Vapour Absorption Refrigeration System Research Articles

Energetic performance of a solar driven absorption refrigeration system integrated with humidification dehumidification desalination system

Integrating cooling and desalination systems with a single heat source is a shortcut technique to meet the shortage of fresh water and energy as well as enhancing the efficiency of energy utilization. In this paper, the energetic performance of a double effect vapor absorption refrigeration system integrated with humidification-dehumidification desalination system has been optimized·H2O–LiCl achieves higher system primary energy ratio and needs lower heat source temperature by 5 °C and 11 °C at evaporation temperature of 10 °C and 4 °C, respectively as compared with H2O–LiBr. Therefore, a parametric study has been performed to get the optimum operating conditions for the integrated system using H2O–LiCl as working pair by varying generation, condensation, and evaporation temperatures. The optimum system conditions are generation, condensation, and evaporation temperatures of 103 °C, 103 °C and 7 °C, respectively. The corresponding system COP, GOR and EUF are 1.471, 2.391 and 3.863, respectively. Finally, the transient performance of the proposed integrated system assisted by solar energy has been evaluated for Marsa-Matrouh city in Egypt. The proposed integrated system could save 71.2 % of the input energy without solar assistance and 88.5 % with solar assistance as compared with separated systems.

Investigation of a Hybridized Cascade Trigeneration Cycle Combined with a District Heating and Air Conditioning System Using Vapour Absorption Refrigeration Cooling: Energy and Exergy Assessments

The insufficiency of energy supply and availability remains a significant global energy challenge. This work proposes a novel approach to addressing global energy challenges by testing the supercritical property and conversion of low-temperature thermal heat into useful energy. It introduces a combined-cascade steam-to-steam trigeneration cycle integrated with vapour absorption refrigeration (VAR) and district heating systems. Energetic and exergetic techniques were applied to assess irreversibility and exergetic destruction. At a gas turbine power of 26.1 MW, energy and exergy efficiencies of 76.68% and 37.71% were achieved, respectively, while producing 17.98 MW of electricity from the steam-to-steam driven cascaded topping and bottoming plants. The cascaded plant attained an energetic efficiency of 38.45% and an exergy efficiency of 56.19%. The overall cycle efficiencies were 85.05% (energy) and 77.99% (exergy). More than 50% of the plant’s lost energy came from the combustion chamber of the gas turbine. The trigeneration system incorporated a binary NH3–H2O VAR system, emphasizing its significance in low-temperature energy systems. The VAR system achieved a cycle exergetic efficiency of 92.25% at a cooling capacity of 2.07 MW, utilizing recovered waste heat at 88 °C for district hot water. The recovered heat minimizes overall exergy destruction, enhancing thermal plant performance.

A Review of Multistage Vapor Absorption Refrigeration System Under Different Heat Sources

This review paper systematically analyzes the state-of-the-art developments, innovations, and applications of multistage vapour absorption refrigeration systems, emphasizing their adaptability to various heat sources. The manuscript navigates through the fundamental principles of vapor absorption refrigeration, highlighting the advantages and drawbacks of single-stage systems. It then delves into the intricacies of multistage systems and their potential to enhance performance and efficiency. Various configurations are explored, offering insights into the key factors influencing system performance. The core of the review revolves around the compatibility of multistage vapor absorption refrigeration systems with a diverse range of heat sources, including waste heat, solar energy, geothermal sources, and industrial processes. Furthermore, this review paper addresses the challenges, limitations, and future prospects of multistage vapor absorption refrigeration systems, paving the way for an informed discussion on the advancement of sustainable cooling technologies. Key Words: Gas energy sources, VARS, VCRS, Absorption cooling system.

