The Geometry of a Prechamber’s Impact on Temperature Distribution and Heat Flow

Abstract

Prechambers are systems that can easily be implemented onto currently existing engines. They provide an increase in fuel efficiency and decrease in emissions if designed properly. This study looks to determine how the geometry and the convection of the gas due to propagation impacts the temperature distribution of the system. The temperature was mapped radially using MATLAB with an emphasis on the surface temperatures of the prechamber walls. It was mapped using parabolic profiles for the convection of the gas and coolant and linear conduction through the metal wall. The heat transfer coefficient of both the gas and coolant impacts the surface temperatures and radial path undergone. However, the focus of the study is on the impact of the convection undergone by the gas because the impact of the coolant is much lower than that experienced by the gas. The derivations for convection within an engine was created for the purpose of the main chamber, but these derivations are fundamentally wrong for prechambers due to the large volume change. Volume also propagates further effects in the system due to its tendency to change pressure and temperature after combustion. Finally, the wall thickness impacts how much the gas convection and coolant convection impact one another and the slope at which heat loss occurs. Altering convection always has an impact on both surface temperatures but increasing the wall thickness mitigates that. The wall thickness also increases the inner temperature in every scenario. This study looks to create a design guide for the temperature distribution. It aims to demonstrate how geometrical alterations and radical changes in convection caused by mass flow rate can affect the temperatures experienced with the system.