The uniformity principle of temperature difference field is very useful in heat exchanger analyses and optimizations.In this paper, we analyze some other heat transfer optimization problems in the thermal management s...The uniformity principle of temperature difference field is very useful in heat exchanger analyses and optimizations.In this paper, we analyze some other heat transfer optimization problems in the thermal management system of spacecrafts,including the cooling of thermal components, the one-stream series-wound heat exchanger network, the volume-to-point heat conduction problem, and the radiative heat transfer optimization problem, and have found that the uniformity principle of temperature difference field also holds. When the design objectives under the given constraints are achieved, the distributions of the temperature difference fields are uniform. The principle reflects the characteristic of the distribution of potential in the heat transfer optimization problems. It is also shown that the principle is consistent with the entransy theory. Therefore, although the principle is intuitive and phenomenological, the entransy theory can be the physical basis of the principle.展开更多
Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality.However,a significant technical challenge in grinding is the potential increas...Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality.However,a significant technical challenge in grinding is the potential increase in temperature due to high specific energy,which can lead to surface thermal damage.Therefore,ensuring control over the surface integrity of workpieces during grinding becomes a critical concern.This necessitates the development of temperature field models that consider various parameters,such as workpiece materials,grinding wheels,grinding parameters,cooling methods,and media,to guide industrial production.This study thoroughly analyzes and summarizes grinding temperature field models.First,the theory of the grinding temperature field is investigated,classifying it into traditional models based on a continuous belt heat source and those based on a discrete heat source,depending on whether the heat source is uniform and continuous.Through this examination,a more accurate grinding temperature model that closely aligns with practical grinding conditions is derived.Subsequently,various grinding thermal models are summarized,including models for the heat source distribution,energy distribution proportional coefficient,and convective heat transfer coefficient.Through comprehensive research,the most widely recognized,utilized,and accurate model for each category is identified.The application of these grinding thermal models is reviewed,shedding light on the governing laws that dictate the influence of the heat source distribution,heat distribution,and convective heat transfer in the grinding arc zone on the grinding temperature field.Finally,considering the current issues in the field of grinding temperature,potential future research directions are proposed.The aim of this study is to provide theoretical guidance and technical support for predicting workpiece temperature and improving surface integrity.展开更多
Comprehensively considering the factors such as descaling cooling, air cooling, water cooling, frictional heat and deformation heat in gap of every stand, heat conduction between work roll and strip etc, a model of tw...Comprehensively considering the factors such as descaling cooling, air cooling, water cooling, frictional heat and deformation heat in gap of every stand, heat conduction between work roll and strip etc, a model of two-dimensional transient temperature field of finish rolling section in hot tandem rolling was built with finite difference method to calculate the temperature fields of strip and work roll. So two-dimensional accurate analysis and calculation of strip temperature were realized, and the theoretical basis for predicting and controlling strip temperature was provided. The simulated results show that the model is practical and reliable.展开更多
The uniformity principle of temperature difference field is a phenomenological principle,which has not been theoretically proved.For one-dimensional two-and three-stream heat exchangers,the extremum principle of entra...The uniformity principle of temperature difference field is a phenomenological principle,which has not been theoretically proved.For one-dimensional two-and three-stream heat exchangers,the extremum principle of entransy dissipation was used to optimize the heat transfer process by variational calculus.It was indicated that the temperature difference field between the hot and cold fluids should be completely uniform if the entransy dissipation reached a minimum for a given heat duty,or if the heat duty reached a maximum for a given entransy dissipation.So,the uniformity principle of temperature difference field of heat exchangers was primarily proved.展开更多
基金Project supported by the Science Fund for Creative Research Groups of National Natural Science Foundation of China(Grant No.51621062)
文摘The uniformity principle of temperature difference field is very useful in heat exchanger analyses and optimizations.In this paper, we analyze some other heat transfer optimization problems in the thermal management system of spacecrafts,including the cooling of thermal components, the one-stream series-wound heat exchanger network, the volume-to-point heat conduction problem, and the radiative heat transfer optimization problem, and have found that the uniformity principle of temperature difference field also holds. When the design objectives under the given constraints are achieved, the distributions of the temperature difference fields are uniform. The principle reflects the characteristic of the distribution of potential in the heat transfer optimization problems. It is also shown that the principle is consistent with the entransy theory. Therefore, although the principle is intuitive and phenomenological, the entransy theory can be the physical basis of the principle.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52205481,51975305 and 52105457)Shandong Natural Science Foundation(Grant Nos.ZR2020ME158,ZR2023QE057,ZR2022QE028,ZR2021QE116,ZR2020KE027,and ZR2022QE159)+1 种基金Qingdao Science and Technology Planning Park Cultivation Plan(23-1-5-yqpy-17-qy)China Postdoctral Science Foundation(2021M701810).
文摘Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality.However,a significant technical challenge in grinding is the potential increase in temperature due to high specific energy,which can lead to surface thermal damage.Therefore,ensuring control over the surface integrity of workpieces during grinding becomes a critical concern.This necessitates the development of temperature field models that consider various parameters,such as workpiece materials,grinding wheels,grinding parameters,cooling methods,and media,to guide industrial production.This study thoroughly analyzes and summarizes grinding temperature field models.First,the theory of the grinding temperature field is investigated,classifying it into traditional models based on a continuous belt heat source and those based on a discrete heat source,depending on whether the heat source is uniform and continuous.Through this examination,a more accurate grinding temperature model that closely aligns with practical grinding conditions is derived.Subsequently,various grinding thermal models are summarized,including models for the heat source distribution,energy distribution proportional coefficient,and convective heat transfer coefficient.Through comprehensive research,the most widely recognized,utilized,and accurate model for each category is identified.The application of these grinding thermal models is reviewed,shedding light on the governing laws that dictate the influence of the heat source distribution,heat distribution,and convective heat transfer in the grinding arc zone on the grinding temperature field.Finally,considering the current issues in the field of grinding temperature,potential future research directions are proposed.The aim of this study is to provide theoretical guidance and technical support for predicting workpiece temperature and improving surface integrity.
基金Item Sponsored by Provincial Natural Science Foundation of Henan of China(0111040400)
文摘Comprehensively considering the factors such as descaling cooling, air cooling, water cooling, frictional heat and deformation heat in gap of every stand, heat conduction between work roll and strip etc, a model of two-dimensional transient temperature field of finish rolling section in hot tandem rolling was built with finite difference method to calculate the temperature fields of strip and work roll. So two-dimensional accurate analysis and calculation of strip temperature were realized, and the theoretical basis for predicting and controlling strip temperature was provided. The simulated results show that the model is practical and reliable.
文摘The uniformity principle of temperature difference field is a phenomenological principle,which has not been theoretically proved.For one-dimensional two-and three-stream heat exchangers,the extremum principle of entransy dissipation was used to optimize the heat transfer process by variational calculus.It was indicated that the temperature difference field between the hot and cold fluids should be completely uniform if the entransy dissipation reached a minimum for a given heat duty,or if the heat duty reached a maximum for a given entransy dissipation.So,the uniformity principle of temperature difference field of heat exchangers was primarily proved.
