Related Resources: heat transfer
Overall Heat Transfer Coefficients in Heat Exchangers
Representative values of the overall heat transfer coefficients in heat exchangers.
Note that the overall heat transfer coefficient ranges from about 10 W/m2· °C for gas-to-gas heat exchangers to about 10,000 W/m2· °C for heat exchangers that involve phase changes. This is very typical since gases have very low thermal conductivities, and phase-change processes involve very high heat transfer coefficients.
|Type of heat exchanger||U, W/m2 · °C*|
|Water-to-gasoline or kerosene||300–1000|
|Steam-to-light fuel oil||200–400|
|Steam-to-heavy fuel oil||50–200|
|condenser (water cooled)||300–1000|
|Ammonia condenser (water cooled)||800–1400|
|Alcohol condensers (water cooled)||250–700|
|Water-to-air in finned tubes (water in tubes)||30–60†
|Steam-to-air in finned tubes (steam in tubes)||30–300†
* Multiply the listed values by 0.176 to convert them to Btu/h · ft2 · °F.
† Based on air-side surface area.
‡ Based on water- or steam-side surface area.