Case Studies in Thermal Engineering最新文献

{"title":"Investigation of a novel thermal and mass stratification effect on second grade fluid: Applications in industrial heat transfer systems","authors":"Uzma Rafique ,&nbsp;Mudassar Nazar ,&nbsp;Shajar Abbas ,&nbsp;Ghada Ragheb Elnaggar ,&nbsp;Ali Arishi ,&nbsp;Barno Abdullaeva","doi":"10.1016/j.csite.2025.106399","DOIUrl":"10.1016/j.csite.2025.106399","url":null,"abstract":"<div><div>This study investigates the unsteady, incompressible, one-dimensional flow of a second grade flow over an infinitely vertical moving cylinder, emphasizing novel thermal and mass stratification effects relevant to industrial engineering and heat transfer systems. Employing the Caputo time-fractional derivative framework, the model incorporates the combined buoyant forces due to mass and heat transfer, offering a generalized perspective on transient behavior in complex fluid systems. Using the Laplace transform technique, analytical equations for temperature, velocity, and concentration profiles are generated to simplify the analysis, assuming unit values for the Schmidt and Prandtl numbers. Comparative assessments between long-term steady-state and unsteady-state solutions are conducted, highlighting dynamic transitions. The effects of significant dimensionless parameters on solutal and thermal transfer are thoroughly examined. Graphical results for Sherwood and Nusselt numbers and skin friction provide insights into boundary layer characteristics. The findings demonstrate that both thermal and mass stratifications significantly alter the flow dynamics, underlining their importance in the design, optimization, and performance analysis of industrial engineering applications involving fluid flow and heat exchange, such as chemical reactors, thermal regulation units, and energy conversion systems.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106399"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144254524","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":"Comparison of O2-enriched and N2O oxidizers on dual-flame structure and entropy generation","authors":"Yueh-Heng Li ,&nbsp;Po-Hung Lin ,&nbsp;Wen-Yuan Tsai ,&nbsp;Janusz Lasek","doi":"10.1016/j.csite.2025.106485","DOIUrl":"10.1016/j.csite.2025.106485","url":null,"abstract":"<div><div>This study utilizes a triple concentric burner to generate a dual-flame structure and investigates the impact of dual flames on entropy generation under varying fuel-oxidizer velocity ratio (R), ultimately identifying the dominant pathways. The study also examined the substitution of nitrous oxide (N₂O) with a nitrogen-oxygen (N₂−O₂) mixture to understand the influence of N₂O decomposition on entropy generation. The research evaluated the irreversibility of chemical reactions in the presence of a dual-flame structure. It was observed that the chemical reaction term in the N₂O case (R = 3) was approximately twice as intense as in the O₂-enriched case (R = 5) due to the more vigorous reaction of N₂O, despite similar energy input. Reactions involving N₂O, such as those related to the cyanato radical (NCO) and isocyanic acid (HNCO), were slightly more pronounced in the N₂O case compared to the O₂-enriched case, even though the R ratio was lower in the N₂O case. In conclusion, increased entropy generation reduces exergy and decreases second-law efficiency (ηII) from 88.5 % to 78.8 % in O₂-enriched cases and from 74.3 % to 66.3 % in N₂O cases as R increases. This decrease is more pronounced in dual-flame structures, where η_II drops below 80 %, primarily due to heat conduction and chemical reactions.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106485"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272387","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 simulation of fluid flow and heat transfer of two-phase slug flow in inclined pipes","authors":"Sirui Lu ,&nbsp;Hao Lu ,&nbsp;Wenjun Zhao ,&nbsp;Zhibo Xiao","doi":"10.1016/j.csite.2025.106447","DOIUrl":"10.1016/j.csite.2025.106447","url":null,"abstract":"<div><div>Gas-liquid two-phase slug flow is characterized by significant stochasticity and uncertainty while widely used in practical engineering applications. However, for inclined downward pipes, the fluid flow and fluid heat transfer mechanisms deserve further investigation. Therefore, in this study, hydrodynamic models and heat transfer models applicable to inclined pipes are considered together. First, a hydrodynamic model of a two-phase slug flow in an inclined regular-size channel was created using the slug cell method. Each slug cell was assumed to consist of a liquid slug and a Taylor bubble region. In addition, variables such as two-phase pressure drop and overall void fraction were used to derive the local heat transfer coefficients of the liquid plug and Taylor bubble regions and thus to integrate the total heat transfer coefficient. Experimental verification confirms