Experimental Performance Evaluation of a PV-Powered Refrigeration System

摘要

As the technology evolves and the price of fossil fuel resources grows rapidly, the increasing focus on renewable energy resources is observed [1]. Recently, energy conservation and reduction of global warming effect become one of the most important subjects in the worldwide. Since the proportion of the refrigeration systems' energy consumption in overall energy consumption is steadily increasing, these systems are under research. Many vehicles used in transportation of goods or recreation such as trucks, caravans, boats, cars, etc. are often equipped with small cooling appliances. Compressor of these kind of applications might be designed to operate low voltage direct current, such as, 12-24 volts. The electrical energy produced by renewable energy systems like photovoltaic panels is in the form of the DC electrical energy [2]. Also, because there are innumerable places in the developing countries where the power supply is still intermittent and irregular, for the storage of vaccines and life saving drugs in such areas, refrigeration systems based on usage of solar energy can be considered to be the optimal solutions. The electricity supplied is mainly from conventional fuel based power plants which are the greatest contributors to global warming [3]. Environment friendly solutions are mandatory for the sustainable world. Therefore, solar PV power system applications are increasing. The photovoltaic power systems are becoming important in the power production market with each succeeding year what can be determined by the skyrocketing development of cumulative installed power of the PV installations in the EU countries and worldwide [4]. Considering the fact that the cooling demand increases with the intensity of solar radiation, solar refrigeration has been considered a logical solution. PV refrigeration systems with batteries have existed for several decades but have only been used in limited applications. A PV powered refrigerator or freezer has a cooling capacity lower than typical alternative current (AC) unit because of its smaller compressor. Using the energy efficiently in solar or other renewable energy powered systems is more crucial than others since the limited sources and high costs for the storage capacity. The second law of thermodynamics (or exergy analysis) deals with the quality of energy. More specifically, it is concerned with the degradation of energy during a process, the entropy generation/irreversibility, and the lost opportunities to do work; and it offers plenty of space for improvement. The second law of thermodynamics has proved to be a very powerful tool in the optimization of complex thermodynamic systems [5]. In this study, exergy analyses of a household refrigerator, powered by a photovoltaic has been investigated to obtain efficient operation conditions based on experimental data.