The knowledge representation mode and inference control strategy were analyzed according to the specialties of air-conditioning cooling/heating sources selection. The constructing idea and working procedure for knowle...The knowledge representation mode and inference control strategy were analyzed according to the specialties of air-conditioning cooling/heating sources selection. The constructing idea and working procedure for knowledge base and inference engine were proposed while the realization technique of the C language was discussed. An intelligent decision support system (IDSS) model based on such knowledge representation and inference mechanism was developed by domain engineers. The model was verified to have a small kernel and powerful capability in list processing and data driving, which was successfully used in the design of a cooling/heating sources system for a large-sized office building.展开更多
NCEP/NCAR reanalysis data and a 30-year precipitation dataset of observed daily rainfall from 109 gauge stations are utilized in this paper.Using the REOF we analyzed the spatial distribution of precipitation in the 1...NCEP/NCAR reanalysis data and a 30-year precipitation dataset of observed daily rainfall from 109 gauge stations are utilized in this paper.Using the REOF we analyzed the spatial distribution of precipitation in the 109 stations in the Yangtze River Basin in Meiyu periods from 1978 to 2007.The result showed that the spatial distribution of precipitation in the Yangtze River Basin can be divided into the south and north part.As a result,relationships between an atmospheric heating source(hereafter called <Q_1>) over the Asian region and the precipitation on the south and north side of Yangtze River in Meiyu periods were separately studied in this paper.The results are shown as follows.The flood/drought to the north of Yangtze River(NYR) was mainly related to the <Q_1> over the East Asia summer monsoon region:when the <Q_1> over the Philippines through Western Pacific and the south China was weakened(strengthened),it would probably result in the flood(drought) in NYR;and the precipitation on the south side of Yangtze River(SYR)was related to the <Q_1> over the east Asia and Indian summer monsoon region:when the <Q_1> over the areas from south China to the northern East China Sea and Yellow Sea and south-eastern Japan was strengthened(weakened),and the <Q_1> over the areas from the Bay of Bengal to south-eastern Tibetan Plateau was weakened(strengthened),it will lead to flood(drought) in SYR.展开更多
Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed...Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed in a cylindrical quartz tube. A flow of Ar and H2 gas mixture is purged througll the tube. A narrow section of the, boat is assmned to be exposed to a constant heat rate produced b v an rf coil located outside the quartz tube. The results of this analysis provide essential information about various parameters such as the shape of tile molten zone, required power and temperature gradient in the system.展开更多
Line heating method is widely used to manufacture curved surfaces in ship building. The main factors governing the quality of the manufactured products are the moving velocity of the heating source, heating strength, ...Line heating method is widely used to manufacture curved surfaces in ship building. The main factors governing the quality of the manufactured products are the moving velocity of the heating source, heating strength, and heating ways. In this study, the temperature distributions of the heated plate were investigated with the condition that the line heating process was automatic. The temperature variations were also investigated with the changes of those three variables. The numerical results showed that the peak temperature decreased as the moving velocity of the heating source increased. It also revealed that the peak temperatures changed linearly with the changes of the heating source.展开更多
An air source heat pump system (ASHPS) used in an office building is set up and studied experimentally. Its operating performance in winter is evaluated based on test data and a comparative discussion is given on the ...An air source heat pump system (ASHPS) used in an office building is set up and studied experimentally. Its operating performance in winter is evaluated based on test data and a comparative discussion is given on the effect of climate conditions and heating load ratio on the operation behavior. Then heating capacity variation caused by evaporator frosting is analyzed as well. Finally, the defrosting parameters and the technical feasibility are studied for a constant heating demand. The experimental results indicate that both the outlet water temperature drop and the system COP should be taken into account when setting defrosting parameters, and ASHPS is a viable technology for space heating and hot-water production in winter in Tianjin, which can maintain the room temperature above 19 ℃ when the outdoor temperature is -2 ℃.展开更多
For heating systems based on electricity storage coupled with solar energy and an air source heat pump(ECSA),choosing the appropriate combination of heat sources according to local conditions is the key to improving e...For heating systems based on electricity storage coupled with solar energy and an air source heat pump(ECSA),choosing the appropriate combination of heat sources according to local conditions is the key to improving economic efficiency.In this paper,four cities in three climatic regions in China were selected,namely Nanjing in the hot summer and cold winter region,Tianjin in the cold region,Shenyang and Harbin in the severe cold winter region.The levelized cost of heat(LCOH)was used as the economic evaluation index,and the energy consumption and emissions of different pollutants were analyzed.TRNSYS software was used to simulate and analyze the system performance.The Hooke-Jeeves optimization algorithm and GenOpt software were used to optimize the system parameters.The results showed that ECSA systemhad an excellent operation effect in cold region and hot summer and cold winter region.Compared with ECS system,the systemenergy consumption,and the emission of different pollutants of ECSA system can be reduced by a maximum of 1.37 times.In cold region,the initial investment in an air source heat pump is higher due to the lower ambient temperature,resulting in an increase in the LOCH value of ECSA system.After the LOCH value of ECSA system in each region was optimized,the heating cost of the system was reduced,but also resulted in an increase in energy consumption and the emission of different pollutant gases.展开更多
