Abstract
Valves of combustion engines are often hollow. Liquid metal oscillates in these cavities due to the movement of the valve, thereby cooling it. The aim of our experiments is to investigate if the addition of loose disruptive bodies such as spheres or the alteration of the thermophysical properties of the cooling medium by adding metallic nanoparticles improves the cooling performance. The expectation is that especially mobile spheres enhance the impingement of the liquid metal on the inner valve walls and therewith the local heat transfer.
The study presents seventeen experiments employing a generic valve body made of AISI 316L. The working fluid is the eutectic gallium-indium-tin alloy. The experiments comprise five different combinations of disruptive bodies and one test with the gallium alloy modified with metallic nanoparticles. The results show that the equivalent thermal conductivity of the system is doubled when adding one single large sphere to the liquid alloy compared to the reference case. Adding three such disruptive bodies leads to a nearly quadruplication of the equivalent thermal conductivity.
