Exergy analysis in an HCCI engine powered with hydrogen enriched natural gas

Abstract

HCCI combustion is a very promising technology as it provides low NOx and soot formations with high efficiency. In the present investigation, the performance of turbocharged HCCI engine operated with hydrogen enriched natural gas was assessed using exergy analysis. The impact of equivalence ratio, turbocharger pressure, atmospheric temperature, and hydrogen enrichment has been ascertained on the engine's energy and exergy efficiencies. Special attention is given to identification and quantification of irreversibility of combustion and heat transfer processes using the concept of entropy generation and exergy loss. It is demonstrated that combustion and heat transfer irreversibilities in HCCI engine can be reduced from 55% to 43.4% and its power output is augmented from 31.4% to 38.4% if natural gas is replaced with 100% hydrogen. Overall, the results of second law analysis for engine under consideration show that variations of operational parameters examined have considerably affected the exergy transfer, irreversibilities and efficiencies.