A new type of microchannel condenser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this study.The operating performance of the ASHPWH was frst tested.Then,the structure of...A new type of microchannel condenser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this study.The operating performance of the ASHPWH was frst tested.Then,the structure of the microchannel condenser was optimized with the implement of vortex generators.Finally,a numerical model of the ASHPWH was established and the optimized microchannel condenser was studied.The experimental results showed that the average coefficient of performance(COP)of the 1HP(735 W)ASHPWH reached 3.48.In addition,the optimized microchannel condenser could be matched with a 3 HP(2430W)ASHPWH with an average heating capacity of 10.30 kW,and achieving an average COP of 4.24,14.6%higher than the limit value in the national standard.展开更多
To enhance system stability,solar collectors have been integrated with air-source heat pumps.This integration facilitates the concurrent utilization of solar and air as energy sources for the system,leading to an impr...To enhance system stability,solar collectors have been integrated with air-source heat pumps.This integration facilitates the concurrent utilization of solar and air as energy sources for the system,leading to an improvement in the system’s heat generation coefficient,overall efficiency,and stability.In this study,we focus on a residential building located in Lhasa as the target for heating purposes.Initially,we simulate and analyze a solar-air source heat pump combined heating system.Subsequently,while ensuring the system meets user requirements,we examine the influence of solar collector installation angles and collector area on the performance of the solar-air source heat pump dual heating system.Through this analysis,we determine the optimal installation angle and collector area to optimize system performance.展开更多
Ground source heat pump systems demonstrate significant potential for northern rural heating applications;however,the effectiveness of these systems is often limited by challenging geological conditions.For instance,i...Ground source heat pump systems demonstrate significant potential for northern rural heating applications;however,the effectiveness of these systems is often limited by challenging geological conditions.For instance,in certain regions,the installation of buried pipes for heat exchangers may be complicated,and these pipes may not always serve as efficient low-temperature heat sources for the heat pumps of the system.To address this issue,the current study explored the use of solar-energy-collecting equipment to supplement buried pipes.In this design,both solar energy and geothermal energy provide low-temperature heat to the heat pump.First,a simulation model of a solar‒ground source heat pump coupling system was established using TRNSYS.The accuracy of this model was validated through experiments and simulations on various system configurations,including varying numbers of buried pipes,different areas of solar collectors,and varying volumes of water tanks.The simulations examined the coupling characteristics of these components and their influence on system performance.The results revealed that the operating parameters of the system remained consistent across the following configurations:three buried pipes,burial depth of 20 m,collector area of 6 m^(2),and water tank volume of 0.5 m^(3);four buried pipes,burial depth of 20 m,collector area of 3 m^(2),and water tank volume of 0.5 m^(3);and five buried pipes with a burial depth of 20 m.Furthermore,the heat collection capacity of the solar collectors spanning an area of 3 m^(2)was found to be equivalent to that of one buried pipe.Moreover,the findings revealed that the solar‒ground source heat pump coupling system demonstrated a lower annual cumulative energy consumption compared to the ground source heat pump system,presenting a reduction of 5.31%compared to the energy consumption of the latter.展开更多
An innovative and accurate method for controlling the interfacial structure of Mg-alloy/steel direct lap joints using a hybrid laser-gas tungsten arc(GTA)flexible control heat source was proposed.The study investigate...An innovative and accurate method for controlling the interfacial structure of Mg-alloy/steel direct lap joints using a hybrid laser-gas tungsten arc(GTA)flexible control heat source was proposed.The study investigated the impact of spatial regulation of a flexible hybrid heat source on the thermal gradient distribution across the joint geometry and the resulting stress states in the joints,revealing the respective bonding and strengthening mechanisms.The findings indicate that the malposition alters the thermal gradient distribution within the joint,influencing the metallurgical bonding area,interfacial structure,fracture mode,and fracture path.Furthermore,the results showed that varying the laser pulse frequency affected the frequency of the laser-induced arc and the number of keyholes generated per unit length of the joint,which effectively altered the joint geometry and interfacial stress state,and could be used to enhance the load-bearing capacity of the joints.The joint's maximum load was measured to be 325.2 N/mm,which is approximately 88%of the Mg-alloy matrix and the highest reported strength for Mg alloy-steel dissimilar lap joints.A composite interfacial layer structure was achieved,consisting of Al_(11)(Mn,Fe)_(4)and a small amount of Mg_(2)Al_(3)intermetallic compounds(IMCs)at the weld front,along with Al_(11)(Mn,Fe)_(4)and Fe3Al IMCs in the weld middle.The key factors to achieving a high bonding strength of Mg-alloy/steel lap joints have been summarized.This study provides a technical and theoretical reference for the precise collaborative control of joint geometry,interfacial structure,and mechanical properties of dissimilar material lap joints.展开更多
