Boot-strap Evaporative Air Cooling System

A boot-strap air cycle evaporative cooling system is shown above. It is similar to the boot-strap air cycle cooling system except that the addition of an evaporator between the second heat exchanger and the cooling turbine. The T-s diagram for a boot-strap air evaporative cooling system is shown:

The various processes of this cycle are same as a simple boot-strap system except the process 5''-6 which represents cooling in the evaporator using any suitable evaporant.

If Q tonnes of refrigeration is the cooling load in the cabin, then the quantity of air required for the refrigeration purpose will be:

Power required for the refrigeration system is given by:

and C.O.P. of the refrigerating system

Note: Since the temperature of air leaving the cooling turbine in boot-strap evaporative system is lower than the simple boot-strap system, therefore mass of air (ma) per tonne of refrigeration will be less in boot- strap evaporative system.