Lecture 15 Steady Flow Devices

Lecture 15 Steady - Thermal and Fluids Engineering I Prof Deborah A Kaminski Lecture 15 Steady Flow Devices Compressors and Pumps A compressor is

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Thermal and Fluids Engineering I Prof. Deborah A. Kaminski Lecture 15 – Steady Flow Devices Compressors and Pumps A compressor is the opposite of a turbine. In a compressor, work is done on a gas or vapor to raise it to a higher pressure. Axial Flow Compressor The first law for a compressor is the same as that for a turbine. From the first law for an open system 22 cv i e cv cv i i i e e e dE QW m h g z mh g z dt ⎛⎞ =−+ + + − + + ⎜⎟ ⎝⎠ ∑∑ ± ± ±± VV In a compressor, kinetic and potential energy are generally negligible. The first law becomes cv cv cv i i e e dE m h m h dt ± ± Compressors operate with one inlet and one exit cv cv cv i e dE Q W mh mh dt =−+− ± ± Lecture 15 Page 1
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Thermal and Fluids Engineering I Prof. Deborah A. Kaminski If the compressor is adiabatic and operating in steady state () 0 cv i e Wm hh =− + ± ± A pump is, in some ways, similar to a compressor. Compressors raise the pressure of gases; pumps raise the pressure of liquids. The first law for a pump in steady operation reduces to cv i e ± ± Designating the entrance as state 1 and the exit as state 2 ( ) 12 cv ± ± compressor, pump The liquid traveling through a pump can usually be considered as incompressible and isothermal. In that case, the enthalpy change is ( 21 hhv PP −= ) pump Combining the last two equations produces ( ) cv v ± ± pump Lecture 15 Page 2
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This note was uploaded on 04/06/2009 for the course ENGR 2250 taught by Professor Borca-tasciuc during the Spring '08 term at Rensselaer Polytechnic Institute.

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Lecture 15 Steady - Thermal and Fluids Engineering I Prof Deborah A Kaminski Lecture 15 Steady Flow Devices Compressors and Pumps A compressor is

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