11-04-2014, 12:09 PM
DESIGN AND FABRICATION OF A SOLAR POWERED VAPOUR COMPRESSION REFRIGERATING SYSTEM
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INTRODUCTION
Background of the Study.
Solar power is the conversion of sunlight into electricity. Sunlight can be converted directly into electricity using photovoltaic (PV), or indirectly with concentrated solar power (CSP), which normally focuses the sun's energy to boil water which is then used to provide power. Other technologies also exist, such as Sterling engine dishes which use a Sterling cycle engine to power a generator. Photovoltaic were initially, and still are, used to power small and medium-sized applications, from the calculator powered by a single solar cell to off-grid homes powered by a photovoltaic array. They are an important and relatively inexpensive source of electrical energy where grid power is inconvenient, unreasonably expensive to connect, or simply unavailable.
Solar power is the conversion of sunlight into electricity, either directly using photovoltaic (PV), or indirectly using concentrated solar power (CSP). Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam.
Vapor-compression refrigeration
Refrigeration’ may be defined as the process of removing heat from a substance under controlled conditions. It also includes the process of reducing and maintaining the temperature of a body below the general temperature of its surroundings. In other words, the refrigeration means a continued extraction of heat from a body whose temperature is already below temperature of its surroundings. In a refrigerator, heat is virtually pumped from a lower temperature to a higher temperature. According to Second Law of Thermodynamics, this process can only be performed with the aid of some external work. It is thus obvious that supply of power is regularly required to drive a refrigerator. Theoretically, a refrigerator is a reversed heat engine or a heat pump which pumps heat from a cold body and delivers it to a hot body. The substance which works in a pump to extract heat from a cold body and to deliver it to a hot body is known as refrigerant. Vapor-compression refrigeration is one of the many refrigeration cycles available for use. It has been and is the most widely used method for air-conditioning of large public buildings, offices, private residences, hotels, hospitals, theaters, restaurants and automobiles. It is also used in domestic and commercial refrigerators, large-scale warehouses for chilled or frozen storage of foods and meats, refrigerated trucks and railroad cars, and a host of other commercial and industrial services. Oil refineries, petrochemical and chemical processing plants, and natural gas processing plants are among the many types of industrial plants that often utilize large vapor-compression refrigeration systems.
SIGNIFICANCE OF THE STUUDY
A solar powered refrigerator has the following benefits:
1. Longevity – it can be able to operate continuously for several years. This capability has been proved by some of the prototypes that have been implemented and tested in several countries across the globe.
2. Scalable – it is possible to have a cooling system in a manageable size. It is possible to have small refrigerators or even big ones that are the size of a building depending on the needs.
3. Environmentally friendly – This type of refrigerator makes use of the sun energy hence minimizing the reliance on the use of fossil fuels. It also reduces the usage of batteries that can be very damaging to the environment when they are disposed off.