Exergy-based sustainability analysis of combined cycle gas turbine plant integrated with double-effect vapor absorption refrigeration system

Exergy-based sustainability analysis of combined cycle gas turbine plant integrated with double-effect vapor absorption refrigeration system

Experimental investigation of diesel engine driven micro-cogeneration system integrated with thermal energy storage for power and space cooling

In this paper the performance and emission characteristics of thermal energy storage integrated micro-cogeneration system was investigated. This system was developed by connecting the vapor absorption refrigeration (VAR) system and thermal energy storage (TES) system with the exhaust gas pipe of a single-cylinder diesel engine. The vapor absorption refrigeration system has the cooling capacity of 500 W. A cabin of 1500 mm length, 1200 mm width and 1500 mm height was fabricated with proper insulation as space for cooling. The cabin temperature drop of 8.6 ℃ was achieved in 45 min. The cooling capacity of the VAR system was 302 W, and the COP of the VAR system was 0.398. The cabin temperature drop decrease with decrease in engine RPM but it was maintain stable (8.6℃) for 25 min by using TES. The overall efficiency of the cogeneration system was 1.79 % higher than the single generation. Hence, the result showed that the small capacity (5 kW) stationary diesel can be successfully converted into a cogeneration system to produce power and space cooling simultaneously.

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.

Performance evaluation of absorption cooling assisted transcritical CO2 refrigeration systems

Studies have shown appreciable improvements in system performance by subcooling the working fluid in transcritical CO2 refrigeration systems. The use of a dedicated vapour absorption refrigeration system (VARS) for subcooling the high side working fluid downstream of the heat rejection device is proved to be a viable option. The heat available in the discharged gas downstream of the compressor in the transcritical CO2 system is used to drive a LiBr-H2O VARS. This study examines the performance of an absorption cooling-assisted transcritical CO2 system. Three different configurations of the absorption system are considered, namely, single effect (SE), series double effect (DE), and series double effect with dual heat input (DEDH). The performance analysis is carried out for gas cooler exit temperatures (Tgc) ranging from 30 to 50 °C and evaporation temperatures ranging from -10 to 5 °C. The average COP improvement of the CO2 system is found to be 29 and 27% using SE and DEDH systems respectively.

Thermoeconomic and environmental analyses based single objective optimization of subcooled compression-absorption cascaded refrigeration system using evolutionary techniques

ABSTRACT This article analyses a subcooled compression-absorption cascaded refrigeration system (SCRS) in comparison with a standalone compression-absorption cascaded refrigeration system (CRS) based on thermoeconomic optimization. Three different absorbent solution/solution mixture-refrigerant combinations have been tested as working pairs in vapor absorption refrigeration system (VARS), whereas four environmentally friendly refrigerants have been utilized in vapor compression refrigeration system (VCRS). The total annual cost of the system is formulated using energy, exergy, and economic performance of the system and is minimized for optimal operational parameters by implementing five recent evolutionary optimization techniques. The effect of compression subcooling on various operational parameters of the cascaded system is reported. Amid all absorbent solution/solution mixture-refrigerant-refrigerant combinations, R290 combined with (CaCl2-LiBr-LiNO3)-H2O provides the minimum total annual cost of 13,164.8 US$ yr−1 and 15,401.9 US$ yr−1 for CRS and SCRS, respectively. Sanitized Teaching Learning Based Optimization (sTLBO) and Coyote Optimization Algorithm (COA) obtain the optimal total annual cost for most VARS-VCRS absorbent solution/solution mixture-refrigerant-refrigerant combinations. Though the coefficient of performance (COP) of an optimal SCRS is about 250% higher than its optimal CRS, higher compressor work results in a higher penalty cost for the optimal SCRS, which is almost 190% higher than the optimal CRS. A quick convergence is observed for sTLBO and COA.

