Case Studies in Thermal Engineering最新文献

{"title":"Thermal and economic benefits of a coil-column ground heat exchanger with recycled concrete backfill in horizontal ground source heat pump applications","authors":"Huu-Ba Dinh, Hanh Nguyen-Cong, Bang Yeon Lee, Young-Sang Kim","doi":"10.1016/j.csite.2025.106344","DOIUrl":"https://doi.org/10.1016/j.csite.2025.106344","url":null,"abstract":"In this study, we constructed a full-scale in-situ thermal response test (TRT) bed to evaluate the heat exchange performance of a newly developed coil-column system (CCS) as a novel ground heat exchanger (GHE) for a horizontal ground source heat pump (GSHP) system. The TRT was also performed for the conventional GHE (U-type) to compare and investigate the feasibility of the CCS. This study also aimed to propose a recycled concrete-based backfill material (RCB) to improve the heat exchange ability of the horizontal GSHP system, reduce material costs, and mitigate environmental impact. Engineering properties and thermal conductivity were examined through laboratory tests. Furthermore, the in-situ heat transfer performance of the proposed materials was evaluated using the full-scale TRT. After that, a numerical analysis-based finite element code was used to compare the performance of full-scale CCS and other GHEs (U-type and spiral-coil type) and conduct economic analysis. The results showed that the proposed backfill material possesses high thermal conductivity and satisfies all the engineering property requirements for general backfill applications. The heat exchange capacity of the CCS is 1.2 times higher than that of the conventional U-type GHE, despite requiring 5.75 times less installation length. Thus, the CCS combined with the proposed backfill material is a highly feasible GHE compared to that of the U-type and spiral-coil type: 776 % and 65 % higher in net present value, 150 % and 23 % higher in internal rate of return, and 6 years and 5 years shorter in payback period, respectively.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"133 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144130785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of the outdoor training effects on fatigue performance and thermal comfort in summer","authors":"Tianwei Tang, Yongcheng Zhu, Shaodong Huang, Zhang Lin, Zhaosong Fang","doi":"10.1016/j.csite.2025.106341","DOIUrl":"https://doi.org/10.1016/j.csite.2025.106341","url":null,"abstract":"Climate change and rising global temperatures have raised concerns regarding outdoor activities and physical training. These issues require special attention in China, where physical training is common for university students. This study was conducted in Guangzhou, China, from September 2 to September 17, 2022, where students were trained for approximately two weeks, and 1180 valid questionnaires were collected to investigate the correlation between fatigue and training time by evaluating thermal sensations during physical training and analyzing changes in physiological parameters and fatigue levels throughout the training. The fatigue level and its correlates were discussed using Kaplan-Meier (KM) survival analysis and hazard analysis. The results revealed a substantial correlation and significant relationship between the mean thermal sensation vote and thermal index. Total fatigue scores were significantly correlated with the universal thermal climate index (UTCI), and fatigue levels were positively correlated with UTCI. According to the percentage distribution of each fatigue level with training time, more than 15 % of the subjects should rest after 11 a.m. Additionally, hot weather accelerated fatigue events. The increased caloric index exacerbated physical fatigue and symptomatic performance. Additionally, the proportion of negative emotions among students increased in hot environments, consequently, increasing mental fatigue. Fatigue was studied using KM survival and hazard analyses related to training time by incorporating several factors. UTCI, heart rate, tympanic temperature, and T<ce:inf loc=\"post\">skin</ce:inf> were found to produce a greater risk of fatigue events when they reached certain values. Based on the results, training time was recommended to be adjusted to 3.0 h and 2.5 h in the morning and afternoon, respectively. The results of this study will assist in adjusting student training time, reducing the occurrence of heat strokes in students during training, and maintaining overall student health.