Experimental evaluation of temperature rise in centrifugal pumps at partial flow rates

Abstract

When the centrifugal pumps operate near shut-off condition, different kinds of energy losses happen from inlet to discharge nozzle leading to lower hydraulic performance and overall efficiency. A part of dissipated energy turns into heat and increases the operating liquid temperature. This may seem to be very dangerous when talking about pumping oil or any other flammable chemical liquids. In the present investigation, several centrifugal pumps were selected to perform experimental analysis of measuring temperature rise at inlet and discharge nozzles during part load operation. Pumps were entirely insulated using glass wool to prevent heat leakage from pump casing to the environment and pure water was selected to play as the working fluid. Temperature rise of pumps was reported from start time up to assuaging steady-state condition. Obtained results demonstrated that higher rotational speed of impeller led to higher value of outlet water temperature in a shorter time rather than lower rotational speeds. Steady-state temperature values were used to establish a novel relation for temperature rise that can be implemented for wide range of centrifugal pumps. Keywords Experimental evaluation Á Centrifugal pump Á Off-design condition Á Temperature rise Abbreviations AH Absorbed heat by working fluid (W) C P Specific heat (J/kg K) D 2 Diameter (m) g Gravity (m/s 2) H Pump outlet head (m) LR Loss rate (W) n Rotational speed (rpm) _ m Mass flow rate (kg/s) P Useful power (W) Q Volumetric flow rate (m 3 /s) Q * Dimensionless flow rate (-) Q n Nominal volumetric flow rate (m 3 /s) DT Temperature rise (K) DT max Maximum temperature rise (K) Greek symbols c Specific weigh (kg/m 2 s 2) g Overall efficiency p Dimensionless number (-) l Dynamic viscosity (Pa s) q Density (kg/m 3

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The Influence of Different Working Fluid Temperatures on the Hydraulic Performance of Magnetic Vortex Pumps

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