Single-effect Absorption Refrigeration Cycle Research Articles

Multi-objective optimization and exergoeconomic analysis of a novel solar desalination system with absorption cooling

This paper presents a novel design for a solar-powered desalination system utilizing a single-effect absorption refrigeration cycle with a flat-plate solar collector. The NH3-H2O working fluid pair in the refrigeration subsystem produces chilled water while the rejected heat from the condenser drives a humidification-dehumidification (HDH) subsystem for freshwater generation. This cycle has been analyzed thermodynamically and exergetically to understand its key performance parameters. Furthermore, for a detailed examination and optimization, an exergoeconomic analysis was also conducted. Design parameters for this study include the tilt angle of the solar collector, Volume fraction of nanoparticles in the CuO nanofluid, Solar collector area, Base fluid mass flow rate in the collector, Mass flow rate of the strong solution, Absorber and condenser temperatures, Mass ratio and Humidifier effectiveness. The Objective functions used to evaluate the system, performance are the Cooling effect of performance (COP), Energy performance (EP), Exergy efficiency (μExe), and the Total product cost rate of the system (Ċp,Tot). The genetic algorithm optimization is employed to find the best system performance using two sets of three objective functions. The effectiveness of multi-objective optimization using LINMAP, TOPSIS, and Shannon Entropy methods is demonstrated. LINMAP and TOPSIS consistently achieved improvements in COP (32–42 %), exergy efficiency (33–48 %), and reduced total cost (89–90 %) compared to the base point, while Shannon Entropy offered slightly lower gains. These methods consistently identify superior system configurations, achieving significant improvements in performance while minimizing the total product cost rate.

Thermodynamic Analysis and Performance Assessment of a Novel Solar-Based Multigeneration System for Electricity, Cooling, Heating, and Freshwater Production

Abstract This study offers a comprehensive assessment of the thermodynamic performance of a novel solar-based multigeneration system, which caters to the energy needs of a sustainable community by producing electricity, cooling, heating, and freshwater. The solar-based multigeneration system is comprised of four main components: the thermal subsystem of the parabolic trough collector (PTC) employing CO2 as a heat transfer fluid, a single-effect absorption refrigeration cycle (ARC), a supercritical CO2 (S-CO2) cycle, and an adsorption desalination (AD) cycle with heat recovery employing aluminum fumarate metal–organic framework (MOF) adsorbent material. A comprehensive parametric study was performed on the proposed solar-based multigeneration system by varying key parameters to evaluate its performance. It is found that the thermal and exergy efficiencies of a PTC were evaluated to be 68.35% and 29.88%, respectively, at a fixed inlet temperature of 225 °C and solar irradiation of 850 W/m2 and also a slight reduction in the ARC cycle when examining the variation in the thermal and exergetic COPs for the generator temperature. Additionally, the thermal and exergy efficiencies of electricity, cooling, and heating were determined to be 20.41% and 21.93%, 41.34% and 3.51%, and 7.14% and 3.07%, respectively, at the operating condition. The maximum specific daily water production (SDWP) value of 12.91 m3/ton/day and a gain output ratio (GOR) of 0.64 were obtained under steady operating conditions in the AD cycle.

Thermoeconomic assessment of a renewable hybrid RO/PEM electrolyzer integrated with Kalina cycle and solar dryer unit using response surface methodology (RSM)

In this research, a non-dimension model of renewable generation system encompassing a solar-geothermal driven Proton Exchange Membrane (PEM) electrolyzer in integration with Kalina cycle (KC), Single-effect Absorption Refrigeration Cycle (SEAC), and Reverse Osmosis (RO) unit is introduced. Cooling and heating loads, electricity, distilled water, Hydrogen, Oxygen, and dry air are the main products of the mentioned system. This scheme is investigated from the energetic, exergetic, and exergoeconomic (3E) standpoints by writing a code in engineering equation solver (EES) and is totally validated by the literature survey. Subsequently, to enhance the operating condition of the CCHP system devised, six decision variables are designated for the optimization procedure using the RSM via the Minitab software; the response variables are sum unit cost of products (SUCP) and exergetic efficiency. Here, the desirability of the accuracy of the regression models attained from the analysis of variance for the objective functions is entirely verified. Moreover, the optimal condition reveals the best exergetic efficiency and SUCP of 31.71% and 1.75 $/GJ, respectively.

