Pub Date : 2025-02-01DOI: 10.1016/j.csite.2024.105734
Xuetao Xi , Huijun Feng , Lingen Chen , Yanlin Ge
Combining constructal theory with entropy-generation-minimization theory, a model of a stacked chip with tree-shaped high-thermal-conductivity channels (TSHTCC) is established, and its performance are optimized with minimizing non-dimensional maximum temperature-difference (MTD) and non-dimensional entropy-generation-rate (EGR), respectively. Effects of length ratio of first order channel to elemental channel, length and width of first order channel, heat-generation-rate per volume, temperature of heat sink and thermal-conductivity of TSHTCC on its MTD and EGR are analyzed. The results show that optimal construct of TSHTCC obtained with minimum EGR objective stretches slightly towards the center than that with minimum MTD objective. When thickness is 28 μm and width of second order channel is 1500 μm, non-dimensional MTD reaches its minimum at value of 0.824, and is reduced by 17.6 % compared to initial design. When thickness is 29 μm and width of second order channel is 1500 μm, non-dimensional EGR reaches its minimum at value of 0.759, and is reduced by 24.1 % compared to initial design. Non-dimensional MTD and non-dimensional EGR are reduced by 67.9 % and 83.5 %, respectively, compared to those of a model without TSHTCC. Therefore, heat dissipation performances of stacked chip are increased.
{"title":"A tree-shaped high thermal conductivity channel in a stacked chip with minimizing maximum temperature difference and entropy generation rate","authors":"Xuetao Xi , Huijun Feng , Lingen Chen , Yanlin Ge","doi":"10.1016/j.csite.2024.105734","DOIUrl":"10.1016/j.csite.2024.105734","url":null,"abstract":"<div><div>Combining constructal theory with entropy-generation-minimization theory, a model of a stacked chip with tree-shaped high-thermal-conductivity channels (TSHTCC) is established, and its performance are optimized with minimizing non-dimensional maximum temperature-difference (MTD) and non-dimensional entropy-generation-rate (EGR), respectively. Effects of length ratio of first order channel to elemental channel, length and width of first order channel, heat-generation-rate per volume, temperature of heat sink and thermal-conductivity of TSHTCC on its MTD and EGR are analyzed. The results show that optimal construct of TSHTCC obtained with minimum EGR objective stretches slightly towards the center than that with minimum MTD objective. When thickness is 28 μm and width of second order channel is 1500 μm, non-dimensional MTD reaches its minimum at value of 0.824, and is reduced by 17.6 % compared to initial design. When thickness is 29 μm and width of second order channel is 1500 μm, non-dimensional EGR reaches its minimum at value of 0.759, and is reduced by 24.1 % compared to initial design. Non-dimensional MTD and non-dimensional EGR are reduced by 67.9 % and 83.5 %, respectively, compared to those of a model without TSHTCC. Therefore, heat dissipation performances of stacked chip are increased.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 ","pages":"Article 105734"},"PeriodicalIF":6.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.csite.2025.105757
Athraa Hameed Turki , Ali Khaleel Kareem , Ali M. Mohsen
This study investigated the thermal performance enhancement in a cubic shell heat exchanger (CSHE) equipped with rotating tubes and utilizing nanofluids under turbulent flow conditions. Water based nanofluids using Al₂O₃, SiO₂, ZnO, and CuO nanoparticles (diameters from 20 nm to 80 nm) were utilized under turbulent flow with concentrations ranging from 0 % to 2 %. The numerical simulations were carried out using the Reynolds-averaged Navier-Stokes (RANS) solver and the realizable k-ε turbulence model. It is shown a highest increase in Nusselt number of 15 % was achieved when using a 20 nm SiO₂ nanoparticles suspended in water compared to pure water. Further improvement in Nusselt number by up to 10 % was observed by increasing the nanoparticles volume fraction to 2 %. For Reynold’s numbers between 15000 and 30000, a 20 % improvement in the heat transfer was obtained due to increased turbulence. Surprisingly, the rotating inner tube introduced minimal effect compared to stationary configuration, with stationary tube slightly outperforming the rotating ones in most cases. The data suggests that significant enhancement in heat exchanger performance can be achieved by optimizing nanofluids properties and Reynold’s numbers, while tube rotations provided no additional benefits to the efficiency of the facility.
