Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107589
Ali Keçebaş , Hongwei Wu , Mustafa Ertürk , C Ahamed Saleel
This study presents an innovative methodology for estimating building heating demand by incorporating the solar-air temperature concept into heating degree hour (HDH) and free heating degree hour (HDHfree) calculations. Unlike conventional methods that rely solely on ambient temperature, this approach integrates for solar radiation and radiative heat loss, providing a more accurate assessment of heating demand and free heating potential. The results indicate that lowering indoor setpoint temperatures to 18 °C can reduce annual heating demand by 25–40 %, while optimizing the heat transfer coefficient (ho = 1.8 W/m2K) results in an 82 % increase in HDHfree. This increase is attributed to a reduction in conductive heat losses through the building envelope, allowing solar gains to be retained for a longer period while maximizing passive heating effectiveness. Lower ho values also minimize radiative and convective heat losses, enabling the absorbed solar energy to remain within the building for an extended duration, ultimately enhancing free heating efficiency. The study also highlights the importance of material properties, with higher solar absorptivity (0.7) leading to a 40 % improvement in energy savings and lower surface emissivity (0.35) contributing to better heat retention. The methodology was validated using data from Muğla, Turkey, demonstrating significant energy cost savings and carbon footprint reductions, especially in electricity-based systems. Future research should focus on refining the solar-air temperature model by incorporating building-specific variables and expanding its application to different climates. This approach offers a valuable contribution to sustainable building design by optimizing passive heating and reducing reliance on mechanical systems.
{"title":"Optimizing building heating demand through solar-air temperature integration: A comprehensive analysis of free heating potential and energy savings","authors":"Ali Keçebaş , Hongwei Wu , Mustafa Ertürk , C Ahamed Saleel","doi":"10.1016/j.csite.2025.107589","DOIUrl":"10.1016/j.csite.2025.107589","url":null,"abstract":"<div><div>This study presents an innovative methodology for estimating building heating demand by incorporating the solar-air temperature concept into heating degree hour (HDH) and free heating degree hour (HDH<sub>free</sub>) calculations. Unlike conventional methods that rely solely on ambient temperature, this approach integrates for solar radiation and radiative heat loss, providing a more accurate assessment of heating demand and free heating potential. The results indicate that lowering indoor setpoint temperatures to 18 °C can reduce annual heating demand by 25–40 %, while optimizing the heat transfer coefficient (h<sub>o</sub> = 1.8 W/m<sup>2</sup>K) results in an 82 % increase in HDH<sub>free</sub>. This increase is attributed to a reduction in conductive heat losses through the building envelope, allowing solar gains to be retained for a longer period while maximizing passive heating effectiveness. Lower h<sub>o</sub> values also minimize radiative and convective heat losses, enabling the absorbed solar energy to remain within the building for an extended duration, ultimately enhancing free heating efficiency. The study also highlights the importance of material properties, with higher solar absorptivity (0.7) leading to a 40 % improvement in energy savings and lower surface emissivity (0.35) contributing to better heat retention. The methodology was validated using data from Muğla, Turkey, demonstrating significant energy cost savings and carbon footprint reductions, especially in electricity-based systems. Future research should focus on refining the solar-air temperature model by incorporating building-specific variables and expanding its application to different climates. This approach offers a valuable contribution to sustainable building design by optimizing passive heating and reducing reliance on mechanical systems.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107589"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145822873","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}
Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107586
Juan Cheng , Chengyang Cao , Chong Xia , Guangyao Zheng , Chuan Zhang , Hongyun Hu
Nitrobenzene (NB), as a critical chemical intermediate with annual consumption exceeding one million tons, is widely used in the chemical manufacturing industry. However, its poor thermal stability when contaminated with impurities has caused multiple fire and explosion incidents. This study aims to investigate the effects of two typical phenols, p-nitrophenol (PNP) and o-nitrophenol (ONP), on the thermal behaviors of NB, and elucidate the impact mechanism. Experimental results indicate that the addition of 10 % wt. PNP or ONP significantly reduces the main decomposition peak temperature of NB, initiating low-temperature exothermic reactions. Kinetic analysis reveals that while these additives increase the activation energy, the dramatic rise in pre-exponential factor indicates fundamental changes in the decomposition pathway. Specifically, NB-ONP exhibits the highest apparent activation energy due to intramolecular hydrogen bonding. Cleavage of these hydrogen bonds generates highly reactive phenoxy radicals that drive an efficient nitro-reduction pathway, leading to the most pronounced thermal hazard. Pure NB decomposition follows a second-order reaction model (F2), while mixtures with PNP or ONP conform to nucleation-growth (A3) and first-order (F1) models, respectively. Product analysis confirms that phenolic impurities reconstruct the reaction network through more complex pathways. Consequently, the thermal hazard risk follows NB-ONP > NB-PNP > NB. These findings provide crucial guidance for NB production: priority should be given to controlling high-risk ONP impurity generation by optimizing nitration process conditions to suppress relevant side reactions. The study clarifies the microscopic mechanism and provides important theoretical basis for targeted impurity management and safe NB production.
