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Unformatted text preview: 2 has far-reaching implications in engineering regarding devices that produce or consume work steadily such as turbines, compressors,
and pumps. It is obvious from this equation that the reversible steady-flow
work is closely associated with the specific volume of the fluid flowing
through the device. The larger the specific volume, the larger the reversible
work produced or consumed by the steady-flow device (Fig. 7–42). This conclusion is equally valid for actual steady-flow devices. Therefore, every effort
should be made to keep the specific volume of a fluid as small as possible during a compression process to minimize the work input and as large as possible
during an expansion process to maximize the work output.
In steam or gas power plants, the pressure rise in the pump or compressor is
equal to the pressure drop in the turbine if we disregard the pressure losses in
various other components. In steam power plants, the pump handles liquid,
which has a very small specific volume, and the turbine handles vapor, whose
specific volume is many times larger. Therefore, the work output of the
turbine is much larger than the work input to the pump. This is one of the reasons for the overwhelming popular...
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This document was uploaded on 11/28/2012.
- Spring '09