In order to meet the operation requirements of the 42 Tesla(T) resistive magnet which will be built by Chinese High Magnetic Field Laboratory(CHMFL) in future, the cooling water system needs to be upgraded accordingly. The cooling water system will improve its performance based on the existing cooling system. This paper will make a detailed analysis about the system upgrading and transformation plan. In terms of the refrigeration, in order to meet the requirements of larger refrigeration temperature difference, a new centrifugal chiller with large temperature difference will be added in series with the existing unit of the refrigeration. With the increase of heat load, the system will connect a new plate heat exchanger in parallel on the basis of the original heat exchange capacity. However, the circulating cooling water flow rate of the 42 T resistive magnet is expected to exceed 1200 m3/h, the purification flow rate of the de-ionized water also need to be upgraded, and the purification ratio is expected to reach more than 6%. In addition, the control system will be also combined with the new equipment and pipelines to realize a variety of chilled water storage and supply modes to better meet the operation of the new-built magnet.
为满足中国高磁场实验室（CHMFL）未来建设的 42 特斯拉（T）电阻磁体的运行要求，需要对冷却水系统进行相应升级。冷却水系统将在现有冷却系统的基础上提高其性能。本文将对系统的升级改造方案进行详细分析。在制冷方面，为满足更大制冷温差的要求，将新增一台大温差离心式冷水机组与现有制冷机组串联。随着热负荷的增加，系统将在原有换热能力的基础上并联一台新的板式换热器。但 42 T 电阻磁体的循环冷却水流量预计将超过 1200 m3/h，去离子水的净化流量也需要升级，净化率预计将达到 6% 以上。此外，控制系统还将结合新设备和管道，实现多种冷冻水储存和供应模式，以更好地满足新建磁体的运行需要。
{"title":"Design of the Cooling Water System Upgrade for 42T Resistive Magnet at the CHMFL","authors":"Jiali Tang, Ming Fang, Chenfei Zhou, Peng Zhou","doi":"10.1115/1.4065919","DOIUrl":"https://doi.org/10.1115/1.4065919","url":null,"abstract":"\u0000 In order to meet the operation requirements of the 42 Tesla(T) resistive magnet which will be built by Chinese High Magnetic Field Laboratory(CHMFL) in future, the cooling water system needs to be upgraded accordingly. The cooling water system will improve its performance based on the existing cooling system. This paper will make a detailed analysis about the system upgrading and transformation plan. In terms of the refrigeration, in order to meet the requirements of larger refrigeration temperature difference, a new centrifugal chiller with large temperature difference will be added in series with the existing unit of the refrigeration. With the increase of heat load, the system will connect a new plate heat exchanger in parallel on the basis of the original heat exchange capacity. However, the circulating cooling water flow rate of the 42 T resistive magnet is expected to exceed 1200 m3/h, the purification flow rate of the de-ionized water also need to be upgraded, and the purification ratio is expected to reach more than 6%. In addition, the control system will be also combined with the new equipment and pipelines to realize a variety of chilled water storage and supply modes to better meet the operation of the new-built magnet.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141657086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Monte Carlo ray tracing (MCRT) has been a widely implemented and reliable computational method for calculating light-matter interaction in porous media, the computational modeling of porous media and performing MCRT becomes significantly expensive when dealing with intricate structures and numerous dependent variables. Hence, Machine Learning (ML) models have been utilized to overcome computational burdens. In this study, we investigate two distinct frameworks for characterizing radiative properties in porous media for pack-free and packing-based methods. We employ two different regression tools for each case, namely Gaussian process regressions for pack-free MCRT and Convolutional Neural Network (CNN) models for pack-based MCRT to predict the radiative properties. Our study highlights the importance of selecting the appropriate regression method based on the physical model, which can lead to significant computational efficiency improvement. Our results show that both models can predict the radiative properties with high accuracy (>90%). Furthermore, we demonstrate that combining MCRT with ML inference not only enhances predictive accuracy but also reduces the computational cost of simulation by more than 96% using the GP model and 99% for the CNN model.
