In order for economically viable distributed generation systems for apartment buildings to spread, it is essential to develop an efficient and low-cost heat supply system. We have developed a new eogeneration system c...In order for economically viable distributed generation systems for apartment buildings to spread, it is essential to develop an efficient and low-cost heat supply system. We have developed a new eogeneration system called the Neighboring Cogeneration system （NCG）. The key concept of this system is to install a heat accumulator with a hot water supply and a room heating function at each household and to connect different households by a single loop of hot water pipe. As a result, time leveling of the heat supply and heat transferring among households becomes possible. Thus, the costs of the pipe and the heat source equipment decrease. Furthermore, because all of the heat accumulators store heat, the total heat storage capacity is large enough for cogeneration to generate exhaust heat according to the electricity demand and with a high operating rate. In this paper, we report the results of the NCG system for 7 lived-in households. The controlling system worked efficiently. All of the households were able to use hot water without any difficulties. Further, we report the results of the energy saving effect of the NCG system for 50 lived-in households by means of a simulation based on the experimental results for NEXT21.展开更多
The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the...The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the lower atmosphere over central China to be smaller than the fluxes over southern and northern China by generating more clouds. The existence of a larger quantity of clouds over central China reflects a greater amount of solar radiation back into space. The vertical gradients of upward shortwave radiative fluxes in the atmosphere below 8 km are greater than those above 8 km. The latitudinal-altitude distributions of downward longwave radiative fluxes show a slantwise decreasing trend from low latitudes to high latitudes that gradually weaken in the downward direction. The upward longwave radiative fluxes also weaken in the upward direction but with larger gradients. The maximum heating rates by solar radiation and cooling rates by longwave infrared radiation are located over 28 40°N at 7 8 km mean sea level (MSL), and they are larger than the rates in the northern and southern regions. The heating and cooling rates match well both vertically and geographically.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
The flow of pseudoplastic power-law fluids with different flow indexes at a microchannel plate was studied using computational fluid dynamic simulation.The velocity distribution along the microchannel plate and especi...The flow of pseudoplastic power-law fluids with different flow indexes at a microchannel plate was studied using computational fluid dynamic simulation.The velocity distribution along the microchannel plate and especially in the microchannel slits,flow pattern along the outlet arc and the pressure drop through the whole of microchannel plate were investigated at different power-law flow indexes.The results showed that the velocity profile in the microchannel slits for low flow index fluids was similar to the plug flow and had uniform pattern.Also the power-law fluids with lower flow indexes had lower stagnation zones near the outlet of the microchannel plate.The pressure drop through the microchannel plate showed huge differences between the fluids.The most interesting result was that the pressure drops for power-law fluids were very smaller than that of Newtonian fluids.In addition,the heat transfer of the fluids through the microchannel with different channel numbers in a wide range of Reynolds number was investigated.For power-law fluid with flow index(n=0.4),the Nusselt number increases continuously as the number of channels increases.The results highlight the potential use of using pseudoplastic fluids in the microheat exchangers which can lower the pressure drop and increase the heat transfer efficiency.展开更多
A dual-mode scramjet can operate in a wide range of flight conditions. Higher thrust can be generated by adopting suitable combustion modes. Based on the net thrust, an analysis and preliminary optimal design of a ker...A dual-mode scramjet can operate in a wide range of flight conditions. Higher thrust can be generated by adopting suitable combustion modes. Based on the net thrust, an analysis and preliminary optimal design of a kerosene-fueled parameterized dual-mode scramjet at a cru- cial flight Mach number of 6 were investigated by using a modified quasi-one-dimensional method and simulated annealing strategy. Engine structure and heat release distrib- utions, affecting the engine thrust, were chosen as analytical parameters for varied inlet conditions （isolator entrance Mach number： 1.5-3.5）. Results show that different opti- mal heat release distributions and structural conditions can be obtained at five different inlet conditions. The highest net thrust of the parameterized dual-mode engine can be achieved by a subsonic combustion mode at an isolator entrance Mach number of 2.5. Additionally, the effects of heat release and scramjet structure on net thrust have been discussed. The present results and the developed analytical method can provide guidance for the design and optimization of high-performance dual-mode scramjets.展开更多
