Table of Contents

Solar Powered Refrigerator Report PDF Download – Mini Mechanical project

INTRODUCTION

Electricity generation is the leading cause of industrial air pollution in the country. Most of our electricity comes from coal, nuclear, and other non-renewable power plants. Producing energy from these resources takes a severe toll on our environment, polluting our air, land. Renewable energy sources can be used to produce electricity with fewer environmental impacts. It is possible to make electricity from renewable energy sources without producing CO2.
Renewable energy is energy derived from natural resources that replenish themselves over a period of time without depleting the Earth’s resources. These resources also have the benefit of being abundant, available in some capacity nearly everywhere, and they cause little, if any, environmental damage. Energy from the sun, wind, and thermal energy stored in the Earth’s crust are examples. For comparison, fossil fuels such as oil, coal, and natural gas are not renewable, since their quantity is finite once we have extracted them they will cease to be available for use as an economically-viable energy source. While they are produced through natural processes, these processes are too slow to replenish these fuels as quickly as humans use them, so these sources will run out sooner or later.
So this project is intended at the development of a solar based compressor free mini fridge. This fridge will be suitable for cooling purposes meant for small objects and will have a relatively small chilling time as compared to the normal refrigeration systems. Also for the backup, this fridge will be attached to a dynamo based charging system which will maintain the smooth operation of fridge in case of non-availability of solar power.

CONSTRUCTION AND DESIGN

solar powered refrigerator mini mechanical projects

Dimensions of the fridge

1. Outer Dimensions

Length: 30 cm
Breadth: 20 cm
Height: 21 cm (including the stands)

2. Inner Dimensions

Length: 25.5 cm
Breadth: 15.5 cm
Height: 8 cm

3. Volume of the fridge 3.162 Litres

Steps in the construction of the fridge

Firstly a box of thermocol is made of given dimensions and then the inner walls of the box are covered with the aluminium sheet and the outer walls by the chart paper.
The taping of the box from outer side is done so as to provide mechanical support and blocking of air.
The two Peltier units are well placed in the two holes made in the box and kept on the heat sink with hot side attached to the heat sink surface and cold side inside the box.
The heat sink is linked with a fan which is used to dissipate the heat of heat sink into the outer atmosphere i.e. out of the thermocol box. So, the hot side of peltier unit is unable to affect the temperature inside the box.
All the electrical connections are made putting a switch for on/off and a LED as an indicator whether the fridge is working or not. Two batteries each of 12 Volts DC, 7.5 Ah are connected in parallel with the peltier units connected in series and the two cooling fans.
All the electrical connections are made strong by soldering them and all the wires are arranged properly so as to avoid any inconvenience for the user.

WORKING OF THE PROJECT

Fridge

The fridge is provided power supply form a 12 volt DC 7.5 amphrs battery.
To start the fridge, the switch on the fridge is turned on.
When the switch is turned on, a led starts glowing indicating that the fridge is now online.
Now two Peltier thermoelectric devices which are insulated from the cooling side and arranges in the fridge generates cooling effect on inner side and heat is dissipated on outer side.
On the heat side of the peltier unit, a heat sink along with the fan works to dissipate the heat from the peltier unit in the outer environment.
The Peltier thermoelectric Device will be so arranged in a box with proper insulation system and heat sink so that efficient cooling takes place at all the time.
To turn off the fried, switch can be turned off. Then the glowing led will also stop glowing indicating no power for the fridge.

Battery charging

The batteries used in the fridge are charged from the solar panels using a charge controller rated 12volts, 10 amps. The battery is connected to the charge controllers which get supply from the solar panels and feeds it to the battery.