that the model accurately predicts the heat transfer coefficients. Finally, the heat transfer performance of slug flow was analyzed and synthesized by six characteristic parameters. The results indicate that under laminar flow, the enhancement of heat transfer through pipe inclination was more important. The apparent gas velocity and the two-phase heat transfer multiplier show an approximate quadratic relationship in the small inclination (0°∼40°) and low Reynolds number intervals (<em>Re</em>: 124–332). In terms of heat transmission, the two-phase slug flow outperformed the liquid single-phase flow. Additionally, compared to the thin thermal boundary layer with large inclination, the heat transfer coefficient of thick thermal boundary layer with low inclination is only 37 %–56 %. Pipe inclination promotes the heat transfer coefficient better than increasing the gas-phase velocity alone. The maximum increase in the two-phase heat transfer coefficient due to an increase in inclination was 3520 W/(m·K), while the maximum increase in two-phase heat transfer coefficient due to increase in superficial gas Reynolds number is 1050 W/(m·K). The optimum pipe inclination to maximize the heat transfer coefficient and minimize the pressure loss is in the range of (50°∼60°).</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106447"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263832","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 approach to enhance solidification by incorporating hybrid nanoparticles and employing porous foam","authors":"Mohammed A. Tashkandi ,&nbsp;Ali Basem ,&nbsp;Hussein A.Z. AL-bonsrulah ,&nbsp;Moaz Al-lehaibi ,&nbsp;Lotfi Ben Said ,&nbsp;Walid Aich ,&nbsp;Abd Elmotaleb A.M. A. Elamin ,&nbsp;Lioua Kolsi","doi":"10.1016/j.csite.2025.106489","DOIUrl":"10.1016/j.csite.2025.106489","url":null,"abstract":"<div><div>Cold energy storage units using PCM (phase change material) are crucial in applications such as cryogenic cooling, refrigeration, and energy-efficient building design. However, the slow solidification rate of conventional PCMs limits their performance. This study presents a numerical investigation aimed at accelerating the freezing process of water by simultaneously employing porous foam, radial fins, and hybrid nanoparticles, along with the effect of radiative heat transfer. A hybrid nanofluid composed of water and mixed nano-powders is introduced to improve thermal conductivity, while the inclusion of porous media enhances heat extraction. The governing equations are solved applying the Galerkin finite element approach, with adaptive meshing to accurately capture the transient freezing front. Radiation effects are modeled using the Rosseland approximation to reflect realistic thermal behavior. Validation is performed by comparing the numerical model against established experimental benchmarks. Outputs indicated that the use of hybrid nano-powders alone reduces freezing time by 6.62 %, while radiation cooling (without porous foam) further reduces it by 13.83 %. The most substantial enhancement occurs with the inclusion of porous foam, leading to an 80.6 % reduction in freezing time. These findings confirm the synergistic effect of porous structures, nanoparticle enhancement, and radiative cooling, offering a novel cold energy storage systems.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106489"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289881","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":"Comprehensive analysis of a novel coal-fired cogeneration system with integrated dual heat pumps","authors":"Shifei Zhao,&nbsp;Fan Duan,&nbsp;Ze Tian,&nbsp;Hanbo Huang,&nbsp;Jiale Wang,&nbsp;Chunlan Wang","doi":"10.1016/j.csite.2025.106413","DOIUrl":"10.1016/j.csite.2025.106413","url":null,"abstract":"<div><div>The low-carbon transformation of the global energy system requires flexible energy supply technologies. This paper proposes a novel coal-fired cogeneration system with integrated dual heat pumps. The return water is cooled by the absorption heat pump, which significantly expands the range of water temperature rise and the waste heat recovery. Based on EBSILON professional, the thermodynamic, operation, and techno-economic analysis is conducted. The results show that the upper limit of the thermal capacity of the novel system is increased by 164 MW, leading to a 9.86% enhancement in gross efficiency. Additionally, at a thermal load of 400 MW, the power load regulation ratio of the novel system is boosted by 10.57%. Furthermore, as the heat load varied from 200 MW to 600 MW, the minimum power load difference between the two systems increased from 28.00 MW to 100.18 MW. Technological-economic analysis conducted elucidates that the deployment of the novel system is projected to yield a substantial reduction in coal consumption by approximately 49.27 kilotons per heating season, resulting in an annual net revenue of 49.09 million CNY and a dynamic payback period of 4.59 years. The research could provide technical references for energy saving and flexibility optimization of cogeneration systems.