Your task is to design an environmental control system for a

Your task is to design an environmental control system for a jet aircraft using your knowledge of thermodynamics. The following diagram is from the systems manual of an F-15, depicting a portion of the environmental control system (ECS). The \"working fluid\" of the ECS is air. An F-15 is flying at an altitude of 30,000\' where the standard day outside air temperature is - 44 degree C. Two ECS states of air are identified, State 1 and State 2. Two additional locations associated with ambient conditions are identified, Location A and Location B. Answer or solve the following: In one or two sentences maximum, explain \"bleed air\" and where it originates from within the aircraft: Temperatures may or may not be expected to vary between the four locations (1, 2, A & B). Use the symbols (, =) between each of the three temperature pairs to depict the most likely relationships: T_1 T_2 Explain: T_2 T_A Explain: T_A T_B Explain: If State 2 were to directly supply comfortable air to the pilot at 22 degree C and the heat transfer across the \"left primary heat exchanger\" is 156.63 kJ/kg, what is the initial temperature of the bleed air?

Solution

Bleed air is the air extracted from one of the stages of compressor which can be used for either ECS aur domestic purppses. Bleed is generally taken from 2 stages of compressor, one for ground idle condition and other for cruise conditions.

For temperatures:

T1> T2: this is because temperature at location 1 is taken from stage 13 of compressor which has compressed the gas and has highr temperature. When this air passes through heat exchanger it would loose heat and hence T2 will be lower than T1.

T2>TA: this is because we are cooling bleed air with intake duct air. This intake duct has some diffusion while passing through intake duct hence its temperature will be higher than ambient air. When intake air duct temperature is higher than Ambient air, it can never cool any air to temperatures below ins own temperature. Hence T2will be higher than TA.

TB>TA: TV is the air which has been compressed due to ram effect hence it will have highr temperature than Ambient air.

Energy transfer = 156.63kj/kg

Q= mCpT

156.63=1*1.005*T

T=155.85°C

Hence T1= 175.85°C