Question

Air initially at 15 psla and 60 F is compressed to 75 psia and 400 F. The power input to air under steady state condition is 5 hp and heat loss of 4 Btu/lbm occurs during the process. If the change in Potential energy and kinetic energles are neglected, what will be the mass flowrate in lbm/min.?

Answer 1

Answer:
`\dot{m}=3.46lbm/min`

Step-by-step explanation:

Initial conditions

`P_1=15 psia`

`T_1=60 F^(\circ)`

Final conditions

`P_2=75 psia`

`T_2=400F^(\circ)`

Steady flow energy equation

`\dot{m}\left [ h_1+(v_1^2)/(2)+gz_1\right ]+\dot{Q}=\dot{m}\left [ h_2+[tex](v_2^2)/(2)+gz_2\right ]+\dot{W}`

`\dot{m}\left [ c_pT_1+(0^2)/(2)+g0\right ]+\dot{Q}=\dot{m}\left [ c_pT_2+(0^2)/(2)+g0\right ]+\dot{W}`

`\dot{m}c_p\left [ T_1-T_2\right ]+\left [ -5hp\right ]=\dot{W} -5* 746* 3.4121`

`-4\dot{m}-\dot{m}* 0.24* \left [ 400-60\right ]`

`-81.6\dot{m}-4\dot{m}=-4.949 BTU/sec`

`\dot{m}=0.057821lbm/sec`

`\dot{m}=3.46lbm/min`