蒙特卡洛射线追踪（MCRT）是计算多孔介质中光与物质相互作用的一种广泛应用且可靠的计算方法，但在处理复杂结构和众多因变量时，多孔介质的计算建模和执行 MCRT 变得非常昂贵。因此，人们利用机器学习（ML）模型来克服计算负担。在本研究中，我们针对无填料和基于填料的方法，研究了表征多孔介质辐射特性的两种不同框架。我们针对每种情况采用了两种不同的回归工具，即无填料 MCRT 的高斯过程回归和基于填料的 MCRT 的卷积神经网络（CNN）模型来预测辐射特性。我们的研究强调了根据物理模型选择适当回归方法的重要性，这可以显著提高计算效率。我们的研究结果表明，这两种模型都能以较高的准确率（大于 90%）预测辐射特性。此外，我们还证明了将 MCRT 与 ML 推理相结合不仅能提高预测精度，而且还能降低模拟计算成本，使用 GP 模型可降低 96% 以上，使用 CNN 模型可降低 99%。
{"title":"Enhancing Computational Efficiency in Porous Media Analysis: Integrating Machine Learning with Monte Carlo Ray Tracing","authors":"Farhin Tabassum, S. Hajimirza","doi":"10.1115/1.4065895","DOIUrl":"https://doi.org/10.1115/1.4065895","url":null,"abstract":"\u0000 Monte Carlo ray tracing (MCRT) has been a widely implemented and reliable computational method for calculating light-matter interaction in porous media, the computational modeling of porous media and performing MCRT becomes significantly expensive when dealing with intricate structures and numerous dependent variables. Hence, Machine Learning (ML) models have been utilized to overcome computational burdens. In this study, we investigate two distinct frameworks for characterizing radiative properties in porous media for pack-free and packing-based methods. We employ two different regression tools for each case, namely Gaussian process regressions for pack-free MCRT and Convolutional Neural Network (CNN) models for pack-based MCRT to predict the radiative properties. Our study highlights the importance of selecting the appropriate regression method based on the physical model, which can lead to significant computational efficiency improvement. Our results show that both models can predict the radiative properties with high accuracy (>90%). Furthermore, we demonstrate that combining MCRT with ML inference not only enhances predictive accuracy but also reduces the computational cost of simulation by more than 96% using the GP model and 99% for the CNN model.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141681704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Downsizing double-pipe heat exchangers is possible by deploying ribs on the two sides of the heat exchangers. The shape of these ribs, along with two key geometric variables – pitch and height, are crucial in the selection of energy-efficient rib configurations. This is because, the enhancement in heat transfer performance comes at the cost of increased pressure drop. Thus, the goal of this three-dimensional numerical investigation is to identify favourable rib shapes and explore the effect of truncation on triangular ribs, something which is missing from existing literature. Truncation is expected to greatly affect the performance of triangular ribs, either adversely or favorably. To explore this conclusively, an unbiased and exhaustive analysis is carried out by comparing the performance of confinements with modified and regular triangular ribs, keeping plain confinements as the baseline. Furthermore, the effects of two principal design variables – rib height and rib pitch are explored for each shape. Separate results are presented for the inner and outer confinements of the double-pipe heat exchangers (pipes and annuli) to allow for the extrapolation of results for a wide range of applications employing internal flows in pipes and annuli. A phenomenological model is developed to classify the thermo-hydraulic performance of each confinement and identify optimal geometrical configuration and identify best performing design(s). Once optimal rib pitch-height combinations are identified, performance at this optimal combination is evaluated at different Reynolds numbers, spanning from 10,000 to 30,000.
