Solar Absorption Refrigeration Research Articles

Experimental analysis and performance evaluation of a solar PV-driven diffusion absorption refrigeration system

Experimental analysis and performance evaluation of a solar PV-driven diffusion absorption refrigeration system

Thermodynamic characteristics of a novel solar single and double effect absorption refrigeration cycle

Solar absorption refrigeration systems provide one of the economical options for air conditioning. In order to reduce the complexity and economic cost, a more advanced solar single-double-effect switching system is proposed. The innovation of this system is that it replaces the single-effect and high-pressure generators in previously developed single-double-effect switching system with a specific generator. The optimal heat source switching temperature of the new system was determined by the genetic algorithm to be 125.5 °C. Compared with the original single-double-effect switching system, the average coefficient of performance of the system is increased by 8.6 %, and the fluctuation of refrigeration capacity during the switching period is reduced by 48 %. The new solar single-double-effect switching system is investigated based on thermodynamic characteristics, energy, exergy, and economy aspects. The results showed that heat exchangers of the system have strong coupling. The cooling water temperature has a greater impact on the performance of the dual-effect mode. In the single-effect mode, the special-pressure generator has the largest exergy destruction (39 %), while in the double-effect mode, the absorber has the largest exergy destruction (41 %). Besides, the economic analysis demonstrated that the new system is economically viable with a payback period of 9.33 years.

Investigation on hourly characteristics of solar absorption refrigeration cycle integrated with a dual-cooling grade-compression cycle

Solar absorption refrigeration cycle consumes almost no electricity, but its low refrigeration efficiency and intermittent operation issues need addressing. Based on the viewpoint of cold energy grade production matching air-conditioning cooling load grade, a solar absorption refrigeration cycle integrated with a dual-cooling grade-compression cycle (SARC-DGC) is proposed to boost the solar utilization and achieve all-weather cooling, which includes solar absorption refrigeration (SAR) subsystem, subcooled water circulating (SWC) subsystem and dual-cooling grade-compression refrigeration (DGR) subsystem. The simulation models of proposed cycle are developed by lumped-parameter and distributed-parameter methods, and the simulation results are validated with experimental results. The hourly characteristics of SARC-DGC cycle on a typical day are evaluated and compared with those of the conventional solar absorption refrigeration (SAR) cycle and air-cooled compression refrigeration (ACR) cycle. The results show that the hourly cooling performance of SARC-DGC cycle is well matched with the building cooling load demand, so as to realize the cold energy grade production and utilization. The working hours of SAR subsystem are 42.86 % longer than that of conventional SAR cycle, with a 31.92 % increase in daily cooling capacity, while the daily power consumption of the proposed cycle is on average 27.31 % lower than that of conventional ACR cycle.

Compression-assisted absorption refrigeration cycle employing organic working pairs for ultra-low grade heat recovery

Solar absorption refrigeration technology is considered an ideal alternative to energy-intensive refrigerated warehouses due to its decarbonization and environmental friendliness. However, it faces challenges in competing with vapor compression refrigeration, such as high driving heat source temperature (>100 °C) and a long payback period. In this paper, we address these challenges by focusing on cycle structure and working pair, and propose a compression-assisted absorption refrigeration cycle (CARC) using R32/dimethylacetamide (DMAC) as working pair. The aim is to significantly reduce driving heat source temperature by adjusting absorption pressure utilizing an auxiliary compressor, enabling the cycle to be connected to low-cost and efficient non-concentrating solar collectors, thereby effectively shortening its payback period. This cycle includes two operating modes: CARC mode powered by solar energy during the daytime and vapor compression refrigeration cycle mode driven by off-peak electricity at night, ensuring 24-hour cooling capacity for refrigerated warehouses. The results indicate that this cycle can flexibly utilize 60∼80 °C solar hot water easily obtained as driving heat source and its evaporation temperature decreases to -20 °C. To assess its performance benefits, a compression-assisted absorption refrigeration system is developed and implemented. By utilizing the limited roof area of a refrigerated warehouse, it can achieve an 18.2 % reduction in electricity consumption and a 24.2 % reduction in carbon emissions compared to the vapor compression one annually. Additionally, during peak electricity demand periods in summer, the system exhibits significant energy-saving effects, and its payback period is about 4.2 years. Ultimately, this cycle provides a viable solution for energy-saving and emission reduction in refrigerated warehouses.