Cogeneration system combining reversible PEM fuel cell, and metal hydride hydrogen storage enabling renewable energy storage: Thermodynamic performance assessment

The world is still largely dependent on oil and natural gas for its energy requirements which are harmful to the environment; therefore, it is high time that we look for alternative technologies for our growing energy needs. One such emerging area is fuel cell technology which produces clean energy in the form of electrical power. Integrating a Metal Hydride Hydrogen Storage (MHHS) system with a fuel cell can help increase energy efficiency. The heat dissipated during hydrogen absorption in MHHS can be used in other applications. In this paper, energy and exergy analysis of a fuel cell-based integrated system is performed. The system presents a Reversible Proton Exchange Membrane Fuel Cell capable of working in dual modes, i.e., as an Electrolyser as well as a fuel cell. The MHHS and Vapour Absorption Refrigeration System (VARS) are coupled with a reversible fuel cell for hydrogen storage and cooling applications, respectively. While working in the fuel cell mode, maximum efficiency of 47.84% is evaluated at 80 °C. The system efficiency with and without the VARS system at 80 °C was 73.29% and 47.84%, respectively. On the contrary, in the electrolyzer mode, the maximum efficiency comes out to be 85.65%. The use of the MHHS system for hydrogen storage results in excess heat release, and as a result, the overall efficiency of the electrolyzer was increased to 94.05%.

First Law Optimization and Review of Double and Triple-Effect Parallel Flow Vapor Absorption Refrigeration Systems

Parallel flow double and triple-effect vapor absorption cooling systems (VACS) are trying to meet the challenges of vapor compression cooling systems due to their better performance. Therefore, the present study deals with the review, thermodynamic analysis, and optimization of operating parameters for both double and triple-effect VACS. Lithium bromide water was selected as the working fluid, while liquified petroleum gas (LPG) and compressed natural gas (CNG) were taken as the source of energy to drive both the VACS. Detailed First Law analysis, i.e., coefficient of performance (COP), was examined along with the optimization of operating parameters (such as salt concentration and operating generators temperature at different pressure levels) and the volume flow rate of the gases. Optimization was carried out for maximum COP of the VACS using an iterative technique. Our results show that the COP of the triple-effect system was approximately 32% higher than the double effect, while 15–20% less consumption of the gases (LPG and CNG) was observed. The most optimum stage for the operation of triple-effect VACS was reached at Te = 4 °C and Tc = Ta = 30 °C, Tg = 180 °C, Tc4 = 104 °C, Tc3 = 66 °C, Z1 = 0.5, and Z2 = 0.45.

Enhancing energy efficiency and sustainability in ejector expansion transcritical CO2 and lithium bromide water vapour absorption refrigeration systems

Enhancing energy efficiency and sustainability in ejector expansion transcritical CO2 and lithium bromide water vapour absorption refrigeration systems

Evaluation of Multi-Utility Models with Municipal Solid Waste Combustion as the Primary Source under Specific Geographical and Operating Conditions

Developments in waste incineration technology in terms of efficient fuel preparation, combustion, and emissions reduction, as well as the growing needs of the community in terms of electricity, water, and air conditioning loads, are the prime motive for this study. This study presents a novel approach, in which three models of the fluidized bed combustion of municipal waste for simultaneous power generation, freshwater production, and district cooling are analyzed for their energy and exergy performance. The three simultaneously evaluated utility models are different configurations of a fluidized bed combustion system with Rankine cycle power generation, cooling with a vapor absorption refrigeration system, and fresh water production using multiple effect desalination. The output from the turbine, cooling system, and desalination system is determined using the Engineering Equations Solver for different boiler operating pressures. Energy and exergy analysis data for different pressures are used to identify the best configuration. Two variants of the absorption cooling system, namely, single effect and double effect, are considered. The variants of the multiple-effect desalination are the three-stage and five-stage methods. Input parameters used in this study are municipal solid waste generation and composition data collected for an urban community in an arid climate zone with high demand for electric power, cooling, and fresh water. Model 2, which contains two turbines with the reheating and cooling systems connected to a high-pressure turbine and water desalination connected to a low-pressure turbine, gave the best overall performance. Significant savings in terms of the replacement of conventional energy were observed from these waste conversion plants with greater benefits in arid weather conditions. The results obtained by different models under different operating criteria constitute a guideline for municipal planners for the selection of appropriate waste utilization technology, as well as the appropriate operations.

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%.