{"title":"Thermal hazard risk and decomposition mechanism identification of nitrobenzene with mononitrophenol impurities: Combined kinetic and products analysis","authors":"Juan Cheng , Chengyang Cao , Chong Xia , Guangyao Zheng , Chuan Zhang , Hongyun Hu","doi":"10.1016/j.csite.2025.107586","DOIUrl":"10.1016/j.csite.2025.107586","url":null,"abstract":"<div><div>Nitrobenzene (NB), as a critical chemical intermediate with annual consumption exceeding one million tons, is widely used in the chemical manufacturing industry. However, its poor thermal stability when contaminated with impurities has caused multiple fire and explosion incidents. This study aims to investigate the effects of two typical phenols, p-nitrophenol (PNP) and o-nitrophenol (ONP), on the thermal behaviors of NB, and elucidate the impact mechanism. Experimental results indicate that the addition of 10 % wt. PNP or ONP significantly reduces the main decomposition peak temperature of NB, initiating low-temperature exothermic reactions. Kinetic analysis reveals that while these additives increase the activation energy, the dramatic rise in pre-exponential factor indicates fundamental changes in the decomposition pathway. Specifically, NB-ONP exhibits the highest apparent activation energy due to intramolecular hydrogen bonding. Cleavage of these hydrogen bonds generates highly reactive phenoxy radicals that drive an efficient nitro-reduction pathway, leading to the most pronounced thermal hazard. Pure NB decomposition follows a second-order reaction model (F2), while mixtures with PNP or ONP conform to nucleation-growth (A3) and first-order (F1) models, respectively. Product analysis confirms that phenolic impurities reconstruct the reaction network through more complex pathways. Consequently, the thermal hazard risk follows NB-ONP > NB-PNP > NB. These findings provide crucial guidance for NB production: priority should be given to controlling high-risk ONP impurity generation by optimizing nitration process conditions to suppress relevant side reactions. The study clarifies the microscopic mechanism and provides important theoretical basis for targeted impurity management and safe NB production.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107586"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145823731","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}
Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107608
Jinhui Kang , Feilong Song , Xin Chen , Yun Wu , Dengcheng Zhang , Xiaopeng Sun , Jiaojiao Wang , Zhao Yang
<div><div>The intake blockage of the rotating detonation combustor (RDC) results from the interaction between the high-pressure detonation wave and the intake air of the combustor, which affects the working stability and performance parameters of the combustor. Based on this research background, a series of experiments were conducted under different flow rates and nozzle structures. A method for calculating the intake blockage based on the throat pressure of the combustor was proposed. The intake characteristics of the combustor under three intake states were analyzed, and the discrimination criteria for different intake states of the combustor were proposed. The proportion of intake blockage of the combustor was fitted by the dimensionless discrimination parameters. After correction by the fitting function, the proportion of intake blockage of the combustor was predicted with high accuracy (<span><math><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.98</mn></mrow></math></span>). The propagation mode and stability of the detonation wave under different working conditions were analyzed, and the relationship between the proportion of intake blockage and the propagation characteristics of the detonation wave was explored. It was found that when the proportion of intake blockage was zero, the detonation wave propagated in a single wave mode. With the decrease in throat flow capacity and the increase in intake blockage ratio, unstable modes begin to occur, accompanied by reduced stability in detonation wave propagation. When the throat was in fully subsonic flow, the intake filling speed of the combustor decreased significantly, and the longitudinal pulsed detonation mode were easily induced. The relationship between the intensity of the pressure feedback and the upstream chamber pressure rise ratio and the intake blockage was analyzed, and the relevant relationships were fitted for the construction of the prediction model. The research results show that with the increase of the proportion of intake blockage, the intensity of the pressure feedback and the upstream chamber pressure rise ratio both increase. The intensity of the pressure feedback is affected by many factors and is simultaneously influenced by the detonation wave intensity and the throat flow state, so its fitting accuracy is relatively low (<span><math><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.855</mn></mrow></math></span>). However, the upstream chamber pressure rise is mainly induced by the intake blockage, so a higher fitting accuracy can be achieved (<span><math><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.98</mn></mrow></math></span>). However, due to the additional aerodynamic losses caused by the feedback shock wave, the predicted results are lower than the experimental measurement values. In summary, this research work clarifies the relationship between the intake blockage of the rotating detonation combustor and the working characteristics of the