{"title":"Heat transfer in a 3D cubic shell heat exchanger with rotating tubes and turbulent flow","authors":"Athraa Hameed Turki , Ali Khaleel Kareem , Ali M. Mohsen","doi":"10.1016/j.csite.2025.105757","DOIUrl":"10.1016/j.csite.2025.105757","url":null,"abstract":"<div><div>This study investigated the thermal performance enhancement in a cubic shell heat exchanger (CSHE) equipped with rotating tubes and utilizing nanofluids under turbulent flow conditions. Water based nanofluids using Al₂O₃, SiO₂, ZnO, and CuO nanoparticles (diameters from 20 nm to 80 nm) were utilized under turbulent flow with concentrations ranging from 0 % to 2 %. The numerical simulations were carried out using the Reynolds-averaged Navier-Stokes (RANS) solver and the realizable k-ε turbulence model. It is shown a highest increase in Nusselt number of 15 % was achieved when using a 20 nm SiO₂ nanoparticles suspended in water compared to pure water. Further improvement in Nusselt number by up to 10 % was observed by increasing the nanoparticles volume fraction to 2 %. For Reynold’s numbers between 15000 and 30000, a 20 % improvement in the heat transfer was obtained due to increased turbulence. Surprisingly, the rotating inner tube introduced minimal effect compared to stationary configuration, with stationary tube slightly outperforming the rotating ones in most cases. The data suggests that significant enhancement in heat exchanger performance can be achieved by optimizing nanofluids properties and Reynold’s numbers, while tube rotations provided no additional benefits to the efficiency of the facility.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 ","pages":"Article 105757"},"PeriodicalIF":6.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.csite.2024.105668
Biao Yang , Baowei Song , Cheng Cheng , Youpeng Zhao , Haiqin Yang , Yuchen Li , Zhongyi He
To address the issues of uneven temperature distribution and the difficulty of temperature control in microwave heating, a composite leader cluster consensus decision optimization strategy for multiple microwave source agents is proposed. This strategy aims to optimize the temperature field distribution and improve heating control accuracy. First, a distributed control framework for joint heating was established. Second, within this structure, multiple leader systems within the composite leader system were used for decision-making. Consensus decisions between multiple leader decision points were made through a weight allocation algorithm, achieving a dynamic balance between temperature control and temperature field optimization. Then, on the basis of the composite leader decision information, the feeding power of the microwave source cluster was coordinated via a consensus algorithm, achieving dynamic coordination and complementarity between the leader cluster and the follower cluster. Finally, the simulation results revealed that after adopting this strategy, the temperature control error rate ranged from 0.25% to 1.43%. Compared with a single leader decision system, the composite leader decision system improved the uniformity in the horizontal and vertical sections by 1% to 37% and 3.5% to 26.5%, respectively. Compared with traditional microwave heating methods, the uniformity in the horizontal and vertical sections was improved by 25.3% to 61.2% and 24.2% to 66.6%, respectively. These results verify that the proposed consistency heating strategy under composite leader consensus decision-making is feasible and efficient, achieving precise temperature control and optimization of the temperature field.