A combined conduction and radiation heat transfer model was used to simulate the heat transfer within wafer and investigate the effect of thermal transport properties on temperature non-uniformity within wafer surface...A combined conduction and radiation heat transfer model was used to simulate the heat transfer within wafer and investigate the effect of thermal transport properties on temperature non-uniformity within wafer surface. It is found that the increased conductivities in both doped and undoped regions help reduce the temperature difference across the wafer surface. However, the doped layer conductivity has little effect on the overall temperature distribution and difference. The temperature level and difference on the top surface drop suddenly when absorption coefficient changes from 104 to 103 m-1. When the absorption coefficient is less or equal to 103 m-1, the temperature level and difference do not change much. The emissivity has the dominant effect on the top surface temperature level and difference. Higher surface emissivity can easily increase the temperature level of the wafer surface. After using the improved property data, the overall temperature level reduces by about 200 K from the basis case. The results will help improve the current understanding of the energy transport in the rapid thermal processing and the wafer temperature monitor and control level.展开更多
Through the comparison of calcination conditions between cement preclinkering technology and cement precalcining technology,we studied the characteristics of temperature field distribution of cement preclinkering tech...Through the comparison of calcination conditions between cement preclinkering technology and cement precalcining technology,we studied the characteristics of temperature field distribution of cement preclinkering technology systems including cyclone preheater,preclinkering furnace,and rotary kiln.We used numericalsimulation method to obtain data of temperature field distribution.Some results are found by system study.The ratio of tailcoalof cement preclinkering technology is about 70%,and raw mealtemperature can reach 1070 ℃.Shorter L/D kiln type of preclinkering technology can obtain more stable calcining zone temperature.The highest solid temperature of cement preclinkering technology is higher than 80 ℃,and high temperature region（〉1450 ℃）length is 2 times,which is beneficialfor calcining clinker and higher clinker quality.So cement preclinkering technology can obtain more performance temperature filed,which improves both the solid-phase reaction and liquid-phase reaction.展开更多
The goal of this paper is to present a versatile framework for solution verification of PDE＇s. We first generalize the Richardson Extrapolation technique to an optimized extrapolation solution procedure that construc...The goal of this paper is to present a versatile framework for solution verification of PDE＇s. We first generalize the Richardson Extrapolation technique to an optimized extrapolation solution procedure that constructs the best consistent solution from a set of two or three coarse grid solution in the discrete norm of choice. This technique generalizes the Least Square Extrapolation method introduced by one of the author and W. Shyy. We second establish the conditioning number of the problem in a reduced space that approximates the main feature of the numerical solution thanks to a sensitivity analysis. Overall our method produces an a posteriori error estimation in this reduced space of approximation. The key feature of our method is that our construction does not require an internal knowledge of the software neither the source code that produces the solution to be verified. It can be applied in principle as a postprocessing procedure to off the shelf commercial code. We demonstrate the robustness of our method with two steady problems that are separately an incompressible back step flow test case and a heat transfer problem for a battery. Our error estimate might be ultimately verified with a near by manufactured solution. While our pro- cedure is systematic and requires numerous computation of residuals, one can take advantage of distributed computing to get quickly the error estimate.展开更多
