Comprehensive Parametric Study of a Solar Absorption Refrigeration System to Lower Its Cut In/Off Temperature

Osman Wageiallah Mohammed,Guo Yanling

doi:10.3390/en10111746

Osman Wageiallah Mohammed, Guo Yanling

Open Access

https://doi.org/10.3390/en10111746

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Journal: Energies	Publication Date: Oct 31, 2017
Citations: 8	License type: CC BY 4.0

Affiliation: Northeast Forestry University

Abstract

Solar-driven ammonia-water absorption refrigeration system (AARS) has been considered as an alternative for the conventional refrigeration and air-conditioning systems. However, its high initial cost seems to be the main problem that postpones its wide spread use. In the present study, a single-stage NH3/H2O ARS is analyzed in depth on the basis of energetic and exergetic coefficients of performance (COP and ECOP, respectively) to decrease its cut in/off temperature. This study was carried out to lower the required heat source temperature, so that a less-expensive solar collector could be used. Effects of all parameters that could influence the system’s performance and cut in/off temperature were investigated in detail. Presence of water in the refrigerant and evaporator temperature glide was considered. Results revealed that appropriate selection of system’s working condition can effectively reduce the driving temperature. Besides, the cut in/off temperature can be significantly decreased by inserting an effective solution heat exchanger (SHX). Required driving temperature can be lowered by up to 10 °C using SHX with 0.80 effectiveness. The results also showed that effects of water content in the refrigerant could not be neglected in studying NH3/H2O ARS because it affects both COP and ECOP. Additionally, a large temperature glide in the evaporator can substantially decrease the ECOP.

Highlights

According to the International Institute of Refrigeration, about 15% of total world’s electricity generation is consumed for refrigeration and air-conditioning purposes [1]
To reduce the consumption of fossil fuels and at the same time to promote the use of sustainable energy, exploitation of existing solar energy to operate a refrigeration system is rational
Coefficient of performance (COP), exergetic coefficient of performance (ECOP), cut in/off temperature, circulation ratio (CR), power consumed for solution pumping (Wpump ) and the different components’ thermal loads were determined

Summary

Introduction

According to the International Institute of Refrigeration, about 15% of total world’s electricity generation is consumed for refrigeration and air-conditioning purposes [1]. 80% of the world’s electricity is generated by using fossil fuels that significantly enhance CO2 emissions, leading to augment the global warming [2]. Many developing countries face a shortage of electricity supply [3], during the summer when the need for refrigeration and air-conditioning is obviously increased [4]. Many countries enjoy abundant amounts of solar energy, which is freely available throughout the year [5]. To reduce the consumption of fossil fuels and at the same time to promote the use of sustainable energy, exploitation of existing solar energy to operate a refrigeration system is rational. It is quite feasible to harness the solar energy as the demand for cooling and amount of available solar energy are directly proportional to each other [6]

Objectives

Results

Conclusion