Absorption Refrigeration Research Articles

Performance assessment of PTSC-driven organic Rankine cycle systems integrated with bottoming Kalina and absorption chiller cycles: A parametric study

It is crucial to evaluate the impact of key parameters of multi-generation systems on their performance characteristics in order to develop efficient systems. The present study conducts parametric analysis of a PTSC-driven trigeneration system with a novel energy distribution based on directfed ORC and bottom-cycled arrangement of double-effect absorption refrigeration cycle and Kalina cycle system. Three different ORC structures (simple, regenerative, and ORC integrated with intermediate heat exchanger ? IHE) are proposed. Effect of key ORC parameters namely ORC evaporator pinch point temperature and pump inlet temperature is examined on the thermodynamic performance of systems. Decrease of pinch point temperature enhances overall efficiencies and heating power in all three configurations, and increases (decreases) the net electrical power for ORC and regenerative ORC (RORC) based systems. This also enhances the cooling power of the RORC based system, though it has no impact on the cooling power of the ORC and ORC-IHE based systems. Reduction of the ORC pump inlet temperature increases overall exergy efficiency in all hybrid systems and overall energy efficiency in the ORC and ORC-IHE based systems, whereas it slightly decreases for the RORC based system. Based on a comparative study, performance of the proposed systems is found to be higher than related solar-driven multi-generation systems in the literature.

Comparative energy and exergy analysis of water-LiBr absorption chiller configurations with ejector integration, and implementation of artificial neural network on the optimal selection

Comparative energy and exergy analysis of water-LiBr absorption chiller configurations with ejector integration, and implementation of artificial neural network on the optimal selection

Comparative Energy and Exergy Analysis of Water-LiBr Absorption Chiller Configurations with Ejector Integration, and Implementation of Artificial Neural Network on the Optimal Selection

Comparative Energy and Exergy Analysis of Water-LiBr Absorption Chiller Configurations with Ejector Integration, and Implementation of Artificial Neural Network on the Optimal Selection

Investigation of Solar Powered Single Effect Absorption System

Cooling processes like refrigeration and air conditioning are known for their high energy consumption. Since most Indian states experience abundant sunshine year-round, solar refrigeration is a suitable technology for the country. Solar-powered absorption refrigeration systems offer a viable alternative to traditional refrigeration, providing not only cooling and ice-making capabilities but also energy savings and environmental benefits. However, further research is necessary to enable widespread industrial adoption and the replacement of conventional refrigeration systems with solar powered absorption system. Using solar energy for an air-conditioning system is typically more cost-effective, when it can fulfil both heating and cooling needs. This research focuses on the thermodynamic modelling of a system, specifically the effect of various temperature on COP. Thermodynamic modelling was done with the help of first law of thermodynamics. Using engineering equation solver software, study simulated the cycle and equations were developed for energy and mass flow for each component. Further, before proceeding to analysis some assumptions were also made. We then analysed how the Coefficient of Performance (COP) changed when varying the temperatures across each component. Our findings show that COP increases with increase in condenser, evaporator, and absorber temperatures, but it is declined with decrease in generator temperature.

Development of an Integrated Solar-Biomass Energy System for Near-Zero Energy Buildings: A Technical and Environmental Study

The present study aims to satisfy the energy demands of a set of Norwegian residential structures with the least carbon dioxide and most renewable energy. Real-time data on building domestic hot water (DHW), heating, and electricity usage is used to plan and expand the renewable energy supply side. PVT panels provide DHW and electricity in the hybrid solar and biomass energy system. Heat is produced by the digester and heat pump. Also used is a twofold effect absorption refrigeration system for cooling. Rule-based regulation manages heat streams and redirects flows on the supply side. We provide the plant's size and execute the dynamic energy simulation. Electricity and biomass expenses determine building heating. The system is then tuned for operational conditions and compared to the design point. PVT may generate over 80% of annual DHW. Summertime radiation is more intense and can be turned into cooling energy, therefore 64.8% of cooling output comes from it. Digester/CC heats 66.55% of the structure, suggesting designers use biomass in winter due to increased energy costs. A parametric analysis shows that increasing PVT duration and tank size affects efficiency and emissions differently. Cost, efficiency, and emission index at TOPSIS are 9.73 $/hr, 36.8%, and 7.75 kg/MWh, according to optimization findings.

