Energy Transfer
Energy Transfer
Energy Transfer
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MOVING BOUNDARY WORK (cont’d)• Note P is the absolute pressure, which is alwayspositive. However, the volume change dV ispositive during an expansion process (volumeincreasing) and negative during a compressionprocess (volume decreasing).• Thus, the boundary work is positive during anexpansion process and negative during acompression process. Therefore the aboveequation can be viewed as an expression forboundary work output, W b,out . A negative resultindicates boundary work input (compression)<strong>Energy</strong> <strong>Transfer</strong> 13© Copyright 2005 Prof. Arun S. Mujumdar.
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