Low carbon development of blast furnaces is one of the key technological directions in the current development of ironmaking.Owing to the differences in the physical and chemical properties of hydrogen and carbon,hydr...Low carbon development of blast furnaces is one of the key technological directions in the current development of ironmaking.Owing to the differences in the physical and chemical properties of hydrogen and carbon,hydrogen-rich media entering a blast furnace will change the heat distribution,thus affecting the stability of production.Accordingly,a heat distribution model was proposed to study the temperature distribution in a blast furnace,simultaneously considering gas-solid heat exchange,slag and iron melting,and chemical reactions.The model was used to analyze the temperature distribution of a 2300 m^(3) blast furnace and was verified via comparison with actual production data.Subsequently,the effects of the injection rate of hydrogen-rich media,H2 concentration,and oxygen enrichment rate of the blast on the temperature distribution were investigated.Results indicated that the increase in the injection rate of the hydrogen-rich media decreased the amount of direct reduction and led to an increase in the furnace temperature.Furthermore,an increase in the oxygen enrichment rate led to a decrease in the furnace temperature,but could reduce the solid fuel ratio,while the change in H2 concentration had less effect on the temperature distribution.The combination of hydrogen-rich media injection and the increase in the oxygen enrichment rate would help to adjust the temperature distribution to the same level as the conventional blast furnace conditions.展开更多
With the advancement of clean heating projects and the integration of large-scale distributed heat pumps into rural distribution networks in northern China,power grid companies face tremendous pressure to invest in po...With the advancement of clean heating projects and the integration of large-scale distributed heat pumps into rural distribution networks in northern China,power grid companies face tremendous pressure to invest in power grid upgrades,which bring opportunities for renewable power generation integration.The combination of heating by distributed renewable energy with the flexible operation of heat pumps is a feasible alternative for dealing with grid reinforcement challenges resulting from heating electrification.In this paper,a mathematical model of the collaborative planning of distributed wind power generation(DWPG)and distribution network with large-scale heat pumps is developed.In this model,the operational flexibility of the heat pump load is fully considered and the requirements of a comfortable indoor temperature are met.By applying this model,the goals of not only increasing the profit of DWPG but also reducing the cost of the power grid upgrade can be achieved.展开更多
Maintaining suitable temperature level around tomato in the greenhouse is essential for the high-quality production.However,in summer,the temperature level around the tomato is usually unclear except using a high-prec...Maintaining suitable temperature level around tomato in the greenhouse is essential for the high-quality production.However,in summer,the temperature level around the tomato is usually unclear except using a high-precision temperature imager.To solve this problem,thermal performance of 3D(three-dimensional)tomato model built based on SolidWorks was investigated by the computational fluid dynamics(CFD)simulations.To assess the effect of temperature distribution around the tomato,a simplified 3D tomato numerical model was firstly validated by a set of field measurement data.The light intensity and indoor ventilation were regarded as the mainly environment factors in the Venlo greenhouse,thermal stratification around tomatoes at different time of day was further studied.The numerical results illustrated the different temperature distribution around tomato body under different radiation intensity.It was found that ventilation could obviously adjust the temperature gradient around the tomato,and alleviate high temperature effect particularly in summer.Suitable ventilation could create a suitable thermal environment for the tomato growth.This study clearly demonstrated 3D temperature distribution around tomatoes,which is beneficial to provide the reference for accurate detection of 3D tomato temperature and appropriate thermal environment design.展开更多
The heat loss and its,distribution are of great importance for the calculation and simulation of COREX process. Based on Baosteel COREX process, a method was applied to measure the heat loss of the furnace shell, the ...The heat loss and its,distribution are of great importance for the calculation and simulation of COREX process. Based on Baosteel COREX process, a method was applied to measure the heat loss of the furnace shell, the accessory equipments and the cooling water system. Then, a static model was established based on the measured heat loss of COREX process. The results showed that the main heat loss of furnace shells took place at the dome of the COREX melter-gasifier and the reducing gas entrance position of the shaft furnace while the main heat loss caused by cooling water occurred at the tap hole area. And the heat loss caused by cooling water accounts for about 85% of the total heat loss in COREX process. The measured total heat loss for producing every 1 t hot metal was 542. 164 MJ, which accounted for about 92 % of the theoretical total heat loss.展开更多
