Low-cost, eco-friendly diesel with a thermally insulated combustion chamber

Abstract

The performance of a diesel engine has been studied using well-known types of ceramic thermal insulating HIC or thermal barrier TBC coatings. This problem is relevant for a diesel engine with low thermal losses of the combustion chamber, in which the intense radiant component (in the near-IR range) reaches ∼ 50 % of the total heat flow. In this paper, the authors continued to study these coatings, but as translucent (SHICs or STBCs) with bulk absorption of penetrating radiant energy. The spectrophotometric modeling of the optical parameters of these coatings made it possible to estimate the characteristics of the temperature field being formed with a reduced near-surface temperature gradient (compared to opaque coatings), causing a significant decrease in heat loss through the heat-insulated piston. A translucent STBC coating based on partially stabilized zirconia (PSZ ceramics ZrO2 + 8 % Y2O3) was chosen, determining the formation of the optimum temperature profile in the piston head. For bench testing was used experimental single-cylinder tractor diesel. With a rotation frequency of n > 2800 1/min, the heat loss did not exceed 0,2 MW/m2 through the bottom of the piston with the heat-shielding layer. The tests performed showed a lower specific fuel consumption of ∼ 2-3 % in comparison with the combustion chamber of a diesel engine with an uncoated ceramic piston. At the same time, torque and effective power increased by ∼ 2-5 %.