Centrifugal pumps move liquids while compressors move gases
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Centrifugal pumps move liquids, while compressors move gases; both achieve pressure increase. Why does the temperature of the gas rise so much that a compressor requires an intercooler, whereas a centrifugal pump does not?
Gas heats up when pressure increases, and absorbs heat when pressure decreases； Liquids, in theory, shouldn’t be compressible; the compression process would involve compressing the gases dissolved in the liquid. Compared to compressing gases, the amount involved is much smaller, right?
Both liquids and gases can absorb heat. It’s just that when gas absorbs heat, its volume expands; failing to cool it down in time poses a safety risk
This post was last edited by jmdc on 2018-10-25 at 13:25. Is gas decompression exothermic? Liquids cannot be compressed, so how do liquids increase in pressure? How does a liquid without dissolved gases heat up?
Because the volume of gas changes significantly, and due to its inherent properties, its ability to retain heat is limited. Liquids, on the other hand, are considered incompressible; in other words, their volume does not change much, so they generate little heat. Moreover, they carry away the heat they produce, thus not causing any significant or excessive thermal effects on the system. :)
Gases are compressible; according to the equation pv=nrt, a decrease in volume results in heat release. Moreover, gases have a low specific heat capacity, which means they can carry away less heat, so the temperature rises rapidly； For liquids, compressibility is virtually none; heating occurs only due to friction, with little heat generated. Their high specific heat allows this heat to be easily dissipated, resulting in a slow rise in temperature
In simple terms, the energy conversion performed by the compressor on the fluid is not taken into account. The specific heat of gases is much lower than that of liquids, so for the same amount of energy absorbed, the temperature rise of gases is greater.