An inverse analysis is presented to estimate line heat source in two-dimensional steady-state and transient heat transfer problems.A constant heat source is considered in the steady-state heat transfer problem(a param...An inverse analysis is presented to estimate line heat source in two-dimensional steady-state and transient heat transfer problems.A constant heat source is considered in the steady-state heat transfer problem(a parameter estimation problem)and a time-varying heat source is considered in the transient heat transfer problem(a function estimation problem).Since a general irregular 2D heat conducting body is considered,a body-fitted grid generation is used to mesh the domain.Then governing equations and associated boundary and initial conditions are transformed from the physical domain to the computational domain and finite difference method is used to solve the governing equations to obtain the temperature distribution in the body.Using an efficient,accurate,and very easy to implement sensitivity analysis incorporated in a gradient based minimization method(here,steepest descentmethod),the unknown heat source is estimated accurately.In the function estimation part,it is assumed that there is no prior information on the functional form of the heat source and the estimation process can be performed with a reasonable initial guess for the heat source.The main advantage of the proposed inverse analysis is that the sensitivity matrix(and hence,the objective function gradient with respect to the unknown variables)can be computed during the direct heat transfer solution through newyet simple explicit expressions with no need to solve extra equations such as the sensitivity and adjoint problems and impose additional computational costs comparable to the direct problem solution ones.Some test cases are presented to investigate the accuracy,efficiency,and effect of measurement error on the estimated parameter and function for the line heat source.展开更多
In order to investigate the alternate operation characteristics of a solar-ground source heat pump system（SGSHPS）,various alternate operation modes are put forward and defined.A two-dimensional mathematical model wi...In order to investigate the alternate operation characteristics of a solar-ground source heat pump system（SGSHPS）,various alternate operation modes are put forward and defined.A two-dimensional mathematical model with freezing/melting phase changes is developed for the heat transfer analysis of the soil.Based on the numerical solution of the model,the variation trends of underground soil temperature of the SGSHPS operated in various alternate operation modes are discussed.The results indicate that,for the day-night and short-time interval alternate operation modes without solar energy,the operation time fraction of a solar heat source should be confined to from 50% to 58% when operated in an alternate period of 24 h.Meanwhile,the disadvantages of a natural resumption of soil temperature can be overcome effectively by solar energy filling,and an optimal operation effect can be achieved by integrating the mode of solar energy filling with other alternate modes.In addition,the accuracy of the presented model is verified by the experimental data of borehole wall temperatures.The conclusions can provide a reference for the optimization operation of the SGSHPS.展开更多
By reduction to one dimensional, periodic as well as rotating pulse heat sources, investigation on heat transfer characteristics with rotating body is carried out. Similar to the fluid flow, a new set of dimensionless...By reduction to one dimensional, periodic as well as rotating pulse heat sources, investigation on heat transfer characteristics with rotating body is carried out. Similar to the fluid flow, a new set of dimensionless numbers, namely quasi-Peclet numbers Pe 1, Pe 2 and Biot number Bi composed of angular velocity ω , thermophysical parameter, and geometry size are proposed, and applied to the dimensionless equations. Simulation result shows that it plays a decisive role in the process of the heat transfer. However, more important is that the numerical simulation depicts the difference between microcosmic and macroscopic structures of the temperature distribution, and reveals the influence of the relative relation of the dimensionless criterion numbers upon heat transfer characteristics.展开更多
Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data,...Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data, this paper discusses the interannual variability of the heat regime and its relation to atmospheric circulation It is shown that the interannual variability is pronounced, with maximal variability in spring and autumn, and the variability is heterogeneous horizontally. In the years with the weak (or strong) winter cold source, the deep trough over East Asia is to the east (or west) of its normal, which corresponds to strong (or weak) winter monsoon in East Asia. In the years with the strong (or weak) sum mer heat source, there exists an anomalous cyclone (or anticyclone) in the middle and lower troposphere over the QXP and ifs neighborhood and anomalous southwest (or northeast) winds over the Yangtze River valley of China, corresponding to strong (or weak) summer monsoon in East Asia. The summer heat source of the QXP is related to the intensity and position of the South Asia high. The QXP snow cover condition of April has a close relation to the heating intensity of summer. There is a remarkable negative correlation between the summer heat source of the QXP and the convection over the southeastern QXP, the Bay of Bengal, the Indo-China Peninsula, the southeastern Asia, the southwest part of China and the lower reaches of the Yangtze River and in the area from the Yellow Sea of China to the Sea of Japan.展开更多
The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter （namely, mode station variance percentage） based on 1951-2000 summer rainfall data from 160 stations in Chin...The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter （namely, mode station variance percentage） based on 1951-2000 summer rainfall data from 160 stations in China. Compared with mode variance friction, the mode station variance percentage not only reveals more localized characteristics of the variability of the summer rainfall, but also helps to distinguish the regions with a high degree of dominant EOF modes representing the analyzed observational variable. The atmospheric circulation diagnostic studies with the NCEP/NCAR reanalysis daily data from 1966 to 2000 show that in summer, abundant （scarce） rainfall in the belt-area from the upper-middle reaches of the Yangtze River northeastward to the Huaihe River basin is linked to strong （weak） heat sources over the eastern Tibetan Plateau, while the abundant （scarce） rainfall in the area to the south of the middle-lower reaches of the Yangtze River is closely linked to the weak （strong） heat sources over the tropical western Pacific.展开更多
