Diesel Engine Cold Start Improvement Using THermal Management Techniques

The objective of the research program was to investigate, develop, and demonstrate thermal energy storage systems for the improvement of the starting characteristics of Army Diesel engines exposed to cold temperatures overnight. Because of the effect of the oil temperatures on starting work, a passive thermal protection system that used Phase Change Materials PCM and insulation was designed for the oil pan and filter. Waste heat was stored in the PCM during engine operation, and was released back into the oil system after engine shutdown. Experimental tests were conducted with the PCM applied to the oil pan and filter of an M925 5-ton truck. After engine shut-off the oil temperature at the bottom of the pan was maintained at 50 deg F during a 12 hr exposure to average air temperature of 13 deg F. During cold start tests conducted after overnight cold exposure, the engine with the PCM applied to the oil system started faster and required much less cranking energy from the batteries than the baseline engine under similar conditions. A secondary benefit of the warmer oil is the improved engine lubrication at startup, which can reduce engine wear. A passive thermal protection system was also built and tested for the battery box.