Themes > Science > Physics > Thermodynamics > Applied Thermodynamics > Pumps

A pump is a device used to raise, transfer, or compress liquids and gases. Water is a typical fluid used by pumps in applications such as irrigation and cooling, among others. Applications involving air are often where a vaccum is needed. Even an average leaf blower pumps air out in a focused stream in order to clear leaves from a particular area. Another very typical use of a pump is to force gas into a combustion chamber such as in a jet engine, where it is termed a compressor. Multitudes of uses have been discovered for pumps involving liquids varying from blood to sludge. Although a pump can be used with almost any liquid, certain attributes of the working fluid must be considered when designing a pump. For example, if the pump must displace an acidic fluid, the pump must be composed of materials which will not react with the acid.


In a pump system, there must be some form of work done on the pump to make it operate. In most cases, this would be a motor which would drive either a piston or a type of rotor. The pump then does work on the fluid passing through it, and this work is translated into total energy within the fluid.

ISENTROPIC EFFICENCY

ppum.gif (651bytes)
Where

 

effPs = isentropic effiency of the pump

WACT = actual work input

Ws = isentropic work input

h1 = enthalpy at state 1.

h2ACT = actual enthalpy at state 2.

h2s = isentropic enthalpy at state 2.

REFERENCES : Jones, J. B., & R. E. Dugan. Engineering Thermodynamics.


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