A system level, steady-state thermodynamics model for an automotive PEM fuel cell system was developed to investigate the effects of vehicle speed and operating pressure on the size of the system components, heat and water formation, fuel consumption, fuel cell, and system efficiency. Moreover, the consequences of the choices of membrane’s thickness and ionic conductivity on thermal and system efficiencies as a function of vehicle speed are analyzed. The model consists of a PEM fuel cell stack model and supplementary models for all necessary auxiliary components. Results show that increasing the system pressure has a significant positive impact on the water balance characteristics of the system, since less water is needed to reach the required relative humidity levels for the reactants. On the other hand, the high-pressure system requires more power in order to operate the compressor, which in turn, decreases the system efficiency. Decreasing air stoichiometry at high operating pressures improves the water management but has no effect at low pressures. Results also show that increasing the membrane’s ionic conductivity and decreasing its thickness enhances the system efficiency especially at higher vehicle speeds. Lastly, it is obtained that the system efficiency decreases as the vehicle speed increases.

Enhancing the sustainability and diversification of Iraq’s electricity system is a strategic objective. Achieving this goal depends critically on increasing the use of renewable energy sources (RESs). The significance of developing solar-powered technologies becomes essential at this point. Iraq, similar to other places with high average direct normal irradiation, is a good location for concentrated solar thermal power (CSP) technology. This study aims to recover the waste heat from the gas turbine cycle (GTC) in the Al-Qayara power plant in Iraq and integrate it with a solar power tower. A thermoeconomic analysis has been done to support the installation of an integrated solar combined cycle (ISCC), which uses concentrated solar tower technology. The results indicate that the examined power plant has a total capacity of 561.5 MW, of which 130.4 MW is due to the waste heat recovery of G.T.s, and 68 MW. is from CSP. Due to the waste heat recovery of GTC, the thermal and exergy efficiencies increase by 10.99 and 10.61%, respectively, and the overall unit cost of production is 11.43 USD/MWh. For ISCC, the thermal and exergy efficiencies increase by 17.96 and 17.34%, respectively, and the overall unit cost of production is 12.39 USD/MWh. The integrated solar combined cycle’s lowest monthly capacity was about 539 MW in September, while its highest monthly capacity was approximately 574.6 MW in April.

This study focused on exergo–conomic and parametric analysis for Taji station in Baghdad. This station was chosen to reduce the emission of waste gases that pollute the environment, as it is located in a residential area, and to increase the production of electric power, since for a long time, Iraq has been a country that has suffered from a shortage of electricity. The main objective of this work is to integrate the Taji gas turbine’s power plant, which is in Baghdad, with the Rankine cycle and organic Rankine cycle to verify waste heat recovery to produce extra electricity and reduce emissions into the environment. Thermodynamic and exergoeconomic assessment of the combined Brayton cycle–Rankine cycle/Organic Rankin cycle (GSO CC) system, considering the three objective functions of the First- and Second-Law efficiencies and the total cost rates of the system, were applied. According to the findings, 258.2 MW of power is produced from the GSO CC system, whereas 167.3 MW of power is created for the Brayton cycle (BC) under the optimum operating conditions. It was demonstrated that the overall energy and exergy efficiencies, respectively, are 44.37% and 42.84% for the GSO CC system, while they are 28.74% and 27.75%, respectively, for the Brayton cycle. The findings indicate that the combustion chamber has the highest exergy degradation rate. The exergo–economic factor for the entire cycle is 37%, demonstrating that the cost of exergy destruction exceeds the cost of capital investment. Moreover, the cost of the energy produced by the GSO CC system is USD 9.03/MWh, whereas it is USD 8.24/MWh for BC. The results also indicate that the network of the GSO CC system decreases as the pressure ratio increases. Nonetheless, the GSO CC system’s efficiencies and costs increase with a rise in the pressure ratio until they reach a maximum and then decrease with further pressure ratio increases. The increase in the gas turbine inlet temperature and isentropic efficiency of the air compressor and gas turbine enhances the thermodynamic performance of the system; however, a further increase in these parameters increases the overall cost rates.