{"title":"The optimization of consensus decision-making for a multi-microwave source system based on composite leader-follower clustering for intelligent agent-based joint heating temperature field","authors":"Biao Yang , Baowei Song , Cheng Cheng , Youpeng Zhao , Haiqin Yang , Yuchen Li , Zhongyi He","doi":"10.1016/j.csite.2024.105668","DOIUrl":"10.1016/j.csite.2024.105668","url":null,"abstract":"<div><div>To address the issues of uneven temperature distribution and the difficulty of temperature control in microwave heating, a composite leader cluster consensus decision optimization strategy for multiple microwave source agents is proposed. This strategy aims to optimize the temperature field distribution and improve heating control accuracy. First, a distributed control framework for joint heating was established. Second, within this structure, multiple leader systems within the composite leader system were used for decision-making. Consensus decisions between multiple leader decision points were made through a weight allocation algorithm, achieving a dynamic balance between temperature control and temperature field optimization. Then, on the basis of the composite leader decision information, the feeding power of the microwave source cluster was coordinated via a consensus algorithm, achieving dynamic coordination and complementarity between the leader cluster and the follower cluster. Finally, the simulation results revealed that after adopting this strategy, the temperature control error rate ranged from 0.25% to 1.43%. Compared with a single leader decision system, the composite leader decision system improved the uniformity in the horizontal and vertical sections by 1% to 37% and 3.5% to 26.5%, respectively. Compared with traditional microwave heating methods, the uniformity in the horizontal and vertical sections was improved by 25.3% to 61.2% and 24.2% to 66.6%, respectively. These results verify that the proposed consistency heating strategy under composite leader consensus decision-making is feasible and efficient, achieving precise temperature control and optimization of the temperature field.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 ","pages":"Article 105668"},"PeriodicalIF":6.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.csite.2025.105768
Rusya Iryanti Yahaya , Norihan Md Arifin , Mohd Shafie Mustafa , Ioan Pop , Fadzilah Md Ali , Siti Suzilliana Putri Mohamed Isa
This study analyzes the steady hybrid nanofluid flow over a permeable, non-isothermal cone and wedge. The heat transfer analysis considers the effects of thermal radiation and convective boundary conditions. Non-linear ordinary differential equations, derived through similarity transformation of the governing partial differential equations and boundary conditions, are solved numerically using the bvp4c solver. The resulting triple solutions are then subjected to a stability analysis. It is confirmed that only the first solution is stable and physically meaningful, while the other solutions are unstable. The physical quantities of interest, namely the local skin friction coefficient and local Nusselt number, are found to be higher for assisting mixed convection flow than for opposing flow. Compared to the wedge geometry, hybrid nanofluid flow over the cone exhibits a lower local skin friction coefficient but a higher local Nusselt number. Furthermore, optimization results from the response surface methodology (RSM) indicate that the maximum local Nusselt number, corresponding to the highest heat transfer rate at the cone/wedge surface, can be achieved at high values of the Biot number, radiation parameter, and wall temperature parameter.
{"title":"Mixed convection hybrid nanofluid flow past a non-isothermal cone and wedge with radiation and convective boundary condition: Heat transfer optimization","authors":"Rusya Iryanti Yahaya , Norihan Md Arifin , Mohd Shafie Mustafa , Ioan Pop , Fadzilah Md Ali , Siti Suzilliana Putri Mohamed Isa","doi":"10.1016/j.csite.2025.105768","DOIUrl":"10.1016/j.csite.2025.105768","url":null,"abstract":"<div><div>This study analyzes the steady hybrid nanofluid flow over a permeable, non-isothermal cone and wedge. The heat transfer analysis considers the effects of thermal radiation and convective boundary conditions. Non-linear ordinary differential equations, derived through similarity transformation of the governing partial differential equations and boundary conditions, are solved numerically using the bvp4c solver. The resulting triple solutions are then subjected to a stability analysis. It is confirmed that only the first solution is stable and physically meaningful, while the other solutions are unstable. The physical quantities of interest, namely the local skin friction coefficient and local Nusselt number, are found to be higher for assisting mixed convection flow than for opposing flow. Compared to the wedge geometry, hybrid nanofluid flow over the cone exhibits a lower local skin friction coefficient but a higher local Nusselt number. Furthermore, optimization results from the response surface methodology (RSM) indicate that the maximum local Nusselt number, corresponding to the highest heat transfer rate at the cone/wedge surface, can be achieved at high values of the Biot number, radiation parameter, and wall temperature parameter.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 ","pages":"Article 105768"},"PeriodicalIF":6.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.csite.2025.105748
Zhaoyang Zuo , Junhua Wang , Mohammed A. Alghassab , Nashwan Adnan Othman , Ahmad Almadhor , Fahad M. Alhomayani , Hind Albalawi , Samah G. Babiker , Barno Abdullaeva , Aboulbaba Eladeb
This comprehensive investigation undertakes a holistic examination of the design, simulation, and optimization of a hybrid thermal energy system (HTES) that synergistically integrates wind and solar energy sources for the simultaneous production of electricity, compressed hydrogen, and freshwater. This study introduces an innovative energy system design that integrates a supercritical CO2 Brayton cycle (SCO2-BC) with parabolic trough solar collectors (PTSCs) to increase efficiency and reliability. A key innovation is using waste heat from the SCO2-BC to power an organic Rankine cycle (ORC), which improves the performance and power generation capacity of the proposed system. Additionally, the machine learning optimization technique is employed to optimize the system, significantly reducing computational costs and runtime for the optimization process. The thermal energy input of HTES is supplied by PTSCs, which drive the SCO2-BC, while an ORC unit is employed to recuperate waste heat at the compressor inlet, thereby augmenting electricity generation. Furthermore, the HTES is augmented by a wind turbine to supplement power production. A multidisciplinary techno-economic and environmental framework was applied to analyze the performance of the proposed system. The preliminary simulation results indicate that the solar unit significantly contributes to both exergy destruction and the total cost rate, accounting for 53.8 % of the total exergy losses and 64.9 % of the total costs, respectively. Ultimately, the optimized simulation utilizing a hybrid machine learning approach achieved a peak exergy efficiency of 27.37 % and a minimized total cost rate of 96.2 $/h. Under the optimal operating conditions derived from the multi-objective optimization, the levelized costs of the HTES's products were determined to be 12.63 cents/kWh for electricity, 4.75 $/kg for compressed hydrogen, and 20.59 cents/m3 for freshwater. Furthermore, the environmental assessment indicated that the cost of reducing CO2 emissions is 3.69 $/h under optimal conditions.
