Solar Absorption Air Conditioning System Research Articles

Design of solar thermal absorption air conditioning system using CO2 with synthetic building load

Traditional air conditioning and refrigeration solutions rely on compressor-driven systems, leading to increased electricity consumption and intensified greenhouse gas (GHG) emissions. These systems primarily utilize synthetic refrigerants such as CFCs, HCFCs, and HFCs. Despite their advantages, these refrigerants are either banned or subject to restricted permissions under the Montreal Protocol (1987) and the Kyoto Protocol (1997) due to environmental concerns. According to the Paris Accord, ratified by 196 parties as of 2017, there is a global shift towards low global warming refrigerants and eco-friendly alternatives. COP27 reaffirmed global commitments to limit temperature rise to 1.5 °C, emphasizing urgent action and stronger climate plans to combat global warming. CO2 envisaged by ASHRAE is resurrected as a promising natural refrigerant with the advent of high-pressure technologies the design employs a solar evacuated glass tube collector (EGTC) with U-shaped copper tubes and flat plate collector (FPC) to harness solar thermal energy. An immersed heat exchanger's (HX) based thermal storage tank is incorporated to address the intermittency of solar energy. The CO2 refrigerant offers advantages over other natural refrigerants due to its low critical point.This research conducts a TRNSYS® simulation of a 35.2 kW absorption cooling system with synthetic building load driven by energy captured through FPC and EGTC using R-744, additionally supported by a supplementary boiler for traditional office timing. The system design comprises two solar collectors, the EGTC and FPC, integrated with two different cooling loop configurations (C1 and C2). In C1, the hot water that exits the generator of the absorption chiller is forwarded toward the immersed HX-based hot storage tank, which is connected to the solar and absorption cooling loop. In C2, the working fluid leaving the absorption chiller is diverted directly toward the auxiliary boiler/furnace, if the temperature in the storage tank falls below the necessary level (108.89 °C) and if the tank temperature is greater than this set point temperature, then the flow passes through the storage tank. Both system designs have been developed using TRNSYS, with dynamic simulations conducted throughout the summer.The solar fraction and collector efficiency are considered as key performance indicators to evaluate and compare the system's effectiveness. Then the optimization of system parameters is performed for all four cases (EGTC C1 & C2 and FPC C1 & C2) based on these key performance indicators, all configurations integrated with a fixed synthetic building cooling load. The optimum parameters are found for all four cases, and the optimum parameters for EGTC C1 & C2 are 100 m2, 4 m3, and 11° for collector area, storage tank volume, and collector slope respectively. Similarly, for FPC based configurations, these parameters are 200 m2, 32 m3 for C2 and 4 m3 for C1, and 20° respectively. The results revealed better C2 performance than C1, with EGTC outperforming FPC. The final results were computed for the EGTC based designs due to their high solar fractions, with EGTC C2 emerging as the optimal configuration, achieving a seasonal solar fraction of 0.649.

Modeling and simulation of absorption solar air conditioning to reduce energy consumption: A case of some cities in tropical region

Buildings are one of the most important infrastructure sectors in today’s society. However, in Madagascar, most hotels, malls, hospitals use fossil fuels to meet energy needs, especially in the traditional air conditioning system. they consume a considerable amount of energy that has negative effects on the environment. The emergence of solar cooling systems is a very interesting solution to this problem because the use of renewable energies in this sector contributes to a significant reduction of greenhouse gas emissions in the environment. Madagascar is one of the countries with high renewable energy potential, notably solar energy estimated at 2000kWh/m².an.At present, the rate of exploitation of this potential for the operation of the solar absorption cooling system coupled with the building is still non-existent. This energy is clean, sustainable, profitable and environmentally friendly. This is the main objective of this work which uses this energy source to ensure thermal comfort in a building in Madagascar and contributes to the development of this system. The TRNSYS software helped us to model and simulate this system.  To do this, first we will select 4 big cities of the big island, a building of total surface 80 m² was used. Then, the hourly thermal loads of this building for the whole year were simulated using the TRNbuild sub-program using meteorological data for a typical year of the selected cities. The dimensions of the components of the solar absorption air conditioning system were obtained using the maximum loads of the building. The results of the simulations show, the system meets the cooling load needs of the building with the climatic conditions of each selected city.

