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The heated fuel injectors are designed to bring up fuel temperature so as to reduce HC and CO emissions during cold start. The heated injectors are similar to regular injectors except heaters are placed near the injector inlet and outlet. The heaters, which has the ability to regulate temperature at 180 °C, transform the thermal energy to heat up the liquid fuel through the injector body. The heated injectors are required to heat up fuel to the operating temperature (e.g., 120 °F or 48.9 °C) as quickly as possible and to maintain that fuel temperature for about three minutes. However, test results indicate it takes more than two minutes for the fuel temperature to reach the desired operating temperature. Objective of this work is to find out the mechanisms controlling the slow heating process through CFD analysis. The computational domain covers the whole injector, from inlet to exit, since the heaters located near the top and bottom of the injector.

A small airflow rate at engine idle is required to maintain a low engine speed and to save fuel consumption. Since the throttle plate is almost closed at idle, the plate and bore tolerance becomes important in determining the plate open area and thus the airflow rate. The objective of this work is to use computational fluid dynamics (CFD) analysis as a tool to aid throttle body design and to find out how the tolerance affects the airflow rate. Also, the conventional equation for calculating the throttle plate open area is modified to include the leakage area which is no longer negligible at idle. Throttle bodies with plate closed angles of 4.0 and 4.5 degrees under tight and loose fit conditions were studied. The flow regions above and below the plate are connected by a narrow region between the plate and the bore. This sudden change in flow area creates a big pressure loss across the plate.