The heat exchanger is crucial to all systems and applications that use it. Researchers are primarily focused on improving this component’s thermal conductivity to improve its efficiency. This was achieved by using one or more of the following strategies: inserting tapes with various shapes and numbers, inserting rings of various shapes and spacing between each, and transforming a basic liquid into a nanoliquid by adding nanomaterials with high conductivity and ultra-small particle sizes. Different types of nanomaterials were added in varying concentrations. In earlier studies, it was found that every increase in heat transfer was accompanied by a pressure drop at both ends of the exchanger. The amount of heat transferred and the pressure drop are affected by many factors, such as the torsion tape ratio, the pitch of the ring, and whether the pitch faces the direction of flow or not. Heat transfer rates can also be impacted by factors such as the length and angle of the wings, how many rings and tapes there are, and whether the rings and tapes contain holes or wings. In addition, the Reynolds number, the type, conductivity, and size of nanomaterials, and the base fluid used in the nanofluid affect this. It is possible for the shape of the exchanger tube, as well as varying rates of rise, to introduce such impacts. In this study, the factors, costs, and benefits of using any technology to increase the efficiency of the heat exchanger are reviewed so that the user can make an informed decision about the technology to use.

This study examines the thermo-hydraulic performance of a heat exchanger tube equipped with special fixed ring inserts and twisted tape elements, using a hybrid nanofluid composed of Al₂O₃-CuO/water. Simulations are carried out under turbulent flow conditions, covering Reynolds numbers from 6000 to 14,000. The impact of varying twisted tape torsion ratios (TR = 5, 10, and 15) and hybrid nanofluid volume concentrations (ϕ = 0.3%, 0.6%, and 0.9%) is systematically evaluated. A validated CFD model in ANSYS Fluent demonstrates strong agreement with benchmark data. The results show that, at Re = 14,000, inserting a twisted tape (TR = 5) into a plain tube boosts the Nusselt number (Nu) by 36.28% and the convective heat-transfer coefficient (h) by 36.3% compared to pure water. The tape promotes turbulence and disrupts the thermal boundary layer, enhancing convective heat transfer. However, these gains incur an 8.0% pressure-drop penalty (ΔP). Furthermore, the study highlights the critical role of nanofluid concentration in optimizing heat-exchanger performance. At a 0.9% volume fraction of Al₂O₃–CuO/water nanofluid added to the twisted-tape (TR = 5) configuration, the Nusselt number climbs an additional 3.2%, while the convective heat‐transfer coefficient rises by 18.2%. This nanofluid boost comes with a modest 6.1% pressure-drop penalty (ΔP increases from 284.8 to 302.2 Pa) yet drives the thermal performance factor (TPF) from 1.38 to 3.29. These findings provide a comprehensive understanding of how synergistic passive heat transfer methods and nanofluids can be strategically utilized to enhance the efficiency of industrial heat exchangers.

Libya is facing a serious challenge in its sustainable development because of its complete dependence on traditional fuels in meeting its growing energy demand. On the other hand, more intensive energy utilization accommodating multiple energy resources, including renewables, has gained considerable attention. This article is motivated by the obvious need for research on this topic due to the shortage of applications concerning the prospects of the hybridization of energy systems for electric power generation in Libya. The 283 MW single-cycle gas turbine operating at the Sarir power plant located in the Libyan desert is considered a case study for a proposed Integrated Solar Combined Cycle (ISCC) system. By utilizing the common infrastructure of a gas-fired power plant and concentrating solar power (CSP) technology, a triple hybrid system is modeled using the EES programming tool. The triple hybrid system consists of (i) a closed Brayton cycle (BC), (ii) a Rankine cycle (RC), which uses heat derived from a parabolic collector field in addition to the waste heat of the BC, and (iii) an organic Rankine cycle (ORC), which is involved in recovering waste heat from the RC. A thermodynamic analysis of the developed triple combined power plant shows that the global power output ranges between 416 MW (in December) and a maximum of 452.9 MW, which was obtained in July. The highest overall system efficiency of 44.3% was achieved in December at a pressure ratio of 12 and 20% of steam fraction in the RC. The monthly capital investment cost for the ISCC facility varies between 52.59 USD/MWh and 58.19 USD/MWh. From an environmental perspective, the ISCC facility can achieve a carbon footprint of up to 319 kg/MWh on a monthly basis compared to 589 kg/MWh for the base BC plant, which represents a reduction of up to 46%. This study could stimulate decision makers to adopt ISCC power plants in Libya and in other developing oil-producing countries.