Energy Efficiency and Thermal Performance Analysis of a Centrifugal Pump: Effect of Insulation Retrofit on Heat Loss Reduction

Abstract

Centrifugal pumps are widely used in industry, agriculture, and the home. Their energy efficiency is determined by hydraulic losses, friction, and electrical losses in the drive system. This study experimentally examines the effect of external thermal insulation on the case heat transfer and the overall efficiency of a 0.5HP (0.373 kW) centrifugal pump. The suggested approach studies the case of an uninsulated pump at different insulation thicknesses – 5, 10, 15, 20 mm. The electric power, flow rate, head, surrounding temperature, fluid temperature, and case surface temperature are estimated to evaluate the hydraulic and thermal efficiency of the pump. The approximated heat loss from the case is observed to reduce from 31.5 W (uninsulated) to 16.8 W (with 20 mm insulation), suggesting a 46.7% reduction. The wire-to-water efficiency increases slightly from 12.25% to 12.28%. The findings suggest that insulating the external case might be successful in minimizing heat losses from the pump case. However, its effect on the overall efficiency of the pump seems to be small. The findings have to be considered within the framework of the measurement approach, experimental variability, and the necessity to ensure adequate cooling for the motor and other essential components.

Introduction

Centrifugal pumps are widely used in industrial processes, agricultural irrigation, and water supply systems. However, some of the electrical energy they consume is lost due to motor inefficiency, friction, hydraulic resistance, and heat dissipation from the pump casing. This study investigates the effect of external thermal insulation on the thermal performance and energy efficiency of a 0.5 HP (0.373 kW) centrifugal pump.

The literature review highlights that previous research has mainly focused on hydraulic efficiency, impeller design, pressure head, and flow characteristics, while the effect of casing insulation has received limited experimental attention. The study addresses this research gap by comparing an uninsulated pump with pumps insulated using thicknesses of 5, 10, 15, and 20 mm.

The experiment was conducted using a closed-loop water circulation system equipped with a digital power meter, pressure gauges, a flow meter, and K-type thermocouples. Electrical input power, flow rate, pressure, water temperature, ambient temperature, and casing surface temperature were measured under controlled operating conditions. These measurements were used to estimate casing heat loss and calculate wire-to-water efficiency.

Key Results

The results show that increasing insulation thickness reduces the pump casing temperature and estimated heat loss. With 20 mm of insulation, the casing temperature decreased by 9.36°C, while estimated heat loss decreased by 46.7% compared with the uninsulated condition.

However, wire-to-water efficiency increased only slightly, from 12.25% to 12.28%, representing an improvement of just 0.03 percentage points. Therefore, casing insulation is more effective for reducing external heat dissipation than for improving overall pump efficiency.

Conclusion

This study experimentally examined the energy efficiency and thermal performance of a centrifugal pump before and after a casing insulation retrofit. The findings showed a 46.7% decrease in casing heat loss, from 31.5 W to 16.8 W. The average wire-to-water efficiency improved by 0.03 percentage points, from 12.25% to 12.28%. Although the observed improvement in total efficiency was rather moderate, the results show that casing insulation can significantly reduce thermal losses from the pump casing through a straightforward and inexpensive retrofit. This study\'s energy-balance methodology offers a methodical way to measure thermal losses, and it can be used for other rotodynamic and mechanical devices where thermal losses are an underappreciated part of overall energy consumption. The suggested retrofit can be implemented in existing pumping systems as it does not require alterations to the hydraulic part of the pump. The retrofit evaluation in the context of variable-speed operation, different pump sizes and loads, prolonged operational conditions, and techno-economic analysis, including the cost of installation, energy savings, and payback period, will be the subject of future research.

References

[1] Hydraulic Institute, Rotodynamic Pumps—Guideline for Condition Monitoring, Hydraulic Institute Standards, Parsippany, NJ, USA. [2] J. F. Gülich, Centrifugal Pumps, 3rd ed., Springer, Berlin, Germany, 2014. [3] I. J. Karassik, J. P. Messina, P. Cooper, and C. C. Heald, Pump Handbook, 4th ed., McGraw-Hill, New York, USA, 2008. [4] A. J. Stepanoff, Centrifugal and Axial Flow Pumps: Theory, Design, and Application, 2nd ed., John Wiley & Sons, New York, USA, 1957. [5] J.-E. Yun, “The effect of a Teflon insulation layer installed inside the pump on the insulation of a centrifugal pump for transporting liquid hydrogen,” Energies, vol. 18, no. 23, Art. no. 6356, 2025, [6] P. A. Deshmukh, “Performance enhancement of centrifugal pump by minimizing casing losses using coating,” SN Applied Sciences, vol. 2, Art. no. 252, 2020,

Copyright

Copyright © 2026 Deepak Prasad, Ajay Kumar Singh. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.