For a pump, which expression represents the shaft work in terms of enthalpy?

Prepare for the EPRI Heat Transfer and Fluid Flow Test with flashcards and multiple-choice questions. Every question includes hints and explanations to help you ace your exam!

Multiple Choice

For a pump, which expression represents the shaft work in terms of enthalpy?

Explanation:
In a pump, the steady-flow energy balance (neglecting changes in kinetic and potential energy) gives h2 = h1 + w_s, where w_s is the shaft work per unit mass added to the fluid. Rearranging, w_s = h2 − h1. This is positive because the pump adds energy to raise the fluid’s enthalpy. The other forms would imply the wrong sign or an incorrect relation (for example, summing enthalpies or taking the negative of the difference).

In a pump, the steady-flow energy balance (neglecting changes in kinetic and potential energy) gives h2 = h1 + w_s, where w_s is the shaft work per unit mass added to the fluid. Rearranging, w_s = h2 − h1. This is positive because the pump adds energy to raise the fluid’s enthalpy. The other forms would imply the wrong sign or an incorrect relation (for example, summing enthalpies or taking the negative of the difference).

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