Hot dry rock(HDR)is an important geothermal resource and clean energy source that may play an increasingly important role in future energy management.High-temperature HDR resources were recently detected in deep regio...Hot dry rock(HDR)is an important geothermal resource and clean energy source that may play an increasingly important role in future energy management.High-temperature HDR resources were recently detected in deep regions of the Gonghe Basin on the northeastern edge of the Tibetan Plateau,which led to a significant breakthrough in HDR resource exploration in China.This research analyzes the deep temperature distribution,radiogenic heat production,heat flow,and crustal thermal structure in the Qiaboqia Valley,Guide Plain,and Zhacanggou area of the Gonghe Basin based on geothermal exploration borehole logging data,rock thermophysical properties,and regional geophysical exploration data.The results are applied to discuss the heat accumulation mechanism of the HDR resources in the Gonghe Basin.The findings suggest that a low-velocity layer in the thickened crust of the Tibetan Plateau provides the most important source of constant intracrustal heat for the formation of HDR resources in the Gonghe Basin,whereas crustal thickening redistributes the concentrated layer of radioactive elements,which compensates for the relatively low heat production of the basal granite and serves as an important supplement to the heat of the HDR resources.The negative effect is that the downward curvature of the lithospheric upper mantle caused by crustal thickening leads to a small mantle heat flow component.As a result,the heat flows in the Qiaboqia Valley and Guide Plain of the Gonghe Basin are 106.2 and 77.6 m W/m2,respectively,in which the crust-mantle heat flow ratio of the former is 3.12:1,indicating a notably anomalous intracrustal thermal structure.In contrast,the crust-mantle heat flow ratio in the Guide Plain is 1.84:1,which reflects a typical hot crust-cold mantle thermal structure.The Guide Plain and Zhacanggou area show the same increasing temperature trend with depth,which reflects that their geothermal backgrounds and deep high-temperature environments are similar.These results provide important insight on the heat source mechanism of HDR resource formation in the Tibetan Plateau and useful guidance for future HDR resource exploration projects and target sites selection in similar areas.展开更多
It is common sense that a deeper well implies higher temperature in the exploration of deep geothermal resources, especially with hot dry rock(HDR) geothermal resources, which are generally exploited in terms of enhan...It is common sense that a deeper well implies higher temperature in the exploration of deep geothermal resources, especially with hot dry rock(HDR) geothermal resources, which are generally exploited in terms of enhanced geothermal systems(EGS). However, temperature is always different even at the same depth in the upper crust due to different heat sources. This paper summarizes the heat sources and classifies them into two types and five sub-types: crustorigin(partial melting, non-magma-generated tectonic events and radiogenic heat production), and mantle-origin(magma and heat conducted from the mantle). A review of global EGS sites is presented related to the five sub-types of heat sources. According to our new catalog, 71% of EGS sites host mantle-origin heat sources. The temperature logging curves indicate that EGS sites which host mantle-origin magma heat sources have the highest temperature. Therefore, high heat flow(>100 m W/m^(2)) regions with mantle-origin magma heat sources should be highlighted for the future exploration of EGS. The principle to identify the heat source is elucidated by applying geophysical and geochemical methods including noble gas isotope geochemistry and lithospheric thermal structure analysis. This analytical work will be helpful for the future exploration and assessment of HDR geothermal resources.展开更多
The apparent heat sources (?Q1 ?) and moisture sinks (?Q2 ?) are calculated based on the reanalyzed data of the South China Sea Monsoon Experiment (SCSMEX) from May 1 to August 31, 1998. It is found that the formation...The apparent heat sources (?Q1 ?) and moisture sinks (?Q2 ?) are calculated based on the reanalyzed data of the South China Sea Monsoon Experiment (SCSMEX) from May 1 to August 31, 1998. It is found that the formation and distribution of the atmospheric heat sources are important for the monsoon onset. The earlier onset of the SCS monsoon is the result of enduring atmospheric heating in the Indo–China Peninsula and South China areas. The atmospheric heating firstly appears in the Indo–China Peninsula area and the sensible heat is the major one. The 30–50 day periodic oscillation of atmospheric heat sources between the SCS area and the western Pacific warm pool has a reverse phase distribution before the middle of July and the low frequency oscillation of heat sources in SCS area has an obvious longitudinal propagation. The 30–50 day low frequency oscillation has vital modificatory effects on the summer monsoon evolution during 1998. Key words Apparent heat sources - Apparent moisture sinks - The South China Sea monsoon - Diagnostic Study Sponsored by the National Key Project of Fundamental Research “ SCSMEX” and the Research Fund for the Doctoral Program of Higher Education: “ Study of the Air-sea Interaction in the SCS Monsoon Region”.展开更多