{"title":"Heat Re-process approach and thermally integrated renewable energy system for power, compressed hydrogen, and freshwater production; ANN boosted optimization and techno-enviro-economic analysis","authors":"Zhaoyang Zuo , Junhua Wang , Mohammed A. Alghassab , Nashwan Adnan Othman , Ahmad Almadhor , Fahad M. Alhomayani , Hind Albalawi , Samah G. Babiker , Barno Abdullaeva , Aboulbaba Eladeb","doi":"10.1016/j.csite.2025.105748","DOIUrl":"10.1016/j.csite.2025.105748","url":null,"abstract":"<div><div>This comprehensive investigation undertakes a holistic examination of the design, simulation, and optimization of a hybrid thermal energy system (HTES) that synergistically integrates wind and solar energy sources for the simultaneous production of electricity, compressed hydrogen, and freshwater. This study introduces an innovative energy system design that integrates a supercritical CO<sub>2</sub> Brayton cycle (SCO<sub>2</sub>-BC) with parabolic trough solar collectors (PTSCs) to increase efficiency and reliability. A key innovation is using waste heat from the SCO<sub>2</sub>-BC to power an organic Rankine cycle (ORC), which improves the performance and power generation capacity of the proposed system. Additionally, the machine learning optimization technique is employed to optimize the system, significantly reducing computational costs and runtime for the optimization process. The thermal energy input of HTES is supplied by PTSCs, which drive the SCO<sub>2</sub>-BC, while an ORC unit is employed to recuperate waste heat at the compressor inlet, thereby augmenting electricity generation. Furthermore, the HTES is augmented by a wind turbine to supplement power production. A multidisciplinary techno-economic and environmental framework was applied to analyze the performance of the proposed system. The preliminary simulation results indicate that the solar unit significantly contributes to both exergy destruction and the total cost rate, accounting for 53.8 % of the total exergy losses and 64.9 % of the total costs, respectively. Ultimately, the optimized simulation utilizing a hybrid machine learning approach achieved a peak exergy efficiency of 27.37 % and a minimized total cost rate of 96.2 $/h. Under the optimal operating conditions derived from the multi-objective optimization, the levelized costs of the HTES's products were determined to be 12.63 cents/kWh for electricity, 4.75 $/kg for compressed hydrogen, and 20.59 cents/m<sup>3</sup> for freshwater. Furthermore, the environmental assessment indicated that the cost of reducing CO<sub>2</sub> emissions is 3.69 $/h under optimal conditions.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 ","pages":"Article 105748"},"PeriodicalIF":6.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research aimed to design, develop and evaluate the thermal efficiency of a solar concentrating parabolic collector (CPC) for distilling ethanol. The area of the CPC was 1.7 m2 with a width and depth of 1.0 m × 1.7 m, respectively. A stainless-steel parabola reflector reflected a concentrating beam onto a rectangular receiver with dimensions of 0.06 m × 0.17 m x 1.00 m (Width x Height x Long). The volume of diluted ethanol was 5000 ml, and the distillation temperature ranged from 84 to 90 °C. This experiment measured two factors: thermal efficiency and distilled ethanol volume with high ethanol concentration. The ethanol distilled from a 20 % diluted solution produced the highest ethanol concentration of approximately 72 % with an ethanol volume of about 260 ml, while the highest thermal efficiency of the solar collector was 20.36 % at 11:00. In brief, the first case resulted in the maximum thermal efficiency of 13.72 % and the best ethanol distillation, with a distilled ethanol volume of about 31 ml. In addition, replacing the material of the solar collector increased the thermal efficiency and distilled ethanol volume from the first case by 9.33 % and 32.26 %, respectively.
