Heat Loss from Pipes Submerged in Water

Heat transmission from steam or water heating pipes or tubes submerged in water - assisted (forced) and natural circulation

Steam heating coils in oil tanks

Heat emission from steam or water pipes or tubes submerged in water:

Temperature Difference between the Steam/Water in the Pipe and the Surrounding WaterHeat Transfer Rate to the Surrounding Water
(oF)(oC)(Btu/(ft2 h oF))(W/(m2 oC))
50 28 100 - 225 570 - 1280
100 56 175 - 300 1000 - 1700
200 111 225 - 475 1300 - 2700

Note that with a higher temperature difference there is a more vigorous movement on the water side and the heat transfer rate goes up. Forced or assisted circulation on the water side also results in higher heat transfer rates as indicated below.

For practical applications - the heat transfer rates can roughly be set to:

Type of ApplicationHeat Transfer Rate to the Surrounding Water
(Btu/(ft2 h oF))(W/(m2 oC))
Tank coils with low pressure steam, natural circulation in the tank 100 570
Tank coils with high pressure steam, natural circulation in the tank 200 1100
Tank coils with low pressure steam, forced circulation in the tank 200 1100
Tank coils with high pressure steam, forced circulation in the tank 300 1700

Example - Steam Coil in Water

A DN25 (1") Std steam coil of one meter is submerged in water with temperature 20 oC. The steam pressure is aprox. 1 bar with a steam temperature aprox. 120 oC.

The area of the submerged coil can be calculated as:

A = (1 m) 2 π (0.0334 m) / 2

   = 0.10 m2

With low pressure steam and non-assisted circulation we presume from the table above that the heat transfer rate is 570 W/m2oC.

Heat transfer from steam to water can then be calculated:

Q = (570 W/(m2oC)) (0.10 m2) (120oC - 20oC)

   = 5700 W

   = 5.7 kW

Related Topics

  • Steam and Condensate - Steam & condensate systems- properties, capacities, pipe sizing, systems configuration and more
  • Heating - Heating systems - capacity and design of boilers, pipelines, heat exchangers, expansion systems and more
  • Heat Loss and Insulation - Steam and condensate pipes - heat loss uninsulated and insulated pipes, insulation thickness and more

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