Design And Research Of The Heater For The Small Scale Stirling Engine

Stirling engine, with its high thermal efficiency, low pollution emissions, and the variety of the available energy is widely used in solar power generation, main and auxiliary engine of ship, landfill gas power generation technology and small and medium-sized combined heat and power system and other fields. The small Stirling engine is mainly used in the micro-combined heat and power system, the output power of the engine effecting the efficiency of the system directly. The main role of the heater of the Stirling engine, also known as heat absorber, is to pass the heat released by the fuel combusted in external combustion chamber to the working fluid which flows in the heater and the heater plays a crucial role in the Stirling engine. A high efficient heater can transfer the external heat to the internal working fluid fastly and effectively, and make the temperature of the working fluid increasing fast then has the ability to do work, this is also helpful to improve the output power and stability of the engine. In the small Stirling engine, the simple and compact structure fin heater is used commonly. But the effect of heat transfer of the fin heater is difficult to be improved. Therefor in order to improve the effect of heat transfer of the heater in a small Stirling engine, a tube heater with stronger ability of heat transfer was designed, and the possibility and effect of heat transfer to use the tube heater in small Stirling engine was studied.In this thesis, the following aspects researches were done in order to achieve the purpose of replacing the original fin heater by tube heater.(1) On the basis of retaining the size parameters of original fin heater in the maximum extent, a basic structure of the tube heater used in small Stirling engine was designed based on the existing Stirling engine model. The heat transfer of the designed tube heater and original fin heater was calculated preliminarily according to heat transfer and fluid dynamic knowledge. The best number of the heating pipe, the outside diameter, the inside diameter and the length of the heating pipe were determined. The useless volume, the total heat flux and heat flow of the two kinds of heater were compared, and it proved that the designed tube heater is better than the original fin heater. And the new heater can replace the original fin heater basically.(2) Three options tube heater3D models were created, and the mesh of each options tube heater and original fin heater were generated by meshing software, the heat transfer between the heater of the external flue gas for various options were simulated by fluid dynamics software. The external flue gas flow situation, temperature distribution and heat flux of three options tube heater and fin heater were compared; the advantages and disadvantages of the designed tube heater were analyzed according to the calculation results, and the best option tube heater was determined finally.(3) The coupled thermal analysis of the designed tube heater was done using the static analysis software. The structure strength and the thermal stress intensity were checked. The calculation results show that the structure strength of the final option tube heater meets the design requirement.The research in this thesis designes the basic structure of the tube heater which has the similar efficiency of heat transfer to the original fin heater. With the attempt of using tube heater in small Stirling engine, the paper provids technical supporting on the replacing of fin heater in small Stirling engine.