Linear Fresnel collector system as main solar energy collecting technology is widely studied.The secondary reflector has significant influence on the heat flux distribution on the linear Fresnel collector.In this work...Linear Fresnel collector system as main solar energy collecting technology is widely studied.The secondary reflector has significant influence on the heat flux distribution on the linear Fresnel collector.In this work,the heat flux and temperature distribution on linear Fresnel collector is compared with different secondary reflectors of simple trapezoidal concentrator,segmented parabolic concentrator and compound parabolic concentrator under varied incident ray angle.The uniformity index is applied to evaluate the Linear Fresnel reflector system heat flux distribution performance.The results show that the value of uniformity index increases with the increasing of incident ray angle.The compound parabolic concentrator has the highest value of uniformity index compared with simple trapezoidal concentrator and segmented parabolic concentrator in this work.The highest value of uniformity index is 0.8137 with compound parabolic concentrator.This work provides effective and practical guide to design and evaluate the secondary reflector in linear Fresnel reflector system.展开更多
In this paper,a two-dimensional axisymmetric thermal model using finite element method(FEM)has been established for predicting the temperature distribution pro-file on the work piece during electro discharge machining...In this paper,a two-dimensional axisymmetric thermal model using finite element method(FEM)has been established for predicting the temperature distribution pro-file on the work piece during electro discharge machining(EDM)and obtained material removal rate(MRR)from the temperature isotherm.For prediction of MRR,the model utilizes some important features viz.size and shape of the heat source(Gaussian heat distribution),thermal properties of workpiece,amount of heat distribution among the dielectric fluid,workpiece and tool,material flushing efficiency and pulse off/on time,etc.ANSYS software was used for developing the thermal model for the single spark operation.For this investigation,AISI 304 stainless steel and tungsten carbide was used as workpiece and electrode material,respectively.A comparison study has been carried out for theoretical and experimental MRR for the effect of each process parameter viz.gap voltage,pulse on time and peak current.The temperature distribution along the radial and depth direction of the workpiece has been reported.The model was validated by comparing the theoretical MRR with the experimental MRR and found a good correlation between them.展开更多
文摘In order for economically viable distributed generation systems for apartment buildings to spread, it is essential to develop an efficient and low-cost heat supply system. We have developed a new eogeneration system called the Neighboring Cogeneration system （NCG）. The key concept of this system is to install a heat accumulator with a hot water supply and a room heating function at each household and to connect different households by a single loop of hot water pipe. As a result, time leveling of the heat supply and heat transferring among households becomes possible. Thus, the costs of the pipe and the heat source equipment decrease. Furthermore, because all of the heat accumulators store heat, the total heat storage capacity is large enough for cogeneration to generate exhaust heat according to the electricity demand and with a high operating rate. In this paper, we report the results of the NCG system for 7 lived-in households. The controlling system worked efficiently. All of the households were able to use hot water without any difficulties. Further, we report the results of the energy saving effect of the NCG system for 50 lived-in households by means of a simulation based on the experimental results for NEXT21.
基金supported by the National Natural Science Foundation of China(Grant Nos.40875084and40705012)the National Key Technologies R&D Program of China(Grant No.2008BAC40B00)
文摘The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the lower atmosphere over central China to be smaller than the fluxes over southern and northern China by generating more clouds. The existence of a larger quantity of clouds over central China reflects a greater amount of solar radiation back into space. The vertical gradients of upward shortwave radiative fluxes in the atmosphere below 8 km are greater than those above 8 km. The latitudinal-altitude distributions of downward longwave radiative fluxes show a slantwise decreasing trend from low latitudes to high latitudes that gradually weaken in the downward direction. The upward longwave radiative fluxes also weaken in the upward direction but with larger gradients. The maximum heating rates by solar radiation and cooling rates by longwave infrared radiation are located over 28 40°N at 7 8 km mean sea level (MSL), and they are larger than the rates in the northern and southern regions. The heating and cooling rates match well both vertically and geographically.
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.