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106413"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144254526","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 comprehensive life cycle cost model for high-temperature pipe insulation: balancing heat dissipation, temperature resistance and economic benefits","authors":"Da Huo,&nbsp;Jing Zhao,&nbsp;Zidong Zhao,&nbsp;Xin Zeng","doi":"10.1016/j.csite.2025.106492","DOIUrl":"10.1016/j.csite.2025.106492","url":null,"abstract":"<div><div>Efficient insulation technologies are essential for enhancing energy utilization and maximizing economic benefits. High-temperature pipelines typically use composite insulation, which combine high-temperature resistant materials with conventional insulation materials. Traditional design approaches often focus solely on economic factors, neglecting the temperature resistance requirements. This study applies the life cycle cost method to evaluate the optimal thickness, life cycle cost, energy saving cost, payback period, annual heat dissipation, and other performance indicators for single insulation using aluminum silicate wool (ASW) or aerogel blanket (AB), and composite insulation comprising ASW or AB as the inner layer and glass wool (GW) as the outer layer. Additionally, the study investigates how material temperature resistance, steam temperature, and pipe diameter affect these indicators. The results indicate that composite insulation offers better performance in terms of life cycle cost, energy saving cost, payback period, and heat dissipation compared to single insulation. However, composite insulation requires a greater thickness than of single insulation. Ignoring material temperature resistance leads to underestimation of life cycle costs. Among composite insulation, AB + GW performs better than ASW + GW across all indicators. Furthermore, increasing the temperature resistance of GW results in a higher proportion of GW in the composite insulation, reducing life cycle costs but increasing total thickness. As pipe diameter and steam temperature increase, the proportion of ASW in the ASW + GW increases. The optimal thickness of the AB + GW is influenced by the temperature resistance of GW and the distribution of life cycle cost.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106492"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289879","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":"Improvement in thermal phenomenon due to bioconvective transport of third-grade nanomaterial with variable viscosity and convective boundary constraints: Sustainable energy developments","authors":"Iskander Tlili ,&nbsp;Sohaib Z. Khan ,&nbsp;Abdulrahman Aljabri","doi":"10.1016/j.csite.2025.106483","DOIUrl":"10.1016/j.csite.2025.106483","url":null,"abstract":"<div><div>Novel attention has been devoted to renewable energy reservoirs in the current century. Thermal energy performance is significantly enhanced due to the interaction of nanoparticles. The motivated research indicates the applications of chemically reactive non-Newtonian nanofluid due to bioconvective phenomenon and radiated impact. The fundamentals of heat and mass transfer are analyzed considering the variable effects of viscosity and thermal conductivity. The convective thermal and mass constraints are utilized. A uniformly oscillated surface with a stretching phenomenon endorsed the flow. The governing problem is altered into a nonlinear partial differential system. The convergent approach is followed by simulations. The physical impact against variation of parameters is noticed. It is observed that variable considerations of viscosity and thermal conductivity contributes a beneficial impact for increment of thermal transport. The skin friction oscillates via a periodic approach, and the magnitude of oscillation is enhanced due to material parameters. The claimed results attain applications in the improvement of energy reservoirs and sustainable energy developments. The simulated observations reveal that heat transfer enhances due to third grade fluid parameter while declining effects are examined due to Reynolds number. The heat and mass transfer improves due to thermal Biot number and concentration Biot number, respectively. Moreover, the microorganisms profile enhanced with viscosity parameter.