Question

The following data is for a closed bell coleman air refrigeration cycle.
Pressure at compressor inlet = 2 bar
Pressure at compressor outlet = 10 bar
Temperature at compressor inlet = 18°C
Temperature at expander inlet = 28°C
Load = 100 MJ/hr

What is the volume handled by air compressor?

${\eta }_{\text{mechanical' compressor}}$ = 80%

${\eta }_{\text{mechanical' expander}}$ = 86%

• A. 82.2 l/s
• B. 88.3 l/s
• C. 92.1 l/s
• D. 114 l/s

Answer 1

The correct option is D 114 l/s

$T_1=273+18=291K$

$T_3=273+28=301K$

$\frac{T_4}{T_3}={\left(\frac{P_4}{P_3}\right)}^{\frac{\gamma -1}{\gamma }}={\left(\frac{2}{10}\right)}^{\frac{2}{7}}=0.631$

$T_4=301\times 0.631=189.93K$


$RC=\dot{m}\left(RE\right)$

$\frac{100\times {10}^3}{3600}=\dot{m}{c}_p[T_1-T_4]$

$\frac{100\times {10}^3}{3600}=\dot{m}\times 1.005[291-189.93]$

$\dot{m}=0.273\text{kg/s}$

$P_1{\dot{V}}_1=\dot{m}R{T}_1$

${\dot{V}}_1=\frac{0.273\times 0.287\times 291}{2\times 100}$

${\dot{V}}_1=0.114{\text{m}}^3/s$

${\dot{V}}_1=114l/s$