{"title":"Characterization and predictive modeling of intake blockage in rotating detonation combustor","authors":"Jinhui Kang , Feilong Song , Xin Chen , Yun Wu , Dengcheng Zhang , Xiaopeng Sun , Jiaojiao Wang , Zhao Yang","doi":"10.1016/j.csite.2025.107608","DOIUrl":"10.1016/j.csite.2025.107608","url":null,"abstract":"<div><div>The intake blockage of the rotating detonation combustor (RDC) results from the interaction between the high-pressure detonation wave and the intake air of the combustor, which affects the working stability and performance parameters of the combustor. Based on this research background, a series of experiments were conducted under different flow rates and nozzle structures. A method for calculating the intake blockage based on the throat pressure of the combustor was proposed. The intake characteristics of the combustor under three intake states were analyzed, and the discrimination criteria for different intake states of the combustor were proposed. The proportion of intake blockage of the combustor was fitted by the dimensionless discrimination parameters. After correction by the fitting function, the proportion of intake blockage of the combustor was predicted with high accuracy (<span><math><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.98</mn></mrow></math></span>). The propagation mode and stability of the detonation wave under different working conditions were analyzed, and the relationship between the proportion of intake blockage and the propagation characteristics of the detonation wave was explored. It was found that when the proportion of intake blockage was zero, the detonation wave propagated in a single wave mode. With the decrease in throat flow capacity and the increase in intake blockage ratio, unstable modes begin to occur, accompanied by reduced stability in detonation wave propagation. When the throat was in fully subsonic flow, the intake filling speed of the combustor decreased significantly, and the longitudinal pulsed detonation mode were easily induced. The relationship between the intensity of the pressure feedback and the upstream chamber pressure rise ratio and the intake blockage was analyzed, and the relevant relationships were fitted for the construction of the prediction model. The research results show that with the increase of the proportion of intake blockage, the intensity of the pressure feedback and the upstream chamber pressure rise ratio both increase. The intensity of the pressure feedback is affected by many factors and is simultaneously influenced by the detonation wave intensity and the throat flow state, so its fitting accuracy is relatively low (<span><math><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.855</mn></mrow></math></span>). However, the upstream chamber pressure rise is mainly induced by the intake blockage, so a higher fitting accuracy can be achieved (<span><math><mrow><msup><mi>R</mi><mn>2</mn></msup><mo>=</mo><mn>0.98</mn></mrow></math></span>). However, due to the additional aerodynamic losses caused by the feedback shock wave, the predicted results are lower than the experimental measurement values. In summary, this research work clarifies the relationship between the intake blockage of the rotating detonation combustor and the working characteristics of the ","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107608"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145844937","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}
Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107558
Zhan Wang , Zekuan Liu , Jiang Qin
Solid-liquid phase change processes are recognized as highly potential solutions for thermal energy storage, thermal management and temperature control for significant latent heat capacity and precise temperature regulation capabilities. Nonetheless, the poor thermal conductivity acts as a bottleneck to advancing heat transfer efficiency. Herein, triply periodic minimal surface (TPMS) were employed as thermal conductivity enhancers, and numerical investigates were conducted for the composite phase change materials (CPCMs) with uniform and gradient TPMS structures. Findings suggest that the W-type structure demonstrates significant advantages in liquid fraction distribution, complete melting time, and thermal wall temperature regulation for their high specific surface area and smooth heat transfer pathways. CPCMs with porosity increasing from bottom to top significantly shorten the phase change time but worsen the uniformity of wall temperature distribution. Conversely, CPCMs characterized by a reduction in porosity along the vertical direction from the base to the top exhibit higher thermal resistance and slower phase change rates, while gradient pore density exerts a weaker influence compared to gradient porosity. Furthermore, a dual-gradient porosity structure is further proposed, reducing the complete melting time by 3.69 % compared with the uniform case. More importantly, it markedly improves hot-wall thermal uniformity, lowering temperature inhomogeneity by 47.74 %. This demonstrates that the dual-gradient design can simultaneously accelerate melting and suppress thermal non-uniformity, highlighting its comprehensive performance advantages.