文摘The flow of pseudoplastic power-law fluids with different flow indexes at a microchannel plate was studied using computational fluid dynamic simulation.The velocity distribution along the microchannel plate and especially in the microchannel slits,flow pattern along the outlet arc and the pressure drop through the whole of microchannel plate were investigated at different power-law flow indexes.The results showed that the velocity profile in the microchannel slits for low flow index fluids was similar to the plug flow and had uniform pattern.Also the power-law fluids with lower flow indexes had lower stagnation zones near the outlet of the microchannel plate.The pressure drop through the microchannel plate showed huge differences between the fluids.The most interesting result was that the pressure drops for power-law fluids were very smaller than that of Newtonian fluids.In addition,the heat transfer of the fluids through the microchannel with different channel numbers in a wide range of Reynolds number was investigated.For power-law fluid with flow index(n=0.4),the Nusselt number increases continuously as the number of channels increases.The results highlight the potential use of using pseudoplastic fluids in the microheat exchangers which can lower the pressure drop and increase the heat transfer efficiency.
基金supported by the National Natural Science Foundation of China(Grant 11002148)
文摘A dual-mode scramjet can operate in a wide range of flight conditions. Higher thrust can be generated by adopting suitable combustion modes. Based on the net thrust, an analysis and preliminary optimal design of a kerosene-fueled parameterized dual-mode scramjet at a cru- cial flight Mach number of 6 were investigated by using a modified quasi-one-dimensional method and simulated annealing strategy. Engine structure and heat release distrib- utions, affecting the engine thrust, were chosen as analytical parameters for varied inlet conditions （isolator entrance Mach number： 1.5-3.5）. Results show that different opti- mal heat release distributions and structural conditions can be obtained at five different inlet conditions. The highest net thrust of the parameterized dual-mode engine can be achieved by a subsonic combustion mode at an isolator entrance Mach number of 2.5. Additionally, the effects of heat release and scramjet structure on net thrust have been discussed. The present results and the developed analytical method can provide guidance for the design and optimization of high-performance dual-mode scramjets.
基金Project(N110204015)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2012M510075)supported by the China Postdoctoral Science Foundation
文摘A combined conduction and radiation heat transfer model was used to simulate the heat transfer within wafer and investigate the effect of thermal transport properties on temperature non-uniformity within wafer surface. It is found that the increased conductivities in both doped and undoped regions help reduce the temperature difference across the wafer surface. However, the doped layer conductivity has little effect on the overall temperature distribution and difference. The temperature level and difference on the top surface drop suddenly when absorption coefficient changes from 104 to 103 m-1. When the absorption coefficient is less or equal to 103 m-1, the temperature level and difference do not change much. The emissivity has the dominant effect on the top surface temperature level and difference. Higher surface emissivity can easily increase the temperature level of the wafer surface. After using the improved property data, the overall temperature level reduces by about 200 K from the basis case. The results will help improve the current understanding of the energy transport in the rapid thermal processing and the wafer temperature monitor and control level.
基金Funded by the Major State Basic Research Perelopment Program of China(973 Program)(No.2009CB623102)the Key Fund Project of Sichuan Provincial Department of Education(No.14ZA0086)the Key Fund Project of Professional Scientific Research Innovation Team of Southwest University of Science and Technology(No.14tdfk01)
文摘Through the comparison of calcination conditions between cement preclinkering technology and cement precalcining technology,we studied the characteristics of temperature field distribution of cement preclinkering technology systems including cyclone preheater,preclinkering furnace,and rotary kiln.We used numericalsimulation method to obtain data of temperature field distribution.Some results are found by system study.The ratio of tailcoalof cement preclinkering technology is about 70%,and raw mealtemperature can reach 1070 ℃.Shorter L/D kiln type of preclinkering technology can obtain more stable calcining zone temperature.The highest solid temperature of cement preclinkering technology is higher than 80 ℃,and high temperature region（〉1450 ℃）length is 2 times,which is beneficialfor calcining clinker and higher clinker quality.So cement preclinkering technology can obtain more performance temperature filed,which improves both the solid-phase reaction and liquid-phase reaction.