Design and Fabrication of a LiBr Absorption Refrigeration System to Utilize the Waste Heat of Engine Exhaust Gas for Vehicle Cabin Cooling Application

Design and Fabrication of a LiBr Absorption Refrigeration System to Utilize the Waste Heat of Engine Exhaust Gas for Vehicle Cabin Cooling Application

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)

Technical evaluation of solar-activated absorption refrigeration systems and operating conditions: a case study in Culiacán-Mexico

This research shows the methodology for technical evaluations of the energy performance of absorption refrigeration systems activated with solar energy. This document determines the optimal installation angle of the solar thermal collectors that activate the chiller. Also, the cooling energy Qe, Coefficient of Performance (COP), and hourly Seasonal Coefficient of Performance (SCOP) are determined for each month of the year and recommendations are made for operation in the city of Culiacán, Mexico. The absorption cooling system achieved a Qe of 400.9 kW, a COP of 0.778, and a SCOP of 0.557.

Теоретическая оценка эффективности применения одноступенчатых длинноходовых поршневых компрессоров в холодильной технике и системах сжижения углеводородов

The analysis of the main modern technologies for obtaining low temperatures and liquefying hydrocarbons using compressor equipment is presented and the most significant results of research in the field of low-flow compressors based on low-speed, long-stroke piston stages are presented. A method for calculating an ideal vapor-compression refrigeration cycle is presented, adapted to the object under consideration, taking into account the possibility of implementing quasi-isothermal compression. A comparative computational analysis of temperature conditions and thermodynamic efficiency of a two-stage refrigeration cycle and single-stage refrigeration cycles is carried out during adiabatic and quasi-isothermal compression processes in the boiling temperature range 278 K ... 198 K. It is shown that in terms of the discharge temperature and coefficient of performance, a single-stage vaporcompression ammonia refrigeration machine based on a low-speed quasi-isothermal stage is comparable to a similar two-stage machine based on adiabatic stages. This allows, in relation to actual objects — small refrigeration machines and installations, to predict both the energy and technical advantages of using a single-stage scheme based on low-speed, long-stroke piston compressors. In addition, it has been shown that the effective use of such a compressor is also possible in hydrocarbon liquefaction systems, while ensuring their safe temperature conditions in a wide range of atmospheric temperatures.

Heat and Mass Transfer Characteristics According to the Shape of the Absorber Heat Transfer Tube for Absorption Chiller

Heat and Mass Transfer Characteristics According to the Shape of the Absorber Heat Transfer Tube for Absorption Chiller

Thermodynamic modeling and exergy analysis of a gas turbine and fuel cell hybrid system (SOFC + GT) equipped with single-effect and double-effect absorption chillers

Thermodynamic modeling and exergy analysis of a gas turbine and fuel cell hybrid system (SOFC + GT) equipped with single-effect and double-effect absorption chillers

Exergoeconomic Evaluation of a Cogeneration System Driven by a Natural Gas and Biomass Co-Firing Gas Turbine Combined with a Steam Rankine Cycle, Organic Rankine Cycle, and Absorption Chiller

Considering energy conversion efficiency, pollution emissions, and economic benefits, combining biomass with fossil fuels in power generation facilities is a viable approach to address prevailing energy deficits and environmental challenges. This research aimed to investigate the thermodynamic and exergoeconomic performance of a novel power and cooling cogeneration system based on a natural gas–biomass dual fuel gas turbine (DFGT). In this system, a steam Rankine cycle (SRC), a single-effect absorption chiller (SEAC), and an organic Rankine cycle (ORC) are employed as bottoming cycles for the waste heat cascade utilization of the DFGT. The effects of main operating parameters on the performance criteria are examined, and multi-objective optimization is accomplished with a genetic algorithm using exergy efficiency and the sum unit cost of the product (SUCP) as the objective functions. The results demonstrate the higher energy utilization efficiency of the proposed system with the thermal and exergy efficiencies of 75.69% and 41.76%, respectively, while the SUCP is 13.37 $/GJ. The exergy analysis reveals that the combustion chamber takes the largest proportion of the exergy destruction rate. The parametric analysis shows that the thermal and exergy efficiencies, as well as the SUCP, rise with the increase in the gas turbine inlet temperature or with the decrease in the preheated air temperature. Higher exergy efficiency and lower SUCP could be obtained by increasing the SRC turbine inlet pressure or decreasing the SRC condensation temperature. Finally, optimization results indicate that the system with an optimum solution yields 0.3% higher exergy efficiency and 2.8% lower SUCP compared with the base case.