Study on the thermodynamic performance of solar absorption refrigeration combined with a ‘seasonal cold storage’ system

Inter-seasonal thermal storage technologies are focused on storing and transitioning abundant solar energy from summer to winter for heating, often ignoring the fact that abundant cold energy in winter can also be transferred to summer for cooling. In this paper, a novel solar absorption refrigeration combined with a ‘seasonal cold storage’ system is proposed to store abundant ambient cold energy in the form of chemical potential in winter and is utilized to discharge energy for refrigeration in summer. Moreover, based on the thermophysical properties of LiBr/H2O, LiBr-[BMIM]Br/C2H5OH and LiBr-[BMIM]Cl/CH3OH, the thermodynamic performances under various operating conditions were calculated via MATLAB. The results show that the system using LiBr-[BMIM]Cl/CH3OH obtained a larger energy storage density of 339.22 kJ·kg−1 below the ice point without freezing compared to traditional ice storage. The systems using LiBr-[BMIM]Br/C2H5OH and LiBr-[BMIM]Cl/CH3OH achieved higher coefficients of performance of 0.94 and 0.90, respectively. Moreover, the generation temperature of the system using both the ternary working pairs was below that of LiBr/H2O by more than 5 K, which was beneficial for enhancing the utilization of solar energy and saving the collector area. Overall, this new system using LiBr-[BMIM]Cl/CH3OH exhibited the shortest payback period of 2.73 a, with considerable economic benefits.

Modeling and exergy-economy analysis of residential building energy supply systems combining torrefied biomass gasification and solar energy

A novel hybrid energy system driven by torrefied biomass gasification and solar energy is proposed for the first time, and their complementarity to enhance the system’s energy efficiency is analyzed and shown. The system mainly combines biomass torrefaction, biomass gasification subsystem, solar heat collection and absorption refrigeration technology. The effects of different operating parameters on the gasification products were studied. The economic analysis is carried out based on the theory of exergy economy. The results show that torrefaction pretreatment of biomass can significantly improve its fuel quality and gasification performance. With the increase of torrefied temperature, the volume fraction of CO2 and H2 decreased while the volume fraction of CH4 and CO increased. The economic analysis shows that the expected annual income is $72,735, and the investment recovery period is 2.89 years. Through the calculation of the energy-saving and environmental benefits, it can be concluded that the hybrid energy system can save 1.05 × 106 MJ of heat per year. This equates to about 358.26 tons of standard coal or a CO2 emission reduction of 550.59 tons, the participation of solar energy is conducive to the system emission reduction. By tuning the parameter sensitivity, the influence of biomass price change on the unit exergy cost of system products was more obvious.

Modeling and simulation of a solar absorption refrigeration machine operating with lithium chloride water coupled (H2O-LiCl)

Modeling and simulation of a solar absorption refrigeration machine operating with lithium chloride water coupled (H2O-LiCl)

Multi-Objective Optimization Research on the Integration of Renewable Energy HVAC Systems Based on TRNSYS

Well-designed passive buildings can drastically reduce building energy consumption, and optimal design of air conditioning systems is the key to achieving low operating energy consumption in near-zero energy buildings. TRNSYS was used to build the simulation model for a near-zero-energy building and its air conditioning system in Beijing. The Taguchi method was used to sort the design parameters that affect system performance according to the degree of influence and find the best combination of design parameters to optimize the system, which increased the solar fraction of the system by 4.6% and reduced the annual operating energy consumption by 7.32%. For the optimized system, a multi-objective optimization function of the life cycle costs and carbon emissions was established. By comparing the energy consumption, life cycle costs, and carbon emissions of the air conditioning system under different system configurations, optimal configuration solutions under different design target weights were obtained. It was found that using a ground source heat pump system + solar collector system had better energy-savings benefits, but the operating costs were slightly higher. The application of absorption refrigeration can reduce the system operating costs but will increase the initial investment. The best economic benefits were achieved using the ground source heat pump system + solar collector system for heating in winter and the ground source heat pump system for cooling in summer, and the best environmental benefits were obtaining using the ground source heat pump system + solar collector system for heating in winter and the ground source heat pump system + solar absorption refrigeration system in summer, which provides a reference for the optimization design and research of air conditioning systems in near-zero energy buildings.

