Question

one kg of a perfect gas at 15 degree
Celsius and 100 kPa is heated to 45
degree Celsius by (i) constant
pressure process and (ii) a constant
volume process. Cp=1.042 kJ/kg-K:
R=0.2968 kJ/kg-K. Heat added in the
constant volume (Qv) and constant
pressure (Qp) processes are
a) 22.35 kJ, 31.26kJ
b) 31.26 KJ, 22.35 kJ
c) 31.26 kJ, 31.26 kJ
d) 0,22.35 kJ​

Answer 1

Answer:

a

Explanation:

cv=R/1.4-1,Q v=m×c v×dt

Q p=m×c p×dt

Answer 2

Answer:

(a)22.35kJ,31.26kJ

Explanation:

in this question we will directly use the formulas,

heat added at constant volume(Qv)=mass(m) x specific heat at constant volume x change in temperature(ΔT)               (1)

heat added at constant pressure(Qp)=mass(m) x specific heat at constant pressure x change in temperature(ΔT)     (2)

relation between specific heat at constant pressure and constant volume,

Cp - Cv=R      (3)

R=universal gas constant

as given in question,

m=1kg

T1=15°C

T2=45°C

Cp=1.042KJ/kg-k

R=0.2968KJ/Kg-K

ΔT=T2-T1

by using equation 3 we will get Cv

Cv=Cp-R=1.042-0.2968=0.7452KJ/kg-k

Qv=mCvΔT=1 x 0.7452 x 30=22.356KJ

Qp=mCpΔT=1 x 1.042 x 30=31.26KJ