Analysis of a novel combined cooling and power system by integrating of supercritical CO2 Brayton cycle and transcritical ejector refrigeration cycle

This paper presents a novel combined cooling and power (CCP) system that integrates a supercritical CO2 Brayton (sCO2) cycle and a transcritical ejector refrigeration cycle. The two cycles are combined by a heat exchanger wherein heat is exchanged between CO2 and the refrigerant at supercritical pressures to reduce exergy destruction and improve system performance. A thermodynamic model was established to simulate the CCP system based on energy and exergy balance equations. The transcritical ejector model was validated with experimental and literature data. The performance of the system was studied for different CO2 mass flow rates, turbine inlet temperatures, turbine inlet pressures, turbine outlet pressures, and pump outlet pressures. The thermal, exergy, and effective efficiencies of the CCP system were compared with those of a combined cooling and power system (CCP_ab) that uses a single-effect absorption refrigeration cycle. The CCP system maximum thermal efficiencies of four refrigerants—R32, R134a, R1234yf, and R1234ze—were obtained using a genetic algorithm. The results show that the major components that contribute in exergy destruction are internal heat exchanger, ejector, compressor and turbine, and the heat exchanger has small exergy destruction because of a good variable-temperature match between the supercritical pressure refrigerant and supercritical pressure CO2. The effective efficiency of the CCP system reaches 0.42 at turbine inlet temperature of 873.15 K. The CCP system is more stable and efficient than the CCP_ab system in varying conditions. The CCP system with R32 has the highest thermal efficiency. R1234ze with relatively high thermal efficiency and low Global Warming Potential is a good choice in the future as it is environmentally friendly.

Cascaded model predictive controller performance for the selection of robust working fluids in absorption refrigeration cycles

• Evaluation of the dynamic performance of 13 novel working fluids. • Cascade model predictive control is of superior performance than cascade PI control. • Systematic ranking of ABR fluids based on setpoint tracking and resource utilization. • A multi-criteria assessment approach for working fluid selection is presented. • Acetaldehyde/Dimethylformamide exhibits superior steady state and dynamic performance. Current working fluid selection approaches for the absorption refrigeration cycle are based exclusively on steady-state cycle performance. In real operating conditions, the cycle is subject to exogenous disturbances, with detrimental effects on their performance, resulting in increased resource utilization or even failure to meet load demands. In the present work, the problem of working fluid evaluation for the absorption refrigeration cycle is investigated, by considering both the steady state and the dynamic performance of the system. The evaluation of 13 novel, organic working fluids is performed utilizing a cascaded proportional-integral and a cascaded model predictive controller, implemented on a single-effect absorption refrigeration cycle. A set of previously validated non-linear, dynamic process models, developed in ASPEN Plus are used to create the linear models required for the model predictive controller. The closed loop dynamic performance is evaluated based on speed of response, resource utilization and deviations from the desired operating point (setpoint), while operating under a disturbance scenario involving load demand changes. Multi-criteria assessment results indicate that the cascaded model predictive control is considerably more consistent than the cascade PI controller. The novel mixture of acetaldehyde/dimethylformamide exhibits superior performance than the conventional NH 3 /H 2 O mixture, by 57% in speed of response and 76% in resource utilization. The mixture ιs also 25% and 12% better than NH 3 /H 2 O in steady-state cost per ton of cooling and coefficient of performance, indicating high economic potential and robustness for single-effect ABR systems.