Simulation of a solar absorption air conditioning system for a tropical wet region in Brazil

Simulation of a solar absorption air conditioning system for a tropical wet region in Brazil

Simulation of a solar absorption air conditioning system for a tropical wet region in Brazil

Simulation of a solar absorption air conditioning system for a tropical wet region in Brazil

A case study of thermal analysis of a solar assisted absorption air-conditioning system using R-410A for domestic applications

Sustainable future and green environment goals quest for the development of technologies to utilize renewable energy resources to power the people. This study focuses on the designing, modelling, and simulation of an absorption solar air-conditioning system. Key performance parameters are identified, optimized for maximum efficiency and simulated in transient energy simulation software TRNSYS ®. The designed model comprises five thermal loops: a solar loop consisting of an evacuated glass tube solar collector having R-410A as heat transfer fluid in it and a heat exchanger heat tank, second loop has an absorption chiller, and an auxiliary furnace with hot water stream, third is the cooling tower loop, the fourth loop is of chilled water from the chiller and the final thermal loop is for air delivery of cooling to each room. The system is simulated using Lahore, Pakistan's climate conditions and offered a good tendency for the proposed system to meet air-conditioning demand at the domestic level. The average collector outlet temperature value of 78 °C has been recorded throughout the week. Collector provides useful energy gain at an average rate of 71,065 kJ/h. Average storage tank temperature at the outlet of heat exchanger is 92°C. Average room temperature values of three rooms are 27°C, 30°C and 19°C respectively.

Performance evaluation of a solar absorption air conditioning system under arid climatic conditions

The main objective of the present work is to evaluate the performance of a solar absorption air conditioning system for a supermarket under arid climatic conditions (e.g., Hurghada city (27.26 oN, 33.81 oE), Egypt). To achieve this objective, TRNSYS software as a simulation tool based on the mass and energy conservation equations is used. Model validation showed that an acceptable agreement between the simulated and actual results with an overall annual error 8.4%. Reported results indicated that the annual cooling load and maximum instantaneous cooling load are 463 Wh/m 2and 173 W/m2. Also, the results revealed that solar collector area of 900 m 2, storage tank volume of 25 m3 and collector flow rate 5 kg/h.m2 with annual solar fraction of 0.52 are required.

Thermo-Economic Evaluation of Aqua-Ammonia Solar Absorption Air Conditioning System Integrated with Various Collector Types.

The main objective of this paper is to simulate solar absorption cooling systems that use ammonia mixture as a working fluid to produce cooling. In this study, we have considered different configurations based on the ammonia–water (NH3–H2O) cooling cycle depending on the solar thermal technology: Evacuated tube collectors (ETC) and parabolic trough (PTC) solar collectors. To compare the configurations we have performed the energy, exergy, and economic analysis. The effect of heat source temperature on the critical parameters such as coefficient of performance (COP) and exegetic efficiency has been investigated for each configuration. Furthermore, the required optimum area and associated cost for each collector type have been determined. The methodology is applied in a specific case study for a sports arena with a 700~800 kW total cooling load. Results reveal that (PTC/NH3-H2O)configuration gives lower design aspects and minimum rates of hourly costs (USD 11.3/h) while (ETC/NH3-H2O) configuration (USD 12.16/h). (ETC/NH3-H2O) gives lower thermo-economic product cost (USD 0.14/GJ). The cycle coefficient of performance (COP) (of 0.5).

