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Empirical results indicated that the engine emission and fuel efficiency of low-temperature combustion (LTC) cycles can be optimized by adjusting the fuel-injection scheduling in order to obtain appropriate combustion energy release or heat-release rate patterns. Based on these empirical results the heat-release characteristics were correlated with the regulated emissions such as soot, hydrocarbon and oxides of nitrogen. The transition from conventional combustion to LTC with the desired set of heat-release rate has been implemented. This transition was facilitated with the simplified heat-release characterization wherein each of the consecutive engine cycles was analyzed with a real-time controller embedded with an FPGA (field programmable gate array) device. The analyzed results served as the primary feedback control signals to adjust fuel injection scheduling. The experimental efforts included the boost/backpressure, exhaust gas recirculation, and load transients in the LTC region.

A production V-8 engine was redesigned to run on low temperature combustion (LTC) with conventional Diesel fuel. Two fuel injection strategies were used to attain reduction in soot and NOx; a) early premixed injection strategy: fuel injected early during the compression stroke and b) late premixed injection strategy: fuel injected close to TDC with heavy EGR. The early premixed injection strategy yielded low NOx and soot but struggled to vaporize the fuel as noted in unburned hydrocarbons readings. The late premixed injection strategy introduced the fuel at higher in-cylinder temperatures and densities, improving the fuel's vaporization and limited the unburned hydrocarbon and carbon monoxide. The use of high EGR and high injection pressure for late premixed injection strategy provided sufficiently long ignition delay that resulted in partially premixed cylinder charge before combustion, and thereby prevented high soot, even in presence of high EGR.

Diesel engine exhausts commonly contain a high level of surplus oxygen and a significant amount of thermal energy. In this study the authors have theoretically investigated a way of utilizing the thermal energy and the surplus oxygen of exhaust gases to produce gaseous fuel in a rich combustor placed in an exhaust gas recirculation (EGR) loop. In the rich combustor, a small amount of diesel fuel will be catalytically reformed on a palladium/platinum based catalyst to produce hydrogen and carbon monoxide. Since the catalytic EGR reformer is incorporated in the EGR loop, it enables the partial recovery of exhaust heat. The gaseous fuel produced in the rich combustor can be brought back into the engine in a pre-mixed condition, potentially reducing soot formation. The preliminary energy efficiency analysis has been performed by using CHEMKIN and an in-house engine simulation software SAES.