Energy, exergy and economic analyses and multiobjective optimization of a novel solar multi-generation system for production of green hydrogen and other utilities

Renewable energy based multi-generation systems can help solving energy-related environmental problems. For this purpose, a novel solar tower-based multi-generation system is proposed for the green hydrogen production as the main product. A solar-driven open Brayton cycle with intercooling, regeneration and reheat is coupled with a regenerative Rankine cycle and a Kalina cycle-11 as a unique series of power cycles. Significant portion of the produced electricity is utilized to produce green hydrogen in an electrolyzer. A thermal energy storage, a single-effect absorption refrigeration cycle and two domestic hot water heaters are also integrated. Energy, exergy and economic analyses are performed to examine the performance of the proposed system, and a detailed parametric analysis is conducted. Multiobjective optimization is carried out to determine the optimum performance. Optimum energy and exergy efficiencies, unit exergy product cost and total cost rate are calculated as 39.81%, 34.44%, 0.0798 $/kWh and 182.16 $/h, respectively. Products are 22.48 kg/h hydrogen, 1478 kW power, 225.5 kW cooling and 7.63 kg/s domestic hot water. Electrolyzer power size is found as one of the most critical decision variables. Solar subsystem has the largest exergy destruction. Regenerative Rankine cycle operates at the highest energy and exergy efficiencies among power cycles.

Experimental investigation on the phase behavior of DME/ [P6,6,6,14][Cl] and thermodynamic analysis for absorption refrigeration system

Dimethyl ether (DME), as an environmental-friendly alternative refrigerant, has received broadly attention. Phosphonium-based ionic liquids with good thermophysical properties are regarded as promising absorbents in absorption refrigeration systems. In this work, the measurement of solubility behavior to DME in trihexyltetradecylphosphonium chloride ([P6,6,6,14][Cl]) was carried out from 278.15 K to 348.15 K by means of isochoric saturation method. Non-random two liquid (NRTL) model and Krichevsky-Kasarnovsky (K-K) model were used to correlate the experimental data. The absolute average relative deviation between experimental liquid mole fraction and calculated values was 0.739% and 1.517% for NRTL model and K-K model respectively. Based on the solubility results, the performance of single-effect absorption refrigeration cycle used DME/[P6,6,6,14][Cl] pairs was analyzed, and further compared with other working pairs composed of [P6,6,6,14][Cl].

Theoretical and Experimental lnvestigation on the Absorption Refrigeration Systems.(Dept.M)

In the present work, a theoretical model is developed to study the single-effect absorption refrigeration cycle from the thermodynamic point of view for lithium bromide-water pair und lithium chloride-water pair. The effect of different operating (temperatures on the coefficient of performance (COP) and low ratio (FR) (the weak solution mass flow rate with reference to the refrigerant 113ss low rule) are investigated. This generation process in cui absorption refrigeration cycle using lithium chloride-Water solution is the working pair is experimentally studied. From the theoretical study, it is found that the COP increases an within increases in generation temperature until a certain value, then it decreases slightly. The COP increases with an increase in evaporator temperature and decrease in condenser or absorber temperatures. The rule of decrease in FR is higher at higher condenser and absorber temperatures. The data obtained for lithium bromide-water pair is compared with lithium chloride-water pair it is found that the COP is higher for lithium chloride-water pair than that for lithium bromide-water pair and the FR is lower for the lithium chloride-water pair. The experimental results are plotted to illustrate the effect of generation temperature on the coefficient of performance. low ratio and output variables. Also, the effect of the inlet solution temperature, inlet solution low rate and generator pressure on the generated water Vapor is discussed. A minimum generation temperature must be chosen to boil oil this water from the lithium chloride-water solution. from the measured data a maximum coefficient of performance of 0.812 can be obtained for it single stage system.

Energy, exergy and environmental-based design and multiobjective optimization of a novel solar-driven multi-generation system

In this study, energy, exergy and environmental-based design and multiobjective optimization of a novel solar-driven gas turbine-based multi-generation system is performed. For this purpose, a novel multi-generation system composed of a solar tower-driven gas turbine cycle, a Kalina cycle, an organic Rankine cycle, a single effect absorption refrigeration cycle, an electrolyzer and two domestic hot water heaters is developed. The system can produce electricity, heating and cooling for residential applications, domestic hot water, hydrogen and swimming pool heating, simultaneously from a single renewable energy source. A novel performance indicator, exergetic quality factor (EQF), for performance comparison and multiobjective optimization of multi-generation systems is also introduced. The system is analyzed with energy, exergy, EQF, environmental and exergoenvironmental measures. A detailed parametric study is also performed to analyze the effect of varying design parameters on the performance of the proposed system. The results show that the proposed system has 55.57%, 39.45% and 50.83% of energy efficiency, exergy efficiency, and EQF values, respectively; and inclusion of EQF into multiobjective optimization improves the multi-generation system performance.

