Pub Date : 2024-10-08DOI: 10.1016/j.ijthermalsci.2024.109450
Yuanji Li , Xinyu Huang , Tao Lai , Youruo Wu , Xiaohu Yang , Bengt Sundén
The heat storage efficiency of heat storage tank is a challenge to optimize the utilization of solar energy. Therefore, improving the efficiency of heat storage tank has become the main research focus. In this study, the conical tank design optimized for natural convection and the metal foam addition enhanced for thermal conduction are combined. However, there are some mutual constraints between two optimization methods. Therefore, the single factor analysis coupled response surface optimization method was used in this study to optimize the conical heat storage tank filled with metal foam. Firstly, the influence and optimization interval of each factor are discussed through single factor analysis. Then, the comprehensive influence of three factors is analyzed by response surface method. Finally, the heat storage characteristics, natural convection characteristics, melting fraction and temperature uniformity of the optimized model were evaluated. The results show that the optimized heat storage tank has stronger natural convection intensity and stronger melting heat storage performance than three comparative heat storage tanks.
{"title":"Thermal characteristics of conical heat storage tank filled by metal foam: Optimization by response surface analysis","authors":"Yuanji Li , Xinyu Huang , Tao Lai , Youruo Wu , Xiaohu Yang , Bengt Sundén","doi":"10.1016/j.ijthermalsci.2024.109450","DOIUrl":"10.1016/j.ijthermalsci.2024.109450","url":null,"abstract":"<div><div>The heat storage efficiency of heat storage tank is a challenge to optimize the utilization of solar energy. Therefore, improving the efficiency of heat storage tank has become the main research focus. In this study, the conical tank design optimized for natural convection and the metal foam addition enhanced for thermal conduction are combined. However, there are some mutual constraints between two optimization methods. Therefore, the single factor analysis coupled response surface optimization method was used in this study to optimize the conical heat storage tank filled with metal foam. Firstly, the influence and optimization interval of each factor are discussed through single factor analysis. Then, the comprehensive influence of three factors is analyzed by response surface method. Finally, the heat storage characteristics, natural convection characteristics, melting fraction and temperature uniformity of the optimized model were evaluated. The results show that the optimized heat storage tank has stronger natural convection intensity and stronger melting heat storage performance than three comparative heat storage tanks.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109450"},"PeriodicalIF":4.9,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421688","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 : 2024-10-07DOI: 10.1016/j.ijthermalsci.2024.109464
Rodolfo Prediger Helfenstein, Calisa Katiuscia Lemmertz, Felipe Roman Centeno
A numerical study of a two-room structure (multi-compartment) subjected to fire in the inner room was carried out, employing the CFD (Computational Fluid Dynamics) software called FDS (Fire Dynamics Simulator), to (i) analyze the influence of the fire source position on the hot gas layer temperature, , and its behavior in a multi-compartment fire, and (ii) develop a semi-empirical engineering calculation model to predict in the adjacent room to a pre-flashover well-ventilated fire room, taking into account the fire source position. The results showed that when the fire origin occurs close to walls or elevated above the floor level, a reduced air entrainment is observed in the fire plume and flame, causing an increase in the and a reduction of the smoke production in the fire room. This reduction in the smoke production led to a lower increase in the of the adjacent room in relation to the case when the fire source was at the center of the fire room. It was also observed that the in both rooms was inversely proportional to the ventilation factor (), with a significant increase observed as the ventilation factor decreases, depending on the fire source position. Furthermore, a semi-empirical engineering calculation model was developed to predict the in the adjacent room, considering different fire source locations at ground level and elevated. The model was validated against experimental data from the literature, showing a good agreement (deviation of ≈20 %), thus demonstrating its applicability to other cases.
