EXPERIMENTAL INVESTIGATION OF A SOLID-STATE HEAT ENGINE BASED ON PAM ALLOYSFOR THE UTILISATION OF LOW-GRADE THERMAL ENERGY

<jats:p>This paper presents the results of an experimental study of a solid-state heat engine based on a Ni-Ti shape-memory alloy, designed to utilise low-grade thermal energy and generate mechanical and electrical energy. An experimental prototype of an electromechanical system with an impeller and a system of SMA springs, operating in a cyclic heating and cooling mode, was investigated. Experimental studies were carried out to determine the dependence of the reactive force, rotational speed, torque and mechanical power of the system on the temperature of the heat transfer fluid. A pronounced non-linear nature of the mechanical energy generation processes has been established, associated with the thermomechanical kinetics of phase transitions in the SMA material. The existence of a threshold activation regime for the system has been demonstrated; upon reaching this regime, a sharp increase in the rotational speed, torque and mechanical power of the system is observed. Experimental validation of the previously developed dynamic thermomechanical model of the SMA heat engine has been carried out. A comparison of the results of numerical modelling and experimental data for the temperature dependencies of torque, rotational speed and mechanical power confirmed good agreement between the experimental and calculated characteristics, both in terms of the nature of the non-linear dependencies and the magnitude of the values obtained. It has been demonstrated that the dynamic ODE (Ordinary Differential Equation) model adequately describes the processes of heat transfer, phase kinetics and the generation of mechanical power in an SMA heat engine. Based on the research carried out, the potential for using solid-state SMA heat engines in systems for the utilisation of low-grade heat, autonomous electricity generation and distributed energy systems has been established. References 7, Figures 7.</jats:p>