Optimizing cooling, heating, and power systems for PEMFC using a multi-objective optimization

Combined cooling, heating, and power (CCHP) systems are attractive solutions for providing multiple energy services from a single fuel source. However, designing and operating CCHP systems optimally is challenging due to the complex thermodynamic and economic interactions among the system components. Multi-objective optimization is a powerful technique to find the best trade-off solutions among conflicting objectives. In this paper, an improved version of the World Cup Optimizer (IWCO), a metaheuristic algorithm inspired by the soccer tournament, has been proposed to solve the multi-objective optimization problem of a CCHP system. The IWCO algorithm enhances the exploration and exploitation capabilities of the original WCO algorithm by introducing a new selection mechanism and a new mutation operator. The performance of the IWCO algorithm has been validated by comparing it with other well-known multi-objective optimization algorithms on several benchmark functions. The results show that the IWCO algorithm outperforms the other algorithms in terms of convergence rate and solution quality. We then apply the IWCO algorithm to optimize a CCHP system with three objectives: minimizing the total annual cost, minimizing the total greenhouse gas emissions, and maximizing the system efficiency. The CCHP system consists of a fuel cell, a micro gas turbine, and an absorption chiller. A Pareto front is used to represent the optimal trade-off solutions among the three objectives. The results show that the IWCO algorithm can provide a variety of Pareto-optimal solutions, which can help decision-makers in designing and operating CCHP systems. The results indicate that the IWCOA produces the most favorable optimization outcomes, achieving energy efficiency rates of 78.7 % and a maximum annual reduction of greenhouse gas emissions totaling 5.2e7 g. Additionally, it manages to decrease the yearly cost to 4.139e3 $. These findings provide a valuable means of assessing the effectiveness of different fuel cell technologies based on their operational characteristics. They underscored the considerable potential of the IWCOA in improving the operational efficiency and environmental footprint of CCHP systems, thus making significant contributions to the progress of sustainable energy technology.

Thermo-Economic Analysis and Multi-Objective Optimization of a Poly-Generation System Based on Solid Oxide Fuel Cell/Gas Turbine/Multi-Effect Distillation and Absorption Chiller Using Biogas as Fuel

A poly-generation system for cooling, heating, power, and fresh water is proposed, based on SOFC/GT/MED and an absorption chiller, with biogas as fuel. The performance of the system under the designed condition is analyzed using energy, exergy, and economic methods. An efficiency of 69.02% for comprehensive energy utilization and 35.56% for exergy are demonstrated by simulation results under the designed condition. A freshwater production of 469.93 kg/h is achieved, and a cost rate of 22.51 USD/h is incurred by the system. The effects of various parameters on the system characteristics are examined. Multi-objective optimization methods are employed to determine the final optimum operating condition that yields the best results in two schemes with different objectives. In comparison to the initial design, the optimization of the first scheme results in a 4.58% increase in the comprehensive energy utilization rate and a 2.02% increase in the exergy efficiency. However, the cost rate of the entire system increases by 0.63 USD/h. On the other hand, the optimization of the second scheme leads to a 19.51 kW decrease in the total energy output, a 276.38 kg/h increase in the freshwater production rate, and a 0.42 USD/h decrease in the cost rate of the entire system.

Thermodynamic process control of compression-assisted absorption refrigeration using ocean thermal energy

An efficient control method is crucial for the safe and reliable operation of compression-assisted absorption refrigeration using ocean thermal energy. In this study, a dynamic model of 10 kW compression-assisted absorption refrigeration system is developed, and four integrated control strategies containing two cooling-capacity control approaches (Single input control and Cooperation control) and two temperature glide control approaches (Valve-based control and Compressor-based control) are proposed to control thermodynamic process. The proposed control strategies are evaluated in terms of both control and refrigeration performances. The results indicate that the refrigeration system can operate with stability at 50 % cooling load under the proposed control strategies. Moreover, the cooperative control of the flow rates for both warm-seawater and concentrated solution can significantly speed up cooling-capacity regulation. The rotational speed of compressor is a more suitable manipulated variable for regulating the evaporator temperature glide. The equivalent COP for the compressor-based control strategies is greater than 0.12 at 50 % cooling load, while the equivalent COP for the valve-based control strategies is only 0.064.

