Boot strap air cooling system

refrigeration and air conditioning

1. PRESENTATION ON “BOOT-STRAP AIR COOLING SYSTEM” REFRIGERATION AND AIR CONDITIONING SUBMITTED BY: HIMANSHI GUPTA ( 140120119057)/ ME/A2 GUIDED BY : PROF. NIMESH GAJJAR ( 2161908) GANDHINAGAR INSTITUTE OF TECHNOLOGY

2. BOOT-STRAP AIR COOLING SYSTEM The term Bootstrap as used in Air Cycle Refrigeration indicates a system in which the pressure of the working fluid is raised in two levels by using two compressors, before the working fluid which is air, expands in the turbine section The main components of this system are: T wo heat exchangers (air cooler and after cooler) A secondary compressor, which is driven by the turbine of the cooling system APPLICATION: This system is suitable for high speed aircraft, where in the velocity of the aircraft provides the necessary airflow for the heat exchangers

3. WORKING The air bled from the main compressor is first cooled by the ram air in the first heat exchanger The air is then compressed to a higher pressure and temperature in the compressor of the cooling turbine A substantial amount of heat of compression is removed in the secondary heat exchanger and the air is cooled further as it expands through the turbine section of the c ooling turbine

4. BOOT-STRAP AIR COOLING SYSTEM

5. A mbient air state 1 is pressurized to state 2 due to the ram effect This air is further compressed to state 3 in the main compressor The air is then cooled to state 4 in the air cooler The heat rejected in the air cooler is absorbed by the ram air at state 2 The air from the air cooler is further compressed from state 4 to state 5 in the secondary compressor It is then cooled to state 6 in the after cooler, expanded to cabin pressure in the cooling turbine and is supplied to the cabin at a low temperature T7 T -s diagram for a boot-strap air cooling system

6. 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, C.O.P. of the refrigerating system,

7. ADVANTAGES The air is easily available and there is no cost of the refrigerant The air is non-toxic and non-inflammable The leakage of air in small amounts is tolerable The air is light in weight per tonne of refrigeration The chilled air is directly used for cooling, there by eliminating the cost of separate evaporator The pressure in the whole system is quite low, therefore the piping, ducting etc. are quite simple to design, fabricate and maintain

8. LIMITATIONS The basic system will cool the cabin when the a irplane is on the ground The Bootstrap system requires the airplane to be in flight so that the ram air can cool the heat e xchangers Since the system does not consist of a separate fan for driving the air through the heat exchangers, it is not suitable for ground cooling

9. Thank You 