1. INTRODUCTION
In India road transport is a major mode of transport for goods over large distances. The atmospheric temperature in some parts of India touches 45oC.In such condition studies shows that the temperature inside the cabin of a transport truck even exceeds 55oC (Alam, 2006) [1]. The operation in such hot condition for the truck driver is extremely difficult. Further this extreme heat reduces the working efficiency of the drivers and delays the transport duration over the road. The delay further affects the economy, which is unacceptable. So some measures have to be taken to reduce the temperature inside the cabin of the truck and to provide comfort to the driver. Considering present energy crises all over the world, it is very much necessary to explore new technology and potential to satisfy the need of society. At the same time the efficient management of the production and energy conservation is also equally important. In case of truck large amount of heat as input around 25% of the total heat supplied is going away with exhaust gases at very high temperature and around 25% is going away with cooling water. So if this waste heat can be utilized for powering an air conditioning system it will be economical and the fuel energy can be used effectively. Considering all the above factors different alternatives have been studied and the vapor absorption system is found to be the most promising alternative. The paper deals with the preliminary design of Ammonia water vapor absorption refrigeration system and a simulation model has been developed for both the systems to predict the performance of the systems, designed for given operating conditions, under various off-design operating conditions. The significance of the work is that it will provide space cooling for the truck driver and thereby enhances his performance and efficiency without affecting performance of the engine essentially the fuel economy. Further the vapor absorption cycle use non CFC refrigerant and thereby have little effect on environment.