Second law comparison of single effect and double effect vapour absorption refrigeration systems

2009 ◽  
Vol 50 (5) ◽  
pp. 1279-1287 ◽  
Author(s):  
Rabah Gomri
Keyword(s):  
Double Effect ◽  
Second Law ◽  
Absorption Refrigeration ◽  
Single Effect

THERMODYNAMIC ANALYSIS OF SINGLE- AND DOUBLE-EFFECT ABSORPTION REFRIGERATION SYSTEMS FOR COOLING ETHANOL FERMENTATION PROCESS

2014 ◽  
Vol 22 (04) ◽  
pp. 1450020 ◽  
Author(s):  
HUGO VALENÇA DE ARAÚJO ◽  
JOSÉ VICENTE HALLAK D'ANGELO
Keyword(s):  
Thermodynamic Analysis ◽  
Fermentation Process ◽  
Alcoholic Fermentation ◽  
Double Effect ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Second Law ◽  
Base Case ◽  
Absorption Refrigeration ◽  
Single Effect

Alcoholic fermentation is one of the most important stages in industrial ethanol production process, involving a biochemical and exothermic reaction. Sometimes cooling towers are not capable of supplying a cold utility with a temperature low enough to maintain the fermentative medium temperature in a desirable range. Absorption Refrigeration Systems (ARS) appears to be a good alternative to obtain the necessary refrigeration for the fermentation process. The aim of the present paper was to carry out a thermodynamic analysis of ARS, evaluating their performance through the First and Second Laws of Thermodynamics. ARS with different configurations were studied (single-effect and double-effect with series, parallel and reverse parallel flows), all of them operating with water/lithium bromide mixture as working pair, under different operating conditions in order to satisfy the cooling load required by an industrial alcoholic fermentation process. Another objective of this paper was to investigate the risk of LiBr crystallization, which can result in scaling formation, with the aid of the solid–liquid phase equilibrium curve of H 2 O / LiBr mixture. Among the double-effect configurations studied, it was observed that series flow presents the more significant crystallization risk, which represents a limit to improve its First and Second Law performances. It was verified that the Second Law performance for the single-and double-effect ARS analyzed are similar, but their First Law performance are considerably different. This is due to the amount and quality of the heat consumed in the first effect generators of these systems. For a base case studied, First Law performance measured by coefficient of performance (COP) of double-effect ARS is 72% greater than the one for single-effect, while for Second Law performance, measured by exergetic efficiency, an increase of 5% was observed.

Analysis of Aqueous Lithium Bromide Absorption Refrigeration Systems

2021 ◽  
pp. 1-18
Author(s):  
Dongchuan You ◽  
Hameed Metghalchi
Keyword(s):  
Lithium Bromide ◽  
Double Effect ◽  
Environmental Safety ◽  
Coefficient Of Performance ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Solution Energy ◽  
Exit Temperature ◽  
Single Effect ◽  
Aqueous Lithium Bromide

Abstract Aqueous lithium bromide absorption refrigeration systems have been studied in recent years and their advantages like environmental safety and utilization of low-grade energy have been proved. Research on improving their performance has been increasing lately. In this paper, single effect and parallel flow double-effect aqueous lithium bromide absorption refrigeration systems have been studied. Mass, energy, entropy and exergy balances have been used to model the absorption refrigeration systems. Parametric studies have been done to investigate effects of cooling load, evaporator exit temperature, condenser exit temperature, generator vapor exit temperature, absorber exit temperature, solution energy exchanger effectiveness on the performance of the system. The analyses show coefficient of performance and exergetic efficiency of double-effect absorption refrigeration is higher than those of a single-effect refrigeration. The effect of other parameters on performance of both single and double-effect systems have been described in detail in the article.

Design of a Solar Assisted Absorption Refrigeration System

2014 ◽  
Vol 953-954 ◽  
pp. 66-73
Author(s):  
Yan Ling Liu ◽  
Xue Zeng Shi ◽  
Yuan Yu
Keyword(s):  
High Pressure ◽  
Solar Energy ◽  
System Simulation ◽  
Double Effect ◽  
Absorption Refrigeration ◽  
Refrigeration System ◽  
Absorption System ◽  
Pressure Generator ◽  
Simulation Results ◽  
Absorption Refrigeration System

This paper presents the design of a solar/gas driving double effect LiBr-H2O absorption system. In order to use solar energy more efficiently, a new kind of solar/gas driving double effect LiBr-H2O absorption system is designed. In this system, the high-pressure generator is driven by conventional energy, natural gas, and solar energy together with water vapor generated in the high-pressure generator, which supplies energy to the low-pressure generator for a double effect absorption system. Simulation results illustrate that this kind of system is feasible and economical. Economic evaluation of several systems is also given in this paper in order to get a clear knowledge of the energy consumption of the system.

scholarly journals A solar air-cooled high efficiency absorption system in dry hot climates: Reduction of water consumption and environmental impact

2018 ◽  
Vol 22 (5) ◽  
pp. 2151-2162
Author(s):  
Jose Marcos ◽  
Raquel Lizarte ◽  
Fernando Varela ◽  
Maria Palacios-Lorenzo ◽  
Ana Blanco-Marigorta
Keyword(s):  
Water Consumption ◽  
High Efficiency ◽  
Cooling System ◽  
Double Effect ◽  
Environmental Benefits ◽  
Absorption System ◽  
Solar Cooling ◽  
Single Effect ◽  
Solar Cooling System

A solar cooling system with an optimized air-cooled double-effect water/LiBr absorption machine is proposed as a sustainable alternative to meet cooling demands in dry hot climates. This system allows eliminating the cooling towers in those regions of the planet where water is scarce. This work analyses the environmental benefits of this air-cooled system, as well as its environmental foot-prints, compared to a solar water-cooled single effect. In this regard, a methodology has been applied to calculate the annual saving in water consumption produced in a case study: a hospital located in Almer?a, in South of Spain. Further-more, the reduction in energy consumption and CO2 emissions is also quantified since this machine can be driven by solar energy and with higher efficiency than those of single effect.

Configuration optimization of series flow double-effect water-lithium bromide absorption refrigeration systems by cost minimization

2018 ◽  
Vol 158 ◽  
pp. 359-372 ◽  
Author(s):  
Sergio F. Mussati ◽  
Stefano Cignitti ◽  
Seyed Soheil Mansouri ◽  
Krist V. Gernaey ◽  
Tatiana Morosuk ◽  
...  
Keyword(s):  
Cost Minimization ◽  
Lithium Bromide ◽  
Double Effect ◽  
Absorption Refrigeration ◽  
Configuration Optimization
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