Design and experimental analysis of a shell and tube vapor generator for solar thermal vapor absorption refrigeration

The generator is a crucial component of absorption refrigeration system as it provides a major input to the system. The overall performance of the absorption system mainly depends on vapor generation rate in a generator. Various studies are available in the literature on LiBr-H2O vapor absorption refrigeration systems. However, all these studies are focused on the performance of high-capacity commercial systems. Further, detailed analysis and feasibility of generator designs is not well explored though it is an important component of the system. Thus, present novel study is aimed to provide the idea about generator design and performance for a low-capacity system useful for residential applications. The objective of the present work is to investigate the shell and tube heat exchanger as a vapor generator for a vapor absorption refrigeration system experimentally. A LiBr-H2O vapor absorption refrigeration system requires water separation from LiBr in the vapor generator. The vapor generation depends on the saturation temperature and pressure. In this study, a shell and tube heat exchanger is designed for a vapor absorption refrigeration system of 0.5 ton of refrigeration. The experimental investigations are carried out at different operating conditions to evaluate the unit's performance and define its suitability for low-capacity absorption refrigeration system. Considering the output temperature of hot water from the solar thermal collector (80 –90 ℃) and pressure restrictions on the vapor generation process due to the crystallization of lithium bromide, the presented heat exchanger design is evaluated for pressure ranging between −0.90 bar and −0.65 bar. The experimental evaluation revealed that the heat exchanger is the most effective when the inlet temperature is 80 ℃ at a flow rate of 3 L per minute, and the initial pressure is −0.65 bar, while it is least effective for −0.90 bar. Further, vapor generation is greatest at −0.90 bar and lowest at −0.65 bar. The given configuration is suitable for an absorption system of cooling capacity 0.16 to 0.3 TR, as it can supply the vapor at the required flow rate at a given saturation temperature and pressure suitable for the de-absorption of water from LiBr.

Development of a solar-powered vapour absorption cooling system

In this paper, performance evaluation of a developed Solar-Powered Vapor Absorption Refrigeration (VAR) System using the NH3-H2O solution as working fluid is done. The cooling system has total storage space of 0.038 m3 with capacity to accommodate about 0.04 metric tonnes (40kg) of items such as to cool water and other drinks for human comfort applicable in rural regions where electricity is unreliable or non-existent. A solar Photovoltaic (PV) panel of 300W, 40W Direct Current (DC) heating element with a 20A solar controller were designed to power the developed cooling system. Measurements of important operational parameters such as the generator, ambient, evaporator, cabinet and condenser temperatures were studied and measured from the system. Performance evaluation of the system refrigerating capacity was determined in terms of its cooling performance (COP) and the system efficiency ratio (ƞ) based on no load and on load conditions. The system when tested has COP of 0.1275 at an average cabinet temperature (Tr) of 9.0 ℃ against an average room temperature of 25.8 ℃. Additionally, the system had an overall refrigerating efficiency ratio of 8.25. The performance test results revealed that the developed cooling system performed well in terms of temperature regulation for refrigeration purposes

Towards techno-economics of green hydrogen as a primary combustion fuel for recreational vehicle vapor absorption refrigeration system

The drive towards the integration of hydrogen in the global primary energy mix to achieve a carbon–neutral and sustainable society requires both minor and major technological modifications in current energy systems. In this study, the viability of green hydrogen as a combustion fuel and its economics have been investigated for an absorption–desorption-based cooling system. Specially designed burners have been retrofitted with the portable ammonia-water-based cooling system (cooling area: 1.4 ft3). Furthermore, the effect of hydrogen flow and the distance from the burner has been investigated and optimized. The system has been compared with both electrical resistive heating using a 12 V DC power supply and propane gas. An increase in hydrogen flow rate leads to high cooling rates. Furthermore, the reduction in the distance between flame and heating surface improves the heat transfer rate. The system running on hydrogen exhibited highest performance compared to both electricity and propane at optimum flow rate and distance. The optimum flow rate and distance was observed to be 29.2l/h and 2 cm respectively. System running on optimum hydrogen conditions consumed 77.37Wh energy with is 9.10% less compared system running on electric resistance heating and 29% less compared to system running on propane. In terms of carbon–neutral economics, 1 kg of hydrogen can potentially replace 3.28 kg of propane (costing around 3.60 to 4.30 USD). Whereas, 8–9 kg of CO2 reduction can be achieved per kg of hydrogen being used. The 3.30 to 4.30 USD/kg may be considered a competitive cost of green hydrogen in comparison to propane as a combustion fuel for the portable refrigeration sector. These results are the first time, highlighting the efficient use of hydrogen in space cooling.