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"9 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144130786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing solar collector efficiency and safety: A comparative thermal analysis of non-toxic hybrid nanofluid mixtures using machine learning","authors":"Mohib Hussain ,&nbsp;Meraj Ali Khan ,&nbsp;Hassan Waqas ,&nbsp;Qasem M. Al-Mdallal","doi":"10.1016/j.csite.2025.106221","DOIUrl":"10.1016/j.csite.2025.106221","url":null,"abstract":"<div><div>Ethylene glycol is extensively used in solar energy systems because of its thermo-physical properties; however, its toxicity presents health and environmental risks. To overcome this, non-toxic solutions such as propylene glycol or water-ethylene glycol blends are promoted, keeping system efficiency while enhancing safety and sustainability. This study proposes the integration of advanced machine learning (ML) and artificial intelligence (AI) with computational fluid dynamics (CFD) for the thermal analysis of a mixture comprising three distinct base fluids: Ethylene Glycol (EG)-water, Propylene Glycol (PG)-water, and EG with hybrid nanoparticles, aimed at minimizing toxicity and production costs in solar collector energy systems. The effect of non-Fourier heat flux on the Blasius–Rayleigh–Stokes variable (BSRV) flow of a hybrid nano-fluid across a plate is investigated numerically for this purpose. Hyper-parameter optimization is performed for four alternative AI training methods to determine the best suitable choice. Whereas for numerical simulation, the Keller-Box method (KBM), a modified finite difference methodology, is employed. Regression scores of 1 indicate an impeccable correspondence between numerical information and the predictions. Conclusively, a comparative analysis is presented to support our claim, which states that by using combination of PG-Water, similar heat transfer rate can be achieved, which is less harmful and also cost effective.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"72 ","pages":"Article 106221"},"PeriodicalIF":6.4,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal and hydraulic performance of molten salt steam generation system under varying operating conditions in concentrating solar power plants","authors":"Jiaming Tian,&nbsp;Bo Ren,&nbsp;Yiran Duan,&nbsp;Biao Li,&nbsp;Yueshe Wang","doi":"10.1016/j.csite.2025.106340","DOIUrl":"10.1016/j.csite.2025.106340","url":null,"abstract":"<div><div>To conduct the thermal transport characteristics and operational stability of the steam generation system (SGS) under partial load conditions in concentrating solar power (CSP), a real-scale shell-and-tube steam generator hydrodynamics predictive model is developed. This model integrates lumped parameter methods with the finite volume method to account for heat transfer and phase change. Additionally, in accordance with the prevailing water circulation mode in the CSP plant, a typical model of the natural circulation system is established, while optimal stable operating points of the maximum circulation mass flow rate under varying operating conditions are determined. The results indicate that the inherent stability of the generator strongly lies in the dynamic compromise between its thermodynamic and hydrodynamic characteristics. Under high load conditions, the natural circulation mode demonstrates excellent flow stability. Operating at lower operating pressures results in greater circulation flow and a heightened sensitivity to phase changes. Under system pressures of 13.76, 11.08, 8.39, and 6.71 MPa, the recommended circulation ratios are determined to be 5.38, 7.86, 11.95, and 16.07, respectively. Furthermore, the stability of the circulation curve is optimized by adjusting the structural dimensions of the steam generator. The sensitivity to evaporation capacity and heat exchanger effectiveness is assessed.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"72 ","pages":"Article 106340"},"PeriodicalIF":6.4,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical and artificial neural network framework for predicating MHD radiative flow and heat transfer of hybrid nanofluid with Cattaneo-Christov theory","authors":"Fathi Alimi ,&nbsp;Sohail Rehman ,&nbsp;Mohamed Bouzidi ,&nbsp;Fisal Asiri ,&nbsp;Taoufik Saidani ,&nbsp;Vineet Tirth","doi":"10.1016/j.csite.2025.106311","DOIUrl":"10.1016/j.csite.2025.106311","url":null,"abstract":"<div><div>In this paper, the artificial neural network (ANN) is executed to scrutinize the heat transfer performance of water-based hybrid nanofluid (HNF) flow over a permeable stretching surface under the influence of an inclined magnetic field and thermal radiation. The advanced Cattaneo–Christov heat flux model (CCHFM), is introduced in this study in order to characterize the heat transfer features in a boundary layer (BL) slip flow, with thermal radiation, variable thermal conductivity and nanoparticles diffusion. The equation of energy is renovated taking thermal radiation, variable thermal conductivity, thermal jump and thermal relaxation effects. The flow model is constructed using BL approximation and necessary assumption while the Robin type boundary conditions are obtained by assuming thermal jump and velocity slip. The modified first order differential equations are solved using Bvp4c mechanism. The findings reveals that the coefficient of frictional drag is reduced by the magnetic parameter while contrary behavior is seen for nanoparticle volume fraction. The precision of the ANN model appeared astounding, with an error range of 10 <span><math><mrow><msup><mi>E</mi><mrow><mo>−</mo><mn>8</mn></mrow></msup></mrow></math></span> to 10 <span><math><mrow><msup><mi>E</mi><mrow><mo>−</mo><mn>9</mn></mrow></msup></mrow></math></span>. The regression values that are nearer 1 indicate a good fit between the actual data and the forecasts. The thermal relaxation parameter diminished the temperature and heat dissipation.