Answer to Question #110695 in Thermal Power Engineering for Mohd Amir Hussain

Question

An aircraft air conditioner works between the pressure limits of 1 bar and 5 bar. The
temperature of the air entering the compressor from the cabin and expansion
cylinder are 10o
c and 25oC respectively. The expansion and compression follow the
pv1.3=constant. Find the following:
1. The theoretical C.O.P of the refrigeration cycle:
2. If the load on the system assuming the actual C.O.P is 50% of the theoretical
C.O.P
3. The stroke length and the piston diameter of single acting compressor
running at 300 r.p.m and the volumetric efficiency is 85%.
(Take L/d = 1.5 : cp = 1.005 kJ/kgK ; cv = 0.71 kJ/kgK

Answer 1

Solution.

p₂ = 1 bar;

p₁ = 5 bar;

T₃ = 283 K;

T₁ = 298K;

pv1.3=constant;

L/d = 1.5;

c_p = 1.005 kJ/kgK;

c_v = 0.71 kJ/kgK;

;

Swept volume per stroke =13.36/(2 300) =0.02m³;

V = 0.02 0.85 = 0.019 m³;

Answer: theoretical C.O.P =1.92;

actual C.O.P = 0.96;

d=0.016m;

l = 0.024 m.