利用名为 FDS（火灾动力学模拟器）的 CFD（计算流体动力学）软件，对内室发生火灾的两室结构（多隔间）进行了数值研究，以（i）分析火源位置对多隔间火灾中热气层温度 Tu 及其行为的影响，以及（ii）开发半经验工程计算模型，以预测在考虑到火源位置的情况下，火灾前通风良好的火灾房间相邻房间的 Tu。结果表明，当火源靠近墙壁或高出地面时，火羽和火焰中的空气夹带量会减少，从而导致火室中的 Tu 增加，烟雾产生量减少。与火源位于起火房间中心的情况相比，烟雾产生量的减少导致相邻房间的 Tu 值增加较少。还观察到，两个房间的 Tu 值与通风系数成反比（A.H0.5），随着通风系数的降低，Tu 值会显著增加，这取决于火源的位置。此外，考虑到地面和高架的不同火源位置，还开发了一个半经验工程计算模型来预测相邻房间的 Tu。该模型与文献中的实验数据进行了验证，结果显示两者吻合良好（偏差≈20%），从而证明了该模型适用于其他情况。
{"title":"The impact of fire source location on hot gas layer temperature in multi-compartment pre-flashover fires: Analysis and semi-empirical model development","authors":"Rodolfo Prediger Helfenstein, Calisa Katiuscia Lemmertz, Felipe Roman Centeno","doi":"10.1016/j.ijthermalsci.2024.109464","DOIUrl":"10.1016/j.ijthermalsci.2024.109464","url":null,"abstract":"<div><div>A numerical study of a two-room structure (multi-compartment) subjected to fire in the inner room was carried out, employing the CFD (Computational Fluid Dynamics) software called FDS (Fire Dynamics Simulator), to (i) analyze the influence of the fire source position on the hot gas layer temperature, <span><math><mrow><msub><mi>T</mi><mi>u</mi></msub></mrow></math></span>, and its behavior in a multi-compartment fire, and (ii) develop a semi-empirical engineering calculation model to predict <span><math><mrow><msub><mi>T</mi><mi>u</mi></msub></mrow></math></span> in the adjacent room to a pre-flashover well-ventilated fire room, taking into account the fire source position. The results showed that when the fire origin occurs close to walls or elevated above the floor level, a reduced air entrainment is observed in the fire plume and flame, causing an increase in the <span><math><mrow><msub><mi>T</mi><mi>u</mi></msub></mrow></math></span> and a reduction of the smoke production in the fire room. This reduction in the smoke production led to a lower increase in the <span><math><mrow><msub><mi>T</mi><mi>u</mi></msub></mrow></math></span> of the adjacent room in relation to the case when the fire source was at the center of the fire room. It was also observed that the <span><math><mrow><msub><mi>T</mi><mi>u</mi></msub></mrow></math></span> in both rooms was inversely proportional to the ventilation factor (<span><math><mrow><mi>A</mi><mo>.</mo><msup><mi>H</mi><mn>0.5</mn></msup></mrow></math></span>), with a significant increase observed as the ventilation factor decreases, depending on the fire source position. Furthermore, a semi-empirical engineering calculation model was developed to predict the <span><math><mrow><msub><mi>T</mi><mi>u</mi></msub></mrow></math></span> in the adjacent room, considering different fire source locations at ground level and elevated. The model was validated against experimental data from the literature, showing a good agreement (deviation of ≈20 %), thus demonstrating its applicability to other cases.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109464"},"PeriodicalIF":4.9,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421697","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}
This study investigates the impact of surface characteristics—hydrophilic (copper) and hydrophobic (Teflon-coated copper) surfaces—and environmental conditions such as relative humidity (RH) ranging from 80 % to 96 %, temperature differences (DT) from 4 °C to 10 °C, and airflow velocities (V) from 2 to 8 m/s during 180 min on humid air condensation heat transfer coefficient (HTC) and droplet departure time. The research utilizes a Design of Experiments (DOE) strategy, utilizing the Response Surface Methodology (RSM) paired with a Central Composite Design (CCD) to evaluate the influence of these parameters and provide a correlation relationship between the HTC of each surface and the applied environmental conditions. Hydrophilic surfaces generally exhibited higher average HTCs than hydrophobic ones. However, at a temperature difference of 10 °C, relative humidity of 96 %, and air velocities of 2 and 8 m/s, hydrophilic surfaces significantly decreased HTC due to a condensation regime transition from dropwise to filmwise. The highest recorded average HTC was 1.16 and 1.13 kW/m2°C on the hydrophobic surface under these conditions. The temperature difference had the most significant effect on increasing the HTC. Additionally, it was observed that the relative humidity played a more critical role than the flow velocity. There is a similar process for droplet exit, with the difference that in some experiments, the heat flux of hydrophobic surfaces was slightly higher than that of hydrophilic surfaces. Still, the drop fell on it later and left the surface because of the nature of the hydrophobic surface, which prevents droplets from spreading and coalescence with other droplets.
