Analyzed of vapor absorption refrigeration systems powered by geothermal energy: Site in Ethiopia

This communication presents the energy and exergy analysis of an actual double effect steam powered LiBr – H 2 O vapor absorption refrigeration plant. Exergy loss, COP, exergy efficiency and heat rate for each component of the system are calculated. The effect of generator as well as evaporator temperature on the COP and exergy efficiency is evaluated and it is found that the irreversibility rate is highest in the generator while it is found to be the lowest in the case of absorber and condenser. It is also found that the COP of the system increases with the increase in the evaporator temperature while it is found to be reverse in case of exergy efficiency. Results revealed that average exergy loss is highest in the generator as compared to other components. The results obtained are helpful for designers to bring changes in the actual system for performance optimization and less wastage of energy. The study clearly explain the operational and maintenance problems in the machine and point out the areas of energy wastage which the operational engineer should look into for the optimum operation of the plant.

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Thermodynamic analysis of GAX and hybrid GAX aqua-ammonia vapor absorption refrigeration systems

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2015.09.048 ◽

2015 ◽

Vol 40 (46) ◽

pp. 16256-16265 ◽

Cited By ~ 11

Author(s):

Manoj Dixit ◽

Akhilesh Arora ◽

S.C. Kaushik

Keyword(s):

Thermodynamic Analysis ◽

Ammonia Vapor ◽

Absorption Refrigeration ◽

Aqua Ammonia ◽

Vapor Absorption ◽

Vapor Absorption Refrigeration

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Space Cooling Using the Concept of Nanofluids-Based Direct Absorption Solar Collectors

Volume 7: Fluids and Heat Transfer, Parts A, B, C, and D ◽

10.1115/imece2012-87726 ◽

2012 ◽

Cited By ~ 2

Author(s):

Vivek Vishwakarma ◽

Nitin Singhal ◽

Vikrant Khullar ◽

Himanshu Tyagi ◽

Robert A. Taylor ◽

...

Keyword(s):

Solar Collector ◽

Air Conditioning ◽

Thermal Storage ◽

Temperate Climate ◽

Absorption Refrigeration ◽

Direct Absorption ◽

Parabolic Trough ◽

Space Cooling ◽

Vapor Absorption ◽

Vapor Absorption Refrigeration

A solar-energy based vapor absorption refrigeration system is potentially an excellent alternative air-conditioning system. However, there are several research challenges to ensure sufficient efficiency and reliability for ensuring widespread implementation. Integration of a parabolic trough solar collector utilizing a mixture of nanoparticles and water with a vapor absorption system has the potential to significantly enhance the efficiency of the system. Such a system makes use of the superior thermo-physical properties of the nanofluid compared to the base fluid. Moreover, the direct absorption phenomenon of solar radiation through interaction with the participating medium (nanofluid) results in a higher temperature rise of the medium in conjunction with higher operating efficiencies as well. At the same time there are certain challenges that need to be identified and addressed in the implementation of this novel concept. For instance, to make it reliable, the system further needs to be integrated with a thermal storage system which facilitates air-conditioning even during non-sunshine hours. Integration of vapor absorption refrigeration technology, parabolic trough with water-nanoparticles mixture as the absorbing medium and a thermal storage facility is the uniqueness of this design which under certain conditions and locations may prove to be an efficient and reliable substitute to the conventional electrical air-conditioning systems. In this particular study a space cooling application for approximately 100 Tons of refrigeration is studied. Hourly variation in sunlight as well as seasonal changes for temperate climate conditions is considered. Parameters such as the cooling load of the space, and waste heat produced by electronics are evaluated. The cooling system driven by the nanofluid-based concentrated parabolic solar collector is mathematical modeled and then the optimization is done by varying the nanoparticle size and volume fraction in order to obtain the best result for collector outlet temperature, thermal efficiency and optical efficiency.

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Estimation of Operating Parameters of a Water–LiBr Vapor Absorption Refrigeration System Through Inverse Analysis

Journal of Energy Resources Technology ◽

10.1115/1.4031833 ◽

2015 ◽

Vol 138 (2) ◽

Cited By ~ 11

Author(s):

T. K. Gogoi

Keyword(s):

Objective Function ◽

Inverse Analysis ◽

Exergy Efficiency ◽

Operating Parameters ◽

Absorption Refrigeration ◽

Refrigeration System ◽

Short Period ◽

Vapor Absorption ◽

Absorption Refrigeration System ◽

Vapor Absorption Refrigeration

In this paper, an inverse problem is solved for estimating parameters of a steam-driven water–lithium bromide (LiBr) vapor absorption refrigeration system (VARS) using a differential evolution (DE)-based inverse approach. Initially, a forward model simulates the steady-state performance of the VARS at various operating temperatures and evaporator cooling loads (CLs). A DE-based inverse analysis is then performed to estimate the operating parameters taking VARS coefficient of performance (COP), CL, total irreversibility, and exergy efficiency as objective functions (one objective function at a time). DE-based inverse technique estimates the parameters within a very short period of elapsed time. Over 50 and 100 numbers of generations are sufficient for retrieval of COP and exergy efficiency, respectively, while it requires 150 generations for total irreversibility and CL. The study reveals that multiple combinations of parameters within a given range satisfy a particular objective function which serves as design guidelines in selecting appropriate operating parameters.

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