Energy and exergy analyses of a novel seasonal CCHP system driven by a gas turbine integrated with a biomass gasification unit and a LiBr-water absorption chiller

Combined cooling, heating, and power systems have been studied extensively because of their great potentials. Accordingly, in the present study, an innovative trigeneration system including a gas turbine cycle, a gasification unit, a heating unit, alongside a single effect absorption refrigeration cycle is proposed. The system operates on natural gas and municipal solid waste (MSW) for cooling, heating, and power generation. The designed system was simulated using Engineering Equation Solver (EES) software through two scenarios; constant power output and constant biomass feed rate, considering seasonal and annual periods. In the first scenario, considering the constant power capacity, the basic design state was considered with the biomass mixing ratio of 50%, and the results of the seasonal study showed that the system capacity is 30 MW, 41.9 MW, and 39.24 MW in terms of electricity, heating, and cooling, respectively. The exergy analysis revealed that the combustion chamber, the evaporator of Heat Recovery Steam Generator (HRSG), and the gasifier in both hot and cold seasons have the highest exergy destruction rate, while the economizers and the evaporators of both HRSGs have the lowest exergy efficiency. The constant mass flow rate of MSW was assumed to be 1.5 kg/s and accordingly, the feed rate of natural gas was also 1.5 kg/s for the mixing ratio of 50% in basic design state of the second scenario, and the results indicated that the annual average capacity of the system for electricity, heating, and cooling generation is 27.43 MW, 40 MW, and 34.15 MW, respectively. Furthermore, the system was capable of providing the domestic hot water supply of end-user with an average capacity of 7.5 MW during a year. The annual Energy Utilization Factor (EUF) and the annual exergy efficiency of the overall system were shown to be 71.25% and 30.79%, respectively.

Performance analysis of solar assisted multi-effect absorption cooling systems using nanofluids: A comparative analysis

The performance comparison of multi-effect absorption refrigeration systems has been conducted in the present study. The absorption cooling cycles are operated on the solar heat in order to improve the utilization of high temperature heat sources for absorption systems. The absorption refrigeration cycles of multi-effect are modeled and designed for the identical refrigeration capacity along with the similar operating conditions. The engineering equation solver tool is deployed to analyze the coefficient of performance (COP) and exergetic efficiency of the absorption cooling cycles. Performance simulations were carried out over a range of operating conditions, including the effect of heat transfer fluids (nanofluids) used in solar parabolic trough collectors. The COP of the triple effect absorption refrigeration cycle (TEARC) is observed to be 1.752. The COP of the double effect absorption refrigeration cycle (DEARC) is perceived to be 51.9% higher as compared with single effect absorption refrigeration cycle (SEARC) which has a COP of 0.852. The exergetic efficiency of the TEARC is witnessed to be 16% higher than DEARC, and it is 31% higher than SEARC at an evaporator temperature of 7 ̊C. The effect of nanoparticle's (Al2O3) concentration and percentage of weak and strong solutions of LiBr-H2O is also evaluated at design conditions. A high temperature heat reservoir is required to operate the TEARC, whereas, the SEARC and DEARC operate on lower temperatures than triple effect cycle.

Advanced exergoeconomic analysis of a novel process for production of LNG by using a single effect absorption refrigeration cycle

A novel two refrigeration cycle process configuration for production of the liquefied natural gas is introduced and analyzed. In this process a single effect absorption refrigeration cycle which provides the refrigeration at −30°C is used as the precooling cycle. Coefficient of performance for this cycle is 0.49. The second cycle is a mixed refrigerant vapor compression refrigeration system. The results show that liquefaction efficiency is 0.20 kW hkg LNG. This process is analyzed and compared with the conventional propane precooled mixed refrigerant (C3MR) process. Next conventional and advanced exergoeconomic analysis methods are used to evaluate the modified process. Based on the exergoeconomic factor values, compressors and air coolers investment costs should be considered for improvement of the process. Endogenous exergy destruction in all of the process components is higher than the exogenous. Results of the splitting of exergy destruction costs indicate that avoidable exogenous destruction portion is very small.

