• Energy Research

Abstract The renewable energy is expanding in the sub-systems of distribution electrical grids, due to having low energy costs and high reliability. In this study, off-grid design of the hybrid energy system based-renewable resources is proposed for a house in Hamadan city in Iran. The resources are designed based on economic and climate data such as battery, solar cells, wind turbines, and electrolyser/fuel cell. The design of mentioned resources is done with attention to twofold optimization modelling including operation cost (OC) and net present cost (NPC). The modelling of resources is implemented in HOMER software based on optimal sizing and installation costs. In the numerical simulation, the three optimal designs are presented to meet electrical demand with minimum costs and high reliability.

Today, using systems based on renewable resources is a suitable alternative to fossil fuels. However, due to problems such as the lack of access in all the times needed to supply cargo and high-investment cost, it has not been well-received. Therefore, in this research, the modeling of the photovoltaic system with battery storage has been done to supply the required load, and various scenarios have been evaluated in terms of economic parameters and reliability indicators of the studied system for a better understanding of the comparison indicators. It has been evaluated from two modes, one connected to the network and one disconnected from the network. One of the important results is the supply of 56% of the load by the photovoltaic cell in the presence of the grid, which, in this scenario, the electrical load is supplied by the photovoltaic cell and the grid is 164.155 kWh/yr and 128.504 kWh/yr, respectively.

Stirling engines represent a category of external heat transfer engines that demonstrate versatility by harnessing various heat sources, including solar energy, bio-mass, conventional fuel, and nuclear power. Achieving high thermal efficiency in power production has been a paramount concern driving researchers across the globe to focus on developing Stirling engines. A gamma-type double-piston Stirling engine has been carefully selected for detailed analysis in this research endeavour. A polytropic model is employed in the investigation to gain deeper insights into the engine’s behaviour. The outcomes derived from the polytropic analysis are subsequently compared with a classical adiabatic analysis. Remarkably, the polytropic approach significantly outperforms the classical adiabatic analysis in enhancing the overall performance of the Stirling engine. The power and efficiency obtained from the ideal polytropic analysis were 90.30 W, which is very close to the ideal adiabatic and experimental efficiency. The results hold significant promise for advancing the efficiency and practical application of Stirling engines, reinforcing their position as a prominent contender in pursuing sustainable and highly efficient power generation technologies.

In the foreseeable future, the depletion of finite fossil fuel reserves is a growing concern due to the increasing consumption of these resources by humans. Moreover, the emission of greenhouse gases from fossil fuel consumption contributes to global warming, resulting in significant harm to the Earth’s ecosystem. The Stirling engine (SE) offers an outstanding solution for harnessing various heat sources, including solar, nuclear, and fossil fuels, among others. It provides numerous advantages, such as high efficiency, a long lifespan, low noise levels, and minimal or no emissions. This study conducts a finite physical dimensions thermodynamic analysis (FPDT) on a gamma-type double-piston cylinder engine and compares the results with other isothermal models and experimental data. The current model’s results align closely with those of other thermodynamic models.