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"72 ","pages":"Article 106311"},"PeriodicalIF":6.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144067402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large eddy simulations of pool fires and backdraft in a compartment using FDS and FireFOAM","authors":"Dinesh Myilsamy ,&nbsp;Chang Bo Oh ,&nbsp;Joonho Jeon","doi":"10.1016/j.csite.2025.106337","DOIUrl":"10.1016/j.csite.2025.106337","url":null,"abstract":"<div><div>This study evaluated the performance of two widely used fire simulation codes for predicting heptane pool fires and methane backdrafts occurring within a compartment. The simulation models used were Fire Dynamics Simulator (FDS), which applies a low-Mach-number approximation, and FireFOAM, which performs a compressible flow analysis. Turbulence analysis was conducted using the large eddy simulation (LES) technique. The eddy dissipation model (EDM) was applied to pool fire simulations, and the eddy dissipation concept (EDC) model, which considers a two-step chemical reaction, was applied to backdraft simulations. Both simulation codes reasonably predicted the temperature and key chemical species, such as O₂ and CO₂ concentrations, for the heptane pool fire, with FDS predicting slightly higher temperatures than FireFOAM. For methane backdrafts, both models performed similarly during the gravity current phase; however, significant differences were observed in backdraft onset and propagation. FireFOAM closely matched the experimental pressure data, whereas FDS overestimated the pressure and predicted an earlier peak. FireFOAM also simulates flame distribution and fireball formation more reasonably. FDS, which uses a low-Mach-number approximation, is computationally efficient but less accurate for backdrafts, where pressure changes are crucial.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"72 ","pages":"Article 106337"},"PeriodicalIF":6.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144072255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A fully coupled thermal-fluid-electric-mechanics multiphysics numerical model for comprehensive performance evaluation of annular thermoelectric generators","authors":"Ding Luo ,&nbsp;Zheng Li ,&nbsp;Ying Li ,&nbsp;Haokang Zhang ,&nbsp;Xuehui Wang","doi":"10.1016/j.csite.2025.106329","DOIUrl":"10.1016/j.csite.2025.106329","url":null,"abstract":"<div><div>The maximum thermal stress is an important indicator for evaluating the thermal reliability of thermoelectric generators (TEGs), but theoretical models to simultaneously predict the thermoelectric and thermomechanical performance of TEGs are lacking. Therefore, a fully coupled thermal-fluid-electric-mechanics multiphysics numerical model is established, and it is adopted to conduct a comprehensive numerical analysis of an annular TEG. Additionally, the influences of geometric parameters (height <em>h</em> and angle <span><math><mrow><mi>θ</mi></mrow></math></span>) of thermoelectric elements and exhaust conditions on the performance of the annular TEG are studied. Numerical results reveal that reducing the thermoelectric element height (<em>h</em>) from 5 mm to 2 mm under <em>T</em>_in = 550 K and <em>ṁ</em>_ex = 30 g/s enhances output power by 27.6 % (10.97 W–14.02 W) but lowers conversion efficiency from 3.41 % to 2.99 %, while maximum thermal stress decreases by 11.6 % (289.72 MPa–256.07 MPa). Increasing the angle (<em>θ</em>) from 4° to 7° elevates output power by 11.6 % (12.94 W–14.44 W) yet reduces efficiency by 14.4 % (3.34 %–2.86 %), with thermal stress amplified for larger <em>θ</em>–<em>θ</em>_s mismatches. Both the thermoelectric and thermomechanical performance of the annular TEG are more significantly affected by exhaust temperature compared to mass flow rate. This model integrates fluid dynamics and thermal-electric-mechanics coupling, overcoming limitations of prior studies that simplified boundary conditions. It provides actionable insights for optimizing annular TEGs in automotive waste heat recovery, balancing thermoelectric performance and thermomechanical performance.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"72 ","pages":"Article 106329"},"PeriodicalIF":6.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144072256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling and performance analysis of a solar thermal desalination system using simulation in TRNSYS software","authors":"Mohammad Shykhaee,&nbsp;Hossein Yousefi,&nbsp;Ahmad Hajinezhad,&nbsp;Mahmood Abdoos,&nbsp;Younes Noorollahi","doi":"10.1016/j.csite.2025.106332","DOIUrl":"10.1016/j.csite.2025.106332","url":null,"abstract":"<div><div>Solar energy is one of the clean and sustainable solutions to fight freshwater scarcity in hot and arid regions. The current paper presents the design of a thermal desalination system powered by solar energy for large-scale freshwater production by using the TRNSYS software. Solar collectors' Energy supply accounts for saline Water's required phase change, with a six-stage separator to extract the generated steam from saline Water. More precisely, heat exchangers condense the generated steam and heat the feeding saline water before the solar collectors are in place. Further, the concerned simulation has taken the meteorological data