{"title":"Investigating the effect of environmental conditions and surface type on condensation heat transfer coefficient and droplet departure time","authors":"Parisa Dehghani, Seyed Mostafa Hosseinalipour, Habibollah Akbari","doi":"10.1016/j.ijthermalsci.2024.109466","DOIUrl":"10.1016/j.ijthermalsci.2024.109466","url":null,"abstract":"<div><div>This study investigates the impact of surface characteristics—hydrophilic (copper) and hydrophobic (Teflon-coated copper) surfaces—and environmental conditions such as relative humidity (RH) ranging from 80 % to 96 %, temperature differences (DT) from 4 °C to 10 °C, and airflow velocities (V) from 2 to 8 m/s during 180 min on humid air condensation heat transfer coefficient (HTC) and droplet departure time. The research utilizes a Design of Experiments (DOE) strategy, utilizing the Response Surface Methodology (RSM) paired with a Central Composite Design (CCD) to evaluate the influence of these parameters and provide a correlation relationship between the HTC of each surface and the applied environmental conditions. Hydrophilic surfaces generally exhibited higher average HTCs than hydrophobic ones. However, at a temperature difference of 10 °C, relative humidity of 96 %, and air velocities of 2 and 8 m/s, hydrophilic surfaces significantly decreased HTC due to a condensation regime transition from dropwise to filmwise. The highest recorded average HTC was 1.16 and 1.13 kW/m<sup>2</sup>°C on the hydrophobic surface under these conditions. The temperature difference had the most significant effect on increasing the HTC. Additionally, it was observed that the relative humidity played a more critical role than the flow velocity. There is a similar process for droplet exit, with the difference that in some experiments, the heat flux of hydrophobic surfaces was slightly higher than that of hydrophilic surfaces. Still, the drop fell on it later and left the surface because of the nature of the hydrophobic surface, which prevents droplets from spreading and coalescence with other droplets.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109466"},"PeriodicalIF":4.9,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421687","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}
As an efficient active cooling method, transpiration cooling is employed for thermal protection of blunt nose cones. However, most current systems utilize open-loop control for coolant supply. This study establishes a dynamic model of a one-dimensional blunt nose cone transpiration cooling system that concurrently considers aerodynamic heating, internal heat transfer in porous media, and the thermal insulation process of the air film layer formed by injected coolant. The findings indicate that the coolant film's thermal insulation effect significantly impacts the nose cone cooling system, with flow in the porous media causing a time-delay in the dynamic insulation effect. After implementing a closed-loop feedback controller, the fuzzy PID control algorithm demonstrates superiority over the conventional PID control algorithm in mitigating positive and negative feedback misalignment issues caused by time-delay, resulting in reduced temperature oscillation time and amplitude. Additionally, the fuzzy PID control algorithm achieves faster response and shorter stabilization time when external interference from varying Mach numbers occurs.
