(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Air is to be compressed from 120 kPa and 310 K to 700 kPa and 430 K. A heat loss of 20 kj/kg occurs during the compression process. For air: cv=0.7165 kj/kg.K and R=0.287 kj/kg.K .

A) Neglecting kinetic energy changes determine the power input required for a mass flow rate of 90 kg/min.

3. The attempt at a solution

m = 90 kg/min = 1.5kg/s

Apply 1st law of thermodynamics - energy conservation

Ein = Eout

Win + Mh1 = Qout + mh2

Therefore:

Win + mCpT1 = Qout + mCpT2

Cp = 1.005 Kj/Kg.K

Win + 1.5kg X 1.005 KJ/Kg.K X 310K = 20KJ/Kg/K + 1.5Kg/s X 1.005 KJ/Kg.K X 430K=

Win = 201Kw.

Is this correct?

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# Homework Help: Control volume, steady- state and steady-flow devices, enthalpy

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