{"title":"Energy Efficient Downsizing of Ribbed Confinements for Heat Exchange Applications","authors":"Prabhav Agrawala, Yatharth Lilhare, Amit Arora","doi":"10.1115/1.4065896","DOIUrl":"https://doi.org/10.1115/1.4065896","url":null,"abstract":"\u0000 Downsizing double-pipe heat exchangers is possible by deploying ribs on the two sides of the heat exchangers. The shape of these ribs, along with two key geometric variables – pitch and height, are crucial in the selection of energy-efficient rib configurations. This is because, the enhancement in heat transfer performance comes at the cost of increased pressure drop. Thus, the goal of this three-dimensional numerical investigation is to identify favourable rib shapes and explore the effect of truncation on triangular ribs, something which is missing from existing literature. Truncation is expected to greatly affect the performance of triangular ribs, either adversely or favorably. To explore this conclusively, an unbiased and exhaustive analysis is carried out by comparing the performance of confinements with modified and regular triangular ribs, keeping plain confinements as the baseline. Furthermore, the effects of two principal design variables – rib height and rib pitch are explored for each shape. Separate results are presented for the inner and outer confinements of the double-pipe heat exchangers (pipes and annuli) to allow for the extrapolation of results for a wide range of applications employing internal flows in pipes and annuli. A phenomenological model is developed to classify the thermo-hydraulic performance of each confinement and identify optimal geometrical configuration and identify best performing design(s). Once optimal rib pitch-height combinations are identified, performance at this optimal combination is evaluated at different Reynolds numbers, spanning from 10,000 to 30,000.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141681159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Despite the fact that the process of transferring heat and mass involves a high-pressure decline, microchannels are utilized in research involving extremely efficient heat and mass transfer processes, such as in the systems of the lungs and kidneys. Due to their high surface-to-volume ratio and compact volume, microchannels have demonstrated superior thermal performance. Microchannel flows have been shown to be a high-performance cooling method that dissipates heat flux from tiny localized hot spots over a large surface area. Due to the bidirectional nature of signalling at cell adhesions, it is necessary to examine mechanotransduction in microenvironments that are physiologically pertinent. The need to enable the study of mechanotransduction in environments with physiologically relevant mechanical properties and architecture had prompted the development of microfluidic platforms that improve standard in vitro cell culture. This article emphasizes the modulation of temperature and velocity variations within the working fluid by emphasizing the thermo-fluid coupling effects in micro-channels. In the case of two input boundary conditions, the effect of heat distributions on fluid flow with respect to micro-fins within a microchannel was investigated numerically. After comparing the results for both boundary conditions, it was found that rectangular fins had the highest heat transfer to the fluid flow, while semi-elliptical fins had the lowest heat transf
{"title":"Influence of the presence of different signatures on the heat transfer profile of laminar flow inside a microchannel.","authors":"Arupjyoti Kakati, Saurabh Gupta, Arindam Bit","doi":"10.1115/1.4065856","DOIUrl":"https://doi.org/10.1115/1.4065856","url":null,"abstract":"\u0000 Despite the fact that the process of transferring heat and mass involves a high-pressure decline, microchannels are utilized in research involving extremely efficient heat and mass transfer processes, such as in the systems of the lungs and kidneys. Due to their high surface-to-volume ratio and compact volume, microchannels have demonstrated superior thermal performance. Microchannel flows have been shown to be a high-performance cooling method that dissipates heat flux from tiny localized hot spots over a large surface area. Due to the bidirectional nature of signalling at cell adhesions, it is necessary to examine mechanotransduction in microenvironments that are physiologically pertinent. The need to enable the study of mechanotransduction in environments with physiologically relevant mechanical properties and architecture had prompted the development of microfluidic platforms that improve standard in vitro cell culture. This article emphasizes the modulation of temperature and velocity variations within the working fluid by emphasizing the thermo-fluid coupling effects in micro-channels. In the case of two input boundary conditions, the effect of heat distributions on fluid flow with respect to micro-fins within a microchannel was investigated numerically. After comparing the results for both boundary conditions, it was found that rectangular fins had the highest heat transfer to the fluid flow, while semi-elliptical fins had the lowest heat transf","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141702218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mansu Navaneethan, T. Sundararajan, K. Srinivasan, T. Jayachandran
Liquid film cooling is commonly employed in combustor of a liquid rocket engine to restrict the wall temperature within allowable limits. In the case of reusable rocket systems, additional cooling is carried out by including an ablative nozzle throat section, apart from liquid film cooling. In the present study, applications of both liquid film and ablative cooling methods for a rocket thrust chamber are presented. Most of the earlier studies have considered incompressible flow approach to simulate film cooling heat transfer. Here, a compressible multiphase flow model is used for heat transfer between the hot combustion gas and the liquid film injected along the wall. Phase change of liquid and diffusion of vapor into the gas flow are incorporated. Ablative cooling of nozzle insert is studied, considering material degradation and heat conduction through the wall. The results obtained from the numerical model compare favorably with experimental results available in literature, as well as data obtained from in-house engine tests. Liquid film cooling is observed to protect the thrust chamber from direct exposure to hot combustion gas and restrict the damage of nozzle throat insert to charring alone without causing ablation.