Solar absorption air conditioning systems based on low temperature evaporative air coolers

The purpose of the study is to develop circuit solutions for alternative air conditioning systems based on the use of low-temperature air coolers. The authors developed circuit diagrams of such air coolers with a reduced limit of evaporative cooling of media from the temperature of the wet thermometer supplied to the cooling of the air flow to the dew point temperature. Air coolers are designed in separate and combined layout options. In this case, heat - mass transfer apparatus with a movable fluidized bed "gas - liquid - solid" were used as a promising direction for the development of heat and mass transfer equipment (HMT). This ensures stable operation in extreme conditions, when there is a risk of contamination and deposits on the working surfaces of HMT, as well as the intensification of heat and mass exchange processes and high uniformity of distribution of contacting gas and liquid flows in the HMT volume, especially for implementing processes in evaporative air coolers with direct placement of the heat exchanger in the apparatus. An experimental study made it possible to establish the optimal range of effective density of the packed elements for the implementation of heat and mass transfer processes in a movable nozzle, characterized by stability and homogeneity, a wide working area in terms of gas flow rate with a relatively small dynamic layer height. Based on the obtained experimental data, a comparative analysis of air conditioning systems based on a low-temperature evaporative air cooler - chiller is carried out. The developed solutions allow expanding the field of practical use of evaporative cooling methods, for example, providing air comfort parameters in the air conditioning system without involving traditional refrigeration equipment, as well as improving the basic environmental and energy characteristics of the developed systems.

Research on regeneration performance of the solar steam method for absorption air-conditioning system

Solar absorption air-conditioning system is a hot spot for solar energy application. The key to high system performance lies in the improvement of energy utilization efficiency. On this purpose, the solar steam regeneration method has been proposed: adopting material with special structure, it locates solar energy in the event of evaporation and minimizes heat loss. However, this method has only been applied on evaporation of pure water, no researches have yet been made on absorbent solutions. To reveal the actual performance of this method for absorption system, both theoretical and experimental work have been done in this paper. Models have been developed and some important parameters have been investigated. Preliminary test of the regeneration process has been carried out. Through analysis, the paper exposes the influences of the solution concentration and absorbent variety. With the solar steam method, the efficiency has been increased by 2 or 3 times, approached 40% in experiments. Beyond higher performance, this new method also has advantages on cost and stability, making it a competitive choice for future application.

Possible application of solar steam regeneration method in absorption air-conditioning system

In recent years, solar absorption air-conditioning system have become an important directions of solar energy utilization. Improving solar energy utilization efficiency can effectively solve the problems of energy crisis. In traditional thermal method, low efficiency suffer from the heat loss and the cost is expensive. To improve solar energy utilization efficiency, a solar steam regeneration method was proposed: with corresponding material structure that can locate solar energy in the event of evaporation and minimize heat loss. The material structure has a high absorption in the solar spectrum, thermally insulating, hydrophilic surfaces and interconnected pores which allows the fluid flow to and from the structure. The solar steam regeneration method can be used in solar absorption air-conditioning system. Models have been developed and some important parameters have been investigated. The influence of concentration and absorbent variety has been analyzed in the experiments. Preliminary testing of the evaporation process has been carried out. It found the solar energy utilization efficiency with solar steam method has potential to further increase by 2 or 3 times. The solar energy utilization efficiency of the solar steam regeneration system approached 46%. That indicates it a promising choice for solar desalination and absorption system.

Performance evaluation and life cycle analysis of new solar thermal absorption air conditioning system

The aim of this project is to design a solar thermal absorption air conditioning system that operates under UAE climate conditions. In absorption system, compressor which is normally used in conventional AC system, replaced by a chemical cycle that consists of a generator, absorber, pump, and expansion valve, while the rest of the components such as the evaporator, condenser, and expansion valve remain the same as conventional AC system. In this design, the water and lithium bromide pair is used as a refrigerant and absorbent, respectively. The generator is driven by an evacuated solar collector to heat the lithium bromide in the chemical cycle, while a solar PV panel, which ensures that the system works 100% by solar energy, drives the pumps and fans. An energy storage device also incorporated in the system to run it round the clock. An experimental investigation of the proposed design is presented in the paper. Results suggest that the proposed design match well to meet the cooling load demand which was about 300 watts. Furthermore, the system able to provide a desired as well as uniform comforts temperature at about 23 °C inside the room. The system COP was calculated to be 0.51. Life cycle analyses were also carried out using Eco Audit CES Edu pack software to study the viability of the new design. The results showed that the proposed new system is economically viable and environmentally friendly.

