Adsorption Air-Conditioning (AdAC) for Automobiles Using Waste Heat Recovered from Exhaust Gases

According to a cautious estimate, approximately 10% of the energy available at the crankshaft in a diesel operated vehicle is used for operating the compressor of the vehicle's air-conditioning system. This is a huge loss if one takes into account the fact that the thermal efficiencies of most diesel operated vehicles range from 20-30% when in pristine condition. The bottom line is that a great deal of diesel is consumed to generate electricity. In addition to this, alternating current via an alternator is necessary for the operation of the conventional a/c system. The refrigerant, usually R12 or R22 leaks easily. Being a secondary refrigerant, it is also harmful to the environment. Conventional air conditioning systems are also questioned due to the ODP (ozone depletion potential) and GWP (global warming potential) caused by the CFCs or HCFCs. Increasing recognition of environmental problems associated with CFCs and HCFCs has opened favourable opportunities for the development of green air conditioning technologies. This project report presents a revolutionary silica gel-water adsorption system for air conditioning in automobiles. The cooling effect is achieved by recovering waste thermal energy from the exhaust gases. The system is cheap and easy to fabricate. The refrigerant, being water, is environment friendly. The report provides the details regarding the construction of a prototype fabricated on this technology, by the co-authors. The design of the generator, which is the focal part of the system, is novel yet simple. The experimental results obtained, while conducting tests on a four stroke diesel engine from Mahindra have been included.