Improved Exergy Evaluation of Ammonia-Water Absorption Refrigeration System Using Inverse Method

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Adityabir Singh ◽  
Ranjan Das
Keyword(s):  
Cooling Water ◽  
Coefficient Of Performance ◽  
Exergy Destruction ◽  
Absorption Refrigeration ◽  
Dragonfly Algorithm ◽  
Destruction Rate ◽  
Wide Range ◽  
Mass Flowrate ◽  
Operating Temperatures ◽  
Absorption Refrigeration System

Abstract In this study, the compatibility of exergy destruction minimization (EDM) as the main objective is checked by plotting coefficient of performance (COP), exergy coefficient of performance (ECOP), and overall exergy destruction rate by simultaneously varying input operating temperatures for a 28 TR cooling load absorption system. The component-wise variation in exergy destruction is also considered and it is found that the maxima of COP and ECOP, and the minima of overall exergy destruction lies on a common point, and when the variation of operating temperatures is further extended, the exergy destruction in one of the component becomes negative, which marks the upper bound of the present analysis. At highest valid generator temperature (155 °C), the minimum possible overall exergy destruction rate is 53.50 kW and maximum COP is 0.523. Through inverse optimization (IO) using dragonfly algorithm (DA), the same overall exergy destruction rate is achieved for a wide range of generator temperatures much below than 155 °C, and as low as 127.34 °C. The above variation is explained in terms of flow ratio, mass flowrate of steam, and mass flowrate of cooling water.

Waste-Heat Driven Miniature Absorption Refrigeration System Using Ionic-Liquid as a Working Fluid

2011 ◽  
Author(s):  
Yoon Jo Kim ◽  
Sarah Kim ◽  
Yogendra K. Joshi ◽  
Andrei G. Fedorov ◽  
Paul A. Kohl
Keyword(s):  
Ionic Liquid ◽  
Waste Heat ◽  
Coefficient Of Performance ◽  
System Level ◽  
Working Fluid ◽  
Operating Efficiency ◽  
Outlet Temperature ◽  
Absorption Refrigeration ◽  
Refrigeration System ◽  
Absorption Refrigeration System

An ionic-liquid (IL) is a salt in a liquid state usually with an organic cation and inorganic anion. ILs provide an alternative to the normally toxic working fluids in absorption systems, such as the ammonia/water system. They also eliminate the problems of poor temperature match, crystallization and metal-compatibility problems of the water/LiBr system. In the present study, an IL is explored the working fluid of a miniature absorption refrigeration system so as to utilize waste-heat within the system for low-cost, high-power electronics cooling. To determine performance benchmarks for the refrigerant/IL (e.g. [bmim][PF6]) pairs, system-level simulations have been carried out. An NRTL model was built and used to predict the solubility of the mixture as well as the mixture properties such as enthalpy and entropy. The properties of the refrigerants were determined using REFPROP 6.0. Saturation temperatures at the evaporator and condenser were 25°C and 50°C, respectively. Chip power was fixed at 100 W with the operating temperature set at 85°C. R32 gave the highest operating efficiency with the maximum coefficient of performance (COP) of ca. 0.55 while R134a and R152a showed comparable performance with the maximum COP of ca. 0.4 at the desorber outlet temperature of 80°C. When waste-heat is available for the system operation, R134a and R152a COPs were comparable or better than that of R32.

Combined Desalination and Refrigeration Systems Driven by Low-Grade Heat

2008 ◽  
Author(s):  
Yongqing Wang ◽  
Noam Lior
Keyword(s):  
Heat Pump ◽  
Gas Turbines ◽  
Air Conditioning ◽  
Saturation Pressure ◽  
Coefficient Of Performance ◽  
Saturated Steam ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Wide Range ◽  
Low Grade Heat

There is often a need for both water desalination and cooling (refrigeration/air-conditioning). The cooling can be used to significantly raise system efficiency by compressor inlet cooling in a dual-purpose power-generation and desalination system using gas turbines, or simply to supply refrigeration or air conditioning beside fresh water. Motivated by the good synergetic potential of energy/exergy utilization through the combination of the LiBr-H2O refrigeration unit, LiBr-H2O heat pump, and low-temperature multi-effect evaporation desalter, two combined refrigeration and water systems, ARHP-MEE (Absorption Refrigeration Heat Pump and Multi-Effect Evaporation desalter) system and ARHP-AHP-MEE (Absorption Refrigeration Heat Pump + Absorption Heat Pump + Multi-Effect Evaporation desalter) system, driven by low-grade heat were configured, modeled and analyzed in detail in the paper. Typically, driving steam with saturation pressure of 0.15–0.35 MPa and correspondingly saturation temperature of 111.4–138.9°C is applicable to run the systems. The main results are: (1) the combined systems have good synergy, with an energy saving rate of 42% in a case study of ARHP-MEE; (2) the refrigeration-heat cogenerated ARHP subsystem is the main reason for the synergy, where the coefficient of performance is around 1.6 and exergy efficiency above 60% when driven by 0.25 MPa saturated steam; (3) at the cost of a more complex configuration, the ARHP-AHP-MEE system has the ability of varying its outputs in very wide range, offering good flexibility on design and operation; (4) the ARHP-MEE system is predicted to have good economics, and its outputs can be varied in a wide range but not independently because their ratio remains almost constant. A parametric analysis was also performed for the ARHP-MEE, further improving the understanding of the system performance.

