On–off-Grid Optimal Hybrid Renewable Energy Systems for House Units in Iraq

This paper addresses the optimal sizing of Hybrid Renewable Energy Systems (HRESs), encompassing wind, solar, and battery systems, with the aim of delivering reliable performance at a reasonable cost. The focus is on mitigating unscheduled outages on the national grid in Iraq. The proposed On–off-grid HRES method is implemented using MATLAB and relies on an iterative technique to achieve multi-objectives, balancing reliability and economic constraints. The optimal HRES configuration is determined by evaluating various scenarios related to energy flow management, electricity prices, and land cover effects. Consumer requirements regarding cost and reliability are factored into a 2D optimization process. A battery model is developed to capture the dynamic exchange of energy among different renewable sources, battery storage, and energy demands. A detailed case study across fifteen locations in Iraq, including water, desert, and urban areas, revealed that local wind speed significantly affects the feasibility and efficiency of the HRES. Locations with higher wind speeds, such as the Haditha lake region (payback period: 7.8 years), benefit more than urban areas (Haditha city: payback period: 12.4 years). This study also found that not utilizing the battery, particularly during periods of high electricity prices (e.g., 2015), significantly impacts the HRES performance. In the Haditha water area, for instance, this technique reduced the payback period from 20.1 to 7.8 years by reducing the frequency of charging and discharging cycles and subsequently mitigating the need for battery replacement

Performance Evaluation of Roughened Solar Air Heaters for Stretched Parameters

Artificial roughness applied to a Solar Air Heater (SAH) absorber plate is a popular technique for increasing its total thermal efficiency (ηt−th). In this paper, the influence of geometrical parameters of V-down ribs attached below the corrugated absorbing plate of a SAH on the ηt−th was examined. The impacts of key roughness parameters, including relative pitch p/e (6–12), relative height e/D (0.019–0.043), angles of attack α (30–75°), and Re (1000–20,000), were examined under real weather conditions. The SAH ηt−th roughened by V-down ribs was predicted using an in-house developed conjugate heat-transfer numerical model. The maximum SAH ηt−th was shown to be 78.8% as predicted under the steady-state conditions of Re = 20,000, solar irradiance G = 1000 W/m2, p/e = 8, e/D = 0.043, and α = 60. The result was 15.7% greater efficiency compared to the default smooth surface. Under real weather conditions, the ηt−th of the roughened SAH with single- and double-glass covers were 17.7 and 20.1%, respectively, which were higher than those of the smooth SAH

Photovoltaic module efficiency evaluation:The case of Iraq

This study aims to evaluate the performance of a photovoltaic module under some extreme climate conditions, and with a case study for Iraq. CFD model is developed for the analysis of the photovoltaic module using the commercial CFD software of COMSOL Multiphysics v5.3a for the transient conditions. The results are verified with the analytical solution to the one-dimensional non-linear energy balance equation using Matlab. The results are also compared with measurements reported in the literature for validation. The results reveal that the free convection currents in inclined and horizontal positions of the module were weaker relative to the vertical position. Also, the increase in the length of inclined photovoltaic module, up to 1.3 m, enhances the heat transfer rate. However, beyond this length, the temperature of the module becomes higher, and the convective heat transfer coefficients are reduced regardless of the inclination. In the horizontal position, the convective heat transfer rate is lower, particularly on the bottom surface of PV system

