Design And Fabrication Of Solar Fridgeration System

ABSTRACT

This paper presents the design of a solar powered refrigeration system. The design of the system takes into account the solar sorption principles which include both the absorption and adsorption. Research has been conducted and it has been proven that the design and implementation of solar refrigeration system comes with several advantages. It helps in meeting the demand for energy conservation and the protection of the environment.

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                           BACKGROUND OF THE STUDY

The solar refrigerator is the refrigeration system that runs on the solar energy. They don’t use domestic power supply, rather use power produced by the solar panels.
The solar refrigerator is the refrigeration system that runs on the solar energy. The solar refrigerator comprises of all the traditional components like the compressor, condenser, expansion valve and the evaporator or the freezer. The power is supplied not by the domestic electrical supply system, but from the solar panel.
The solar system of the solar refrigerator comprises of the solar panel that collects the solar energy. The solar panels are fitted with photovoltaic cells that convert the solar energy into electrical energy and store it in the battery. During the normal running of the solar refrigerator the power is supplied directly by the solar panel, but when the output power of solar panels is less, the additional power is supplied by the battery. The battery is recharged when excess amount of power is produced by the solar panels.

The production of most of the systems that use solar power for refrigeration purposes are in small scale. However, there is need for more research to be done in order to ensure that larger systems are also manufactured to aid the process of cooling through the use of solar energy. In this project, we will concentrate only on designing a refrigeration system that uses solar energy as its main source of power. The design will also see the implementation of a prototype so as to help us in determining the viability of the project. Solar powered refrigeration system has been a subject that has received a lot of publicity in the recent past. Several governments have put in place mechanisms of controlling harmful emissions to the environment and also devise ways of controlling the amount of energy consumed. Designing a system that relies on entirely solar energy will help in achieving some of the goals for the developing countries of having a clean source of energy and also reduce their reliance on fossil fuels and national electricity grid. This study was therefore commissioned in order to design a system that could be used to provide an alternative to the traditional cooling systems that not only damages the environment through the emissions of CFCs and HCFCs that deplete the ozone layer but also reduce the stretching on the national electricity grid in terms of energy consumption. This paper therefore covers the design issues of the solar refrigeration system and also proposes a prototype that can be used to demonstrate the functionalities of the system.

The output supply of the batteries and the solar panel is DC with voltage of about 12V. A typical solar system produces 300W or 600W of power depending upon the size of the desired refrigerator. The voltage regulator is connected to the battery to convert the low voltage DC supply to high voltage AC supply to run the compressor. It is advantageous to use the AC supply compressor since it can run on domestic electrical supply also. Some of the solar refrigerators use compressors that can run directly on DC supply.

Another application where the solar energy can be very useful is the vapor absorption refrigeration system. In these systems heat from the steam is used to heat water mixed with lithium bromide or ammonia that act as the refrigerant. In these machines, the heat produced by the steam can be replaced by the heat produced by solar energy.

1.2                                STATEMENT OF THE PROBLEM

In developing countries there is a growing interest in refrigeration for food and vaccine preservation. Simple solar refrigerators working without need for electricity supply would be very valuable in rural areas where there may be no electricity supply. Mechanical refrigerators powered by solar cells are available, but are too expensive. In the last twenty years, adsorption refrigerators using water as a refrigerant and Zeolite as an adsorber have been successfully developed. In areas with abundant sunshine, solar radiation is the most easily accessible energy source. Solar refrigerators can work independently of the electrical network. Extensive vaccination programmes are in progress throughout the developing world in the fight against common diseases. To be effective, these programmes must provide immunization services to rural areas. All vaccines have to be kept within a strict temperature range throughout transportation and storage. The provision of refrigeration for this aim is known as the vaccine cold chain. In Africa about 1800 solar refrigerators are used to store vaccines (WHO). Usually, refrigeration is produced by a vapour compression cycle, which is driven by electric power produced or generated by solar cells. However, the investment of about USD 2000 is high and the population cannot afford such systems, in addition, the high-tech production of solar cells seems to be difficult in developing countries.

1.2                                              PURPOSE OF THE PROJECT

Solar power for refrigeration purposes are in small scale. However, there is need for more research to be done in order to ensure that larger systems are also manufactured to aid the process of cooling through the use of solar energy. In this project, we will concentrate only on designing a refrigeration system that uses solar energy as its main source of power.

1.3                                            AIM OF THE PROJECT

The main aim of work is to design a refrigerator which runs on energy directly provided by sun, and may include photovoltaic or solar thermal energy. Solar-powered refrigerators are able to keep perishable goods such as meat and dairy cool in hot climates, and are used to keep much needed vaccines at their appropriate temperature to avoid spoilage. Solar-powered refrigerators may be most commonly used in the developing world to help mitigate poverty and climate change.

1.4                                             OBJECTIVE OF THE PROJECT

• To make effective refrigerator using solar
• To build a refrigerator that can be use in rural
• Pollution free
• A refrigerator that can be used in food storage plants.
• Refrigeration system having low maintenance cost
• One time investment with minimum running expense
• To make refrigerator with less moving parts

1.5                                         SIGNIFICANCE OF THE PROJECT

The advantages of the solar refrigerator are similar to the ones offered by the other solar energy devices. Since the solar refrigerator runs on solar energy there is lots of saving of electrical power that would have been produced by the conventional power plants causing lots of pollution. The solar energy is available freely, abundantly and is a clean source of energy. One of additional advantage is that the excess power produced by the solar refrigerator can be used for the other domestic purposes. The solar refrigerators can be very useful in far off remote places where there is no continuous supply of electricity.

1.6                                           LIMITATION OF THE PROJECT

The limitation of the solar refrigerator is that the production of power is not uniform since solar energy is not available throughout the day and it also changes in intensity during various times of the year. Hence, it can be used only in places where strong sun rays are available throughout the year and most parts of the day. The other major limitation of the solar refrigerator is the size of the solar collector occupying large areas of the home. To produce power sufficient for the refrigerator big solar panels are required. The solar collectors can be kept on the terrace, but still they will occupy lots of space.

A number of solar refrigerators have been developed, and they are being used successfully. However, the technology has not been developed to the stage for carrying out commercial production of the solar refrigerators. There are few companies manufacturing solar refrigerators, but high costs of the solar equipment, their low efficiency and their large sizes have not yet made them the popular choice.