Speed and load effects on the availability balances and irreversibilities production in a multi-cylinder turbocharged diesel engine

摘要

This work presents an analysis of the operation of a multi-cylinder, turbocharged, indirect injection diesel engine from a second-law analysis point of view. For this purpose, a single-zone thermodynamic model following the filling and emptying modelling technique is developed. A second-law analysis is performed in all parts of the diesel engine plant, which provides all the existing availability terms and accounts for the evaluation of every component's irreversibilities. A complete second-law terms tabulation is given for the maximum speed-full load operation case, which is compared with its first-law counterpart. A detailed parametric study is performed in all parts of the diesel engine plant comprising the effects of speed and load on the availability terms in a range that covers the whole operation of the engine under turbocharged action. Various second-law (availability) terms, such as indicated and brake work, heat transfer, inlet air, exhaust gas and friction, are presented, together with all the processes' irreversibilities, as a percentage of the fuel's chemical availability, for each engine operating condition. It is thus highlighted how the two basic engine operating parameters, i.e. speed and load, affect the operation of this engine under a second-law perspective. A compression ratio investigation on the availability terms is also performed.