{"title":"Application of fuzzy PID control algorithm in hypersonic vehicle transpiration cooling control","authors":"Yanqi Diao , Xue Liu , Yuyang Bian , Jiayue Zheng , Weixing Zhou , Pengyu Zhang","doi":"10.1016/j.ijthermalsci.2024.109457","DOIUrl":"10.1016/j.ijthermalsci.2024.109457","url":null,"abstract":"<div><div>As an efficient active cooling method, transpiration cooling is employed for thermal protection of blunt nose cones. However, most current systems utilize open-loop control for coolant supply. This study establishes a dynamic model of a one-dimensional blunt nose cone transpiration cooling system that concurrently considers aerodynamic heating, internal heat transfer in porous media, and the thermal insulation process of the air film layer formed by injected coolant. The findings indicate that the coolant film's thermal insulation effect significantly impacts the nose cone cooling system, with flow in the porous media causing a time-delay in the dynamic insulation effect. After implementing a closed-loop feedback controller, the fuzzy PID control algorithm demonstrates superiority over the conventional PID control algorithm in mitigating positive and negative feedback misalignment issues caused by time-delay, resulting in reduced temperature oscillation time and amplitude. Additionally, the fuzzy PID control algorithm achieves faster response and shorter stabilization time when external interference from varying Mach numbers occurs.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109457"},"PeriodicalIF":4.9,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421771","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 : 2024-10-04DOI: 10.1016/j.ijthermalsci.2024.109458
Ruinan Zhu , Chaowei Ma , Yulei Ma , Yong Yu , Cheng Tan , Jianhang Hu , Hua Wang
Copper slag ladle cooling process is divided into two stages: air-cooling and water-cooling, is one of the important processes in copper production process from copper slag flotation recovery of valuable metals. This study investigates the transient heat transfer behavior of copper slag ladle during air-cooling mechanism based on the finite-volume method. The innovative aspect of this research lies in development of a 1:1 scale 3D model of slag ladle based on industrial-scale dimensions, obtaining the relevant thermophysical parameters of copper slag by experiment, and validating simulation results against actual industrial production data. The results of study show that: (i) The temperature distribution of copper slag within slag ladle exhibits a “concentric circle” pattern with the formation of a “liquid core” zone, indicating that the temperature is significantly higher in central region compared to periphery, revealing a notable temperature gradient during the air-cooling process; (ii) The heat flux is most concentrated in the central region of slag ladle, suggesting that the heat transfer intensity is the greatest in this area, the temperature variation of copper slag in proximity to this region is the most pronounced; (iii) The cooling path of copper slag proceeds from outer layers to inner layers, with the cooling rate decreasing from fast to slow, reflecting the temperature change trend of copper slag during air-cooling, which transitions from rapid to gradual cooling. This study provides new perspectives and data support for exploring air-cooling process of copper slag ladle and contributes to the further advancement of this field.
{"title":"Numerical simulation for heat transfer behavior of copper slag ladle under air-cooling mechanism","authors":"Ruinan Zhu , Chaowei Ma , Yulei Ma , Yong Yu , Cheng Tan , Jianhang Hu , Hua Wang","doi":"10.1016/j.ijthermalsci.2024.109458","DOIUrl":"10.1016/j.ijthermalsci.2024.109458","url":null,"abstract":"<div><div>Copper slag ladle cooling process is divided into two stages: air-cooling and water-cooling, is one of the important processes in copper production process from copper slag flotation recovery of valuable metals. This study investigates the transient heat transfer behavior of copper slag ladle during air-cooling mechanism based on the finite-volume method. The innovative aspect of this research lies in development of a 1:1 scale 3D model of slag ladle based on industrial-scale dimensions, obtaining the relevant thermophysical parameters of copper slag by experiment, and validating simulation results against actual industrial production data. The results of study show that: (i) The temperature distribution of copper slag within slag ladle exhibits a “concentric circle” pattern with the formation of a “liquid core” zone, indicating that the temperature is significantly higher in central region compared to periphery, revealing a notable temperature gradient during the air-cooling process; (ii) The heat flux is most concentrated in the central region of slag ladle, suggesting that the heat transfer intensity is the greatest in this area, the temperature variation of copper slag in proximity to this region is the most pronounced; (iii) The cooling path of copper slag proceeds from outer layers to inner layers, with the cooling rate decreasing from fast to slow, reflecting the temperature change trend of copper slag during air-cooling, which transitions from rapid to gradual cooling. This study provides new perspectives and data support for exploring air-cooling process of copper slag ladle and contributes to the further advancement of this field.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109458"},"PeriodicalIF":4.9,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421564","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 : 2024-10-04DOI: 10.1016/j.ijthermalsci.2024.109467
W. Gao , Z.G. Qu , J.F. Zhang , Binbin Jiao
The optimized microchannel heat sinks could enhance flow boiling for effectively tackling the electronics cooling. The flow boiling experiment for three microchannel heat sinks integrated with different layouts of entrenched pin fins is conducted at flow rate of 273.6–456 kg/(m2.s) and inlet subcooling of 35∼50 K. The overall/local heat transfer features, pressure drop and boiling mechanism are studied. The hybrid pattern presents earliest initial boiling and lower superheat than the microchannel heat sink with uniform pin fins arrangement at moderate and large flow rates. The trend of overall and local HTC (heat transfer coefficient) is similar, which occurs peak at onset nucleation boiling, and then decreasing with increasing heat flux. At the largest flow rate, the hybrid pattern exhibits 2.7–3.5 times peak HTC promotion than other patterns. As for lowest flow rate, the hybrid pattern does not manifest remarkably superior performance due to downstream vapor cores clogging effect. The hybrid pattern shows largest pressure drop, and the smaller inlet subcooling manifests inferior heat transfer and resistance performance. The comprehensive performance factor (CPF) is proposed, and the pattern with uniform small-sized pin fins shows optimal CPF especially for low flow rate, which is considerable compared with the reference heat sink structures until high heat flux. This study may provide some insight into the design of microchannel for flow boiling heat dissipation.