Experimental evaluation on thermal performance of an air-cooled absorption refrigeration cycle with NH3–LiNO3 and NH3–NaSCN refrigerant solutions

This paper experimentally analyzes thermal performance of an air-cooled type single effect absorption refrigeration cycle with ammonia–lithium nitrate and ammonia–sodium thiocyanate solutions as working pairs. Ammonia/salt system has simple construction, low evaporating temperature (<0°C) and high working efficiency. Ammonia is one kind of environment-friendly refrigerants. Hence, ammonia/salt absorption refrigeration cycles are considered to be the most possible ones for practical application in small capacity refrigeration units. An experimental apparatus has been designed and built in Wuhan, China, to evaluate the cycle thermal performance of air-cooled type single effect ammonia/salts absorption refrigeration system. The experimental apparatus operates steadily under different working conditions. A set of tests have been conducted and the corresponding experimental data are measured and recorded to show the variation of the system performances with different system working parameters. For the NH3–LiNO3 system, the measured lowest evaporation temperature reaches −13.1°C with corresponding average system COP of 0.15, and the average refrigerating capacity is about 670W. For the NH3–NaSCN system, with a measured evaporation temperature of −7.5°C, the corresponding average COP is 0.20, and the average refrigerating capacity was about 590W. According to the experimental results, the actual measured COP of NH3–NaSCN system are in the range of 0.20–0.35, which are a little higher than that of NH3–LiNO3 system (actual measured COP ranging from 0.15 to 0.29). Under similar working condition, NH3–LiNO3 system can reach a lower evaporation temperature than that of NH3–NaSCN system. The experimental results of the present study demonstrate the feasibility and capability of ammonia/salt absorption refrigeration cycle for freezing purpose under air cooling conditions. Although the coefficient of performance of the experimental apparatus is below expectation while comparing with the theoretical results, optimization methods are put forward by the present paper for further research.

Single-effect absorption refrigeration cycle boosted with an ejector-adiabatic absorber using a single solution pump

This paper presents a numerical model of a single-effect absorption refrigeration cycle incorporating a triple purpose liquid–vapor ejector acting as pressure booster for refrigerant vapor, adiabatic absorber and controlled solution expansion valve. The promising ammonia-lithium nitrate solution is selected as working pair, being able to produce cold at subzero temperatures, thus valid either for air conditioning or industrial refrigeration. With the use of the liquid–gas ejector, the absorption pressure becomes higher than the evaporation pressure, besides recovering part of the solution pump energy. Results of the simulation show that this innovation behaves like a compressor boosted hybrid cycle without carrying its complexity. It allows decreasing the activation temperature (about 15 °C for a recirculation ratio of 3) and increasing the cooling capacity (reaching a gain of about 100% for a generation temperature of 80 °C).

Performance prediction of absorption refrigeration cycle based on the measurements of vapor pressure and heat capacity of H2O + [DMIM]DMP system

In this paper, the thermophysical properties of the H2O+1,3-dimethylimidazolium dimethylphosphate ([DMIM]DMP) system were studied. The boiling point method was adopted to measure the vapor pressures of the system at mass fraction of ionic liquids (ILs) in the range from 0.10 to 0.90 as well as pressures range from 2kPa to 101kPa. And the general non-random two-liquid (NRTL) activity coefficient model was used to correlate the experimental data. The heat capacities of the system were determined by a BT2.15 Calvet microcalorimeter at mass fraction of ILs in the range from 0.10 to 0.90 and temperatures range from 303.15K to 353.15K. A polynomial equation on temperature and concentration was correlated with satisfactory results. And then theoretical analysis of the coefficient of performance (ω) of a single-effect absorption refrigeration cycle was simulated using H2O+[DMIM]DMP as working pair on the basis of the models of vapor pressure and heat capacity. The simulation results show that the ω of H2O+[DMIM]DMP system is close to that of conventional working pair H2O+LiBr. In addition, the H2O+[DMIM]DMP system improved the limitations of crystallization and corrosion of H2O+LiBr system.