Energy–exergy analysis for performance improvement of Brayton–Rankine combined cycle system by utilizing a solar absorption refrigeration cycle (case study: Kahnuj Combined Cycle Power Plant)

AbstractGas–steam combined cycle power plants are the most efficient electricity‐generation units based on fossil fuels. However, these power plants are prone to efficiency decrease in hot climates as high ambient temperatures adversely influence the gas turbine's output. The present study investigated the effect of incorporating a solar absorption refrigeration (SAR) system into an actual combined cycle power plant for the first time. First, the energy and exergy analyses were performed using THERMOFLOW software. Then, the influence of the ambient temperature (10°C–52.5°C) on the power plant's performance and its components was investigated. The SAR system was then used to cool the compressor's input air and improve the power generation capacity by employing TRNSYS software. The results showed that the power plant reached its maximum efficiency at an ambient temperature of 26.6°C. However, its overall efficiency and net power generation were dropped with a further increase in the ambient temperature. Employing the SAR system for each gas turbine in the power plant on a sunny day until 2 p.m. would decrease the compressor's input air temperature. For example, for the refrigeration capacities of 450, 700, and 1000 tons for each gas turbine, the temperature was reduced by nearly 3°C, 5°C, and 7°C, respectively. Under the same condition, power generation capacity improved by 12.5, 24, and 32.5 MW, and the overall efficiency rose by 0.6%, 1.4%, and 2%. Such an increase in power and efficiency occurred during peak demand, which was significant.

Enhancement of Condenser Performance in Vapor Absorption Refrigeration Systems Operating in Arid Climatic Zones—Selection of Best Option

Generators and condensers are the two vital equipment items that determine the output of vapor absorption refrigeration systems. Arid weather conditions produce a significant reduction in the performance of the vapor absorption refrigeration cycle due to low condenser heat dissipation despite high generator temperatures. Although numerous studies on condenser cooling methods in vapor compression systems have been reported in the literature, solar-operated vapor absorption systems have not been studied. Limitations in generator temperatures of solar-operated vapor absorption systems necessitate a focused study in this area. This study makes the selection of the best choice for condenser cooling from among four different condenser cooling methods which have an impact on the performance of the vapor absorption refrigeration system for effective cooling using solar energy. A solar vapor absorption refrigeration system working with low-grade heat using a compound parabolic collector is considered in this study. Analysis of a vapor absorption refrigeration system for cooling in arid weather conditions is carried out using different condenser cooling methods with Engineering Equation Solver. Initially, the model used in the study is compared with a similar study reported in the literature. Techniques considered are air, water, evaporative, and hybrid cooling techniques. The performance of the vapor absorption cooling system was analyzed using experimental values of a solar compound parabolic collector obtained from real-time measurements for simulating the model. Results show that water cooling can provide suitable condenser cooling and improve the coefficient of performance of the solar vapor absorption refrigeration system using the solar collector. The water-cooled condenser has 1.9%, 3.3%, and 2.1% higher COP when compared to air-cooled condensers for spring, summer, and autumn seasons respectively, whereas the water-cooled condenser cooling recorded 6%, 14%, and 8% higher COP relative to the evaporative cooling method. Cost comparison showed maximum cost for water-cooled condensers and minimum cost for hybrid-cooled condensers. The effect of each cooling method on the environment is discussed.

Solar Powered Air-Conditioning Using Absorption Refrigeration Technique

The present work includes design, construction and operates of a prototype solar absorption refrigeration system, using methanol as a refrigerant to avoid any refrigerant that cause global warming and greenhouse effect. Flat plate collector was used because it’s easy, ninexpensive and efficient. Many test runs (more than 50) were carried out on the system from May to October, 2013; the main results were taken between the period of July 15, 2013 to August 15, 2013 to find the maximum C.O.P, cooling, temperature and pressure of the system. The system demonstrates a maximum generator temperature of 93.5 oC, on July 18, 2013 at 2:30 pm, and the average mean generator temperature Tgavr was 74.7 °C, for this period. The maximum pressure Pg obtained was 2.25 bar on July 19, 2013 at 2:00 pm. The current system shows cooling capacity of 0.15 ton with coefficient of performance of 0.48, and minimum evaporator temperature obtained was 14.2oC. A comparison of the present with previous works, showed that most of the previous work used ammonia as the main refrigerant, and even that used methanol it was as aqua methanol, or to be part of pair refrigerant, while the present work use the methanol as the main and the only refrigerant in the system. The results and the factors that provided by the current work, give a good understanding for using the methanol as a refrigerant with the solar absorption system. And the system can work in continuous operation cycle. This work gave fundamental understanding for designing solar refrigeration system, by using the results of present study to design air-conditioning unit, with one ton capacity, using the solar energy, and the methanol as a refrigerant.