{"title":"Experimental study of subcooled flow boiling in microchannel heat sinks integrated with different embedded pin fin arrays microstructures","authors":"W. Gao , Z.G. Qu , J.F. Zhang , Binbin Jiao","doi":"10.1016/j.ijthermalsci.2024.109467","DOIUrl":"10.1016/j.ijthermalsci.2024.109467","url":null,"abstract":"<div><div>The optimized microchannel heat sinks could enhance flow boiling for effectively tackling the electronics cooling. The flow boiling experiment for three microchannel heat sinks integrated with different layouts of entrenched pin fins is conducted at flow rate of 273.6–456 kg/(m<sup>2</sup>.s) and inlet subcooling of 35∼50 K. The overall/local heat transfer features, pressure drop and boiling mechanism are studied. The hybrid pattern presents earliest initial boiling and lower superheat than the microchannel heat sink with uniform pin fins arrangement at moderate and large flow rates. The trend of overall and local <em>HTC</em> (heat transfer coefficient) is similar, which occurs peak at onset nucleation boiling, and then decreasing with increasing heat flux. At the largest flow rate, the hybrid pattern exhibits 2.7–3.5 times peak <em>HTC</em> promotion than other patterns. As for lowest flow rate, the hybrid pattern does not manifest remarkably superior performance due to downstream vapor cores clogging effect. The hybrid pattern shows largest pressure drop, and the smaller inlet subcooling manifests inferior heat transfer and resistance performance. The comprehensive performance factor (CPF) is proposed, and the pattern with uniform small-sized pin fins shows optimal CPF especially for low flow rate, which is considerable compared with the reference heat sink structures until high heat flux. This study may provide some insight into the design of microchannel for flow boiling heat dissipation.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109467"},"PeriodicalIF":4.9,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421770","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 : 2024-10-03DOI: 10.1016/j.ijthermalsci.2024.109460
Raj Agravat , Abdullah Baz , Shobhit K. Patel
Sustainable and Renewable Energy is essential because it's non-polluted and available in nature. Solar energy is the most important of them all as its the essential of them all. Sun energy is a clean and finest alternative to renewable energy sources. The slotted cylinder-shaped Mxene-based resonator solar absorber (SCMRSA) achieved an average of 95.06 % efficient absorption. The MXene material is used as a resonating material above the titanium oxide layer based on the MXene layer. The wide angle of incidence is achieved which is analyzed by changing the different angles of incidence. The E-field response is also observed for the TE and TM modes. The results show a similar response for both TE and TM modes. The optimization of the structure is also observed for different variable variations and the final optimized design is used for the highly efficient absorptance results. The SCMRSA is also applicable for various solar thermal applications and energy harvesters.
