Internal Combustion Engines: Modeling Internal Temperature as a Function of Time

by Garrett Fandrich

Submitted : Spring 2022

            Just like any thermodynamic system, combustion engines must be cooled to eliminate friction due to heat. Without proper cooling, internal components, such as connecting rods, rod bearings, and pistons can be severely damaged due to thermal expansion, leading to severe damage to the engine block or outright catastrophic failure. Modern engines are cooled using coolant, which flows through internal passageways within the engine block to pull heat away from the system. The use of coolant and external components, such as a water pump, radiator, and thermostat allow an engine to efficiently warm to standard operating temperature and remain at said temperature. Using standard calculus and differential equations, the model for the idle coolant temperature increase inside of an engine block as it approaches a steady state can be obtained. For overall application purposes, this model includes an arbitrary number of inlets and exits for coolant to flow through. This model can also be applied to air cooled or electric systems, such as small engines or electrical motors which produce a quantifiable amount of heat.

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