Research Of Shape Memory Alloy Heat Engine

SMA heat engine is a novel vehicle taking advantage of waste heat to meet thegovernment policy of energy conservation and emissions reduction. Reasonableforce/motion characteristics, a compact size, a high work output, silent operation anddesign simplicity are its advantages. It is driven by waste heat, so the system ofheating and cooling SMA spring is the key. This heat engine is composed of threeparts: the system of recycling heat, the slider-crank mechanism and the main shaft.The SMA spring is designed to drive the actuator in its original shape. Then theslider-crank mechanism is driven by the actuator to rotate the main shaft. The modelof driver is established by analyzing the performance of the shape memory alloyspring. A validation experiment is performed to verify that the new designed actuatoris suitable to heat engine. The main contents of the thesis are as follows:In chapter1, the background and significance of this project are presented, thedevelopment status at home and abroad of shape memory alloys heat engine aresummarized, the main objective of this project is shown at the end of this chapter.In chapter2, the specific design of SMA spring driver. The working principleand type of SMA spring driver are studied. Several typical constitutive models ofSMA are introduced, one model is chose which is considered to be suitable for thisproject and the relationship equations are established between stress, strain andtemperature. Then the SMA spring is designed according to the formula of ordinaryspring. Finally, the strength of SMA spring is checked to ensure the reliability.In chapter3, the overall structure of SMA heat engine is studied. Thecomponents are designed including transmission components, supporting componentsand connection components. The movement of slider crank mechanism is analyzed,and the simulation diagram is presented by using ADAMS.In chapter4，the working principle of heat engine is detailed. The mathematicalmodel of the thermal cycle system is established according to the performance of theshape memory alloy spring. The simulation diagrams on temperature-displacementand temperature-force are presented by using MATLAB. The water heating andcooling SMA spring is analyzed by using Fluent, and the average temperature ofmixed water is calculated to choose the suitable flow velocity of cold water. In chapter5, it is mainly on experimental study of SMA driver. Theexperiment principle is presented. The data is obtained by doing the experiment. Thenthe data is compared to the result from simulation to verify the reasonability of driver.In chapter6, the major research work is elaborated. Future development ispredicted in order to provide references for the future research on this project.