Section summary |
---|

1. Definition |

2. Calculation |

3. Use |

How to calculate the rate of temperature rise in a centrifugal pump ?

In US units [1]

With :

ΔT_{r} = temperature increase in pump (°F/min)

P_{so} = pump power at no flow (BHP)

W_{1} = weight of liquid in the pump (lb)

C_{p} = specific heat of the liquid in the pump (BTU/lb/°F)

In SI units - adapted from [1]

With :

ΔT_{r} = temperature increase in pump (°c/min)

P_{so} = pump power at no flow (kW)

W_{1} = weight of liquid in the pump (kg)

C_{p} = specific heat of the liquid in the pump (kJ/kg/°c)

In US units [1]

With :

ΔT_{r} = temperature increase in pump (°F/min)

H = pump head at no flow, low flow at the corresponding efficiency η
(ft)

C_{p} = specific heat of the liquid in the pump (BTU/lb/°F)

η = efficiency of the pump at low flow- decimal value

In SI units - adapted from [1]

With :

ΔT_{r} = temperature increase in pump (°c/min)

H = pump head at no flow, low flow at the corresponding efficiency η
(m)

C_{p} = specific heat of the liquid in the pump (kJ/kg/°c)

η = efficiency of the pump at low flow- decimal value

In normal operation, part of the energy transferred from the shaft
is lost in heat, the other behind converted as pressure for the
liquid. The formula below is proposed to estimate by how much the
liquid is heated up when passing through the pump.

With :

ΔT_{liquid} = temperature increase of the liquid through the
pump (°c)

Qshaft = shaft power at the corresponding efficiency η (kW)

m = throughput of liquid through the pump (kg/s)

C_{p} = specific heat of the liquid in the pump (kJ/kg/°c)

η = efficiency of the pump at low flow- decimal value

The calculation of the temperature increase at low flow should be used to calculate the minimal flow that needs to be ensured through a centrifugal pump, often thanks to a bypass line, in order to make sure the heat is not damaging the pump.

**Source**

Applied process design volume 1, Ludwig, Gulf Professional, page 207