本研究旨在设计、开发和评估用于蒸馏乙醇的太阳能聚光抛物面集热器（CPC）的热效率。CPC面积为1.7 m2，宽1.0 m × 1.7 m，深1.0 m × 1.7 m。不锈钢抛物面反射器将集中光束反射到尺寸为0.06米× 0.17米× 1.00米（宽×高×长）的矩形接收器上。稀释后的乙醇体积为5000 ml，蒸馏温度为84 ~ 90℃。本实验测定了高乙醇浓度下的热效率和蒸馏乙醇体积两个因素。当乙醇体积约为260 ml时，从稀释20%的溶液中蒸馏的乙醇产生的最高乙醇浓度约为72%，而太阳能集热器在11:00时的最高热效率为20.36%。简而言之，第一种情况下的热效率最高，达到13.72%，乙醇蒸馏效果最好，乙醇蒸馏体积约为31 ml。此外，更换太阳能集热器材料后，热效率和乙醇蒸馏体积分别比第一种情况提高了9.33%和32.26%。
{"title":"Evaluation of thermal efficiency in ethanol distillation by solar concentrating parabolic collector","authors":"Sumol Sae-heng Pisitsungkakarn, Thansita Thomrungpiyathan","doi":"10.1016/j.csite.2025.105779","DOIUrl":"10.1016/j.csite.2025.105779","url":null,"abstract":"<div><div>This research aimed to design, develop and evaluate the thermal efficiency of a solar concentrating parabolic collector (CPC) for distilling ethanol. The area of the CPC was 1.7 m<sup>2</sup> with a width and depth of 1.0 m × 1.7 m, respectively. A stainless-steel parabola reflector reflected a concentrating beam onto a rectangular receiver with dimensions of 0.06 m × 0.17 m x 1.00 m (Width x Height x Long). The volume of diluted ethanol was 5000 ml, and the distillation temperature ranged from 84 to 90 °C. This experiment measured two factors: thermal efficiency and distilled ethanol volume with high ethanol concentration. The ethanol distilled from a 20 % diluted solution produced the highest ethanol concentration of approximately 72 % with an ethanol volume of about 260 ml, while the highest thermal efficiency of the solar collector was 20.36 % at 11:00. In brief, the first case resulted in the maximum thermal efficiency of 13.72 % and the best ethanol distillation, with a distilled ethanol volume of about 31 ml. In addition, replacing the material of the solar collector increased the thermal efficiency and distilled ethanol volume from the first case by 9.33 % and 32.26 %, respectively.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 ","pages":"Article 105779"},"PeriodicalIF":6.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.csite.2025.105760
Jiazhi Sun , Lixin Yang , Jianjun Zhou
A concentric annular heat pipe is designed for the thermal protection of infrared sensors in high-temperature environments. A key to thermal protection is the rapid analysis of the heat pipe's heat transfer characteristics, particularly in calculating thermal resistance and temperature, which remains challenging. To address this issue, a network model considering various structural and operational conditions is developed based on the CAHP heat transfer process and network theory. The model's accuracy is validated through experiments, and the effects of filling ratio, wick structure, and installation angle are analyzed. Model analysis results indicate that the thermal resistance is higher when the working liquid is in the wick, but the evaporator's circumferential temperature distribution is uniform. As the filling ratio increases, the vapor chamber transitions into a top gas and bottom liquid state. This leads to an increase in the temperature difference between the top and bottom regions of the evaporator and condenser. The heat pipes' thermal resistance with circumferential grid wick (CGW) is lower than that of circumferential uniform wick (CUW). However, there is a significant temperature difference between the CGW's wick-chamber region. When the evaporator is positioned below the condenser, the thermal resistance is lower, and temperature difference between the top and bottom regions of the evaporator and condenser is smaller. This study can provide theoretical guidance for the CAHP's structural design and sensor placement.