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106483"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144288890","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":"Effect of asymmetric diffuser deflector on even distribution of steam leaving blade section of steam turbine: comparative computational study","authors":"Marek Bobčík ,&nbsp;Jiří Pospíšil ,&nbsp;Jan Fiedler","doi":"10.1016/j.csite.2025.106490","DOIUrl":"10.1016/j.csite.2025.106490","url":null,"abstract":"<div><div>This study presents a computational analysis comparing two designs of steam turbine diffuser deflectors: a conventional axisymmetric design and an innovative asymmetric design. The computational comparison is carried out for a real turbine with a power output of 1.090 MW. Utilizing ANSYS CFX simulations based on the finite volume method, the innovative deflector demonstrates extending the steam expansion, which is directly related to the up to 5 % increase in the output power of the turbine last stage blades. The asymmetric steam turbine diffuser deflector geometry promotes a more uniform static pressure distribution and reduces flow separation and recirculation zones, leading to decreased pressure losses between the turbine's inner and outer casings.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106490"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144280559","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 study of building heating potential from deep-buried pipes under dynamic loads: A case study of Xi'an, China","authors":"Chao Jiang ,&nbsp;Chao Li ,&nbsp;Xiaogang Zhang ,&nbsp;Jinxing Ma ,&nbsp;Jiachen Wang ,&nbsp;Jiale Wu","doi":"10.1016/j.csite.2025.106482","DOIUrl":"10.1016/j.csite.2025.106482","url":null,"abstract":"<div><div>The utilization of geothermal energy through deep ground heat exchangers (DGHE) primarily serves building heating purposes, posing challenges in understanding the heat transfer characteristic of buried pipes under dynamic loads. Based on practical DGHE engineering in Xi'an, China, this study establishes a three-dimensional full-size numerical model coupling the inside and outside of the pipes. It examines the heat transfer properties of DGHE when subjected to varying dynamic thermal loads and investigates how they change with different dynamic load clipping rates. A novel assessment approach for determining the heating capacity of DGHE systems in buildings is introduced. The study demonstrates a direct correlation between the building heating area (<em>A</em>) and the minimum inlet water temperature (<em>T</em>_in-Min) during the DGHE heating phase. It identifies an optimal dynamic load peak-clipping rate of around 40 %. Once this rate is set, the heating potential of DGHE in specific geological conditions, ground temperatures, and pipe sizes can be forecasted using the relationship between <em>T</em>_in-Min and <em>A</em>. This research offers valuable insights for predicting the heating potential of DGHE, aiding in the scientific planning and execution of relevant engineering projects.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106482"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144243249","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":"Mitigation of flow instabilities in multiport minichannel thermosyphon through a modified loop design with separate vapor-liquid paths","authors":"Jaya Antony Perinba Selvin Raj ,&nbsp;Lazarus Godson Asirvatham ,&nbsp;Appadurai Anitha Angeline ,&nbsp;Bairi Levi Rakshith ,&nbsp;Jefferson Raja Bose ,&nbsp;Stephen Manova ,&nbsp;Vivek Vengatoor Mana ,&nbsp;Mostafa Safdari Shadloo ,&nbsp;Somchai Wongwises","doi":"10.1016/j.csite.2025.106495","DOIUrl":"10.1016/j.csite.2025.106495","url":null,"abstract":"<div><div>Multiport minichannel thermosyphons with hydraulic diameters below 1.2 mm often encounter severe flow instabilities and oscillations in vapor and condensate movement, which hinder effective phase change processes. These instabilities can cause partial and localized dry-out, resulting in higher operating temperatures and reduced thermal performance. To overcome these limitations, a novel multiport minichannel thermosyphon loop (MPMCTSL) is proposed. This design integrates a compensation chamber (CC) to ensure uniform fluid distribution across all channels and suppress instabilities near the evaporator. Additionally, the loop features separate flow paths for vapor and liquid to mitigate entrainment issues. The study experimentally investigates the thermal performance of MPMCTSL using acetone as the working fluid, considering fill ratios of 40 %, 50 %, and 60 %, inclination angles of 0°, 30°, 60°, and 90°, and varying heat loads from 10 to 80 W. Results demonstrate that 5 mm CC length delivers optimal performance by stabilizing condensate flow and ensuring continuous fluid replenishment to the evaporator. This results in minimum thermal resistance of 0.34 K/W and a peak vapor velocity of 4.36 m/s at 80 W heat load. Furthermore, the observed flow regime transition from churn to annular with increasing heat input confirms the improved stability and effectiveness of the MPMCTSL design.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"73 ","pages":"Article 106495"},"PeriodicalIF":6.4,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289880","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}