Analysis of Homogeneous Charge Compression Ignition (HCCI) Engines for Cogeneration Applications

This paper presents an evaluation of the applicability of homogeneous charge compression ignition (HCCI) engines for small-scale cogeneration $(<1MWe)$ in comparison to five previously analyzed prime movers. The five comparator prime movers include stoichiometric spark-ignited (SI) engines, lean burn SI engines, diesel engines, microturbines, and fuel cells. The investigated option, HCCI engines, is a relatively new type of engine that has some fundamental differences with respect to other prime movers. The prime movers are compared by calculating electric and heating efficiency, fuel consumption, nitrogen oxide $(NOx)$ emissions, and capital and fuel costs. Two cases are analyzed. In case 1, the cogeneration facility requires combined power and heating. In case 2, the requirement is for power and chilling. The results show that HCCI engines closely approach the very high fuel utilization efficiency of diesel engines without the high emissions of $NOx$ and the expensive diesel fuel. HCCI engines offer a new alternative for cogeneration that provides a combination of low cost, high efficiency, low emissions, and flexibility in operating temperatures that can be optimally tuned for cogeneration systems. HCCI is the most efficient engine technology that meets the strict 2007 CARB $NOx$ standards for cogeneration engines, and merits more detailed analysis and experimental demonstration.