1992-02-01

The Intercooled-Turbocharged Gas Generator/ Expander Engine - A Feasibility Study by Computer Simulation - Part II: Engine Operating Characteristics 920062

In the first part of this two-part article, a piston-gasifier is designed, and its quasi-steady operating characteristics are predicted by a numerical model. The objective of this second part of article is to study the operating characteristics of the whole engine system. Intercoolers are designed, and their effectivenesses are solved by a combination of analytical solution and empirical correlations. The turbocharging compressors and turbine are described by steady state performance maps. The power turbine is described by the modified Stodola Ellipse with efficiency assumed constant. The numerical model matches the operations of all components to predict the performance of whole engine system.
Utilizing the operating characteristics of the piston-gasifier, the cycle analysis of the whole engine system indicates that there is an optimum intake pressure of the piston-gasifier for each set of crankshaft speed and piston-gasifier exhaust temperature. Considering practical limitations, a reference operating point is chosen for the piston-gasifier. The turbocharging compressors and turbine are then ‘selected’ by scaling performance maps, based on the reference operating point of piston-gasifier.
The numerical simulations cover a wide range of engine operations. The results of the temperature at engine final exhaust show minor variations in the exhaust energy loss among all operations. Excellent fuel economy is obtained, especially at part load operations. Operating at 16* of the engine rated power, the specific fuel consumption of the engine only increases by 20* than full load operation. All these improvements can be attributed to the utilization of turbocharging and intercooling, as well as the use of piston-gasifier.

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