{"title":"Research on thermal resistance network model of concentric annular heat pipe heat for the sensor thermal protection","authors":"Jiazhi Sun , Lixin Yang , Jianjun Zhou","doi":"10.1016/j.csite.2025.105760","DOIUrl":"10.1016/j.csite.2025.105760","url":null,"abstract":"<div><div>A concentric annular heat pipe is designed for the thermal protection of infrared sensors in high-temperature environments. A key to thermal protection is the rapid analysis of the heat pipe's heat transfer characteristics, particularly in calculating thermal resistance and temperature, which remains challenging. To address this issue, a network model considering various structural and operational conditions is developed based on the CAHP heat transfer process and network theory. The model's accuracy is validated through experiments, and the effects of filling ratio, wick structure, and installation angle are analyzed. Model analysis results indicate that the thermal resistance is higher when the working liquid is in the wick, but the evaporator's circumferential temperature distribution is uniform. As the filling ratio increases, the vapor chamber transitions into a top gas and bottom liquid state. This leads to an increase in the temperature difference between the top and bottom regions of the evaporator and condenser. The heat pipes' thermal resistance with circumferential grid wick (CGW) is lower than that of circumferential uniform wick (CUW). However, there is a significant temperature difference between the CGW's wick-chamber region. When the evaporator is positioned below the condenser, the thermal resistance is lower, and temperature difference between the top and bottom regions of the evaporator and condenser is smaller. This study can provide theoretical guidance for the CAHP's structural design and sensor placement.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 ","pages":"Article 105760"},"PeriodicalIF":6.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.csite.2025.105765
Rui Kong , Shaojun Xia , Zhihui Xie , Yu Lin
The methanol steam reforming (MSR) reaction is a prospective method in hydrogen generation because of its operability and high conversion efficiency. Most of the current thermodynamic studies involving MSR use classical thermodynamic methods, while fewer studies have been conducted on the irreversibility of the reaction process using finite-time thermodynamic (FTT) methods. In this paper, the kinetic data are fitted to obtain the MSR reaction rate equation and the FTT theory is used to model the MSR reactor. The optimal reactor configuration is investigated with the optimization objective of total entropy generation rate (EGR) minimization at a fixed hydrogen production rate. Based on reference reactor with constant temperature heat supply, optimal control theory is applied to obtain optimal reactors for three cases, i.e. fixed inlet temperature, free inlet temperature, free inlet temperature and steam/carbon (S/C) ratio. Compared with the reference reactor, the optimized total EGR values are reduced by 0.61 %, 5.93 % and 10.37 % respectively. The comparisons show that the decrease in total EGR after optimization is mainly caused by reducing the heat transfer irreversibility, and the optimal profiles of control temperature have a similar distribution pattern. The local EGR due to heat transfer is more uniformly distributed in the axial direction, which conforms approximately to the equalization principle of the entropy production. The findings of the study may provide theoretical guidance for energy-efficient design and industrial application of MSR reactors.