{"title":"Modulation of phase change heat transfer performance in triply periodic minimal surface based porous structures","authors":"Zhan Wang , Zekuan Liu , Jiang Qin","doi":"10.1016/j.csite.2025.107558","DOIUrl":"10.1016/j.csite.2025.107558","url":null,"abstract":"<div><div>Solid-liquid phase change processes are recognized as highly potential solutions for thermal energy storage, thermal management and temperature control for significant latent heat capacity and precise temperature regulation capabilities. Nonetheless, the poor thermal conductivity acts as a bottleneck to advancing heat transfer efficiency. Herein, triply periodic minimal surface (TPMS) were employed as thermal conductivity enhancers, and numerical investigates were conducted for the composite phase change materials (CPCMs) with uniform and gradient TPMS structures. Findings suggest that the W-type structure demonstrates significant advantages in liquid fraction distribution, complete melting time, and thermal wall temperature regulation for their high specific surface area and smooth heat transfer pathways. CPCMs with porosity increasing from bottom to top significantly shorten the phase change time but worsen the uniformity of wall temperature distribution. Conversely, CPCMs characterized by a reduction in porosity along the vertical direction from the base to the top exhibit higher thermal resistance and slower phase change rates, while gradient pore density exerts a weaker influence compared to gradient porosity. Furthermore, a dual-gradient porosity structure is further proposed, reducing the complete melting time by 3.69 % compared with the uniform case. More importantly, it markedly improves hot-wall thermal uniformity, lowering temperature inhomogeneity by 47.74 %. This demonstrates that the dual-gradient design can simultaneously accelerate melting and suppress thermal non-uniformity, highlighting its comprehensive performance advantages.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107558"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784659","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}
Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107557
Xingchen Liu , Feng Huang , Yang Hu , Aichen Zheng , Dong Yang
Thermal damage induces changes in the mechanical properties of rock, making it crucial to clarify the thermal damage characteristics of rock and describe the thermo-mechanical coupling behavior of thermally damaged rock. Limestone samples were heat-treated at 100–600 °C, followed by triaxial compression tests on the thermally damaged samples. Scanning electron microscopy (SEM) was used to observe their microscopic thermal damage characteristics. Based on the micro-element concept, a pore compaction coefficient was defined. Integrating the Hooke-Brown strength criterion and the micro-element cumulative damage parameter, a Weibull distribution-based thermo-mechanical coupling statistical damage constitutive model for limestone was established. The coefficient of determination (R2) between the model-calculated results and the experimental stress-strain curves reached 0.98. Microscopically, high-temperature-induced rock damage is characterized by crack propagation and pore erosion. As temperature increases, the elastic modulus decreases nonlinearly, while the peak compressive strength first increases and then decreases. Under compressive loading, the total pore closure strain increases with the heat-treatment temperature. The proposed constitutive model effectively captures the nonlinear deformation characteristics during the initial compaction stage.