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.

Thermodynamics analysis of a novel absorption heat transformer-driven combined refrigeration and desalination system

Preservation of food and medicines below sub-zero temperatures is the need of the present times. To achieve the required temperature using renewable energy, a waste heat-driven vapour absorption refrigeration system can be implemented. Majority of the available waste heat is available in the low temperature range i.e. between 60–80 °C, which cannot be directly used to provide refrigeration. Therefore, an absorption heat transformer (AHT) is coupled with the VARS (Vapour absorption refrigeration system) system which increases temperature of this waste heat, and the upgraded heat is utilized to produce required refrigeration effect. Further, the rectifiers’ waste heat of the absorption system will be used to power humidification-dehumidification (HDH) desalination cycle. Although all these three components (AHT, VARS, and HDH) have been studied individually, but they have never been combined altogether. This paper presents a mathematical model for the proposed system and its validation against published available literature. The performance parameters such as coefficient of performance, gain output ratio and refrigeration effect of the system is evaluated at different evaporator and desorber temperatures. For 300 kW waste heat at 80 °C, evaporator (VARS) temperature of −10 °C, the system reported 70 kW of refrigeration effect is provided with 20 kg/hr of distillate production rate. An exergy destruction of 82.64 kW has been reported for total input exergy of 142.2 kW, for refrigeration capacity of 157 kW.

Energy and Exergy Analysis of Single Effect Water-LiBr Vapour Absorption Refrigeration System

Vapor absorption refrigeration system (VARS) is one of the emerging technology in thermal-driven refrigeration systems and has too many benefits in comparison with another cooling system as their performance is good and the cost is low. Different mathematical models of various complexities have been developed for performance analysis, optimization, and design of such systems. In this study energy and exergy of a single effect LiBr vapor absorption refrigeration system is analyzed with different mathematical model developed so far. The effect of varying the temperature for each component of the system on the coefficient of performance (COP) and exergetic efficiency (COPex) is briefly discussed. The results show that increasing generator temperature from 86oc to 102oc for constant refrigerant mass flow rate causes COP of the system to increase, due to the decrease in circulation ratio. In another case, increasing the evaporator temperature from 2oc to 14oc for a constant temperature input of the generator has a positive effect on both the first and second law efficiency of the VARS as the load on the generator decrease. From the result, it can also be concluded that increasing absorber temperature has a negative impact on both COP and exergetic efficiency of VARS.

Energy and Exergy Analysis of Single Effect Water-LiBr Vapour Absorption Refrigeration System

Vapor absorption refrigeration system (VARS) is one of the emerging technology in thermal-driven refrigeration systems and has too many benefits in comparison with another cooling system as their performance is good and the cost is low. Different mathematical models of various complexities have been developed for performance analysis, optimization, and design of such systems. In this study energy and exergy of a single effect LiBr vapor absorption refrigeration system is analyzed with different mathematical model developed so far. The effect of varying the temperature for each component of the system on the coefficient of performance (COP) and exergetic efficiency (COPex) is briefly discussed. The results show that increasing generator temperature from 86oc to 102oc for constant refrigerant mass flow rate causes COP of the system to increase, due to the decrease in circulation ratio. In another case, increasing the evaporator temperature from 2oc to 14oc for a constant temperature input of the generator has a positive effect on both the first and second law efficiency of the VARS as the load on the generator decrease. From the result, it can also be concluded that increasing absorber temperature has a negative impact on both COP and exergetic efficiency of VARS.