基金Sandia Nat.Lab.Sandia is a multiprogram laboratory operated by Sandia Corporation,a Lockheed Martin Company,for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000
文摘The goal of this paper is to present a versatile framework for solution verification of PDE＇s. We first generalize the Richardson Extrapolation technique to an optimized extrapolation solution procedure that constructs the best consistent solution from a set of two or three coarse grid solution in the discrete norm of choice. This technique generalizes the Least Square Extrapolation method introduced by one of the author and W. Shyy. We second establish the conditioning number of the problem in a reduced space that approximates the main feature of the numerical solution thanks to a sensitivity analysis. Overall our method produces an a posteriori error estimation in this reduced space of approximation. The key feature of our method is that our construction does not require an internal knowledge of the software neither the source code that produces the solution to be verified. It can be applied in principle as a postprocessing procedure to off the shelf commercial code. We demonstrate the robustness of our method with two steady problems that are separately an incompressible back step flow test case and a heat transfer problem for a battery. Our error estimate might be ultimately verified with a near by manufactured solution. While our pro- cedure is systematic and requires numerous computation of residuals, one can take advantage of distributed computing to get quickly the error estimate.
基金support from the National Key R&D Program of China(Grant No.2019YFC1905701)the Chongqing Young Talent Program(Grant No.cstc2022ycjh-bgzxm0172).
文摘Low carbon development of blast furnaces is one of the key technological directions in the current development of ironmaking.Owing to the differences in the physical and chemical properties of hydrogen and carbon,hydrogen-rich media entering a blast furnace will change the heat distribution,thus affecting the stability of production.Accordingly,a heat distribution model was proposed to study the temperature distribution in a blast furnace,simultaneously considering gas-solid heat exchange,slag and iron melting,and chemical reactions.The model was used to analyze the temperature distribution of a 2300 m^(3) blast furnace and was verified via comparison with actual production data.Subsequently,the effects of the injection rate of hydrogen-rich media,H2 concentration,and oxygen enrichment rate of the blast on the temperature distribution were investigated.Results indicated that the increase in the injection rate of the hydrogen-rich media decreased the amount of direct reduction and led to an increase in the furnace temperature.Furthermore,an increase in the oxygen enrichment rate led to a decrease in the furnace temperature,but could reduce the solid fuel ratio,while the change in H2 concentration had less effect on the temperature distribution.The combination of hydrogen-rich media injection and the increase in the oxygen enrichment rate would help to adjust the temperature distribution to the same level as the conventional blast furnace conditions.
文摘With the advancement of clean heating projects and the integration of large-scale distributed heat pumps into rural distribution networks in northern China,power grid companies face tremendous pressure to invest in power grid upgrades,which bring opportunities for renewable power generation integration.The combination of heating by distributed renewable energy with the flexible operation of heat pumps is a feasible alternative for dealing with grid reinforcement challenges resulting from heating electrification.In this paper,a mathematical model of the collaborative planning of distributed wind power generation(DWPG)and distribution network with large-scale heat pumps is developed.In this model,the operational flexibility of the heat pump load is fully considered and the requirements of a comfortable indoor temperature are met.By applying this model,the goals of not only increasing the profit of DWPG but also reducing the cost of the power grid upgrade can be achieved.
