Musbah Mahfoud and Ahmad Bin Marzook

Department of Mechanical Engineering Technology
College of the North Atlantic-Qatar

Abstract

Sun-light is an abundant and infinite source of energy that is currently being overlooked. The sate of Qatar, which is located close to the tropic of Cancer, is well positioned to exploit this potential. The country’s climate is sunny most of the year with temperatures ranging from 12oC to 58oC. In addition to being sunny, the climate is typically hot and humid. To avoid these extreme weather conditions, the population of Qatar depends on enclosed air-conditioned areas and other forms of refrigeration. Since the early 30’s, the country has spent millions of riyals on refrigeration and air conditioning to strive and survive in this climate.

Thus far, the main form of energy used in Qatar has been fossil fuels, a non-renewable energy source. Solar energy, an abundant renewable energy source, is available in the country, but has yet to be exploited. Solar energy has been used throughout the world in various applications such as cars, calculators and heating water, but its use as an energy provider for refrigeration has not been widely investigated. Some household items currently operated electronically can be replaced with solar powered alternatives. Thus, solar energy can reduce cost and save energy if exploited in Qatar.

The direct conversion of sunlight into electricity is a very elegant process that generates environmentally friendly, renewable energy. The purpose of this study was to present a method to attain cooling using solar thermal energy.

In terms of refrigeration, the idea was to investigate the possibility of developing a refrigeration system that depends fully on solar energy. The current project consists of the physical construction of a Solar Refrigeration System. The project involved analyzing, designing and assembling a solar system consisting of (along with other accessories) a laboratory refrigeration unit and a solar panel.

In terms of air conditioning, the objective was accomplished with a parabolic solar reflector and a heat absorption cooling system using ammonia, water, and hydrogen. It is shown that such a system can indeed produce significant cooling using solar thermal energy alone.

Introduction

A crucial response to the dangers of global warming is the worldwide utilization of solar energy. Solar thermal technology is modular, operated silently and is therefore suited to a broad range of applications and can contribute substantially to future energy needs. From a sustainability perspective, directly using solar energy is attractive because of its universal availability, low environmental impact, and low or no ongoing fuel cost. Solar cooling could be a useful technology in areas of the world where there is a demand for cooling, high insulation levels and no firm electricity supply to power conventional systems.

Solar systems are relevant to Qatar because:

o Ambient temperatures are high through out the year in most parts of the country. Higher ambient temperatures mean more energy is consumed in refrigeration. o Solar insulation is high in most parts of the country. This implies that we have more energy at our disposal.

o There is huge potential demand for refrigeration in rural areas, which are best suited for solar energy based refrigeration systems.

o There is a high potential for cost and energy savings.

Literature Review

Cooling using solar thermal heat was first patented by Shipman1 in 1936. The idea was not applied on a wide scale because the process was relatively inefficient and other forms of energy were cheap and readily available. Erickson and Donald2 have demonstrated recently that there has been a renewed interest in the process. Uli et al3 completed detailed studies on the performance of the bubble pump (the device that drives the process) last year. Erickson and Donald2 presented a large scale application of this process in their paper, which was published during the course of the research for the present work. They mentioned that heat absorption cooling is currently used to cool Cochise Community College in Arizona.