Dynamic simulation of an engine: gamma-type Stirling case

Dynamic simulation of an engine: gamma-type Stirling case. Modelling and numerical simulation allow(b) the exploration of the different controlling parameters in order to identify the optimal working conditions. This numerical approach permits also to quantify instantaneous and local physical fields. These numerical tools are now resolving more and more complex systems with the help of the computer power increases. We describe in the present study the reciprocating thermal engine of Stirling type, with its varied external heat sources and efficiency improving regenerator. These engines are an alternate solution to be taken into account for an efficient conversion of renewable energies into work. For this use, a good operating efficiency and a great versatility are two qualities that distinguish this engine. Moreover, it is able of running at low temperature differential (LTD) which is especially attractive for low level heat recovery. The optimisation of such machine is strongly dependent of geometrical and physical parameters such as dimensions, heat transfer coefficients, heat source temperatures, regenerator characteristics. Such approach permits to get the instantaneous values of several local physical variables during established regime (pressure, temperature, speed and volume). The energy balance and the efficiencies are deduced. The approach is based on the numerical resolution of the compressible anisothermal fluid flow in an axisymetrical (2D) engine. As validation process, the obtained numerical results are compared with the available experimental results that we got; on LTD Stirling engine prototype. The observed good agreement on the P-V cycle illustrates the interest of the presented methodology.