{"title":"SIMULATIONS WITH COMPRESSIBLE MULTIPHASE FORMULATION ON HEAT TRANSFER STUDIES IN A ROCKET THRUST CHAMBER WITH EXPERIMENTAL VALIDATION","authors":"Mansu Navaneethan, T. Sundararajan, K. Srinivasan, T. Jayachandran","doi":"10.1115/1.4065855","DOIUrl":"https://doi.org/10.1115/1.4065855","url":null,"abstract":"\u0000 Liquid film cooling is commonly employed in combustor of a liquid rocket engine to restrict the wall temperature within allowable limits. In the case of reusable rocket systems, additional cooling is carried out by including an ablative nozzle throat section, apart from liquid film cooling. In the present study, applications of both liquid film and ablative cooling methods for a rocket thrust chamber are presented. Most of the earlier studies have considered incompressible flow approach to simulate film cooling heat transfer. Here, a compressible multiphase flow model is used for heat transfer between the hot combustion gas and the liquid film injected along the wall. Phase change of liquid and diffusion of vapor into the gas flow are incorporated. Ablative cooling of nozzle insert is studied, considering material degradation and heat conduction through the wall. The results obtained from the numerical model compare favorably with experimental results available in literature, as well as data obtained from in-house engine tests. Liquid film cooling is observed to protect the thrust chamber from direct exposure to hot combustion gas and restrict the damage of nozzle throat insert to charring alone without causing ablation.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141698036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The objective of this study is to investigate the impact of different porous metal samples on the hydro-thermal characteristics of a single cylinder with porous fins using computational fluid dynamics. Commercially used porous samples with pore densities of 10, 20, and 40 PPI were used in this study for heat recovery from exhaust flue gas. The three-dimensional computational domain with porous aluminium fins attached to a tube over which high-temperature exhaust gas flows in a crossflow arrangement mimics a waste heat recovery system. Computations were performed at Reynolds number of 6000-9000, using the realisable κ-ϵ turbulence model. Three fin diameter to tube diameter ratios (Df/D = 2, 2.5, and 3) were considered. The local thermal non-equilibrium model is implemented for energy transfer, as it is more accurate for a high-temperature gradient scenario in a waste heat recovery system. The foam sample with the highest pore density was observed to have the highest pressure drop due to low permeability. A maximum heat transfer and Nusselt number were achieved for a 40 PPI foam sample due to a reduced flow rate inside the porous zone. The overall performance of metal foam samples at varying fin diameters was evaluated based on the area goodness factor (j/f) and a heat transfer coefficient ratio to pumping power per unit heat transfer surface (Z/E). Analysis of these two parameters suggests using 20 PPI foam at Df/D = 2.