{"title":"Investigation of the mechanical characteristics of limestone after high-temperature treatment and the T-M coupling constitutive model based on statistical damage","authors":"Xingchen Liu , Feng Huang , Yang Hu , Aichen Zheng , Dong Yang","doi":"10.1016/j.csite.2025.107557","DOIUrl":"10.1016/j.csite.2025.107557","url":null,"abstract":"<div><div>Thermal damage induces changes in the mechanical properties of rock, making it crucial to clarify the thermal damage characteristics of rock and describe the thermo-mechanical coupling behavior of thermally damaged rock. Limestone samples were heat-treated at 100–600 °C, followed by triaxial compression tests on the thermally damaged samples. Scanning electron microscopy (SEM) was used to observe their microscopic thermal damage characteristics. Based on the micro-element concept, a pore compaction coefficient was defined. Integrating the Hooke-Brown strength criterion and the micro-element cumulative damage parameter, a Weibull distribution-based thermo-mechanical coupling statistical damage constitutive model for limestone was established. The coefficient of determination (R<sup>2</sup>) between the model-calculated results and the experimental stress-strain curves reached 0.98. Microscopically, high-temperature-induced rock damage is characterized by crack propagation and pore erosion. As temperature increases, the elastic modulus decreases nonlinearly, while the peak compressive strength first increases and then decreases. Under compressive loading, the total pore closure strain increases with the heat-treatment temperature. The proposed constitutive model effectively captures the nonlinear deformation characteristics during the initial compaction stage.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107557"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784660","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}
Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107571
Do Hyun Lee , Cheolhee Lee , Chan Ho Chu , Sihyung Park , Seungho Ryu , Jae Hyun Park , Minsung Kim , Dong Kyu Kim
This study investigates the integration of cryogenic exergy of liquid hydrogen into data center power saving and cooling using an organic Rankine cycle (ORC). In the proposed system, the cryogenic exergy is first utilized for supplementary power generation and then for supplying low-temperature cooling, resulting in improved overall energy efficiency. Parametric analyses were conducted to evaluate the effects of hydrogen supply conditions on overall system performance. As the inlet temperature of liquid hydrogen decreased to 20 K, both the net power output and cooling capacity increased, reducing the power usage effectiveness (PUE) to 1.30. Increasing the mass flow rate of liquid hydrogen further improved the total energy efficiency to 69.2 % and decreased the PUE to 1.14. Working fluid optimization using particle swarm optimization (PSO) demonstrated that R170 and R1270 achieved the best performance with a total energy efficiency of approximately 70 % and a PUE of 1.1. Under the optimized conditions, 1.7 MW of cryogenic exergy can be recovered by integrating ORC and cooling loops, improving data center PUE by up to 36 % and recovering approximately 10 % of available exergy. These results suggest a promising pathway for reducing the electrical burden and advancing the sustainable development of both digital and hydrogen infrastructures.
{"title":"Integration of cryogenic exergy from liquid hydrogen into data center operation using an organic Rankine cycle","authors":"Do Hyun Lee , Cheolhee Lee , Chan Ho Chu , Sihyung Park , Seungho Ryu , Jae Hyun Park , Minsung Kim , Dong Kyu Kim","doi":"10.1016/j.csite.2025.107571","DOIUrl":"10.1016/j.csite.2025.107571","url":null,"abstract":"<div><div>This study investigates the integration of cryogenic exergy of liquid hydrogen into data center power saving and cooling using an organic Rankine cycle (ORC). In the proposed system, the cryogenic exergy is first utilized for supplementary power generation and then for supplying low-temperature cooling, resulting in improved overall energy efficiency. Parametric analyses were conducted to evaluate the effects of hydrogen supply conditions on overall system performance. As the inlet temperature of liquid hydrogen decreased to 20 K, both the net power output and cooling capacity increased, reducing the power usage effectiveness (PUE) to 1.30. Increasing the mass flow rate of liquid hydrogen further improved the total energy efficiency to 69.2 % and decreased the PUE to 1.14. Working fluid optimization using particle swarm optimization (PSO) demonstrated that R170 and R1270 achieved the best performance with a total energy efficiency of approximately 70 % and a PUE of 1.1. Under the optimized conditions, 1.7 MW of cryogenic exergy can be recovered by integrating ORC and cooling loops, improving data center PUE by up to 36 % and recovering approximately 10 % of available exergy. These results suggest a promising pathway for reducing the electrical burden and advancing the sustainable development of both digital and hydrogen infrastructures.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107571"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784671","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}
Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107513
N. Vishnu Ganesh , Qasem M. Al-Mdallal , G. Hirankumar , Ali J. Chamkha
Enhancing natural convection with finned surfaces is essential yet challenging for effective thermal management in electronic devices, industrial cooling units, and heat-dissipation systems. This study investigates the thermal performance of four heated fin configurations—Bottom-Multi-Fin, Top-Multi-Fin, Left-Multi-Fin, and Right-Multi-Fin—placed inside a square enclosure filled with an incompressible viscous fluid, a set of configurations not previously examined in a unified framework. The walls opposite the heated fins are maintained at a cold temperature, while the adjacent walls are insulated, representing practical passive cooling conditions. The non-dimensional governing equations are solved using the Galerkin finite element method to assess the influence of the Rayleigh number number () on flow structure, temperature distribution, and both local and average Nusselt numbers. Results show that the Bottom-Multi-Fin and Top-Multi-Fin configurations are conduction dominated and provide minimal enhancement in natural convection, even at high Rayleigh numbers. In contrast, the Left-Multi-Fin and Right-Multi-Fin configurations generate stronger buoyancy-driven circulation and significantly improve heat transfer. The Right-Multi-Fin arrangement delivers the highest cooling performance at elevated Rayleigh numbers, making it the most efficient orientation for natural convection applications.
{"title":"Effectiveness of multi-fin array orientations on convective heat transfer in viscous fluid-filled square enclosures","authors":"N. Vishnu Ganesh , Qasem M. Al-Mdallal , G. Hirankumar , Ali J. Chamkha","doi":"10.1016/j.csite.2025.107513","DOIUrl":"10.1016/j.csite.2025.107513","url":null,"abstract":"<div><div>Enhancing natural convection with finned surfaces is essential yet challenging for effective thermal management in electronic devices, industrial cooling units, and heat-dissipation systems. This study investigates the thermal performance of four heated fin configurations—Bottom-Multi-Fin, Top-Multi-Fin, Left-Multi-Fin, and Right-Multi-Fin—placed inside a square enclosure filled with an incompressible viscous fluid, a set of configurations not previously examined in a unified framework. The walls opposite the heated fins are maintained at a cold temperature, while the adjacent walls are insulated, representing practical passive cooling conditions. The non-dimensional governing equations are solved using the Galerkin finite element method to assess the influence of the Rayleigh number number (<span><math><mrow><msup><mn>10</mn><mn>3</mn></msup><mo>≤</mo><mi>R</mi><mi>a</mi><mo>≤</mo><mn>6</mn><mo>×</mo><msup><mn>10</mn><mn>5</mn></msup></mrow></math></span>) on flow structure, temperature distribution, and both local and average Nusselt numbers. Results show that the Bottom-Multi-Fin and Top-Multi-Fin configurations are conduction dominated and provide minimal enhancement in natural convection, even at high Rayleigh numbers. In contrast, the Left-Multi-Fin and Right-Multi-Fin configurations generate stronger buoyancy-driven circulation and significantly improve heat transfer. The Right-Multi-Fin arrangement delivers the highest cooling performance at elevated Rayleigh numbers, making it the most efficient orientation for natural convection applications.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107513"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784675","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}
Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107565
Zhong-Feng Duan , Fang-Yu Dong , Jia-Hui Zhai , Fu-Lai Li , Hao Chen , Bin Ding
Pyroelectric dye decomposition is a potential technology to convert low-grade waste heat into oxidation charges for the removal of pollutants in wastewaters. Herein, a tubular heat exchanger was utilized to transfer the heat energy from hot water to the dye wastewater with suspended pyroelectric particles for dye decomposition. A CFD model integrated pyroelectric kinetics was firstly established to simulate the heat transfer and dye degradation of dye wastewaters. The effects of the flow rate of the dye wastewater qv,c (0.5–16 L/h), the flow rate of hot water qv,h (1–16 L/h), and the inlet temperature of the hot water Tin,h (35–80 °C) on the heat recovery Q and the dye degradation rate R of the tubular heat exchanger have been investigated. Moreover, the mass of indigo carmine (IC) degradation per heat transfer power ηwQ has been investigated to analyze the energy efficiency of the pyroelectric dye degradation process. Comprehensive consideration the dye removal η, the depth of heat recovery of the hot water ηT, and the heat recovery Q, the optimal R of IC solution (2.93 g h−1) was appeared at the qv,h of 4 L/h and the qv,c of 8 L/h, while the ηT was 74.4 % at the Tin,h of 80 °C.