{"title":"Ultra-broadband polarization-insensitive versatile solar thermal harvester","authors":"Raj Agravat , Abdullah Baz , Shobhit K. Patel","doi":"10.1016/j.ijthermalsci.2024.109460","DOIUrl":"10.1016/j.ijthermalsci.2024.109460","url":null,"abstract":"<div><div>Sustainable and Renewable Energy is essential because it's non-polluted and available in nature. Solar energy is the most important of them all as its the essential of them all. Sun energy is a clean and finest alternative to renewable energy sources. The slotted cylinder-shaped Mxene-based resonator solar absorber (SCMRSA) achieved an average of 95.06 % efficient absorption. The MXene material is used as a resonating material above the titanium oxide layer based on the MXene layer. The wide angle of incidence is achieved which is analyzed by changing the different angles of incidence. The E-field response is also observed for the TE and TM modes. The results show a similar response for both TE and TM modes. The optimization of the structure is also observed for different variable variations and the final optimized design is used for the highly efficient absorptance results. The SCMRSA is also applicable for various solar thermal applications and energy harvesters.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109460"},"PeriodicalIF":4.9,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421562","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}
The large heat loss of the cavity receiver limits its application in parabolic trough collectors, matching the environmental factors in alpine areas, in this paper, adding a glass cover plate as a heat shield at the aperture of the trough inverted trapezoidal cavity receiver is investigated. To quantify the optimization of the system performance by adding, an analytical study is carried out for the cavity receiver using theoretical calculations of heat transfer and indoor experimental tests, while “thermal uniformity” is introduced as an indicator of the temperature distribution inside the cavity, and further verifies experimentally by the outdoor real-area environment. The findings indicate that adding a heat shield is significantly effective in reducing heat loss in windy areas. At the flow rate of 250 L/h and inlet temperature of 323 K, the maximum experimental heat loss value is significantly reduced by 70.01 % in the range of 1–5 m/s wind speeds compared to the one without a heat shield. When the wind direction is from −60° to 60°, the heat loss inside the cavity is small after adding, forming a stable stratified flow, and the thermal uniformity decreases by only 0.02, indicating that the stability of the temperature field inside the cavity is high. Furthermore, outdoor validation experiments demonstrate a slower change in heat loss rate with adding the heat shield compared to without, the growth rate of the former is close to 1/3 that of the latter, with a maximum suppressed heat loss rate of 23.49 %. This study provides the theoretical basis and data guidance for optimizing cavity receiver performance in alpine areas.
空腔接收器的热损耗较大，限制了其在抛物面槽式集热器中的应用，为了与高寒地区的环境因素相匹配，本文研究了在槽式倒梯形空腔接收器的开孔处添加玻璃盖板作为隔热层的问题。为了量化加装后系统性能的优化，利用传热理论计算和室内实验测试对空腔接收器进行了分析研究，同时引入了 "热均匀性 "作为空腔内部温度分布的指标，并通过室外实际环境进行了进一步的实验验证。研究结果表明，在多风地区，加装隔热罩能明显有效地减少热量损失。流量为 250 L/h、入口温度为 323 K 时，在 1-5 m/s 的风速范围内，实验的最大热损耗值比不加隔热箱的热损耗值明显降低了 70.01%。当风向为 -60° 至 60° 时，加入隔热罩后，空腔内的热损失很小，形成了稳定的分层流，热均匀度仅降低了 0.02，表明空腔内温度场的稳定性很高。此外，室外验证实验表明，与不加隔热罩相比，加隔热罩后热损失率变化较慢，前者的增长率接近后者的 1/3，最大抑制热损失率为 23.49%。这项研究为优化高寒地区空腔接收器的性能提供了理论依据和数据指导。
{"title":"Theoretical and experimental study on the effect of the heat shield on the trough solar cavity receiver in alpine areas","authors":"Zhimin Wang , Shangyu Yue , Wenwu Chan , Gangxing Bian","doi":"10.1016/j.ijthermalsci.2024.109445","DOIUrl":"10.1016/j.ijthermalsci.2024.109445","url":null,"abstract":"<div><div>The large heat loss of the cavity receiver limits its application in parabolic trough collectors, matching the environmental factors in alpine areas, in this paper, adding a glass cover plate as a heat shield at the aperture of the trough inverted trapezoidal cavity receiver is investigated. To quantify the optimization of the system performance by adding, an analytical study is carried out for the cavity receiver using theoretical calculations of heat transfer and indoor experimental tests, while “thermal uniformity” is introduced as an indicator of the temperature distribution inside the cavity, and further verifies experimentally by the outdoor real-area environment. The findings indicate that adding a heat shield is significantly effective in reducing heat loss in windy areas. At the flow rate of 250 L/h and inlet temperature of 323 K, the maximum experimental heat loss value is significantly reduced by 70.01 % in the range of 1–5 m/s wind speeds compared to the one without a heat shield. When the wind direction is from −60° to 60°, the heat loss inside the cavity is small after adding, forming a stable stratified flow, and the thermal uniformity decreases by only 0.02, indicating that the stability of the temperature field inside the cavity is high. Furthermore, outdoor validation experiments demonstrate a slower change in heat loss rate with adding the heat shield compared to without, the growth rate of the former is close to 1/3 that of the latter, with a maximum suppressed heat loss rate of 23.49 %. This study provides the theoretical basis and data guidance for optimizing cavity receiver performance in alpine areas.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109445"},"PeriodicalIF":4.9,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421563","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 : 2024-10-01DOI: 10.1016/j.ijthermalsci.2024.109433