Performance of Solar Hybrid Cooling Operated by Solar Compound Parabolic Collectors under Weather Conditions in Riyadh, Kingdom of Saudi Arabia

The scientific aim of this work is to encourage energy conservation. This article offers a fresh perspective on renewable energy in the air conditioning sector, the country’s economic growth, and environment-friendly techniques to overcome global warming challenges. In this research, a solar vapor absorption refrigeration (SVAR) system was combined with a conventional vapor compression refrigeration (VCR) system to analyze their combined performance, employing a compound parabolic collector (CPC). The goal was to assess the performance of a solar hybrid cooling system using this non-tracking solar collector. CPC was validated for heat output with 2.9% uncertainty by utilizing an engineering equation solver (EES). Other system components were also validated with EES and then extended to a larger-capacity solar hybrid cooling system. The results of this research indicate that CPC is effective in providing the required heat to SVAR throughout the year without any tracking, and the integration of SVAR in series with the VCR condenser produces 83% higher COP than the system that integrates VCR with the condenser of the SVAR system for Riyadh. The configuration results in high values of exergy COP and an efficiency of 88% and 84%, respectively, increases the cooling capacity of the VCR by 68%, and decreases the carbon emission by 166.4%.

Optimization and Analysis of an Integrated Liquefaction Process for Hydrogen and Natural Gas Utilizing Mixed Refrigerant Pre-Cooling

Liquefying hydrogen is an efficient way to store and transport hydrogen. However, the hydrogen liquefaction process is energy intensive. Therefore, an integrated liquefaction process of hydrogen and natural gas utilizing the mixed refrigerant cycle and the hydrogen Claude cycle is proposed. The process not only couples a steam methane reforming process to produce hydrogen and a carbon dioxide refrigeration cycle to assist in pre-cooling, but also employs a solar energy absorption refrigeration system to enhance energy efficiency. The proposed process is simulated and optimized using HYSYS and the particle swarm optimization algorithm, and energy, exergy, and economic analyses are performed. The energy analysis shows that the specific energy consumption of the proposed process is 5.2201 kWh/kg, a reduction of 10.67% compared to the base case. The exergy loss and exergy efficiency are 64,904 kW and 62.21%, which are 13.63% and 6.63% lower than the base case, respectively. The economic analysis shows that the total annualized cost of the process is USD 28.6 million per year. The proposed integrated liquefaction process not only realizes the high efficiency of energy utilization but also follows the development trend of integrated energy systems.

Investigations on Solar Powered Vapour Absorption Refrigeration based Air Conditioning

A solar-operated vapor absorption refrigeration cycle is environment-friendly refrigeration system that holds the potential to be used for refrigeration and air conditioning systems. Such a system requires a solar concentrator to run the vapor absorption refrigeration cycle using LiBr-H2O-based refrigeration/air conditioner for small capacity applications. With the solar-powered pumping process, this refrigeration system becomes completely free from electricity requirements. However, the limitations of all time solar radiation availability, low-pressure maintenance requirement of the LiBr-H2O system, low efficiency, and low COP as compared to other vapour compression refrigeration based air conditioning system are the key deterrents. In the present study, the modeling and analysis of various components used in the proposed arrangement of solar vapor absorption refrigeration - air conditioning system has been carried out to improve the performance It is seen that altering the geometrical property of the bubble pump, as well as heat input through a solar concentrating collector, use of hydrogen as a third fluid increases the rate of evaporation which in turn increases the cooling effect as well as COP of the cycle. At 54% concentration of LiBr and 4.5kW heat input, the COP of the proposed layout is found to be 0.61.

Mathematical modeling and performance analysis of a solar assisted vapour absorption refrigeration system

Climate change is the hottest topic today on earth. Traditional HVAC’s harm the environment and stand out to be a major contributor to global warming. One of the many techniques to mitigate the current climate crisis is by utilizing the abundantly available solar radiation. Solar evacuated tube collectors are used to absorb solar radiation. This solar power is used to provide solar cooling technologies. Unlike the conventional HVAC’s thermally driven absorption cooling is a boon in today’s era. In the following research work, the study aims to provide numerical modeling of a solar assisted air-conditioning unit through the first law of thermodynamics using mass balancing equations for the province of Delhi in July. This research work’s aim is to build and evaluate a Li-Br absorption cooler with a capacity of 1 KW. This paper aims to provide characteristic design features of components and measures the efficiency of the system at operating conditions. PCM based thermal energy storage tank is adopted which helps to supply cold air even at no sunlight hours. As a result of this research study, such solar assisted air conditioners turn out to be a chosen solution for sustainability.

