An experimental study of a Gamma-type MTD Stirling engine

Abstract

In this work, a prototype of a γ-type Moderate Temperature Differential (MDT) Stirling engine is manufactured, evaluated, and structurally optimized. An inexpensive mathematical evaluation is carried out based on the finite-dimension thermodynamics (FDT) approach. The optimum swept volume ratio, which contributes to the maximized work and efficiency, is achieved under various conditions based on the temperature difference of 450 K. A computer program is developed to evaluate the performance of the Stirling engine under the assumed working conditions. The swept volume ratio of the engine is found to be 3 for the temperature difference of 450 K. The engine dimensions are then adjusted to fulfil the computed swept volume ratio. The bore and stroke for piston are chosen as 63 mm and 40 mm, respectively. For the displacer, they are selected as 90 mm and 60 mm, respectively, based on the chosen swept volume ratio. Experiments are designed and carried out to verify the output power of the engine at various swept volume ratios, while the device is powered by a Liquefied Petroleum Gas (LPG) heater as simulator of solar energy under atmospheric pressure. The FDT results are shown to be in a very good agreement with the experimental outcomes, whereby the validity of the theoretical approach is confirmed. The findings of this research can be useful as guideline for optimization of MTD Stirling engines.