As a huge,intense,and elevated atmospheric heat source(AHS) approaching the mid-troposphere in spring and summer,the Tibetan Plateau(TP) thermal forcing is perceived as an important factor contributing to the formatio...As a huge,intense,and elevated atmospheric heat source(AHS) approaching the mid-troposphere in spring and summer,the Tibetan Plateau(TP) thermal forcing is perceived as an important factor contributing to the formation and variation of the Asian summer monsoon.Despite numerous studies devoted to determine the strength and change of the thermal forcing of the TP on the basis of various data sources and methods,uncertainties remain in quantitative estimation of the AHS and will persist for the following reasons:(1) Routine meteorological stations cover only limited regions and show remarkable spatial inhomogeneity with most distributed in the central and eastern plateau.Moreover,all of these stations are situated at an altitude below 5000 m.Thus,the large area above that elevation is not included in the data.(2) Direct observations on heat fluxes do not exist at most stations,and the sensible heat flux(SHF) is calculated by the bulk formula,in which the drag coefficient for heat is often treated as an empirical constant without considering atmospheric stability and thermal roughness length.(3) Radiation flux derived by satellite remote sensing shows a large discrepancy in the algorithm in data inversion and complex terrain.(4) In reanalysis data,besides the rare observational records employed for data assimilation,model bias in physical processes induces visible errors in producing the diabatic heating fields.展开更多
NCEP/NCAR reanalysis data and a 47-year precipitation dataset are utilized to analyze the relationship between an atmospheric heat source （hereafter called 〈 Q1 〉） over the Qinghai-Xizang Plateau （QXP） and its s...NCEP/NCAR reanalysis data and a 47-year precipitation dataset are utilized to analyze the relationship between an atmospheric heat source （hereafter called 〈 Q1 〉） over the Qinghai-Xizang Plateau （QXP） and its surrounding area and precipitation in northwest China. Our main conclusions are as follows： （1） The horizontal distribution of 〈 Q1 〉 and its changing trend are dramatic over QXP in the summer. There are three strong centers of 〈 Q1 〉 over the south side of QXP with obvious differences in the amount of yearly precipitation and the number of heat sinks predominate in the arid and semi-arid regions of northwest China （NWC）, beside the northern QXP with an obvious higher intensity in years with less precipitation. （2） In the summer, the variation of the heat source＇s vertical structure is obviously different between greater and lesser precipitation years in eastern northwest China （ENWC）. The narrow heat sink belt forms between the northeast QXP and the southwestern part of Lake Baikal. In July and August of greater precipitation years, the heating center of the eastern QXP stays nearly over 35°N, and at 400 hPa of the eastern QXP, the strong upward motion of the heating center constructs a closed secondary vertical circulation cell over the northeast QXP （40~ 46~N）, which is propitious to add precipitation over the ENWC. Otherwise, the heating center shifts to the south of 30°N and disappears in July and August of lesser precipitation years, an opposite secondary circulation cell forms over the northeast QXP, which is a disadvantage for precipitation. Meanwhile, the secondary circulation cell in years with more or less precipitation over the ENWC is also related to the heat source over the Lake Baikal. （3） The vertical structure of the heat source over the western QXP has obvious differences between greater and lesser precipitation years in western northwest China in June and July. The strong/weak heat source over the western QXP produces relatively strong/weak ascending motion and correspondingly constructs a secondary circulation cell in lesser/greater precipitation years.展开更多
文摘The knowledge representation mode and inference control strategy were analyzed according to the specialties of air-conditioning cooling/heating sources selection. The constructing idea and working procedure for knowledge base and inference engine were proposed while the realization technique of the C language was discussed. An intelligent decision support system (IDSS) model based on such knowledge representation and inference mechanism was developed by domain engineers. The model was verified to have a small kernel and powerful capability in list processing and data driving, which was successfully used in the design of a cooling/heating sources system for a large-sized office building.
基金National Natural Science Foundation of China(41275080)China Meteorological Administration Special Public Welfare Research Fund(GYHY201306022)Open Research Fund Program of Plateau Atmosphere and Environment Key Laboratory of Sichuan Province(PAEKL-2010-C3)
文摘NCEP/NCAR reanalysis data and a 30-year precipitation dataset of observed daily rainfall from 109 gauge stations are utilized in this paper.Using the REOF we analyzed the spatial distribution of precipitation in the 109 stations in the Yangtze River Basin in Meiyu periods from 1978 to 2007.The result showed that the spatial distribution of precipitation in the Yangtze River Basin can be divided into the south and north part.As a result,relationships between an atmospheric heating source(hereafter called <Q_1>) over the Asian region and the precipitation on the south and north side of Yangtze River in Meiyu periods were separately studied in this paper.The results are shown as follows.The flood/drought to the north of Yangtze River(NYR) was mainly related to the <Q_1> over the East Asia summer monsoon region:when the <Q_1> over the Philippines through Western Pacific and the south China was weakened(strengthened),it would probably result in the flood(drought) in NYR;and the precipitation on the south side of Yangtze River(SYR)was related to the <Q_1> over the east Asia and Indian summer monsoon region:when the <Q_1> over the areas from south China to the northern East China Sea and Yellow Sea and south-eastern Japan was strengthened(weakened),and the <Q_1> over the areas from the Bay of Bengal to south-eastern Tibetan Plateau was weakened(strengthened),it will lead to flood(drought) in SYR.
文摘Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed in a cylindrical quartz tube. A flow of Ar and H2 gas mixture is purged througll the tube. A narrow section of the, boat is assmned to be exposed to a constant heat rate produced b v an rf coil located outside the quartz tube. The results of this analysis provide essential information about various parameters such as the shape of tile molten zone, required power and temperature gradient in the system.
