Experimental research and application possibilities of microcogeneration system with Stirling engine

The first part of this paper presents the thermodynamic analysis for a microcogeneration system with the Stirling engine, for the most commonly used working gases, among others: helium, nitrogen, and air. The methods of regulating performance for the Stirling engine were depicted, among which the increase of gas pressure in the working chamber and rise in temperature of the upper heat source can be rated. The results of the experimental tests are shown: the influence of the rise in pressure and temperature on the working gases, which in this experiment were: helium, nitrogen, and air. The paper also focuses on maximum power flow. The tests were performed on a laboratory test stand with a single-action alpha type Stirling engine, located at the Faculty of Automotive and Construction Machinery Engineering, Warsaw University of Technology, at the Integrated Laboratory of the Mechatronic Systems of Vehicles and Construction Machinery. In the second part of the paper the authors presented the power flow in a hybrid system (Senkey diagram) on the internal combustion engine with the Stirling engine, which is employed as a microcogeneration device of distributed generation. It enables high-temperature waste heat to be transformed into mechanical work and transition of mechanical work into electric energy with the help of an electrical appliance, for possible sale to the mains. While analyzing the power flow in the hybrid cogeneration system, attention was paid to low-temperature heat which can be utilized through electrical thermogenerators, among other things. The proposed microgeneration assembly (Stirling engine and electrical thermogenerators) could be used to recover energy from waste heat produced by the combustion engine during combustion of landfill biogas. The influence of microcogeneration systems on boosting the general efficiency of the combustion engine was taken into consideration in this work. The paper presents test results of combustion gas temperatures in the exhaust system of the combustion engine fuelled by biogas, at full-load conditions. Various limitations of the Stirling engine build are discussed, in the context of cooperation with the combustion engine and the use of waste gases as a high-temperature heat source.