Submerged Coils - Heat Transfer Coefficients
The overall heat transfer coefficients for steam coils with medium pressure - or hot water coils or pipes - submerged in oil or fat:
| Type of Coil | Heat Transfer Coefficient - U - | |
|---|---|---|
| (W/m2 oC) | (Btu/hr ft2 oF) | |
| Steam to Aqueous Solutions, agitated | 800 - 1200 | 140 - 210 |
| Steam to Aqueous Solutions, natural convection | 340 - 570 | 60 - 100 |
| Steam to Light Oil, natural convection | 170 | 30 |
| Steam to Heavy Oil, natural convection | 85 - 115 | 15 - 20 |
| Steam to Heavy Oil, agitated | 140 - 310 | 25 - 55 |
| Steam to Fat, natural convection | 30 - 60 | 5 - 10 |
| Steam to Organics, agitated | 510 - 800 | 90 - 140 |
| Hot Water to Oil, natural convection | 34 - 140 | 6 - 25 |
| Hot Water to Water, natural convection | 200 - 370 | 35 - 65 |
| Hot Water to Water, agitated | 480 - 850 | 90 - 150 |
| Heat transfer oil to Organics, agitated | 140 - 280 | 25 - 50 |
| Salt brine to Water, agitated | 280 - 630 | 50 - 110 |
| Cooling Water to Glycerine, agitated | 280 - 430 | 50 - 75 |
Example - Heat Transfer from a Steam Coil
A 50 mm steam coil with outside diameter 60.3 mm(0.0603 m) and length 10 m with 1 bar absolute pressure and steam temperature 120 oC is submerged in an oil bath with temperature 50 oC.
The surface area of the coil can be calculated by multiplying the pipe circumference with pipe length as
A = π (0.0603 m) (10 m)
= 1.89 m2
From the table above the heat transfer coefficient is 170 W/m2 oC for "Steam to Light Oil, Natural Convection". The heat transfer can be calculated as
Q = (1.89 m2)((120 oC) - (50 oC))(170 W/m2 oC)
= 22491 W
Related Topics
• Heat Loss and Insulation
Heat loss from pipes, tubes and tanks - with and without insulation - foam, fiberglass, rockwool and more.
Related Documents
Arithmetic and Logarithmic Mean Temperature Difference
Arithmetic Mean Temperature Difference in Heat Exchangers - AMTD - and Logarithmic Mean Temperature Difference - LMTD - formulas with examples - Online Mean Temperature Calculator.
Condensation of Steam - Heat Transfer
Heat transfer when steam condensates.
Heat Exchangers - Overall Heat Transfer Coefficients
Overall heat transfer coefficients in common heat exchanger designs - tubular, plate or spiral.
Heat Transfer Coefficients in Heat Exchanger Surface Combinations
Average overall heat transmission coefficients for fluid and surface combinations like Water to Air, Water to Water, Air to Air, Steam to Water and more.
Oil Filled Tanks - Heat Loss
Heat loss from insulated and uninsulated, sheltered and exposed heated oil tanks.
Oil Tanks - Heat Loss
Heat loss from lagged and unlagged, sheltered and exposed oil tanks.
Overall Heat Transfer Coefficients
Walls or heat exchangers - calculate overall heat transfer coefficients.
Pipes Submerged in Oil or Fat - Heat Emission
Heat emission from steam or water heating pipes submerged in oil or fat - forced and natural circulation.
Pipes Submerged in Water - Heat Emission
Heat emision from steam or water heating pipes submerged in water - assisted (forced) or natural circulation.
Steam Heating Processes - Load Calculating
Calculating the amount of steam in non-flow batch and continuous flow heating processes.