A Review on Solar Powered Air Conditioning System

Abstract

The twenty first century is rapidly becoming the perfect energy storm, modern society is faced with volatile energy prices and growing environmental concerns as well as energy supply and security issues. One of the greatest challenges facing mankind in the twenty first century is energy. Fossil fuels such as coal, petroleum and natural gas have been the main energy resources for everything vital for human society. The burning of fossil fuels has caused and is causing damage to the environment of earth. By 2050 the demand for energy could double or even triple as the global population grows and developing countries expand their economies. This has already raised concerns over potential supply difficulties, depletion of energy resources and expediting environmental impacts like ozone layer depletion, global warming and climate change etc. The most abundant energy resource available to human society is solar energy. The utilization of solar energy is as old as human history. Among various types of renewable energy resources, solar energy is the least utilized. Air conditioning is essential for maintaining thermal comfort in indoor environments, particularly for hot and humid climates. Today, air conditioning comprising cooling and dehumidification has become a necessity in commercial and residential buildings and industrial processes. During the summer, the demand for electricity greatly increases because of the extensive use of air-conditioning systems. This is a source of major problems in the country's electricity supply and contributes to an increase of CO2 emissions causing the environmental pollution and global warming. On the other hand, vapour compression air conditioning systems have impacts on stratospheric ozone depletion because of the chlorofluorocarbons (CFC) and the hydro fluorocarbon (HCFC) refrigerants. The use of solar energy to drive cooling cycles is attractive since the cooling load is roughly in phase with solar energy availability. To cool with solar thermal energy, one solution is to use an absorption chillier using water and lithium bromide solution. Solar air conditioning systems help to minimize fossil fuel energy use. Among the evolving energy efficient air conditioning technologies are liquid desiccant air conditioning (LDAC) systems, which have showed promising performance during the past decades and are believed to be a strong competitor with the widely used conventional air conditioning systems (CAC). Desiccant evaporation cooling technology is environmental friendly and can be used to condition the indoor environment of buildings. Unlike conventional air conditioning systems, the desiccant air conditioning systems can be driven by low grade heat sources such as solar energy and industrial waste heat. In this study, a focus is made on reduction in Air Conditioning capacity, fuel savings and emission reductions attainable through the use of solar energy.