Hong Long, Kaiyang Li
To investigate the relationship between cell metabolism heat production and breast diseases, and to differentiate the benign and malignant nature of breast tumors based on this foundation, this study established a refined three-dimensional model of the breast suitable for analyzing the temperature field of the breast, based on the anatomical structure and physiological characteristics of the breast, using the Pennes bio-heat transfer equation. Compared to traditional breast models, this model closely approximates the physiological structure of the breast, thereby enabling a more accurate simulation of the temperature distribution within the breast for both normal and embedded tumors. This study obtains the heat production of the corresponding position of the lesion area in patients with breast tumors through the multi-point heat source model. The heat production is embedded in the breast model containing the tumor. Then, the temperature field analysis is conducted on the normal breast model and the breast model with malignant and benign tumors. Finally, the obtained temperature values are compared. The analysis reveals that the temperature values in the malignant tumor regions are higher than those in the benign tumor regions. Furthermore, based on the distribution of temperature fields, tumor sizes are estimated and compared with those observed in ultrasound images, demonstrating a close correspondence between the results. Therefore, this paper provides an essential novel analytical approach for distinguishing between benign and malignant breast cancer.
{"title":"Simulation and clinical validation of the breast temperature field based on a multi-point heat source model","authors":"Hong Long, Kaiyang Li","doi":"10.1016/j.ijthermalsci.2024.109433","DOIUrl":"10.1016/j.ijthermalsci.2024.109433","url":null,"abstract":"<div><div>To investigate the relationship between cell metabolism heat production and breast diseases, and to differentiate the benign and malignant nature of breast tumors based on this foundation, this study established a refined three-dimensional model of the breast suitable for analyzing the temperature field of the breast, based on the anatomical structure and physiological characteristics of the breast, using the Pennes bio-heat transfer equation. Compared to traditional breast models, this model closely approximates the physiological structure of the breast, thereby enabling a more accurate simulation of the temperature distribution within the breast for both normal and embedded tumors. This study obtains the heat production of the corresponding position of the lesion area in patients with breast tumors through the multi-point heat source model. The heat production is embedded in the breast model containing the tumor. Then, the temperature field analysis is conducted on the normal breast model and the breast model with malignant and benign tumors. Finally, the obtained temperature values are compared. The analysis reveals that the temperature values in the malignant tumor regions are higher than those in the benign tumor regions. Furthermore, based on the distribution of temperature fields, tumor sizes are estimated and compared with those observed in ultrasound images, demonstrating a close correspondence between the results. Therefore, this paper provides an essential novel analytical approach for distinguishing between benign and malignant breast cancer.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109433"},"PeriodicalIF":4.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421561","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 : 2024-10-01DOI: 10.1016/j.ijthermalsci.2024.109454
Yang Wang , Jingmin Dai , Yufeng Zhang
Infrared emissivity is a fundamental parameter that characterizes the thermal radiation of materials, and has a large number of measured needs in the fields of aerospace, nuclear power generation, solar energy utilization, and building energy conservation. Based on the principle of Fourier transform spectrometer, a high-temperature directional spectral emissivity measurement device was constructed using an interferometer module, liquid nitrogen cooled HgCdTe (MCT-LN) detector, and infrared focal plane array (IRFPA) detector. The device was designed with a built-in calibration radiation source, which can timely correct the stored calibrated black body data at multiple temperature points based on the changes in detector spectral responsiveness, breaking away from the dependence of traditional measurement devices based on energy comparison method on the bulky and cumbersome black body, and providing technical exploration and application possibility for the field application of high-temperature emissivity measurement devices. In addition, the focal plane detection that can achieve synchronous thermal imaging function is applied in the device, which is beneficial for the optical path alignment and heating state discrimination of the target to be measured. In the experiment, the emissivity values of GH5188 superalloy from 473 K to 1473 K after heat treatment were proportional to the temperature change, and the total hemispherical emissivity values increased by 0.204. The total directional emissivity of 0–60° changed slightly, but decreased sharply at 60°. The measured data were compared with data from published literatures, at the same temperature, the maximum deviation in spectral emissivity values for SiC material 316 L stainless steel material is 0.044 and 0.022 and the comparison results showed satisfactory consistency. Through uncertainty analysis, the results indicate that the combined uncertainty of the measuring device was less than 2.6 %.