Optimum operational strategies for a solar absorption cooling system in an isolated school of Mexico

In this work, we present the simulation study of a LiBr-H2O solar thermal absorption air conditioning system, installed in an isolated primary school in the community of Puertecitos, Mexico. The collection system consists of 110 m2 of evacuated tube solar collectors that produce the thermal energy needed to activate the chiller, while four cooling coils of 8.75 kW each cool the classrooms of the school with the chilled water produced. The characteristics of the system's equipment are used and a simulator is developed to determine the optimum operational strategies, given the conditions to which it will be subjected before the start-up of the plant. This is intended to ensure the comfort conditions of the students within the classrooms during the weekly class periods. The results show that the installed system is capable of satisfying the cooling needs of the school with the simulated strategies, but for a stable operation, periods of time must be dedicated for the recovery of energy inside the thermal storage tank. Some experiences are mentioned, both of the start-up and economic, related to an installation in an isolated community. The cost of the balance of plant was the highest with 36% of the total project, followed by the chiller and the solar field with 25 and 18%, respectively. The preliminary experimental results obtained during the implementation of the system are presented, where some of the operational strategies resulting from the simulation study can be confirmed.

Life cycle assessment of a solar absorption air-conditioning system

Abstract Environmental impacts of an experimental Solar Absorption Air-Conditioning System based on a Life-Cycle Assessment were evaluated for the first time in Mexico. For comparison, a Commercial Air Conditioning System that uses electricity from fossil fuels was also evaluated. In both cooling systems, the construction, operation and end-of-life stages were analysed. Environmental impacts were evaluated using the SimaPro® software and TRACI 2.1 method. Ten impact categories were analysed, among which the ecotoxicity, fossil fuel depletion, and global warming potentials represented the most important issues. A considerable reduction of environmental impacts was achieved by using the solar cooling system in comparison with those large impacts produced by the commercial cooling system. This reduction was due to the use of solar energy in contrast with the conventional cooling system which uses electricity sourced from fossil fuels. The main contribution of environmental impacts in the solar cooling system was the consumption of energy and raw materials for the construction, whereas for the commercial cooling system, the electricity consumption, and the use of refrigerant were the major impacts of the operation stage. An overall emission saving of ∼80% of the global warming potential as carbon footprint was obtained from the solar cooling system, whereas, for the fossil fuel depletion and ecotoxicity impact categories, a decrease of 85% and 20% was achieved, respectively. Further details of this environmental sustainability study are outlined in the present work.

Performance Study of Small Capacity Solar Autonomous Absorption Air-Conditioning System Coupled with a Low-Energy Residential Building Under Batna (Algeria) Climate

Solar absorption cooling technology has enormous potential for air-conditioning applications as the need for cooling coincides mostly with the availability of solar radiation. Due to the geographical nature and vast territory of Algeria and the presence of many isolated rural areas, there is a great need for autonomous systems that use only solar energy without auxiliary boiler to meet the cooling demand in summer. In this study, we propose a dynamic simulation model for solar autonomous absorption air-conditioning systems developed using the TRNSYS-EES software. The model used to study the feasibility and evaluate the functioning of the system under Batna, Algeria weather conditions. The proposed system uses solar thermal flat plate collectors to drive a small capacity single-effect LiBr/water absorption chiller to meet the cooling demand of a typical low-energy residential building covering a total floor area of 120[Formula: see text]m2. A model of 4.5[Formula: see text]kW commercial absorption chiller has been modeled with EES software. The validation results showed excellent agreement between the prediction and the experimental data ([Formula: see text]) and proved the model ability to predict the performance of the chiller. The analysis of dynamic results indicates that the proposed system and selected size enable the chiller to work for a duration of up to 10[Formula: see text]h a day. This allowed ensuring a sufficient and continuous cold water supply (between 8[Formula: see text]C and 18[Formula: see text]C) and maintaining the comfort temperature between 26[Formula: see text]C and 28[Formula: see text]C.

