Technical Paper
Study of Surface Insulation Structures to Reduce Cooling Loss in Heavy-Duty Diesel Engines
2023-04-11
2023-01-0948
Cooling loss reduction is essential to enable further increases in thermal efficiency of reciprocating internal combustion engines. Many in-cylinder cooling loss reduction studies have been carried out by applying various thermal barrier coatings to the piston and/or other in-cylinder surfaces, taking advantage of the lower thermal effusivity of ceramic materials. However, the end result was mostly minimal or in some cases, negative. In our previous study, significant cooling loss reduction was experimentally confirmed by utilizing a mirror-like polished stainless-steel thermal sprayed surface (HVOF: high velocity oxy-fuel) on a forged steel piston. This study firstly investigated an alternative insulating layer material to stainless-steel, along with effects of its thickness on heat transfer by a one-dimensional unsteady numerical model. Results showed that lower thermal effusivity doesn’t always reduce heat transfer, but increases nonuniformity of surface temperature.