Bootstrap Air Cycle Refrigeration System

By: Siddharth Bhatnagar B2 |

147

Presented To: Mr. Ashish Nayyar

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.

Consists of a Primary Heat Exchanger, a Secondary Heat Exchanger and a Cooling Turbine.

Ram Air is used as a sink in the Primary and Secondary Heat Exchangers.

Bootstrap Air Cycle Refrigeration

System.

#1

The Bootstrap refrigeration system is mostly used in Transport Aircrafts. The Basic System will cool the Cabin when the Airplane is on the Ground. The Bootstrap system requires the Airplane to be in flight so that the Ram Air can cool the Heat Exchangers.

High Pressure air is first cooled in the Primary 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 Cooling Turbine.

Bootstrap Air Cycle Refrigeration

System.

#2

Bootstrap Air Cycle Refrigeration

System.Fig.1: Bootstrap Air Cycle Refrigeration System.

#3

Bootstrap Air Cycle Refrigeration

System.

Ambient 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. #

4

Bootstrap Air Cycle Refrigeration

System.Fig.2: Bootstrap Cycle Temperature- Pressure Diagram.

#5

References.

Refrigeration and Air Conditioning Lecture Version I, IIT Kharagpur.

Wikipedia. Google.

#6

Questions are Welcomed THANK YOU!