1997-02-24

An Experimental Heat Release Rate Analysis of a Diesel Engine Operating Under Steady State Conditions 970889

An experimental heat release rate analysis was conducted on a six cylinder, 12.7 liter Detroit Diesel Series 60 turbocharged engine operating under steady state conditions. The overall chemical, or gross, rate of heat release and the net apparent rate of heat release were determined from experimental measurements. The gross, time averaged, heat release rate was determined by two separate concepts/methods using exhaust gas concentration measurements from the Nicolet Rega 7000 Real Time Exhaust Gas Analyzer and the measured exhaust gas flow rate. The net apparent rate of heat release was determined from the in-cylinder pressure measurements for each of the six cylinders, averaged over 80 cycles. These pressure measurements were obtained using a VXI based Tektronix data acquisition system and LabVIEW software. A computer algorithm then computed the net apparent rate of heat release from the averaged in-cylinder pressure measurements. Thus, a simple but powerful technique of experimentally determining the average overall rate of heat transfer to the walls is proposed by taking the difference between the gross and net apparent rates of heat release. An error analysis then investigated the feasibility of this method. The possible sources of error are (1) the confidence limits of the exhaust gas concentration measurements; (2) errors in the fuel and air flow measurements; and (3) error in the determination of the net heat release rates from the in-cylinder pressure measurements. This is the first step towards the eventual objective of developing an experimental technique that determines these rates of heat release for various transient conditions. Both of these techniques can then be used to validate engine heat transfer models and examine the effects of insulated ceramic coatings in the cylinder.

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