Analytical modelling of food storage cooling with solar ammonia-water absorption system, powered by parabolic trough collectors. Method

The study presents a new analytical model capable to reveal the thermal behaviour of all the components of the solar ammonia-water absorption system, powered by parabolic trough collectors, serving different types of food storages: refrigeration chamber, refrigerated food storage, freezing chamber and frozen food storage. The heat inputs, that determine the total cooling load, for each food storage spaces consist of: heat gains through walls, heat gains through ventilation (fresh air), heat that must be dissipated from the stored products (technological cooling load required to cool down the products) and heat gains through operation. The influence of the number of solar parabolic trough collectors and of the storage tank size on different parameters of the refrigeration plant are investigated under low and high storage temperatures.•Food cooling with solar absorption refrigeration system.•Hourly based variation of NH3-H2O solar absorption system performances.•Long term simulation of solar absorption cooling for refrigeration and cooling.

Multi-objective evolutionary optimization and thermodynamics performance assessment of a novel time-dependent solar Li-Br absorption refrigeration cycle

Multi-objective evolutionary optimization and thermodynamics performance assessment of a novel time-dependent solar Li-Br absorption refrigeration cycle

Simulation of solar absorption refrigeration cycle with CuO nanofluid for summer cooling of a residential building

• A H 2 O/LiBr absorption refrigeration cycle is integrated with trough collector. • Constant magnetic field and nanoparticles increase the system‘s heat transfer. • Performance of the system‘s energy for supplying a building is evaluated. • The temperature of the outlet water from the solar collector increases by 7 °C. The purpose of this study is to design a solar cooling system to provide the cryogenic load of a residential building. The heating cycle of a system comprises a solar trough collector, heat storage as a hot water tank, and a heat exchanger to transfer heat to the absorption cooling system converter. A constant magnetic field is used in the solar trough collector and fan-coil to increase heat transfer from magnetic nanoparticles in the collectors and nanorefrigerants in the absorption chiller evaporator. The system performance is modeled and simulated using TRNSYS. In general, the annual efficiency of the solar trough collector is above 40 %. If a magnetic field with 0.5 % nanofluid volume concentration is applied, it is seen that the maximum energy absorbed by the solar collector in the system increases by more than 250 kJ/h. However, the maximum room temperature is decreased by 2 ℃ compared to the case in which the improvements are not applied, and the minimum temperature is decreased from 12 ℃ to 9 ℃, indicating a 3 ℃ reduction. The maximum received energy occurs for a 770 T magnetic field with a nanofluid volume concentration of 0.5 %, where the received energy is 7000 kJ/h.

Simulation of an improved solar absorption refrigeration system with phase change materials

Aiming at the problems of low solar energy utilization rate, poor intermittent, low stability and poor energy saving effect in traditional solar absorption refrigeration system, a lithium bromide-water absorption refrigeration system driven by solar in Tai’an was taken as the research object. An improved solar absorption refrigeration system with phase change was presented. In typical day and whole refrigeration period, the traditional solar absorption refrigeration system with and without phase change were simulated by TRNSYS transient simulation software. Their collector efficiency, unit cooling capacity and COP were comparatively analyzed. The results showed that the collector efficiency of the improved solar absorption refrigeration system with phase change was 4.2% higher than that of the traditional solar absorption refrigeration system without phase change. The unit cooling capacity was 2.8% lower than that of the traditional system, which store the excess cooling capacity with the help of PCMs. The average COP of traditional absorption system and improved solar absorption refrigeration system were 0.737 and 0.679, respectively. This manuscript provides a theoretical basis for the development of solar phase change heat storage absorption refrigeration system.

Influence of disturbances in the operating conditions on the refrigeration performance of a regenerative solar absorption refrigeration system with a biomass assisted combustion device

To reduce the fluctuation of the heat source water temperature and ambient temperature caused by variations in solar radiation, a solar absorption refrigeration system with a supplementary biomass combustion device for the office area of a factory was designed. A numerical model of the solar energy absorption refrigeration system based on the Aspen Plus software was developed. In particular, the effects of the heat source water temperature, condenser temperature, evaporation temperature, and dilute solution flow rate on the cooling capacity, coefficient of performance, unit equipment duty, and generator temperature during actual operation were investigated. The heat load of each piece of equipment in the unit were found to increase correspondingly with the increase of the heat source temperature when the evaporating temperature and condensing temperature are constant. The coefficient of performance of the unit decreased as the condensing temperature increased keeping the temperature of the heat source constant. The results demonstrated that the flow rate of the dilute solution has effects on the occurrence temperature, cooling capacity, and the unit performance coefficient.