Reda M. Bata

Performance Evaluation of Low Heat Rejection Engines

Improving the performance of the Chinese B135 six-cylinder direct injection turbocharged and turbocompounded Low Heat Rejection Engine (LHRE) was based on experimental and analytical studies. The studies were primarily applied on a B1135 single-cylinder LHR engine and a conventional water-cooled B1135 single-cylinder engine. Performance of the B1135 LHRE was worse than that of the conventional B1135 due to a deterioration in the combustion process of the B1135 LHRE. The combustion process was improved and the fuel injection system was redesigned and applied to the B135 six-cylinder LHRE. The new design improved the performance of the LHRE and better fuel economy was realized by the thermal energy recovered from the exhaust gases by the turbocompounding system.

Development and Validation of a Thermodynamic Model for an SI Single-Cylinder Engine

A multizone quasi-dimensional model that illustrates the intake, compression, combustion, expansion, and exhaust processes has been developed for a single-cylinder four-stroke spark-ignition engine. The model takes into consideration mass and energy conservation in the engine cylinder, intake and exhaust plenums, and crankcase plenum. The model calculates instantaneous variations in gas thermodynamic states, gas properties, heat release rates, in-cylinder turbulence, piston ring motion, blowby, nitric oxide, and carbon monoxide formation. The cycle simulation accounts for the induced gas velocities due to flame propagation in the turbulence model (k-e type), which is applied separately to each gas zone. This allows for the natural evolution of the averaged mean and turbulent velocities in burned and unburned gas regions. The present model predictions of thermal efficiency, indicated mean effective pressure, peak values of gas pressure, ignition delay, concentrations of nitric oxide, carbon monoxide, and carbon dioxide are proven to be in agreement with experimental data.

A Numerical Investigation of the Cooling Effect of Compressed Natural Gas Throttling on Engine Delivery Ratio

A theoretical study was conducted to investigate the cooling effect of throttling compressed natural gas during the pressure regulation process. The concept of using this effect in cooling down the induction air was investigated. A thermodynamic model was developed for a typical fuel delivery system used on a vehicle fueled with compressed natural gas. The model was based on a set of integral conservation laws applied to each component of the fueling system. Several heat exchanging arrangements between the throttled gas and the inlet air were examined. The effect of the added heat exchanger on engine delivery ratio was examined for different engine sizes as well as for different operating conditions. An increase of 1 to 2.5% in engine delivery ratio was predicted due to the added heat exchanger.