This research presents an innovative application of evaporative cooling to provide thermal comfort in the cabin of slow and medium speed vehicles. Conventionally vapor compression refrigeration systems are used for air conditioning in automobiles which account for significant fuel/energy consumption under high cooling loads. Additionally, use of CFC based refrigerants imposes threat for global warming. Application of Evaporative cooling in residential applications had significantly reduced these drawbacks, and similar results are anticipated if adopted for mobile applications. The proposed design for automobile application is cheaper and highly suitable for a wide range of regions of the world having arid and semi-arid climate. The prototype performance lowered cabin temperature close to acceptable limit with less than 10% of energy consumption compared to vapor compression units when tested under similar hot dry conditions. The unit is very useful in arid climate suitable for small cabin vehicles like trucks, trailers, earthmovers, dumpers, lorries, campers etc. particularly where air conditioners are not fitted/ or not being afforded.

The unit is mounted on vehicle roof and had been tested for 4 seater car cabin space at 100km/hr speed. Even under 48 deg. dry ambient conditions it produces about 33 deg. C comfort in the cabin with just less than 4 litres/hr of water consumption and just about 130 W of energy from car alternator/battery. The designed unit is with just 18"x18"x8" (LxBxH), streamlined and optimised for utilisation of ram effect of the air .

The utilization of the unit can also be made by the driver for overnight sleep in the cabin and can run from battery power.

The attached fig. shows that main pump supplies water from water tank placed at floor level to the unit mounted on roof. The water trickles down from the pipe on the cooling pads which gets wet in the process. The excess water falls down by gravity and gets collected in the collecting channel/chamber where it goes back into the tank by return/drain pipe. A hole is made in the roof to allow fan unit to supply cool air in the cabin. Flushing nozzle is used for instant wetting of pads whenever required.