Study on LiBr-H2O Absorption Refrigeration System with Integral Storage

2014 ◽  
Vol 953-954 ◽  
pp. 752-756
Author(s):  
Qi Chao Yang
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Temperature ◽  
Coefficient Of Performance ◽  
Absorption Refrigeration ◽  
Refrigeration System ◽  
Operation Conditions ◽  
Storage Methods ◽  
Absorption Refrigeration System

The absorption thermal energy storage (TES) system stores the energy in the form of potential energy of solution and is a promising technology for efficient energy transformation process. The performance of the absorption refrigeration system with integral storage for cooling applications using LiBr-H2O as working pair under the condition without crystallization was analyzed on the basis of the first law of thermodynamics. Simulation was employed to determine the coefficient of performance (COP) and energy storage density (ESD) of the absorption TES system under different conditions such as the absorption temperature and storage temperature. The results show that the COP of the system is 0.7453 and ESD is 169.853 MJ/m3 under typical operation conditions in summer. A low absorption temperature yields both a higher COP and ESD. The solution heat exchanger could improve the COP of the system while has no effect on ESD. Results also showed that system has a good advantage when compared to other storage methods since it is do no need thermal insulation. The absorption TES may be considered as one of the promising thermal energy storage methods.

scholarly journals Análise Exergoeconômica de um sistema de trigeração de energia operando com um Ciclo Rankine Orgânico

2021 ◽  
Vol 1 (54) ◽  
pp. 20
Author(s):  
Thiago De Souza Figueredo ◽  
João Luiz De Medeiros Neto ◽  
Adriano Da Silva Marques ◽  
Carlos Antônio Cabral Dos Santos
Keyword(s):  
Steam Generator ◽  
Organic Rankine Cycle ◽  
Industrial Process ◽  
Rankine Cycle ◽  
Exergy Destruction ◽  
Absorption Refrigeration ◽  
Refrigeration System ◽  
Simple Effect ◽  
Absorption Refrigeration System ◽  
Residual Heat

<span class="fontstyle0">This work presents the results of the energetic, exergetic and exergoeconomic evaluation of a trigeneration system which is composed of an Organic Rankine Cycle (ORC), a simple effect Absorption Refrigeration System (SRA) and a boiler. The proposed system is driven by the residual heat of an industrial process. A computational code was developed on the EES (Engineering Equation Solver) platform to solve the thermodynamic and exergoeconomic equation of each equipment. The SPECO method (Specific Exergy Costing) was used for the exergoeconomic evaluation. Results indicated which equipment needs optimization in order of priority. The results show that the greatest destruction of exergy occurs in the ORC steam generator (56% of the total), followed by the condenser that presented an exergy destruction of 33%. Conversely, the pump and expander performed better, with low exergy destruction values. The results of the exergoeconomic evaluation also indicate that the steam generator and condenser from ORC need to be optimized before any other equipment, as they obtained the lowest values of the exergoeconomic factor (f</span><span class="fontstyle0">k</span><span class="fontstyle0">) and the highest values of the specific relative cost (r</span><span class="fontstyle0">k</span><span class="fontstyle0">).</span> <br /><br />

scholarly journals Experimental analysis of triple fluid vapour absorption refrigeration system driven by electrical energy and engine waste heat

2019 ◽  
Vol 23 (5 Part B) ◽  
pp. 2995-3001 ◽  
Author(s):  
Andi Balasubramanian ◽  
Venkatesan Jayaraman ◽  
Suresh Sivan ◽  
Mariappan Vairavan
Keyword(s):  
Thermal Energy ◽  
Waste Heat ◽  
Electrical Energy ◽  
Coefficient Of Performance ◽  
Test Time ◽  
Absorption Refrigeration ◽  
Engine Exhaust ◽  
Power Sources ◽  
Refrigeration Unit ◽  
Absorption Refrigeration System

In this study, performance analysis of absorption refrigeration cycle has been carried out under variable power sources namely electrical and thermal energy sources. The triple fluid vapour absorption system was used in this work. The temperatures at each point in the cycle such as generator, absorber, evaporator and condenser have been measured. The coefficient of performance of the system was calculated and then compared. The results showed that when the cycle driven by electricity, the coefficient of performance varied from 0.28-1.6 along the test time and the generator temperature changed from 66?C to 106?C. When thermal energy used to generate power, the coefficient of performance varied between 0.16 and 0.6 under the generator temperature of 98?C and 150?C. It was observed that the waste heat energy from engine exhaust can be used efficiently and can replace the conventional power source to drive the absorption refrigeration unit.

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