17-07-2012, 01:06 PM
FRABRICATION OF SOLAR AIR COOLER WITH AUTO TRACKING
Solar air cooler with autotracking full doc.doc (Size: 1.84 MB / Downloads: 259)
INTRODUCTION
The human body can be considered as thermal machine with 20% thermal efficiency. The remaining 80% heat must be disposed off from the body to the surroundings otherwise accumulation of heat results and causes discomfort. The human body works best at a particular body temperature like any other machine but cannot tolerate wide range of variation in environmental temperature like thermodynamic machines.
NEED FOR AIR COOLER:
Human beings give off heat, around an average of 100 kcal per hour per person, due to what is known as ‘metabolism’. The temperature mechanism within the human body maintains a body temperature of around 36.9 degree C (98.4degree F). But the skin temperature varies according to the surrounding temperature and relative humidity.
NEED FOR NON-CONVENTIONAL ENERGY
Fuel deposit in the will soon deplete by the end of 2020, fuel scarcity will be maximum. Country like India may not have the chance to use petroleum products. Keeping this dangerous situation in mind we tried to make use of non-pollutant natural resource of petrol energy.
THERMAL EXCHANGE IN HUMAN BODY
The human body works best at certain temperatures like other machines, but it cannot tolerate with range of variations. The human body maintains its thermal equilibrium by three modes of heat transfer i.e. evaporation, radiation and convection.
A human body feels comfortable when the heat produced by metabolism of human body is equal to the sum of heat dissipated to the surroundings.
DIRECT METHOD OF UTILIZATION OF SOLAR ENERGY:
The most useful way of harnessing solar energy is by directly converting it into electricity by means of solar photo-voltaic cells. Sunshine is incident on Solar cells, in this system of energy Conversion that is direct conversion of solar radiation into electricity.
In the stage of conversion into thermodynamic from is absent. The photo-voltaic effect is defined as the generation of an electromotive force as a result of the absorption of ionizing radiation. Energy conversion devices, which are used to convert sunlight to electricity by use of the photo-voltaic effect, are called solar cells.
PHOTOVOLTAIC PRINCIPLES:
The photo-voltaic effect can be observed in nature in a variety of materials that have shown that the best performance in sunlight is the semiconductors as stated above. When photons from the sun are absorbed in a semiconductor, that create free electrons with higher energies than the created there must be an electric field to induce these higher energy electrons to flow out of the semi-conductor to do useful work. A junction of materials, which have different electrical properties, provides the electric field in most solar cells.