本研究的目的是利用计算流体动力学研究不同多孔金属样品对带有多孔鳍片的单气缸水热特性的影响。本研究使用了孔隙密度分别为 10、20 和 40 PPI 的商用多孔样品，用于废气热回收。在三维计算域中，多孔铝翅片附着在一根管子上，高温废气在管子上以横流方式流动，模拟了废热回收系统。计算在雷诺数为 6000-9000 的条件下进行，使用的是可实现的 κ-ϵ 湍流模型。考虑了三种翅片直径与管道直径之比（Df/D = 2、2.5 和 3）。能量传递采用局部热非均衡模型，因为该模型对于余热回收系统中的高温梯度情况更为精确。据观察，孔隙密度最大的泡沫样品由于渗透率低，压降最大。由于多孔区内的流速降低，40 PPI 泡沫样品的传热系数和努塞尔特数达到了最大值。根据面积优良系数 (j/f) 和单位传热表面的传热系数与泵功率比 (Z/E)，对不同翅片直径的金属泡沫样品的整体性能进行了评估。对这两个参数的分析表明，Df/D = 2 时应使用 20 PPI 泡沫。
{"title":"Waste heat recovery from exhaust gases using porous metal fins: a three-dimensional numerical study","authors":"Mohit Raje, A. Dhiman","doi":"10.1115/1.4065722","DOIUrl":"https://doi.org/10.1115/1.4065722","url":null,"abstract":"\u0000 The objective of this study is to investigate the impact of different porous metal samples on the hydro-thermal characteristics of a single cylinder with porous fins using computational fluid dynamics. Commercially used porous samples with pore densities of 10, 20, and 40 PPI were used in this study for heat recovery from exhaust flue gas. The three-dimensional computational domain with porous aluminium fins attached to a tube over which high-temperature exhaust gas flows in a crossflow arrangement mimics a waste heat recovery system. Computations were performed at Reynolds number of 6000-9000, using the realisable κ-ϵ turbulence model. Three fin diameter to tube diameter ratios (Df/D = 2, 2.5, and 3) were considered. The local thermal non-equilibrium model is implemented for energy transfer, as it is more accurate for a high-temperature gradient scenario in a waste heat recovery system. The foam sample with the highest pore density was observed to have the highest pressure drop due to low permeability. A maximum heat transfer and Nusselt number were achieved for a 40 PPI foam sample due to a reduced flow rate inside the porous zone. The overall performance of metal foam samples at varying fin diameters was evaluated based on the area goodness factor (j/f) and a heat transfer coefficient ratio to pumping power per unit heat transfer surface (Z/E). Analysis of these two parameters suggests using 20 PPI foam at Df/D = 2.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141351885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To improve the performance of the CO2 heat pump water heater, the spiral groove tube casing heat exchanger is used as a gas cooler. At present, the flow mode of supercritical CO2 (SCO2) flows between inner and outer tube channels is mainly adopted. However, the efficiency of the gas cooler was studied rarely when the SCO2 flows in the inner tube channel (ITC). So, the heat transfer of SCO2 in the two flow channels are studied and compared in this paper. A physical model of the cooling heat transfer of SCO2 is established for the spiral groove tube casing. The impact of SCO2 pressure, the mass flow ratios of SCO2 and water on the heat transfer attributions of SCO2 in the tube are analyzed using numerical simulation. The outcomes designate that the flow channel in the exchanger can affect the heat transfer attributions of SCO2. When the mass flow ratio of SCO2 becomes lower, the average heat transfer coefficient (h) of SCO2 flowing between inner and outer tube channels is higher, with about 2.09%. As the mass flow ratio of SCO2 rises, the average h of SCO2 flowing in an ITC is higher, with about 3.90%. Moreover, both the safety of the system operation and the heat transfer attributions of the functioning medium should be considered, the flow mode of SCO2 flows in the ITC is recommended.
