Development Of A Stirling Engine For The Dish Solar Power Generation System

The technology of dish solar power generation gets substantial progress internationally in the recent three decades. The dish solar power generation system is receiving more and more attention today due to its great importance attached to the renewable energy and distributed energy supply technology, and its advantages of high solar-electricity conversion efficiency and flexible application. The solar Stirling engine is the key power equipment in the dish solar power generation system, which directly determines the performance of the whole system.A brief introduction is made on the key technology of the Stirling engine and the dish solar power generation system at the beginning, and then the latest related international development in the technological fields is reviewed. The future development of the dish power generation technology in China is also briefly analyzed.The main work of this dissertation is to research and develop (R&D) a Stirling engine which can be used in the dish solar power generation system. The advantages and disadvantages of the existing design methods of Stirling engines are analyzed. Then the classic Schmidt analysis method is modified by using some experimental testing data of several internationally famous Stirling engines, and a design method that can precisely predict the performance of Stirling engines in operation is presented in this dissertation. In addition, a method for analyzing the fluid flow, the heat transfer and the energy conversion in the Stirling engine is provided by starting from the equation set of mass, momentum and energy conservation relations, by introducing a series of dynamic equations, and considering the characters of common loads like generators. The qualitative analysis on the main factors that cause the power loss of Stirling engines in real operation is also presented. A β-type single cylinder Stirling engine is developed by using the modified Schmidt analysis method. The rhombic mechanism is designed into the engine. An experimental system is built to test the performance of the developed Stirling engine, and a series of experimental tests are conducted. During the tests, waste gases with mid-high temperature exhausted from a gasoline engine at no-load running condition are used to drive the Stirling engine as the heat source. The output shaft power could reach3476W at the rotational speed of1248RPM.The pressure loss of the working fluid in the heat exchanger system of the Stirling engine is also studied. The recorded test data show that the loss between the inlet and outlet of the regenerator is more than twice that between the inlet and outlet of the cooler, so the porous metal regenerator is the major factor which causes the pressure loss of the working fluid. The pressure variation is approximately sinusoidally periodic, and the phase difference of the pressure values among the three different locations is almost zero.The solar receivers for the dish power system are also studied and designed. The problem at the interface between the sunlight collector and the solar receiver is studied firstly, and then two solar receivers are developed. One has the feature of U-shape channels to heat the internal working fluid, so the wall temperature could distribute more uniformly and avoid intense thermal stress according to the simulation results. The other one has the feature of involute heater tubes, which could receive more sunlight in a narrow space. The two solar receivers are both trial-produced.On the basis of the above work, a3kW dish solar power generation system is built. The system mainly includes a solar concentrator with its diameter of about5m and a solar Stirling engine with an indicated output power of about3kW near the focus point of the concentrator. This solar Stirling engine is reformed from the above-mentioned β-type Stirling engine.