红外发射率是表征材料热辐射的基本参数，在航空航天、核能发电、太阳能利用、建筑节能等领域有着大量的测量需求。根据傅立叶变换光谱仪的原理，利用干涉仪模块、液氮冷却碲化镉汞（MCT-LN）探测器和红外焦平面阵列（IRFPA）探测器，构建了高温定向光谱发射率测量装置。该装置设计了内置校准辐射源，可根据探测器光谱响应度的变化，对存储的多温度点校准黑体数据进行及时修正，摆脱了传统测量装置基于能量比较法对笨重黑体的依赖，为高温发射率测量装置的现场应用提供了技术探索和应用可能。此外，该装置还应用了可实现同步热成像功能的焦平面探测，有利于光路对准和待测目标的加热状态判别。在实验中，热处理后的 GH5188 超合金从 473 K 到 1473 K 的发射率值与温度变化成正比，总半球发射率值增加了 0.204。0-60° 的总方向发射率变化不大，但在 60° 时急剧下降。将测量数据与已发表的文献数据进行比较，在相同温度下，SiC 材料 316 L 不锈钢材料的光谱发射率值的最大偏差为 0.044 和 0.022，比较结果显示出令人满意的一致性。通过不确定度分析，结果表明测量装置的综合不确定度小于 2.6%。
{"title":"A directional spectral emissivity measurement device with built-in calibration radiation source","authors":"Yang Wang , Jingmin Dai , Yufeng Zhang","doi":"10.1016/j.ijthermalsci.2024.109454","DOIUrl":"10.1016/j.ijthermalsci.2024.109454","url":null,"abstract":"<div><div>Infrared emissivity is a fundamental parameter that characterizes the thermal radiation of materials, and has a large number of measured needs in the fields of aerospace, nuclear power generation, solar energy utilization, and building energy conservation. Based on the principle of Fourier transform spectrometer, a high-temperature directional spectral emissivity measurement device was constructed using an interferometer module, liquid nitrogen cooled HgCdTe (MCT-LN) detector, and infrared focal plane array (IRFPA) detector. The device was designed with a built-in calibration radiation source, which can timely correct the stored calibrated black body data at multiple temperature points based on the changes in detector spectral responsiveness, breaking away from the dependence of traditional measurement devices based on energy comparison method on the bulky and cumbersome black body, and providing technical exploration and application possibility for the field application of high-temperature emissivity measurement devices. In addition, the focal plane detection that can achieve synchronous thermal imaging function is applied in the device, which is beneficial for the optical path alignment and heating state discrimination of the target to be measured. In the experiment, the emissivity values of GH5188 superalloy from 473 K to 1473 K after heat treatment were proportional to the temperature change, and the total hemispherical emissivity values increased by 0.204. The total directional emissivity of 0–60° changed slightly, but decreased sharply at 60°. The measured data were compared with data from published literatures, at the same temperature, the maximum deviation in spectral emissivity values for SiC material 316 L stainless steel material is 0.044 and 0.022 and the comparison results showed satisfactory consistency. Through uncertainty analysis, the results indicate that the combined uncertainty of the measuring device was less than 2.6 %.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109454"},"PeriodicalIF":4.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358517","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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