{"title":"Minimization of entropy generation rate in methanol steam reforming reactor","authors":"Rui Kong , Shaojun Xia , Zhihui Xie , Yu Lin","doi":"10.1016/j.csite.2025.105765","DOIUrl":"10.1016/j.csite.2025.105765","url":null,"abstract":"<div><div>The methanol steam reforming (MSR) reaction is a prospective method in hydrogen generation because of its operability and high conversion efficiency. Most of the current thermodynamic studies involving MSR use classical thermodynamic methods, while fewer studies have been conducted on the irreversibility of the reaction process using finite-time thermodynamic (FTT) methods. In this paper, the kinetic data are fitted to obtain the MSR reaction rate equation and the FTT theory is used to model the MSR reactor. The optimal reactor configuration is investigated with the optimization objective of total entropy generation rate (EGR) minimization at a fixed hydrogen production rate. Based on reference reactor with constant temperature heat supply, optimal control theory is applied to obtain optimal reactors for three cases, i.e. fixed inlet temperature, free inlet temperature, free inlet temperature and steam/carbon (S/C) ratio. Compared with the reference reactor, the optimized total EGR values are reduced by 0.61 %, 5.93 % and 10.37 % respectively. The comparisons show that the decrease in total EGR after optimization is mainly caused by reducing the heat transfer irreversibility, and the optimal profiles of control temperature have a similar distribution pattern. The local EGR due to heat transfer is more uniformly distributed in the axial direction, which conforms approximately to the equalization principle of the entropy production. The findings of the study may provide theoretical guidance for energy-efficient design and industrial application of MSR reactors.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 ","pages":"Article 105765"},"PeriodicalIF":6.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.csite.2024.105718
Rouf Gulzar , Mir Aijaz , Javid Gani Dar , Ibrahim M. Almanjahie
Monitoring temperature profiles of in vivo tissues under harsh conditions is indeed an interesting problem but the problem becomes challenging when the body is covered by clothes. Accurate temperature tracking is crucial during various treatments like radiation therapy, medical examinations, occupational safety, sports performance analysis, etc. The paper investigates temperature variations in cloth-covered skin and subcutaneous tissue at unpleasant temperatures. In order to simulate the issue more accurately, a mathematical model based on the two-dimensional cylindrical bioheat equation along with appropriate initial and boundary conditions has been solved numerically. The temperature distribution in skin and subcutaneous tissue covered by cloth has been determined and the findings of the model were pictured graphically. The results were validated by comparing them with the published research on similar domain and objectives. The results of this study can be implemented to predict how much heat is distributed throughout the tissue and to identify the root causes of why patients undergoing thermal treatments like targeted tumour hyperthermia or cryosurgery might sustain burns or cold injuries.
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Pub Date : 2025-02-01DOI: 10.1016/j.csite.2024.105689
W.M. Farouk , Ayman Hoballah , Z.M. Omara , Fadl A. Essa
This study introduces a novel mathematical model to predict freshwater production and temperature profiles within a tubular solar still (TSS) under varying conditions. Employing RSM (response surface methodology) with a four-factor, five-level central composite design, we evaluated the performance of an Ag-nanomaterial's-improved phase changing material (PCM)-enhanced TSS. RSM effectively modeled the system, enabling optimization of yield (P) and water (Tw) and glass (Tg) temperatures across different PCM thicknesses. Regression models were developed using RSM to predict performance parameters, leading to the identification of optimal process conditions. PCM thickness was varied from 0 to 4 cm. Optimal conditions included a 1.34 cm PCM thickness, 40 °C ambient temperature, 0.73 m/s air speed, and 720 W/m2 radiation. In this case the expected optimum responses of productivity, 5931.15 mL/m2.d. The RSM models demonstrated high accuracy and consistency with experimental data, validating the approach. These findings highlight the potential of RSM for enhancing solar distillation system performance.
{"title":"Predictive modeling and optimization of tubular distiller operation using response surface methodology under silver nanomaterial infused PCM thickness variations","authors":"W.M. Farouk , Ayman Hoballah , Z.M. Omara , Fadl A. Essa","doi":"10.1016/j.csite.2024.105689","DOIUrl":"10.1016/j.csite.2024.105689","url":null,"abstract":"<div><div>This study introduces a novel mathematical model to predict freshwater production and temperature profiles within a tubular solar still (TSS) under varying conditions. Employing RSM (response surface methodology) with a four-factor, five-level central composite design, we evaluated the performance of an Ag-nanomaterial's-improved phase changing material (PCM)-enhanced TSS. RSM effectively modeled the system, enabling optimization of yield (P) and water (Tw) and glass (Tg) temperatures across different PCM thicknesses. Regression models were developed using RSM to predict performance parameters, leading to the identification of optimal process conditions. PCM thickness was varied from 0 to 4 cm. Optimal conditions included a 1.34 cm PCM thickness, 40 °C ambient temperature, 0.73 m/s air speed, and 720 W/m<sup>2</sup> radiation. In this case the expected optimum responses of productivity, 5931.15 mL/m<sup>2</sup>.d. The RSM models demonstrated high accuracy and consistency with experimental data, validating the approach. These findings highlight the potential of RSM for enhancing solar distillation system performance.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 ","pages":"Article 105689"},"PeriodicalIF":6.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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