基金supported by the post BK21 project of the MEST of Koreapartly supported by the NRL program of NRF of Korea (2008-0060153)
文摘Line heating method is widely used to manufacture curved surfaces in ship building. The main factors governing the quality of the manufactured products are the moving velocity of the heating source, heating strength, and heating ways. In this study, the temperature distributions of the heated plate were investigated with the condition that the line heating process was automatic. The temperature variations were also investigated with the changes of those three variables. The numerical results showed that the peak temperature decreased as the moving velocity of the heating source increased. It also revealed that the peak temperatures changed linearly with the changes of the heating source.
基金Supported bythe"11th Five-Year Plan"for National Plans of Major Technology Projects
文摘An air source heat pump system (ASHPS) used in an office building is set up and studied experimentally. Its operating performance in winter is evaluated based on test data and a comparative discussion is given on the effect of climate conditions and heating load ratio on the operation behavior. Then heating capacity variation caused by evaporator frosting is analyzed as well. Finally, the defrosting parameters and the technical feasibility are studied for a constant heating demand. The experimental results indicate that both the outlet water temperature drop and the system COP should be taken into account when setting defrosting parameters, and ASHPS is a viable technology for space heating and hot-water production in winter in Tianjin, which can maintain the room temperature above 19 ℃ when the outdoor temperature is -2 ℃.
基金This work was supported by the National Key Research and Development Program of China(No.2019YFE0193200 KY202001)Science and Technology Planning Project of Beijing(No.Z201100008320001 KY191004).
文摘For heating systems based on electricity storage coupled with solar energy and an air source heat pump(ECSA),choosing the appropriate combination of heat sources according to local conditions is the key to improving economic efficiency.In this paper,four cities in three climatic regions in China were selected,namely Nanjing in the hot summer and cold winter region,Tianjin in the cold region,Shenyang and Harbin in the severe cold winter region.The levelized cost of heat(LCOH)was used as the economic evaluation index,and the energy consumption and emissions of different pollutants were analyzed.TRNSYS software was used to simulate and analyze the system performance.The Hooke-Jeeves optimization algorithm and GenOpt software were used to optimize the system parameters.The results showed that ECSA systemhad an excellent operation effect in cold region and hot summer and cold winter region.Compared with ECS system,the systemenergy consumption,and the emission of different pollutants of ECSA system can be reduced by a maximum of 1.37 times.In cold region,the initial investment in an air source heat pump is higher due to the lower ambient temperature,resulting in an increase in the LOCH value of ECSA system.After the LOCH value of ECSA system in each region was optimized,the heating cost of the system was reduced,but also resulted in an increase in energy consumption and the emission of different pollutant gases.
基金the National Natural Science Foundation of China(No.51776117)。
文摘A new type of microchannel condenser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this study.The operating performance of the ASHPWH was frst tested.Then,the structure of the microchannel condenser was optimized with the implement of vortex generators.Finally,a numerical model of the ASHPWH was established and the optimized microchannel condenser was studied.The experimental results showed that the average coefficient of performance(COP)of the 1HP(735 W)ASHPWH reached 3.48.In addition,the optimized microchannel condenser could be matched with a 3 HP(2430W)ASHPWH with an average heating capacity of 10.30 kW,and achieving an average COP of 4.24,14.6%higher than the limit value in the national standard.
文摘To enhance system stability,solar collectors have been integrated with air-source heat pumps.This integration facilitates the concurrent utilization of solar and air as energy sources for the system,leading to an improvement in the system’s heat generation coefficient,overall efficiency,and stability.In this study,we focus on a residential building located in Lhasa as the target for heating purposes.Initially,we simulate and analyze a solar-air source heat pump combined heating system.Subsequently,while ensuring the system meets user requirements,we examine the influence of solar collector installation angles and collector area on the performance of the solar-air source heat pump dual heating system.Through this analysis,we determine the optimal installation angle and collector area to optimize system performance.
基金supported by 2024 Central Guidance Local Science and Technology Development Fund Project"Study on the mechanism and evaluation method of thermal pollution in water bodies,as well as research on thermal carrying capacity".(Grant 246Z4506G)Key Research and Development Project in Hebei Province:"Key Technologies and Equipment Research and Demonstration of Multiple Energy Complementary(Electricity,Heat,Cold System)for Solar Energy,Geothermal Energy,Phase Change Energy"(Grant 236Z4310G)the Hebei Academy of Sciences Key Research and Development Program"Research on Heat Transfer Mechanisms and Efficient Applications of Intermediate and Deep Geothermal Energy"(22702)。
文摘Ground source heat pump systems demonstrate significant potential for northern rural heating applications;however,the effectiveness of these systems is often limited by challenging geological conditions.For instance,in certain regions,the installation of buried pipes for heat exchangers may be complicated,and these pipes may not always serve as efficient low-temperature heat sources for the heat pumps of the system.To address this issue,the current study explored the use of solar-energy-collecting equipment to supplement buried pipes.In this design,both solar energy and geothermal energy provide low-temperature heat to the heat pump.First,a simulation model of a solar‒ground source heat pump coupling system was established using TRNSYS.The accuracy of this model was validated through experiments and simulations on various system configurations,including varying numbers of buried pipes,different areas of solar collectors,and varying volumes of water tanks.The simulations examined the coupling characteristics of these components and their influence on system performance.The results revealed that the operating parameters of the system remained consistent across the following configurations:three buried pipes,burial depth of 20 m,collector area of 6 m^(2),and water tank volume of 0.5 m^(3);four buried pipes,burial depth of 20 m,collector area of 3 m^(2),and water tank volume of 0.5 m^(3);and five buried pipes with a burial depth of 20 m.Furthermore,the heat collection capacity of the solar collectors spanning an area of 3 m^(2)was found to be equivalent to that of one buried pipe.Moreover,the findings revealed that the solar‒ground source heat pump coupling system demonstrated a lower annual cumulative energy consumption compared to the ground source heat pump system,presenting a reduction of 5.31%compared to the energy consumption of the latter.
