Abstract
In this paper, a conceptual wet ethanol operated homogeneous charge compression ignition (HCCI) engine is proposed to shift the energy balance in favor of ethanol. The investigated option, HCCI engine is a relatively new type of engine that has some fundamental differences with respect to other prime movers. Combined first and second law of thermodynamic approach is applied for a HCCI engine operating on wet ethanol and computational analysis is performed to investigate the effects of turbocharger compressor ratio, ambient temperature, and compressor adiabatic efficiency on first law efficiency, second law efficiency, and exergy destruction in each component. First law and second law efficiencies are found to be an increasing function of the turbocharger pressure ratio, while they are found to be a decreasing function of the ambient temperature. The effect of turbocharger pressure ratio on exergy destruction is found to be more significant than compressor efficiency and ambient temperature. Exergy analysis indicates that maximum exergy is destroyed in HCCI engine which represents about 90.09% of the total exergy destruction in the overall system. Around 4.39% exergy is destroyed by the process of heat transfer in fuel vaporizer and heat exchanger. Catalytic converter contributes about 4.08% of the total exergy destruction. This will provide some original information on the role of operating variables and will be quite useful in obtaining the optimum design of ethanol fuelled HCCI engines.
► Direct utilization of wet ethanol in HCCI engines shift the energy balance in favor of ethanol. ► First and second law efficiencies of wet ethanol operated HCCI engine increases with the increase in the turbocharger pressure ratio and its polytropic efficiency. ► Second law analysis provides a suitable ranking among the components of the system in terms of exergy destruction. ► Analysis of the results clearly showed that the highest irreversibility sources are in the HCCI engine (around 89%) followed by fuel vaporizer (4.9%) and catalytic converter (4.5%). ► Based on simulation results, it is found that second law efficiency of wet ethanol operated HCCI engine is higher than the pure ethanol fuelled HCCI engine.