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An optically-accessible single cylinder small-bore HSDI diesel engine equipped with a Bosch common-rail injection system is used to study the effects of multiple injection. High-speed video is used to study the injector and spray behavior. Laser-induced exciplex fluorescence is used to obtain simultaneous liquid and vapor fuel distributions within the combustion chamber, with tetradecane-TMPD-naphthalene as the base fuel-dopant combination. Significant liquid impingement is seen in the single main injection case, while evidence of liquid impingement is seen only in the first stage of the multiple injection case. No appreciable liquid impingement is seen for the second stage of the multiple injection case. Vapor is seen throughout the jet cross-section regardless of the injection parameters. The majority of the vapor is confined to the bowl region in the single injection case while evidence of vapor is seen outside of the bowl for the multiple injection case.

Lower proof ethanol is shown to be a viable alternate fuel for diesel engines. This type of ethanol can be manufactured economically in small distillation plants from renewable grain supplies. The effect of fumigation of ethanol proofs with a multipoint injection system on a turbocharged direct injection diesel engine at 2,400 rpm and three loads was studied. The addition of the water in the lower proofs reduced the maximum rate of pressure rise and peak pressure from pure ethanol levels. Both of these values were significantly higher than those for diesel operation. HC and CO emissions increased several times over diesel levels at all loads and also with increased ethanol fumigation. NO emissions were reduced below diesel levels for lower proof ethanol at all loads. The tests at this rpm and load with a multipoint ethanol injection system indicate that lower (100 or 125) proof provides optimum performance.

A study has been done to determine the effect of changes in diesel injection timing on engine performance using a multicylinder, turbo-charged diesel engine fumigated with ethanol. Tests at half load with engine speeds of 2000 and 2400 rpm indicated that a 4% increase in thermal efficiency could be obtained by advancing the diesel injection timing from 18 to 29 °BTDC. The effect of changes in diesel timing was much more pronounced at 2400 rpm. Advancing the diesel timing decreased CO and unburned HC levels significantly. The increase in NO levels due to advances in diesel timing was offset by the decrease in NO due to ethanol addition.

This paper reports on the results of using multipoint port injection alcohol fumigation of a four-cycle turbocharged diesel engine in which the fumigation injection cycle was varied. The three cycles, dual with one-half of the alcohol injection on each engine revolution (DIT), single with all of the alcohol injected during the open intake valve revolution (SIO), and single with all of the alcohol injected during the closed intake valve revolution (SIC), lead to significant differences in the engines pressure-volume history and alcohol energy replacement tolerance. The engine was fumigated with both industrial grade ethanol and methanol and complete performance and emissions data (excluding aldehydes) were measured at low, medium, and high values of BMEP and rpm. The results help to explain recently published data showing limited energy replacement, apparent excessive rate of cylinder pressure change, and emissions for single point injection in the same engine.