H. Saberinejad, A. Keshavarz, M. Bastami, M. Payandehdoost,
Volume 7, Issue 1 (3-2017)
Abstract
Although, the Stirling engine (SE) was invented many years ago, the investigation on SE is still interesting due to variety of energy resources can be applied to power it (solar energy, fossil fuel, biomass and geothermal energy). In this paper, the thermodynamic cycle of SE is analyzed by employing a new analytical model and a new method is presented to evaluate output power and efficiency of real engines. Using the correcting functions; represent more accurate results for known Schmidt equations respect to adiabatic model. So without need to employing numerical methods and iterative solver programs, analogous results with accuracy and correctness of open-form solution-adiabatic method is obtained. The modeling of results of two methods is done by Non-linear Multiple Regression and new equations based on Schmidt equations with new correctness factors is presented. The correctness factors are function of structural and operational characteristics of engine. Moreover, available output data of GPU-3 SE was compared. These comparisons show good agreement, indicating that the model is an appropriate method for modeling of SE outputs.
Mohammad Reza Azmoodeh, Prof. Ali Keshavarz, Alireza Batooei, Hojjat Saberinejad, Mohammad Payandeh Doost, Hossein Keshtkar,
Volume 10, Issue 3 (9-2020)
Abstract
A multi-objective optimization and thermal analysis is performed by both experimental and numerical approaches on a Stirling engine cooler and heater. The power generated is measured experimentally by an electrical engine coupled with the crank case, and the friction is estimated by the difference between the necessary power used for rotating the engine at a specific pressure and speed, versus the actual power measured experimentally. In the experimental approach, different conditions were considered; for example, the charge pressure varied from 5-9 bars, and the engine speed varied from 286-1146 rpm. The maximum power generated was 461.3 W and was reported at 9 bars of charge pressure and 1146 rpm engine speed. Numerical approach was carried to simulate thermal balance for investigations on the effect of friction, engine speed and efficiency on generated engine power. Average values of Nusselt number and coefficient of friction were suggested from simulation results.
The multi-objective optimization was held using DOE method for maximizing engine efficiency and power, and also minimizing pressure drop. The top and bottom boundary values for our optimization were 5-9 bars of pressure and 286-1146 rpm of engine speed; for both helium and carbon dioxide. To do so, all three significance factors (engine speed, efficiency and friction) were given different weights, thus different combinations of weight value was investigated
Amongst different interesting findings, results showed that if the efficiency weight factor changed from 1 to 3, for helium in a specific condition, the optimum engine speed would increase by approximately 30.6 %