Ammonia Airship Cooling: An Option for Renewable Cooling in the Tropics

The world is warming, and the demand for cooling is increasing. Developing a future green hydrogen economy will also increase the demand for cooling for hydrogen liquefaction. This increase in cooling demand will happen mainly in tropical and developing countries due to their increase in population, improvements in quality of life, and the export of their renewable potential with liquid hydrogen. To solve this increase in demand for cooling, this paper proposes the use of ammonia airship cooling (AAC). AAC extracts cold from the tropopause (−80 °C) with airships and ammonia refrigeration cycles. The liquid ammonia is then transported back to the surface to provide low temperature cooling services (−33 °C). This cooling service is particularly interesting for lowering the electricity consumption in hydrogen liquefaction plants. If all the technological challenges mentioned in the paper are addressed, it is estimated that the cost of cooling with the technology is 8.25 USD/MWht and that AAC could reduce the electricity demand for hydrogen liquefaction by 30%. AAC is an innovative renewable cooling technology that has the potential to complement other renewable energy sources in a sustainable future.

Exploring an innovative approach to hydrogen generation for fuel cell energy production by integrating a dual organic Rankine system with an absorption chiller powered by geothermal energy

This study delved into the thermodynamic optimization of a geothermal system integrated with a fuel cell unit for energy storage during peak consumption. An innovative system was devised to simultaneously produce cooling, electricity, hydrogen, and freshwater by combining an absorption chiller, reverse osmosis, PEM Electrolyzer, and two double Organic Rankine Cycles. To assess the impact of local weather conditions, case studies were conducted in the cities of Hong Kong (China), Bandar Abbas (Iran), Tepic (Mexico), and Melbourne (Australia). Computational modeling employed EES software, and optimization using Response Surface Methodology aimed to enhance system performance and minimize costs. The geothermal system was engineered to meet the electricity demands of residential households during peak consumption. The optimal results demonstrated that the proposed geothermal system, in its most efficient configuration, could achieve an exergy efficiency of 73.17 % and an energy efficiency of 25.25 % while operating at a cost rate of 74.36 $/h. An economic analysis revealed that among the system components, ORC1 unit and PEME incurred the highest costs. Additionally, the PEME, evaporator, and absorption chiller were identified as the main contributors to exergy destruction. The total exergy destruction rate of the proposed geothermal system is 1840.7 kWh and the total cost rate of the system is 51.73 $/h. Lastly, the assessment of the suggested geothermal system across the studied cities indicated that it performed most effectively in Melbourne, Australia. The results of the study of the production capacity in the four study cities showed that Melbourne has the highest production rate with a rate of 14,573 MWh, Tepic with a rate of 13,425 MWh, and Hong Kong with a rate of 13,174 MWh. The lowest annual rate with the amount of 12,784 MWh belongs to the city of Bandar Abbas. The environmental results showed that by producing 14,573 megawatts of electricity in the city of Melbourne, it is possible to expand 14 hectares of green space per year. Also, prevented the reduction of carbon dioxide emissions by 2972.8 tonsCO2/MWh at 71,349.4 $/tonsCO2. The analysis of the production power of the system showed that the electricity needs of 1533 people can be provided for one year by starting the geothermal system in Melbourne City.

Theoretical and experimental study of the ammonia water absorption refrigeration cycle with side reboiling and side condensing

In the conventional ammonia-water absorption refrigeration cycle, the rectification heat is usually dissipated to the surrounding environment, and the temperature of the weak solution flows at the bottom of the distillation column is normally high. This paper presents an improved cycle implemented with side reboiling by utilizing the heat content of the weak solution, and side condensing by recovering the rectification heat based on the single-effect cycle. The effect of feed thermal conditions and split ratio on the thermal performance of the improved cycle has been explored. The effectiveness of the improved cycle with respect to the single-effect cycle under different operating conditions has been examined. A more conservative effectiveness is selected in this work. The theoretical study demonstrates that the thermal performance of the improved cycle can be as high as 15% more than that of the single-effect cycle, and the improved cycle is more efficient when the heating source temperature or temperature lift is higher. A prototype is developed and tested for experimental verification. The experimental effectiveness ranges from 1.9% to 4.4% based on the test results. The relationship between system performance and temperature lift shows a close tendency with the theoretical results.