基金financially supported by the National Key Research and Development Program of China(No.2022YFB4600900)the National Natural Science Foundation of China(Nos.U1960111 and 52375309)the Liaoning ProvinceApplied Basic Research Program Project(Nos.2023JH2 and 101300157).
文摘An innovative and accurate method for controlling the interfacial structure of Mg-alloy/steel direct lap joints using a hybrid laser-gas tungsten arc(GTA)flexible control heat source was proposed.The study investigated the impact of spatial regulation of a flexible hybrid heat source on the thermal gradient distribution across the joint geometry and the resulting stress states in the joints,revealing the respective bonding and strengthening mechanisms.The findings indicate that the malposition alters the thermal gradient distribution within the joint,influencing the metallurgical bonding area,interfacial structure,fracture mode,and fracture path.Furthermore,the results showed that varying the laser pulse frequency affected the frequency of the laser-induced arc and the number of keyholes generated per unit length of the joint,which effectively altered the joint geometry and interfacial stress state,and could be used to enhance the load-bearing capacity of the joints.The joint's maximum load was measured to be 325.2 N/mm,which is approximately 88%of the Mg-alloy matrix and the highest reported strength for Mg alloy-steel dissimilar lap joints.A composite interfacial layer structure was achieved,consisting of Al_(11)(Mn,Fe)_(4)and a small amount of Mg_(2)Al_(3)intermetallic compounds(IMCs)at the weld front,along with Al_(11)(Mn,Fe)_(4)and Fe3Al IMCs in the weld middle.The key factors to achieving a high bonding strength of Mg-alloy/steel lap joints have been summarized.This study provides a technical and theoretical reference for the precise collaborative control of joint geometry,interfacial structure,and mechanical properties of dissimilar material lap joints.
文摘An inverse analysis is presented to estimate line heat source in two-dimensional steady-state and transient heat transfer problems.A constant heat source is considered in the steady-state heat transfer problem(a parameter estimation problem)and a time-varying heat source is considered in the transient heat transfer problem(a function estimation problem).Since a general irregular 2D heat conducting body is considered,a body-fitted grid generation is used to mesh the domain.Then governing equations and associated boundary and initial conditions are transformed from the physical domain to the computational domain and finite difference method is used to solve the governing equations to obtain the temperature distribution in the body.Using an efficient,accurate,and very easy to implement sensitivity analysis incorporated in a gradient based minimization method(here,steepest descentmethod),the unknown heat source is estimated accurately.In the function estimation part,it is assumed that there is no prior information on the functional form of the heat source and the estimation process can be performed with a reasonable initial guess for the heat source.The main advantage of the proposed inverse analysis is that the sensitivity matrix(and hence,the objective function gradient with respect to the unknown variables)can be computed during the direct heat transfer solution through newyet simple explicit expressions with no need to solve extra equations such as the sensitivity and adjoint problems and impose additional computational costs comparable to the direct problem solution ones.Some test cases are presented to investigate the accuracy,efficiency,and effect of measurement error on the estimated parameter and function for the line heat source.
基金The National Key Technology R&D Program of Chinaduring the 11th Five-Year Plan Period(No.2008BAJ12B04)China Postdoctoral Science Foundation(No.20090461050)+1 种基金the Project of Researchand Development of Ministry of Housing and Urban-Rural Development ofChina(No.2008-K1-26)the New Century Talent Project of Yangzhou University for Excellent Young Backbone Teacher(2008)
文摘In order to investigate the alternate operation characteristics of a solar-ground source heat pump system（SGSHPS）,various alternate operation modes are put forward and defined.A two-dimensional mathematical model with freezing/melting phase changes is developed for the heat transfer analysis of the soil.Based on the numerical solution of the model,the variation trends of underground soil temperature of the SGSHPS operated in various alternate operation modes are discussed.The results indicate that,for the day-night and short-time interval alternate operation modes without solar energy,the operation time fraction of a solar heat source should be confined to from 50% to 58% when operated in an alternate period of 24 h.Meanwhile,the disadvantages of a natural resumption of soil temperature can be overcome effectively by solar energy filling,and an optimal operation effect can be achieved by integrating the mode of solar energy filling with other alternate modes.In addition,the accuracy of the presented model is verified by the experimental data of borehole wall temperatures.The conclusions can provide a reference for the optimization operation of the SGSHPS.
