The escalating thermal management complexity in range-extended electric vehicles (REEVs) necessitates highly integrated systemic solutions. This paper presents a novel integrated thermal management system (ITMS) that unifies the air-conditioning, battery cooling, motor cooling, and engine waste-heat recovery circuits through coordinated control. A high-fidelity ITMS model was developed in LMS AMESim to evaluate its dynamic thermal performance. Under a 40 degrees C ambient condition, the mixed cooling strategy reduced the cabin temperature to 22 degrees C within 180 s and maintained the battery temperature below 28 degrees C within 790 s, while achieving a coefficient of performance (COP) of 3.068. At-10 degrees C, engine waste heat recovery heated the cabin to the target temperature of 22 degrees C within 500 s and concurrently facilitated battery cold-start. The proposed system validates effective adaptive multi-source thermal coupling, ensuring occupant comfort, battery safety, and enhanced energy utilization, thereby providing a scalable framework for next-generation REEV thermal management architectures.
The negative environmental and economic impacts of fossil fuels have made it essential to meet energy supply from renewable energy sources, especially in recent years. Among renewable energy sources, the popularity of solar energy is increasing day by day due to its ease of application and short payback periods. One of the common solar energy applications is rooftop solar energy systems. In this study, a grid-connected rooftop solar energy application was simulated using PVsyst software, utilizing the electricity consumption data of a textile manufacturing factory with a closed area of 5,000 m2 in the Gaziosmanpa & scedil;a neighborhood of Ankara province and considering its geographical location. Taking into account array losses, DC cabling, and system losses, the performance ratio was found to be 77.73%. It has been calculated that 1,002,928 kWh/year of electricity can be generated with the system installed at the facility, which consumes a total of 674,099 kWh/year of electricity. Considering the inflation data of the last two years, with an annual inflation rate of 30% and taking electricity generation into account, it has been determined that the profit to be obtained from the system after 20 years will be 36,406,905 USD. As a result of the environmental impact analysis of the system, it has been calculated that a total of 12,362.1 tons of CO2 emissions can be prevented during the 30-year operational period.
Representative Elementary Unit (REU) simplification has become a standard approach for CFD modeling of structured packings; however, its reliability in predicting dry pressure drop remains a critical yet underexplored issue. In particular, the sensitivity of hydraulic performance to internal geometric parameters is often overlooked in the current literature. This study addresses this gap by calibrating an REU model for Mellapak 500.Y against the semi-empirical correlation of Stichlmair et al. (1989) and experimental data from Tsai (2010). Singlephase simulations were conducted using the SST k-omega turbulence model over a gas-load range of 0.72-4.32 Pa-0.5. Grid independence was established at 0.53 million cells per REU. A domain-sensitivity analysis using one, four, and six REUs yielded deviations below 10%, confirming that a single-unit domain provides sufficient accuracy for dry-flow calibration. The results show that the nominal 2.00 mm sheet spacing leads to substantial underprediction of pressure drop, whereas an effective spacing of 0.24 mm brings the CFD predictions into agreement with Tsai's measurements within a +/- 20% error band and consistent with the Stichlmair correlation across the operating window. These findings identify the effective sheet spacing as the dominant geometric calibration parameter and provide a reproducible, computationally efficient baseline REU for subsequent hydrodynamics simulations in Mellapak 500.Y.
This study employs computational fluid dynamics (CFD) to investigate the heat transfer performance of a shell-and-tube heat exchanger featuring a specially arranged tube bundle, in which no heat-exchange tubes are installed within the circular region at the center of the bundle. Taking the diameter of the tube-free region as a key parameter, a coupled thermo-hydraulic model of the heat exchanger is established to analyze the effects of the tube-free region on flow resistance, heat transfer intensity, and heat transfer uniformity. The results show that the shell-side fluid can participate in heat exchange within the tube-free region, which contributes to the homogenization of heat transfer within the tube bundle. As the tube-free region expands, the degree of heat transfer uniformity increases; however, the overall heat transfer intensity decreases due to the reduction in effective heat transfer area. For the heat exchanger investigated in this study, when the diameter of the tube-free region increases from 140 mm to 440 mm, the shell-side heat transfer coeffi-cient decreases by 22.1%, whereas the heat transfer uniformity improves by 77.1%. A comprehensive performance evaluation based on the TOPSIS decision-making method indicates that a tube-free region diameter of 300 mm provides a favorable balance be-tween flow and heat transfer performance. Under this operating condition, the shell-side pressure drop is 74.95 kPa, the shell-side heat transfer coefficient reaches 8441.03 W/(m2 & centerdot;K), and the relative standard deviation of the tube-side outlet temperature is 0.00969.
The current study investigates heat transfer improvement in a backward-facing step configuration using an inclined flexible fin, through numerical simulation based on the Finite Element Method (FEM). The influence of the position of the flexible fin on thermal and fluid dynamic performance is examined using forced convection of air as the working fluid. The heat transfer characteristics are studied for different Reynolds numbers (Re between 50 and 200) and Cauchy numbers (Ca from 10-8 to 10-4) at three positions (P1, P2, P3) in the channel, with a constant Prandtl number of Pr = 0.71. The results show an enhancement in heat transfer, with the best performance occurring at a Reynolds number of 200 and a Cauchy number of Ca = 10-8, corresponding to the most rigid fin. Specifically, when the fin is located closer to the step, a remarkable 40% increase in the Nusselt number is observed compared to the case without a fin. Additionally, the paper highlights the influence of flow separation and the interaction of recirculation zones with the elastic characteristics of the fin on convective heat transfer. These findings demonstrate the potential of elastic fins as an effective strategy for passive heat transfer enhancement in compact thermal systems.
