| Popis: |
Theoretical and experimental investigations indicate that at high loads such as 3/4 throttling or more and high speeds such as 3000 rpm or more, the exhaust gas temperatures of the Internal Combustion engines are about 900-1000 K. The amount of heat wasted with exhaust gas of the Internal Combustion engines is equivalent to the power of them. By considering this feature of the Internal Combustion engines, a Hybrid engine consisting of an Internal Combustion (IC) engine and a gamma type Stirling engine was proposed and analyzed from the thermodynamic point of view. Hybrid engine is formed by combining the Stirling and IC engines via a common crankshaft and a common cylinder. The Internal Combustion engine may be a four stroke Diesel engine having an unconventional piston consisting of a crown and a rod. Via using this kind of pistons, two chambers are created in the same cylinder where one of them take part at above of the piston crown, while the other is taking part at below of the piston crown. In the combined engine presented here, the chamber at below of the piston crown is used as the expansion volume of the Stirling engine while the other chamber is being used as operational volume of the Diesel engine. In this study the thermodynamic performance of the Hybrid engine was investigated via using statistical values of common Diesel engines. For Stirling engine; 800 K heater surface temperature, 392 K cooler surface temperature, 800 W/m2K heat transfer coefficient in regenerator, 300 W/m2K heat transfer coefficient in cooler and heater, 250 rad/s engine speed and 12.5 bar air charging pressure were used as principal inputs. The output power of the Diesel engine was assumed to be 120 kW which provides 120 kW heat to Stirling engine. The heat transfer areas of cooler, heater and regenerator were optimized as 0.33 m2, 0.6 m2 and 4.6 m2 respectively. The optimum thermal efficiency and power of the Stirling engine were determined as 47 % and 24 kW. The total thermal efficiency of the combined engine is expected to increase 6 % compared to the stand-alone Internal Combustion engine. For 12.5 bar average gas pressure in the cylinder of Diesel engine, the working fluid mass in the Stirling engine was determined as 17g |