from Bandar Abbas due to high solar irradiation and its closeness with seawater from the Persian Gulf. Consequently, the computer-based simulated results highlighted that on occasions of maximum solar radiation, the solar collector exit temperature reached approximately 190 °C. However, in the case of the temperature increase of the water required to produce steam, it takes quite some time; hence, on the ground, this installation operates about 6 h a day despite the available 10-h active solar radiation. On a day like that, 470,000 m³ of Freshwater would have been produced, whereas on one of the hottest weeks during the whole year in late May, it is very confident of showing a yield of 45 %. The system's efficiency was also calculated to be 43 %, even on the year's coldest days. A short comparison with other available studies further confirmed the system's effectiveness. Therefore, this research highlights solar energy's viability as a renewable and clean approach to solving water shortage problems in hot and arid regions.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"72 ","pages":"Article 106332"},"PeriodicalIF":6.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144067401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental assessment of the interaction between indoor air quality and thermal comfort in naturally ventilated secondary classrooms in southern Spain","authors":"R. Escandón ,&nbsp;C.M. Calama-González ,&nbsp;R. Suárez","doi":"10.1016/j.csite.2025.106335","DOIUrl":"10.1016/j.csite.2025.106335","url":null,"abstract":"<div><div>Current European policies focus on achieving climate neutrality by 2050. However, the COVID-19 crisis has disrupted social conditions, reigniting the debate on buildings with high occupancy and static users for long periods, such as schools, given their inadequate health and comfort conditions. In the Mediterranean climate, most school buildings lack suitable ventilation systems, due to either their age or a reluctance to use mechanical ventilation systems.</div><div>This study provides a quantitative analysis of current behavioural and environmental factors affecting pollutant exposure, covering the gap in the existing literature on simultaneous assessment on indoor air quality conditions (CO₂, PM_2.5, PM₁₀), and hygrothermal comfort (temperature and relative humidity) in a post-COVID scenario in existing secondary school buildings in southern Spain. For this purpose, a continuous monitoring of indoor environmental conditions in cooling, mild, and heating seasons is proposed to assess the influence of natural ventilation conditions on indoor air quality and thermal comfort, instead of the short-term monitoring focused on specific periods frequently found in previous studies. The results show a widespread use of natural overventilation through windows, especially in summer (more than 50 % of the occupied hours), to guarantee indoor air quality conditions (with CO₂ below 900 ppm during almost 100 % of the occupied hours). However, in general, this involves clearly compromising thermal conditions (with seasonal average values above 25 °C and 100 % of the occupied hours in discomfort during the hottest weeks) and a moderate loss of cognitive performance during more than 97 % of the summer occupied hours.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"72 ","pages":"Article 106335"},"PeriodicalIF":6.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using MD simulation to evaluate the effects of working fluid, wall material, and wall layering of a nano-grooved flat plate heat pipe","authors":"Gholamreza Ahmadi,&nbsp;Mohammad Ameri,&nbsp;Ali Jahangiri","doi":"10.1016/j.csite.2025.106331","DOIUrl":"10.1016/j.csite.2025.106331","url":null,"abstract":"<div><div>Monitoring and dissipating the heat generated by semiconductor-based components, including microprocessors, is necessary for their stability and optimal performance. The use of heat pipes (HPs) as passive instruments makes this possible without the need for any additional energy sources. The application of flat plate nano-HPs in microprocessors has materialized by recent developments in nanoscale device manufacturing. The effectiveness of a cell of this kind of HP has been investigated in this article. While focusing on the impact of wall thickness, the velocity, density, and temperature profiles, and also mass and heat transmission have been calculated under various circumstances. The molecular dynamics simulation findings indicated that the mass transfer rate has increased as the wall layer numbers have increased, under all circumstances. The atomic structure of the working fluid has a significant impact on the mass transfer rate inside nano-HPs. The maximum and minimum heat fluxes are 1896 W/cm² and 1392 W/cm², which respectively relate to water and argon. The overall performance of HP significantly relates to the circulation rate of the working fluid. Using Cu-EtOH leads to the maximum mean velocity (0.096 Å/ps). Cu-EtOH and Pt-Ar respectively, shows the highest and lowest average temperatures, as 463.1 K and 404.7 K.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"72 ","pages":"Article 106331"},"PeriodicalIF":6.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}