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.

Investigation of separate or integrated provision of solar cooling and heating for use in typical low-rise residential building in subtropical Hong Kong

In this study, the technical effectiveness of solar cooling and heating was investigated for typical low-rise residential building in the subtropical Hong Kong. Since water heating was required for domestic hot water supply rather than space heating, a separate or an integrated provision of solar cooling and heating could be considered. In the separate provision, cooling was handled by an independent solar absorption air-conditioning system, while water heating was offered by a packaged solar thermal collector already equipped with a storage tank. In the integrated provision, all the solar collectors and a centralized hot water storage tank were collectively applied for both driving the absorption chiller and generating domestic hot water. Through year-round dynamic simulation, it was found that the integrated provision could have annual primary energy saving of 13.5% against the separate provision. The effectiveness of the integrated provision was further verified through two energy-saving scenarios, with energy reduction by 17.7% and 18.0% correspondingly as compared to the separate provision. Under the synergistic effect of centralized thermal harness and storage, the integrated solar cooling and heating is more appropriate for typical low-rise residential application in Hong Kong.

Experimental studies on an air-cooled two-stage NH3-H2O solar absorption air-conditioning prototype

An air-cooled two-stage NH3-H2O absorption refrigeration system is proposed for potential application of residential small scale cooling system driven by solar heated hot water. It can reduce the initial fabrication and maintenance costs of both the solar collection system and the absorption chiller. An experimental prototype for 2 kW cooling capacity has been built to investigate the feasibility and performance of the proposed system. The experimental results indicate that the prototype operates smoothly and steadily. When the prototype is driven by 85 °C hot water with an evaporating temperature of 8 °C and ambient air temperature of 29 °C, its thermal COP and electric efficacy (ε) reach 0.21 and 5.1, respectively. COP stabilizes within the range of 0.18–0.25, and ε varies between 3.6 and 5.1 under air-conditioning conditions in summer, which are the right applications of air-cooled two-stage absorption systems. The study reveals the technical feasibility of the air-cooled two-stage NH3-H2O absorption system. It provides a way to develop low-cost small bulk solar absorption air-conditioning systems for residential applications.

Solar powered vapor absorption system using propane and alkylated benzene AB300 oil

This paper describes experimental work on a solar assisted vapour absorption air conditioning system using Propane (refrigerant) and Alkylated Benzene (AB300–refrigeration lubrication oil, absorbent). Preliminary experiments to assess the miscibility of propane in various lubricating oils namely Shell Clavus oils 32 and 64 and Alkylated Benzene oils AB150 and AB300 indicated that Propane is most miscible in Alkylated Benzene AB300. The vapour absorption system is a single stage absorption consisting of evaporator, absorber, generator and condenser. The system is equipped with heat pipes installed between the absorber and the pre-generator to recover the heat of absorption. The heat applied to the generator replicated the solar thermal energy based on the climatic conditions of Jamaica using flat plate collectors commonly used in Jamaica. Experiments at various evaporator, absorber and generator temperatures showed that the coefficient of performance of the system increases with increasing the generator temperature and with decreasing the absorber temperatures. The solar fraction for the flat plate collectors to produce the generator temperature needed to drive the absorption system is up to 50%.

The study of solar absorption air-conditioning systems

An air-conditioning system utilizing solar energy would generally be more efficient, cost wise, if it was used to provide both heating and cooling requirements in the building it serves. Various solar powered heating systems have been tested extensively, but solar powered air conditioning systems have received very little attention. Solar powered absorption cooling systems can serve both heating and cooling requirements in the building it serves. Many researchers have studied the solar absorption air conditioning system in order to make it economically and technically viable. But still, much more research in this area is needed. This paper will help many researchers working in this area and provide them with fundamental knowledge on absorption systems, and a detailed review on the past efforts in the field of solar absorption cooling systems with the absorption pair of lithium-bromide and water. This knowledge will help them to start the parametric study in order to investigate the influence of key parameters on the overall system performance.