Dynamic Simulation of an Ammonia–water Absorption Refrigeration System

A dynamic model of a single-effect absorption refrigeration cycle with realistic thermodynamics has been developed. The thermodynamic properties are obtained from the Redlich–Kwong equation of state for ammonia/water as the refrigerant/absorbent mixture. The governing ordinary differential equations are derived from the mass, momentum and energy balances for the different components of the system. Lumped parameters are assumed, so that at any instant of time the generator, condenser, evaporator and absorber are each characterized by a single temperature, pressure and concentration. Friction factors are used to calculate pressure drops in the pipes. The transient response of the cycle to a step change in pressure rise across the pump is determined from numerical solutions of the governing equations. The dynamic responses of the mass flow rates, heat rates and the coefficient of performance are shown. The rise time seems to be about two loop circulation times.

Simulation research on an EAX (Evaporator-Absorber-Exchange) absorption refrigeration cycle

There are some heat sources whose temperature is much higher than the limited generation temperature of conventional single effect absorption refrigeration cycle but lower than that of conventional double effect absorption refrigeration cycle. These heat sources can not be utilized efficiently by prior cycles. To make efficient use of these heat sources, this paper proposed an EAX (Evaporator-Absorber-Exchange) absorption refrigeration cycle. The proposed cycle can make use of the condensing heat of the vapor separated from high temperature generator to make additional refrigeration. Therefore, the COP (Coefficient of Performance) of the proposed cycle is much higher than that of the conventional single effect cycle. Simulation results show that the COP of the EAX cycle can be 40% higher than that of the conventional single effect cycle at some simulated conditions. ►This paper proposed a novel EAX absorption refrigeration cycle. ►The proposed cycle can make efficient use of the heat source which can not be utilized efficiently by conventional single effect cycle or conventional double effect cycle. ►The proposed cycle can make use of the condensing heat of the vapor separated from high temperature generator to make additional refrigeration. Therefore, its COP is much higher than that of the conventional single effect cycle. ►Relative increasing ratio (η) increases as the temperature of heat source increases. When the temperature of heat source reaches to 145 °C, η is higher than 40%. ►η increases as evaporation temperature increases. When the evaporation temperature reaches to 11 °C, η is higher than 40%.

A novel ejector-absorption combined refrigeration cycle

This paper presents a novel ejector-absorption combined refrigeration cycle. When the temperature of the heat source is high enough, this cycle will work as a double-effect cycle. If the temperature of the heat source is lower than required temperature of heat source used to drive conventional double-effect absorption refrigeration cycle but much higher than required temperature of heat source used to drive conventional single-effect absorption refrigeration cycle, the COP of new cycle will also be higher than that of conventional single-effect absorption refrigeration cycle. Simulation results show that the COP of the cycle is 30% higher than that of the conventional single-effect absorption refrigeration cycle at some working conditions even in the later case.

A novel absorption refrigeration cycle

For the purpose of improving the performance of conventional single effect absorption refrigeration cycle, this paper proposed a novel absorption refrigeration cycle with an expander–compressor. Simulation results show that the COP of the proposed cycle is much higher than that of conventional single effect cycle and two stage cycle at the most simulated conditions when the integrated efficiency is higher than 0.6. In addition, the proposed system can be powered by low grade heat sources and the pump work of this cycle also can be supplied by the expander, which are great advantages compared to conventional cycles.

Exergy analysis: Parametric study on lithium bromide—water absorption refrigeration systems

In the current study, an exergy analysis of a single-effect absorption refrigeration cycle using lithium bromide-water solution is carried out. The cycle has been analysed by considering the mass and energy conservation based on the first and second laws of thermodynamics. This analysis provides a detailed information on the effect of different parameters on the system performance. The coefficient of performance (COP), exergetic efficiency (ECOP), and exergy destruction are determined. The results show that a reduction in cooling water temperature caused an improvement in the COP and ECOP. Increasing the evaporator temperature has also improved the COP, but it caused a reduction in the ECOP of the system. Also it can be seen that the parameters' variation at the solution side has a more significant effect on cycle performances.