Pump - Temperature Rise vs. Volume Flow

No pump is perfect with 100% efficiency. Energy lost in friction and hydraulic losses transforms to heat - heating up the fluid transported through the pump.

The temperature rise can be calculated as

dt = P_s (1 - μ) / (c_p q ρ)                                       (1)

where

dt = temperature rise in the pump (^oC)

q = volume flow through pump (m³/s)

P_s = brake power (kW)

c_p = specific heat of the fluid (kJ/kg^oC)

μ = pump efficiency

ρ = fluid density (kg/m³)

A typical relation between flow, efficiency and power consumption for a centrifugal pump:

Pump - Temperature Rise Calculator

P_s - brake power (kW)

μ - pump efficiency

c_p - specific heat (kJ/kg^oC)

q - volume flow (m³/s)

ρ - density (kg/m³)

Example - Temperature rise in water pump

Temperature rise in a water pump working at normal conditions with flow 6 m³/h (0.0017 m³/s), brake power 0.11 kW and pump efficiency of 28% (0.28) can be calculated as

dt = (0.11 kW) (1 - 0.28) / ((4.2 kJ/kg^oC) (0.0017 m³/s) (1000 kg/m³))

    = 0.011 ^oC

Specific heat of water c_p = 4.2 kJ/kg^oC.

If the flow through the pump is reduced by throttling the discharge valve the temperature rise increase. If the flow is reduced to 2 m³/h (0.00056 m³/s), brake power slightly reduced to 0.095 kW and the pump efficiency reduced to 15% (0.15) - the temperature rise can be calculated as

dt = (0.095 kW) (1 - 0.15) / ((4.2 kJ/kg^oC) (0.00056 m³/s) (1000 kg/m³))

    = 0.035 ^oC

With manufacturing documentation the temperature rise versus throttling can be expressed as:

Temperature ^oC
K
^oF

Length m
km
in
ft
yards
miles
naut miles

Area m²
km²
in²
ft²
miles²
acres

Volume m³
liters
in³
ft³
us gal

Weight kg_f
N
lbf

Velocity m/s
km/h
ft/min
ft/s
mph
knots

Pressure Pa
bar
mm H₂O
kg/cm²
psi
inches H₂O

Flow m³/s
m³/h
US gpm
cfm