# Steam Condensation and Heat Transfer

## Heat transfer when condensing steam

The heat released when condensing steam can be expressed as

Q = h_{e }M_{s }_{ }(1)

where

Q = quantity of heat released (kJ, Btu)

M_{s}= mass of condensing steam (kg, lb)

h_{e}= specific evaporation enthalpy of steam (kJ/kg, Btu/lb)

The heat transfer rate - or power - in a condensing steam flow can be expressed as

q = h_{e }m_{s}(2)

where

q = heat transfer (kW, Btu/h)

m_{s}= steam flow rate (kg/s, lb/h)

### Example - Heat released when Condensing Steam

*5 kg* of steam with atmospheric pressure, temperature *100 ^{o}C* and evaporation enthalpy

*2257 kJ/kg*is condensated. The heat transfer can be calculated as

*Q = (2257 kJ/kg) (5 kg) _{}*

* = 11285 kJ*

### Example - Heat Transfer Rate - or Power - in a Condensing Steam Flow

The heat transfer rate in a condensing steam flow rate of *8 kg/h (0.0022 kg/s), *atmospheric pressure and temperature *100 ^{o}C* - can be calculated as

*q = (2257 kJ/kg) (0.0022 kg/s)*

* = 5 kJ/s (kW)*