ディーゼル機関における冷却損失算出方法の検討 (噴射条件と吸気条件が熱勘定に及ぼす影響)

Abstract

In this study, a new method to calculate cooling loss is proposed. According to previous experimental data, the method which subtracts indicated work, friction loss, exhaust loss, etc., from input energy seems to be reasonable. However, in order to improve its accuracy, exhaust loss should be calculated more precisely. Hence, exhaust loss is calculated by tracking the state of in-cylinder gas from exhaust valve close to intake valve open using the law of energy conservation and mass conservation. In order to estimate the accuracy of this approach, various data acquired with several injection patterns and intake temperature were analyzed. When the main injection is divided and injected by two injectors with two separate common-rail systems, the reduction of cooling loss is verified both with conventional and new heat balance calculation method. In addition, when the main injection is reduced and, on the other hand, after injection increased, the cooling loss is also suppressed hence total thermal efficiency increased according to proposed calculation method.