systems

Energy consumption in the buildings is responsible for 26% of Australia’s greenhouse gas emissions where cooling typically accounts for over 50% of the total building energy use. The aim of this study was to investigate the potential for reducing the cooling systems’ environmental footprint with applications of alternative renewable energy source. Three types of cooling systems, water cooled, air cooled and a hybrid solar-based air-conditioning system, with a total of six scenarios were designed in this work. The scenarios accounted for the types of power supply to the air-conditioning systems with electricity from the grid and with a solar power from highly integrated building photovoltaics (BIPV). Within and between these scenarios, systems’ energy performances were compared based on energy modelling while the harvesting potential of the renewable energy source was further predicted based on building’s detailed geometrical model. The results showed that renewable energy obtained via BIPV scenario could cover building’s annual electricity consumption for cooling and reduce 140 tonnes of greenhouse gas emissions each year. The hybrid solar air-conditioning system has higher energy efficiency than the air cooled chiller system but lower than the water cooled system.

Simulation of Solar Air-Conditioning System with Salinity Gradient Solar Pond

In hot dry climates, due to the high demand for space air conditioning during summer and the abundance of solar radiation, solar air conditioning is a promising approach to reduce the energy consumption and negative environmental impact of buildings. Solar cooling systems have used various types of collectors to drive chillers. In this paper, a salinity gradient solar pond is suggested as a collector to drive an absorption chiller, to provide cool air for a house during hot and dry weather. A coupled simulation between MATLAB and TRNSYS has been used to solve the problem. MATLAB code was written to solve the governing equations for the salinity gradient solar pond and the ground underneath it. TRNSYS software was used to model the solar cooling system including the absorption chiller and building. The weather data used was for Baghdad in Iraq. It was found that the salinity gradient solar pond could be used to drive the absorption chiller and produce cool air for a single family house during the summer period. Different solar pond areas were tested with the same chiller capacity. It was found that a solar pond area of approximately 400 m2 was required to provide satisfactory cooling for a typical house with a floor area of approximately 125 m2.

SOLAR MULTI-STAGE REFRIGERATION SYSTEMS. NEW DEVELOPMENTS AND POSSIBILITIES ANALYSISD GAS LOW-TEMPERATURE CONDENSATION PLANT

The developed schematics for the solar refrigeration systems, based on the use of absorbing cycle and solar energy for the regeneration of absorbent solution are presented in the article. Cascade (two-stage) principle of construction of contours is used with growth of concentration of absorbent on the stages of cascade. The solar absorbing systems in the basic variants of cooling and air-conditioning are developed. Heat-mass-transfer apparatus of film-type, entering in the complement of contours compatible and executed on the basis of multichannel compositions from polymeric materials. The features of film-type flows in the heat-mass-transfer apparatus of the basic solar systems are considered theoretically. Experimental research of processes of heat and mass transfer in the apparatuses of drying (absorber) and cooling (evaporated coolers of air and water of direct and indirect types) contours of the solar system is executed. On the basis of findings on efficiency of processes the comparative analysis of the solar refrigeration and air-conditioning systems possibilities is carried out. Positive influence of growth of concentration of absorbent from the first to the second stage of cooling is shown. The preliminary comparative analysis of the solar refrigeration systems possibilities is proposed.