Analysis of Cogeneration Based Wet Ethanol Operated HCCI Engine Using First and Second Law of Thermodynamics

摘要

In this paper, we computed the available and unavailable energy using first and second law of thermodynamics for wet ethanol operated homogeneous charge compression ignition (HCCI) engine for cogeneration application. Present analysis includes engine and its various subsystems like turbocharger, regenerator, fuel vaporizer, catalytic convertor and heat recovery steam generator (HRSG). This paper also presents the evaluation of effect of ambient temperature, turbocharger compressor pressure ratio and effectiveness of regenerator on the first and second law efficiencies of the system. The numerical computational analysis of the system indicates that the first and second law efficiencies are decreasing with ambient temperature as the increase in ambient temperature increases the charge intake temperature which leads to reduced work output and it finally results in reduced efficiencies. The decrease in first and second law efficiencies with effectiveness of regenerator is also due to similar reasons however these efficiencies increase with the increase of turbocharger compressor pressure ratio due to increase in the charge density at the inlet of the HCCI engine which further results in increase in power output of the engine and finally increase in efficiencies. A computational analysis has been done and the result so obtained is validated for HCCI engine with available literature at mean operating conditions and further waste heat from exhaust is utilized in organic Rankine cycle (ORC) and HRSG for combined production of power and heat . This cogeneration system has a good thermal performance with first law efficiency, second law efficiency and power to heat ratio at 46.47%, 38.5% and 7.64 respectively for the mean operating conditions of T0=300K, Pr=3, ?T=80%, e=79%. Magnitude of exergy destruction is also presented at mean operating conditions as this analysis provides a ranking among the components of the system. The component with higher exergy destruction is more responsible to deteriorate the performance of the system. These results will be useful for the determination of optimum design of such system and it will provide an insight on technical issues related to efficient research and development of such engines.