{"title":"Cooling heat transfer attributions of supercritical CO2 in a spiral groove tube casing heat exchanger: A numerical investigation","authors":"Dong Wang, Sensen Deng, Yinshuang Tao, Tiancheng Jiang, Mengxue Li, Yuehong Lu","doi":"10.1115/1.4065720","DOIUrl":"https://doi.org/10.1115/1.4065720","url":null,"abstract":"\u0000 To improve the performance of the CO2 heat pump water heater, the spiral groove tube casing heat exchanger is used as a gas cooler. At present, the flow mode of supercritical CO2 (SCO2) flows between inner and outer tube channels is mainly adopted. However, the efficiency of the gas cooler was studied rarely when the SCO2 flows in the inner tube channel (ITC). So, the heat transfer of SCO2 in the two flow channels are studied and compared in this paper. A physical model of the cooling heat transfer of SCO2 is established for the spiral groove tube casing. The impact of SCO2 pressure, the mass flow ratios of SCO2 and water on the heat transfer attributions of SCO2 in the tube are analyzed using numerical simulation. The outcomes designate that the flow channel in the exchanger can affect the heat transfer attributions of SCO2. When the mass flow ratio of SCO2 becomes lower, the average heat transfer coefficient (h) of SCO2 flowing between inner and outer tube channels is higher, with about 2.09%. As the mass flow ratio of SCO2 rises, the average h of SCO2 flowing in an ITC is higher, with about 3.90%. Moreover, both the safety of the system operation and the heat transfer attributions of the functioning medium should be considered, the flow mode of SCO2 flows in the ITC is recommended.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141354383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joule-Thomson (J-T) refrigerators or J-T cryocoolers are extensively used in many low-temperature applications. J-T refrigerators operating with nitrogen-hydrocarbon (N2-HC) refrigerant mixtures offer several advantages, such as low operating pressures (<20 bar), high exergy efficiency, no moving parts in the cold section, and low cost. The cooling power or cooling capacity of the J-T refrigerator depends on the hardware used as well as the refrigerant composition. The proposed work focuses on estimating the cooling capacity of a mixed refrigerant J-T (MRJ-T) refrigerator of the given hardware and specified refrigerant. An iterative steady-state full-cycle simulation procedure has been presented in this work to simulate the complete system and estimate the cooling capacity, taking into account the possibility of choking of the expansion capillary. Some of the results have been validated against experimental results of an MRJT refrigerator available in the open literature. The details of the simulation model and the results of our studies on the prediction of stable operating range, maximum cooling capacity, the effect of heat exchanger geometry, expansion capillary geometry, mixture composition, and choking of the refrigerant mixture on the performance of an MRJ-T refrigerator are presented in this paper
{"title":"Effect of Heat Exchanger and Capillary Geometry on the performance of Joule- Thomson Refrigerators operating with different mixtures","authors":"Venkatesh Dasari, G. Venkatarathnam","doi":"10.1115/1.4065721","DOIUrl":"https://doi.org/10.1115/1.4065721","url":null,"abstract":"\u0000 Joule-Thomson (J-T) refrigerators or J-T cryocoolers are extensively used in many low-temperature applications. J-T refrigerators operating with nitrogen-hydrocarbon (N2-HC) refrigerant mixtures offer several advantages, such as low operating pressures (<20 bar), high exergy efficiency, no moving parts in the cold section, and low cost. The cooling power or cooling capacity of the J-T refrigerator depends on the hardware used as well as the refrigerant composition. The proposed work focuses on estimating the cooling capacity of a mixed refrigerant J-T (MRJ-T) refrigerator of the given hardware and specified refrigerant. An iterative steady-state full-cycle simulation procedure has been presented in this work to simulate the complete system and estimate the cooling capacity, taking into account the possibility of choking of the expansion capillary. Some of the results have been validated against experimental results of an MRJT refrigerator available in the open literature. The details of the simulation model and the results of our studies on the prediction of stable operating range, maximum cooling capacity, the effect of heat exchanger geometry, expansion capillary geometry, mixture composition, and choking of the refrigerant mixture on the performance of an MRJ-T refrigerator are presented in this paper","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141355062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohab Soliman, Mohamed Shedid, Hala Mahmoud, H. Abou-Ziyan
This experimental study aimed to investigate the effect of a newly shaped condenser on the thermal performance and operational parameters of a horizontally rotating wickless heat pipe. The new condenser shape has been developed based on assessing the effect of conical external ends and inner tapered wall condensers. The newly developed condenser configuration implies an external conical end of 60° and an inner tapered walls condenser of 3°. The heat pipe was subjected to a consistent rotational speed of 1500 rpm while being exposed to different heat loads, ranging from 25 to 200 W. Various filling ratios of water, from 5 to 55% of the total inner volume of the heat pipe, have been tested at rotation speeds of 750, 1000, and 1500 rpm. The results indicated that the heat pipe with the advanced condenser has a superior performance over the ones with the plain condenser by 46.75%, the conical end condenser by about 31.15%, and the tapered condenser by about 7.54%, on average over the tested heat loads from 25 to 200W. The filling ratio of 25% achieved better performance than the other tested filling ratios as the effective thermal resistance of the heat pipe decreased by 3.1 to 10.1%, 2.8 to 19.5%, and 8.9 to 24.8% for rotational speeds 750, 1000, and 1500 rpm, respectively.