{"title":"Modeling of suspended pyroelectric particles in wastewater for dye decomposition driven by low-grade waste heat in tubular heat exchanger","authors":"Zhong-Feng Duan , Fang-Yu Dong , Jia-Hui Zhai , Fu-Lai Li , Hao Chen , Bin Ding","doi":"10.1016/j.csite.2025.107565","DOIUrl":"10.1016/j.csite.2025.107565","url":null,"abstract":"<div><div>Pyroelectric dye decomposition is a potential technology to convert low-grade waste heat into oxidation charges for the removal of pollutants in wastewaters. Herein, a tubular heat exchanger was utilized to transfer the heat energy from hot water to the dye wastewater with suspended pyroelectric particles for dye decomposition. A CFD model integrated pyroelectric kinetics was firstly established to simulate the heat transfer and dye degradation of dye wastewaters. The effects of the flow rate of the dye wastewater <em>q</em><sub><em>v,c</em></sub> (0.5–16 L/h), the flow rate of hot water <em>q</em><sub><em>v,h</em></sub> (1–16 L/h), and the inlet temperature of the hot water <em>T</em><sub><em>in,h</em></sub> (35–80 °C) on the heat recovery <em>Q</em> and the dye degradation rate <em>R</em> of the tubular heat exchanger have been investigated. Moreover, the mass of indigo carmine (IC) degradation per heat transfer power <em>η</em><sub><em>wQ</em></sub> has been investigated to analyze the energy efficiency of the pyroelectric dye degradation process. Comprehensive consideration the dye removal <em>η</em>, the depth of heat recovery of the hot water <em>η</em><sub><em>T</em></sub>, and the heat recovery <em>Q</em>, the optimal <em>R</em> of IC solution (2.93 g h<sup>−1</sup>) was appeared at the <em>q</em><sub><em>v,h</em></sub> of 4 L/h and the <em>q</em><sub><em>v,c</em></sub> of 8 L/h, while the <em>η</em><sub><em>T</em></sub> was 74.4 % at the <em>T</em><sub><em>in,h</em></sub> of 80 °C.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107565"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145822876","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}
Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107578
Suifan Chen , Hanwei Wang , Qipeng Li , Zihao Song
Optimizing control strategies is crucial for improving the performance of vehicle air-conditioning (AC). To address limitations of thermal comfort variations accuracy across different regions in the mathematical parameter model system, the study introduced a validated 3D model of the heat load in the cabin and coupled it with vehicle AC to generate accurate driver predicted mean vote (PMV) values. Comprehensive AC parametric analysis establishes design rules for a multi-stage collaborative control strategy of compressor speed and evaporator blower airflow (MCS-EBA). The strategy parameters were then optimized based on a genetic algorithm (GA). In this process, a high-precision PMV prediction model was used to circumvent lengthy CFD simulations in the coupling model. The predictive model employed a recurrent neural network (RNN) to learn 60 datasets, which were derived from the mapping relationship between the thermal environment parameters of the cabin and the PMV of the driver under different cooling scenarios in the coupled model. Results demonstrate that the optimized MCS-EBA saves energy consumption by 43.7 %, 5.8 %, and 5.0 % and reduces RMSE (vs. PMV = 0) by 84.7 %, 21.4 %, and 73.1 %, compared to the ON/OFF, PID, and MCCS, respectively. The technical approach of this strategy holds significant engineering application value.
