eat Transfer Coefficients for Submerged Coils.docx

Heat Transfer Coefficients for Submerged Coils Heat transfer coefficients for steam and hot water coils submerged in oil tanks Sponsored Links

The heat transfer from steam coils with medium pressure, or hot water coils or pipes, submerged in oil or fat can be estimated with the values from the table below.

Heat Transfer Coefficient - natural convection Type of Coil 2o

2 o

(W/m C)

(Btu/hr ft F)

Steam to Light Oil

170

30

Steam to Heavy Oil

85 - 115

15 - 20

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Heat Transfer Coefficient - natural convection Type of Coil 2o

2 o

(W/m C)

(Btu/hr ft F)

Steam to Fat

30 - 60

5 - 10

Hot Water to Oil

60

10







Heat emission from steam or water pipes submerged in water are indicated in the tables below:

Temperature Difference between the Steam/Water in the Pipe and the Surrounding Water ( o F)

( oC)

Heat Transfer Rate to the Surrounding Water (Btu/ft 2 h o F)

(W/m 2oC)







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

Type of Application

Heat Transfer Rate to the Surrounding Water (Btu/ft 2 h o F)

(W/m 2oC)

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







2o

With low pressure steam and non-assisted circulation we presume the heat transfer rate to be 570 W/m C . The heat transfer from steam to water can then be calculated as: 2o

2

o

o

Q = (570 W/m C) (0.10 m ) (120 C - 20 C) = 5700 W = 5.7 kW







Properties of Saturated Steam - SI Units A Saturated Steam Table with steam properties as specific volume, density, specific enthalpy and specific entropy Sponsored Links

The steam table below list the properties of steam at varying pressures and temperatures:

Specific Enthalpy of Absolute pressure

Temperature 2

(kPa, kN/m )

o

( C)

Specific Volume 3

(m /kg)

Density - ρ 3

(kg/m )

Specific Entropy of Steam -s-

Liquid - h l l -

Evaporation - h e e -

Steam - h s s -

(kJ/kg)

(kJ/kg)

(kJ/kg)

(kJ/kgK)

0.8

3.8

160

0.00626

15.8

2493

2509

9.058

2.0

17.5

67.0

0.0149

73.5

2460

2534

8.725










Temperature 2

(kPa, kN/m )

35

o

( C)

72.7

Specific Volume 3

(m /kg)

4.53

Density - ρ 3

(kg/m )

0.221


Liquid - h l l -


Steam - h s s -

(kJ/kg)

(kJ/kg)

(kJ/kg)

(kJ/kgK)

304.3

2327

2632

7.717








Temperature 2

(kPa, kN/m )

110

o

( C)

102.3

Specific Volume 3

(m /kg)

1.55

Density - ρ 3

(kg/m )

0.646


Liquid - h l l -


Steam - h s s -

(kJ/kg)

(kJ/kg)

(kJ/kg)

(kJ/kgK)

428.8

2251

2680

7.328








Temperature 2

(kPa, kN/m )

360

o

( C)

139.9

Specific Volume 3

(m /kg)

0.510

Density - ρ 3

(kg/m )

1.96


Liquid - h l l -


Steam - h s s -

(kJ/kg)

(kJ/kg)

(kJ/kg)

(kJ/kgK)

588.5

2144

2733

6.930








Temperature 2

(kPa, kN/m )

750

o

( C)

167.8

Specific Volume 3

(m /kg)

0.255

Density - ρ 3

(kg/m )

3.915


Liquid - h l l -


Steam - h s s -

(kJ/kg)

(kJ/kg)

(kJ/kg)

(kJ/kgK)

709.3

2056

2765

6.682








Temperature 2

(kPa, kN/m )

1300

o

( C)

191.6

Specific Volume 3

(m /kg)

0.151

Density - ρ 3

(kg/m )

6.62


Liquid - h l l -


Steam - h s s -

(kJ/kg)

(kJ/kg)

(kJ/kg)

(kJ/kgK)

815

1971

2785

6.491















eat Transfer Coefficients for Submerged Coils.docx

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