Performance Analysis of Air-Cooled Photovoltaic/Thermal Systems

Photovoltaic (PV) systems have witnessed exceptional development in the last two decades, where it has been shown that PVs may absorb more than 75% of the insolation, however, only limited percentage can be transformed into electricity (7-24%). The remaining energy is released mostly as waste heat in the cells. Overheating may also cause damage to adhesive seals, delamination and non-homogeneous temperatures. Therefore, PV/Thermal (PV/T) systems are a mechanism that can address these issues by keeping the PV cell temperature at the operating range improving efficiency to acceptable levels, as well as producing heat and electricity simultaneously. In this study, PV/T air systems are considered. There are three main challenges to overcome with PV/T air systems; 1) the fan power requirement, 2) extreme weather temperature, 3), and the poor heat capacity of air, which leads to poor thermal performance, compared to other coolants such as water. The aim of this research is to address these challenges developing an efficient and affordable PV/T air system. To achieve this, eleven objectives have been suggested where appropriate several different solution methods are utilised. The CFD software of COMSOL Multiphysics and Matlab are used in this study. The main findings of this research can be divided into three parts. The first part evaluates the performance of the standard PV system utilising theoretical and numerical methods. This system is considered as a reference for subsequent models. The results shows that the convection currents in inclined and horizontal surfaces are weaker relative to the vertical surface. The increase of the PV length enhances heat transfer rate up to length (2L). However, after this length, the PV temperature increases and convective heat transfer coefficients are reduced regardless of the inclination of the PV system. In the case of the horizontal surface, the convective heat transfer rate is lower, especially at the bottom surface of the PV system. It can also be concluded that the effect of inclination appears in the laminar region (short length) and dissipates after this region. The second part numerically and experimentally evaluates the performance of the multi-pass solar air heaters. The impacts of flow configurations on the thermal performance of a solar heater system are investigated. Recycled aluminium cans (RAC) have been utilised as turbulators with a double pass single duct solar air collector. CFD results of the models A, B, and C reveal that model C offers a greater thermal performance of 5.4% and 6.5%, respectively, compared to A and B. Furthermore, an outdoor experiment is performed based on these results. The experimental setup is examined for three configurations of model C, namely, solar air heater (SAH) without RAC model C-I, model C-II and model C-III. A good agreement between model C and the experimental data and model C-III has the best thermal efficiency of 60.2%. The third part, the combination of the two systems from these two parts are evaluated. Firstly, a design optimisation process is performed for different multi-pass PV/T air collectors considering three steps to obtain optimal design. The steps are the selection of design parameters, preliminary parametric studies for the five models (model 1, 2, 3, 4 and 5) and employ model 4 in the optimisation process. The key results from this optimisation demonstrate explicitly the compromise that must be accepted between the conflicting objectives of thermal and electrical efficiencies or the fan power consumption and electrical power generation. It can be concluded that the use of optimisation has contributed clearly in improving both the electrical and thermal performance for finned and plain mod

Thermal and Electrical Performance Evaluation and Design Optimization of Hybrid PV/T Systems

This study aims to evaluate the performance and cooling effectiveness of both photovoltaic (PV) and hybrid PV/thermal systems under various ambient conditions. Two models, namely standard PV module subject to ambient conditions without active cooling and a single-pass hybrid PV/T air collector, have been designed and simulated using the CFD software of COMSOL Multiphysics V5.3a. The PV material used in our analysis is monocrystalline silicon with a power temperature coefficient of 0.41% ºC−1. The thermal and electrical performances of both systems are evaluated numerically and compared to experimental data for validation. The results predicted for cooling effects show noticeable enhancements in both the electrical and thermal efficiencies of the systems, with up to 44% compared to the PV module without active cooling. The electrical PV/T arrangement has increased the performance of air cooling in a laminar flow regime with up to 4%. A numerical-based design optimization is carried out to enhance the system performance

Comparative Analysis of Battery Thermal Management System Using Biodiesel Fuels

Liquid fuel has been the main source of energy in internal combustion engines (ICE) for decades. However, lithium-ion batteries (LIB) have replaced ICE for environmentally friendly vehicles and reducing fossil fuel dependence. This paper focuses on the comparative analysis of battery thermal management system (BTMS) to maintain a working temperature in the range 15–35 °C and prevent thermal runaway and high temperature gradient, consequently increasing LIB lifecycle and performance. The proposed approach is to use biodiesel as the engine feed and coolant. A 3S2P LIB module is simulated using Ansys-Fluent CFD software tool. Four selective dielectric biodiesels are used as coolants, namely palm, karanja, jatropha, and mahua oils. In comparison to the conventional coolants in BTMS, mainly air and 3M Novec, biodiesel fuels have been proven as coolants to maintain LIB temperature within the optimum working range. For instance, the use of palm biodiesel can lightweight the BTMS by 43%, compared with 3M Novec, and likewise maintain BTMS performance