基金supported by Science and Technology Cooperation-Sino-Malta Fund 2019:Research and Demonstration of Real-time Accurate Monitoring System for Early-stage Fish in Recirculating Aquaculture System(AquaDetector,Grant No.2019YFE0103700)Overseas Highlevel Youth Talents Program(China Agricultural University,China,Grant No.62339001)+2 种基金China Agricultural University Excellent Talents Plan(Grant No.31051015)Major Science and Technology Innovation Fund 2019 of Shandong Province(Grant No.2019JZZY010703)National Innovation Center for Digital Fishery,and Beijing Engineering and Technology Research Center for Internet of Things in Agriculture.The authors also appreciate constructive。
文摘Maintaining suitable temperature level around tomato in the greenhouse is essential for the high-quality production.However,in summer,the temperature level around the tomato is usually unclear except using a high-precision temperature imager.To solve this problem,thermal performance of 3D(three-dimensional)tomato model built based on SolidWorks was investigated by the computational fluid dynamics(CFD)simulations.To assess the effect of temperature distribution around the tomato,a simplified 3D tomato numerical model was firstly validated by a set of field measurement data.The light intensity and indoor ventilation were regarded as the mainly environment factors in the Venlo greenhouse,thermal stratification around tomatoes at different time of day was further studied.The numerical results illustrated the different temperature distribution around tomato body under different radiation intensity.It was found that ventilation could obviously adjust the temperature gradient around the tomato,and alleviate high temperature effect particularly in summer.Suitable ventilation could create a suitable thermal environment for the tomato growth.This study clearly demonstrated 3D temperature distribution around tomatoes,which is beneficial to provide the reference for accurate detection of 3D tomato temperature and appropriate thermal environment design.
基金Item Sponsored by National Natural Science Foundation of China(U1260202)Specialized Research Fund for Doctoral Program of Higher Education of China(20120006110002)
文摘The heat loss and its,distribution are of great importance for the calculation and simulation of COREX process. Based on Baosteel COREX process, a method was applied to measure the heat loss of the furnace shell, the accessory equipments and the cooling water system. Then, a static model was established based on the measured heat loss of COREX process. The results showed that the main heat loss of furnace shells took place at the dome of the COREX melter-gasifier and the reducing gas entrance position of the shaft furnace while the main heat loss caused by cooling water occurred at the tap hole area. And the heat loss caused by cooling water accounts for about 85% of the total heat loss in COREX process. The measured total heat loss for producing every 1 t hot metal was 542. 164 MJ, which accounted for about 92 % of the theoretical total heat loss.
基金financially supported by National Natural Science Foundation of China(NSFC)(51906003)Hebei province key research and development program(19214303D)Inner Mongolia Science and Technology Major Project(2021SZD0036)。
文摘Linear Fresnel collector system as main solar energy collecting technology is widely studied.The secondary reflector has significant influence on the heat flux distribution on the linear Fresnel collector.In this work,the heat flux and temperature distribution on linear Fresnel collector is compared with different secondary reflectors of simple trapezoidal concentrator,segmented parabolic concentrator and compound parabolic concentrator under varied incident ray angle.The uniformity index is applied to evaluate the Linear Fresnel reflector system heat flux distribution performance.The results show that the value of uniformity index increases with the increasing of incident ray angle.The compound parabolic concentrator has the highest value of uniformity index compared with simple trapezoidal concentrator and segmented parabolic concentrator in this work.The highest value of uniformity index is 0.8137 with compound parabolic concentrator.This work provides effective and practical guide to design and evaluate the secondary reflector in linear Fresnel reflector system.
文摘In this paper,a two-dimensional axisymmetric thermal model using finite element method(FEM)has been established for predicting the temperature distribution pro-file on the work piece during electro discharge machining(EDM)and obtained material removal rate(MRR)from the temperature isotherm.For prediction of MRR,the model utilizes some important features viz.size and shape of the heat source(Gaussian heat distribution),thermal properties of workpiece,amount of heat distribution among the dielectric fluid,workpiece and tool,material flushing efficiency and pulse off/on time,etc.ANSYS software was used for developing the thermal model for the single spark operation.For this investigation,AISI 304 stainless steel and tungsten carbide was used as workpiece and electrode material,respectively.A comparison study has been carried out for theoretical and experimental MRR for the effect of each process parameter viz.gap voltage,pulse on time and peak current.The temperature distribution along the radial and depth direction of the workpiece has been reported.The model was validated by comparing the theoretical MRR with the experimental MRR and found a good correlation between them.