{"title":"Effect of the State-of-the-art Condenser Configuration on the Performance of Axially Rotating Wickless Heat Pipes","authors":"Mohab Soliman, Mohamed Shedid, Hala Mahmoud, H. Abou-Ziyan","doi":"10.1115/1.4065565","DOIUrl":"https://doi.org/10.1115/1.4065565","url":null,"abstract":"\u0000 This experimental study aimed to investigate the effect of a newly shaped condenser on the thermal performance and operational parameters of a horizontally rotating wickless heat pipe. The new condenser shape has been developed based on assessing the effect of conical external ends and inner tapered wall condensers. The newly developed condenser configuration implies an external conical end of 60° and an inner tapered walls condenser of 3°. The heat pipe was subjected to a consistent rotational speed of 1500 rpm while being exposed to different heat loads, ranging from 25 to 200 W. Various filling ratios of water, from 5 to 55% of the total inner volume of the heat pipe, have been tested at rotation speeds of 750, 1000, and 1500 rpm. The results indicated that the heat pipe with the advanced condenser has a superior performance over the ones with the plain condenser by 46.75%, the conical end condenser by about 31.15%, and the tapered condenser by about 7.54%, on average over the tested heat loads from 25 to 200W. The filling ratio of 25% achieved better performance than the other tested filling ratios as the effective thermal resistance of the heat pipe decreased by 3.1 to 10.1%, 2.8 to 19.5%, and 8.9 to 24.8% for rotational speeds 750, 1000, and 1500 rpm, respectively.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141117447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The space manipulator can assist astronauts to accomplish space activities, including docking, fixing, and grasping. It is subjected to thermal radiation and produces thermal deformation during orbit operation, which makes the operation of the space manipulator deviate from the predetermined trajectory and further affects its positioning accuracy. Therefore, to solve the problem of bidirectional coupling thermal-structure deformation analysis and positioning accuracy for space manipulator, based on the thermal-structural bidirectional coupling deformation analysis, a method of its thermal deformation on the output positioning accuracy of space flexible manipulator is proposed. It analyzes the bidirectional coupling relationship between the temperature and its thermal deformation for the manipulators. Then, the influence of thermal deformation on the output joint error and end positioning accuracy of the space manipulator are analyzed. Finally, the validity of this method is verified by numerical analysis. Compared with the unidirectional coupling model, the bidirectional coupling model comprehensively considers the structure, deformation and temperature of manipulators. It is closer to the real system. Thermal deformation will reduce the reliable runtime of the space manipulator in orbit. The study provides a theoretical basis for its thermal design and control.
{"title":"The study of thermal-structural coupling deformation analysis for flexible space manipulator in orbit","authors":"Fuli Zhang, Fuzhi Zhang, Na Liang","doi":"10.1115/1.4065580","DOIUrl":"https://doi.org/10.1115/1.4065580","url":null,"abstract":"\u0000 The space manipulator can assist astronauts to accomplish space activities, including docking, fixing, and grasping. It is subjected to thermal radiation and produces thermal deformation during orbit operation, which makes the operation of the space manipulator deviate from the predetermined trajectory and further affects its positioning accuracy. Therefore, to solve the problem of bidirectional coupling thermal-structure deformation analysis and positioning accuracy for space manipulator, based on the thermal-structural bidirectional coupling deformation analysis, a method of its thermal deformation on the output positioning accuracy of space flexible manipulator is proposed. It analyzes the bidirectional coupling relationship between the temperature and its thermal deformation for the manipulators. Then, the influence of thermal deformation on the output joint error and end positioning accuracy of the space manipulator are analyzed. Finally, the validity of this method is verified by numerical analysis. Compared with the unidirectional coupling model, the bidirectional coupling model comprehensively considers the structure, deformation and temperature of manipulators. It is closer to the real system. Thermal deformation will reduce the reliable runtime of the space manipulator in orbit. The study provides a theoretical basis for its thermal design and control.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141118136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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