Machinery & Energetics

Analysis and optimisation of internal combustion engine cooling systems to improve thermal efficiency and operational reliability

Viktor Duhanets, Oleksandr Hovorov, Vitaliy Pukas
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Abstract

The study aimed to quantitatively evaluate and optimise the operation of internal combustion engine cooling systems with a view to improving their thermal efficiency and reliability. The methodology combined engine bench tests with measurements of temperature, coolant and fuel flow rates, heat flux calculations with uncertainty assessment following guidance on the expression of measurement uncertainty, computational fluid dynamics in a coupled “fluid-solid” formulation, analysis of the stress-strain state of the cylinder head, and investigation of the transient warm-up regime from 20 to 90°C. The study established that the modernised configurations ensured a 10-17% increase in heat flux under maximum load conditions, a 5-6% and 10-12% reduction in peak temperatures in critical pre-chamber zones, and an 18-22% and 30-35% reduction in internal temperature gradients. This was accompanied by a reduction in equivalent stresses of 18-22% and an increase in the safety factor from 1.45 to 1.87 in the most efficient configuration. In transient mode, the system with an electric drive pump reduced the time to reach operating temperature by 9-12% and reduced integral fuel consumption by 10-12%, whilst the split-loop configuration provided a stable reduction in these figures of 6-8% and 5-7% respectively. An analysis of specific fuel consumption during braking in standard steady-state conditions revealed no statistically significant deterioration in fuel economy for the upgraded systems. The integrated ranking showed that a system with separate circuits provides a balanced combination of reduced of maximum temperature, minimised temperature gradients and increased safety margin without compromising fuel efficiency, whilst an electric drive pump is appropriate for minimising warm-up time and fuel consumption during cold starts. The practical significance of the study is determined by the development of quantitatively substantiated criteria for selecting cooling system configurations and coolant flow control strategies for engineering departments to improve thermal reliability and durability of engines

Keywords

local temperature gradients; thermal stress state; equivalent stresses; safety factor; transient heating regime; integral fuel consumption

Suggested citation
Duhanets, V., Hovorov, O., & Pukas, V. (2026). Analysis and optimisation of internal combustion engine cooling systems to improve thermal efficiency and operational reliability. Machinery & Energetics, 17(2), 7-21. https://doi.org/10.31548/machinery/2.2026.1
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