India is the second most populous country in the world with over 1.21billion people (estimated for April, 2011), more than sixth of the world’s population. India is projected to be world’s most populous country by 2025,surpassing china, its population exceeding 1.6 billion people by 2050.
Comparing with the population there are 2.65 million cars sold in India as of march 2011.According to the society of Indian automotive manufacturer, annual car sales are projected to increase up to 5 million vehicles by 2015 and more than a 9 million by 2020.By 2050,the country is expected to top of the world in car volumes with approximately 611 million vehicles on the nation’s roads.
The above data shows that, as the population increase the no. of vehicles also increase. Today, an automobile is a necessity for everyone. For a long or short journey people need car regard to the safety, environment and most important comfort.
Owing to these reasons, many vehicles are equipped with heating, ventilating and air conditioning system. In today’s world, no one feel comfortable in a vehicle without HVAC system. Therefore, HVAC becomes an integral part of human life. Today’s present HVAC system is very efficient and reliable but it has some demerits.
It has been observed during the last two decades that the O3 –layer is slowly destroyed because of the refrigerant (CFC and HFC) used for the refrigeration and air – conditioning purposes.
The common refrigerant used is HFC’s which are leaked and slowly climb into the atmosphere. When they reach to O3 layer they act on O3 –molecules and the layer of O3 is destroyed. A single molecule of HFC’s can destroy thousand of O3 molecules and that’s why it has created a threat for the not only to maintain earth eco system stable but also to existence of earth.
Even the percentage of HFC’s are emitted into the atmosphere compared to CO2 is negligible but its global warming effect is few thousand times of CO2.The effect of 100 gm of HFC’s can destroy 0.5 tons of O3 molecule. These HFC’s once destroy O3-layer; it takes lack of years to recover its thickness as it is formed by complex reactions.
This is because as HFC’s comes in environment they remain in atmosphere for 18 years. The capacity of HFC’s to increase in earth temperature 10% is contributed by HFC’s only.(see reference) Other demerits includes: – The compressor is driven by the crankshaft of the engine. So it consumes about 5 to10% power of the engine.
This consequently reduces mileage of the vehicle. An Air conditioning system consumes as much as 8 h.p. with a unit capacity of 3 tons or 9072 kcal/hr. approximately. So, due to these the pickup of vehicle decreases. The cost of present HVAC system is very high; it may vary depending upon price and model of vehicle.
Source: IJEST
Authors: Manoj S. Raut
>> Heat Energy and Thermodynamics based Projects for Students