{"title":"Application of machine learning-based thermal comfort model to optimize vehicle air-conditioning control strategies","authors":"Suifan Chen , Hanwei Wang , Qipeng Li , Zihao Song","doi":"10.1016/j.csite.2025.107578","DOIUrl":"10.1016/j.csite.2025.107578","url":null,"abstract":"<div><div>Optimizing control strategies is crucial for improving the performance of vehicle air-conditioning (AC). To address limitations of thermal comfort variations accuracy across different regions in the mathematical parameter model system, the study introduced a validated 3D model of the heat load in the cabin and coupled it with vehicle AC to generate accurate driver predicted mean vote (PMV) values. Comprehensive AC parametric analysis establishes design rules for a multi-stage collaborative control strategy of compressor speed and evaporator blower airflow (MCS-EBA). The strategy parameters were then optimized based on a genetic algorithm (GA). In this process, a high-precision PMV prediction model was used to circumvent lengthy CFD simulations in the coupling model. The predictive model employed a recurrent neural network (RNN) to learn 60 datasets, which were derived from the mapping relationship between the thermal environment parameters of the cabin and the PMV of the driver under different cooling scenarios in the coupled model. Results demonstrate that the optimized MCS-EBA saves energy consumption by 43.7 %, 5.8 %, and 5.0 % and reduces RMSE (vs. PMV = 0) by 84.7 %, 21.4 %, and 73.1 %, compared to the ON/OFF, PID, and MCCS, respectively. The technical approach of this strategy holds significant engineering application value.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107578"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145822878","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}
Pub Date : 2026-01-01DOI: 10.1016/j.csite.2025.107582
Amin Hadidi
The thermodynamic optimization of Stirling engines has gained increasing attention due to their potential for high-efficiency, clean energy conversion. This study develops a constraint-satisfied single- and multi-objective optimization framework to maximize engine efficiency and work output while minimizing internal irreversibilities. Unlike previous studies, which often overlooked essential design constraints or used unrealistic parameter ranges, the proposed approach incorporates internal irreversibilities, dead volume ratios, regenerator effectiveness, and operating parameters to ensure practical and feasible design solutions. The methodology combines thermodynamic modeling with parametric and sensitivity analyses to evaluate the effects of key design variables, including minimum and maximum cycle temperatures, expansion and compression volumes, total and component dead volumes, regenerator effectiveness, and working fluid pressure. Results show that optimizing these parameters leads to a thermal efficiency of 42.93 %, net work output of 836.85 J, and an irreversibility parameter Rs of 0.69, representing improvements of up to 138.5 %, 32 %, and 3 %, respectively, compared to previous studies. Maximizing expansion and compression volumes, minimizing dead volumes, and increasing regenerator effectiveness are the most effective strategies for performance enhancement. Multi-objective optimization confirms that a balanced design yields significant improvements across all performance metrics. The proposed framework provides both methodological innovation and practical design guidelines for high-performance, energy-efficient Stirling engines, offering reliable recommendations for real-world clean energy applications.
{"title":"Enhanced design of Stirling engines via multi-objective optimization: Effects of dead volumes, regenerator effectiveness, and operating parameters","authors":"Amin Hadidi","doi":"10.1016/j.csite.2025.107582","DOIUrl":"10.1016/j.csite.2025.107582","url":null,"abstract":"<div><div>The thermodynamic optimization of Stirling engines has gained increasing attention due to their potential for high-efficiency, clean energy conversion. This study develops a constraint-satisfied single- and multi-objective optimization framework to maximize engine efficiency and work output while minimizing internal irreversibilities. Unlike previous studies, which often overlooked essential design constraints or used unrealistic parameter ranges, the proposed approach incorporates internal irreversibilities, dead volume ratios, regenerator effectiveness, and operating parameters to ensure practical and feasible design solutions. The methodology combines thermodynamic modeling with parametric and sensitivity analyses to evaluate the effects of key design variables, including minimum and maximum cycle temperatures, expansion and compression volumes, total and component dead volumes, regenerator effectiveness, and working fluid pressure. Results show that optimizing these parameters leads to a thermal efficiency of 42.93 %, net work output of 836.85 J, and an irreversibility parameter Rs of 0.69, representing improvements of up to 138.5 %, 32 %, and 3 %, respectively, compared to previous studies. Maximizing expansion and compression volumes, minimizing dead volumes, and increasing regenerator effectiveness are the most effective strategies for performance enhancement. Multi-objective optimization confirms that a balanced design yields significant improvements across all performance metrics. The proposed framework provides both methodological innovation and practical design guidelines for high-performance, energy-efficient Stirling engines, offering reliable recommendations for real-world clean energy applications.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107582"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813771","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}
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