Use of Ionic Liquid as Crystallization Inhibitor in Water-Lithium Bromide Absorption Chiller

Chillers are used in commercial buildings and industrial plants to provide air conditioning, refrigeration, and process fluid cooling. There are two basic types of chiller cycles: vapor compression and sorption. Sorption chillers are available as either absorption or adsorption designs, depending on the state of the sorbent. Absorption chillers use fluid refrigerants and absorbents (liquid or dissolved), while adsorption chillers employ a solid sorbent (typically silica gel) in combination with a fluid refrigerant. Among the former category, the use of highly hygroscopic LiBr salt as absorbent in combination with H2O as refrigerant comprises LiBr-H2O absorption chillers. Such chillers possess cooling capacities ranging from a few kilowatts (kW) to megawatts (MW) which match with small residential to large scale commercial or even industrial cooling needs. One of the major debilitating factors associated with LiBr-H2O absorption chillers is crystallization. A crystallization event causes a loss of cooling and requires de-crystallization by applying external heat, which results in extensive down-time and requires redundancy designed into a chiller plant. We investigated the use of the imidazolium-based ionic liquid, 1-butyl-3-methylimidazolium bromide ([BMIm]-Br), as crystallization inhibitor additive to LiBr-H2O in the ratio 1:19 [BMIm]-Br:LiBr. It was found that under the operating boundary conditions of 27°C/9°C (cooling water inlet temperature/chilled water outlet temperature), the LiBr-H2O absorption chiller can be operated without modifications and with around 10 K higher heating water inlet temperatures when adding [BMIM]-Br before crystallization occurs compared to pure LiBr-H2O solution. When using the [BMIM]-Br ionic liquid, the refrigeration capacity of the absorption chiller under the above operating conditions and at 85°C heating water inlet temperature exhibited 10% increase after optimizing the solution flow, that lead to higher outputs, such as lower cooling water temperatures. By adding the [BMIM]-Br to the aqueous lithium bromide solution the operating range of the absorption refrigeration system could also be extended to resorption mode, which allows refrigeration below 0 °C. Thus, there is an excellent potential for a significant extension of the application range of LiBr-H2O chillers, e.g. in the field of food cooling and refrigeration processes. Figure 1

Whether the off-design characteristics of equipment should be considered in integrated energy system optimization design models – A case study

The operational performance of integrated energy systems (IESs) varies with their configuration. The equipment model directly influences the capacity configuration of IESs. The conventional static model assumes that equipment efficiency is constant, ignoring its off-design characteristics. For this reason, this paper establishes a dynamic model considering the off-design characteristics of the equipment. Based on the dynamic and static models, bi-level optimization models with the minimum total cost as the optimization objective are established to optimize the configuration of IESs, and the optimization results are System 1 and System 2, respectively. Then, the operational performance of the two systems under the dynamic optimal scheduling model is compared. The results demonstrate that the capacity of the absorption chiller (ABC), combined heating and power (CHP) unit in System 1 are larger than in System 2 owing to the difference in equipment models, whereas the capacity of ground source heat pumps (GSHPs) shows the opposite trend. The larger capacity of the GSHP increases the grid power consumption of System 2 but also reduces its operating efficiency. The greater operation energy consumption and grid power consumption make the operating cost, carbon tax, and total cost of System 2 under the design condition higher than that of System 1, with an increased rate of 1.38%, 3.47%, and 1.14%, respectively. As with the design condition, the carbon tax, operating cost, and total cost of System 2 are higher than those of System 1 under both summer and winter operating conditions, particularly under summer operating conditions, where the carbon tax, operating cost, and total cost increase by 2.27%, 1.24%, and 0.88% respectively. Even if the energy price changes, the carbon tax, operating cost and total cost of System 2 in a typical year are still greater than those of System 1. Therefore, it is necessary to consider the off-design characteristics of equipment in the bi-level optimization design model.