文摘By reduction to one dimensional, periodic as well as rotating pulse heat sources, investigation on heat transfer characteristics with rotating body is carried out. Similar to the fluid flow, a new set of dimensionless numbers, namely quasi-Peclet numbers Pe 1, Pe 2 and Biot number Bi composed of angular velocity ω , thermophysical parameter, and geometry size are proposed, and applied to the dimensionless equations. Simulation result shows that it plays a decisive role in the process of the heat transfer. However, more important is that the numerical simulation depicts the difference between microcosmic and macroscopic structures of the temperature distribution, and reveals the influence of the relative relation of the dimensionless criterion numbers upon heat transfer characteristics.
基金the auspices of the National!(G1998040800)CAS's Key Project for Basic Research on the Tibetan Plateau! (KZ951-A1-204, KZ95T-
文摘Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data, this paper discusses the interannual variability of the heat regime and its relation to atmospheric circulation It is shown that the interannual variability is pronounced, with maximal variability in spring and autumn, and the variability is heterogeneous horizontally. In the years with the weak (or strong) winter cold source, the deep trough over East Asia is to the east (or west) of its normal, which corresponds to strong (or weak) winter monsoon in East Asia. In the years with the strong (or weak) sum mer heat source, there exists an anomalous cyclone (or anticyclone) in the middle and lower troposphere over the QXP and ifs neighborhood and anomalous southwest (or northeast) winds over the Yangtze River valley of China, corresponding to strong (or weak) summer monsoon in East Asia. The summer heat source of the QXP is related to the intensity and position of the South Asia high. The QXP snow cover condition of April has a close relation to the heating intensity of summer. There is a remarkable negative correlation between the summer heat source of the QXP and the convection over the southeastern QXP, the Bay of Bengal, the Indo-China Peninsula, the southeastern Asia, the southwest part of China and the lower reaches of the Yangtze River and in the area from the Yellow Sea of China to the Sea of Japan.
基金This work was supported by the National Key Program for Developing Basic Research （Grant No. 2004CB418303）the National Natural Science Foundation of China （Grant No. 40175018）.
文摘The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter （namely, mode station variance percentage） based on 1951-2000 summer rainfall data from 160 stations in China. Compared with mode variance friction, the mode station variance percentage not only reveals more localized characteristics of the variability of the summer rainfall, but also helps to distinguish the regions with a high degree of dominant EOF modes representing the analyzed observational variable. The atmospheric circulation diagnostic studies with the NCEP/NCAR reanalysis daily data from 1966 to 2000 show that in summer, abundant （scarce） rainfall in the belt-area from the upper-middle reaches of the Yangtze River northeastward to the Huaihe River basin is linked to strong （weak） heat sources over the eastern Tibetan Plateau, while the abundant （scarce） rainfall in the area to the south of the middle-lower reaches of the Yangtze River is closely linked to the weak （strong） heat sources over the tropical western Pacific.
基金supported by National Key R&D Program of China(Grant No.2018YFB1501803)。
文摘Hot dry rock(HDR)is an important geothermal resource and clean energy source that may play an increasingly important role in future energy management.High-temperature HDR resources were recently detected in deep regions of the Gonghe Basin on the northeastern edge of the Tibetan Plateau,which led to a significant breakthrough in HDR resource exploration in China.This research analyzes the deep temperature distribution,radiogenic heat production,heat flow,and crustal thermal structure in the Qiaboqia Valley,Guide Plain,and Zhacanggou area of the Gonghe Basin based on geothermal exploration borehole logging data,rock thermophysical properties,and regional geophysical exploration data.The results are applied to discuss the heat accumulation mechanism of the HDR resources in the Gonghe Basin.The findings suggest that a low-velocity layer in the thickened crust of the Tibetan Plateau provides the most important source of constant intracrustal heat for the formation of HDR resources in the Gonghe Basin,whereas crustal thickening redistributes the concentrated layer of radioactive elements,which compensates for the relatively low heat production of the basal granite and serves as an important supplement to the heat of the HDR resources.The negative effect is that the downward curvature of the lithospheric upper mantle caused by crustal thickening leads to a small mantle heat flow component.As a result,the heat flows in the Qiaboqia Valley and Guide Plain of the Gonghe Basin are 106.2 and 77.6 m W/m2,respectively,in which the crust-mantle heat flow ratio of the former is 3.12:1,indicating a notably anomalous intracrustal thermal structure.In contrast,the crust-mantle heat flow ratio in the Guide Plain is 1.84:1,which reflects a typical hot crust-cold mantle thermal structure.The Guide Plain and Zhacanggou area show the same increasing temperature trend with depth,which reflects that their geothermal backgrounds and deep high-temperature environments are similar.These results provide important insight on the heat source mechanism of HDR resource formation in the Tibetan Plateau and useful guidance for future HDR resource exploration projects and target sites selection in similar areas.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFB1501801)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2020067)。
文摘It is common sense that a deeper well implies higher temperature in the exploration of deep geothermal resources, especially with hot dry rock(HDR) geothermal resources, which are generally exploited in terms of enhanced geothermal systems(EGS). However, temperature is always different even at the same depth in the upper crust due to different heat sources. This paper summarizes the heat sources and classifies them into two types and five sub-types: crustorigin(partial melting, non-magma-generated tectonic events and radiogenic heat production), and mantle-origin(magma and heat conducted from the mantle). A review of global EGS sites is presented related to the five sub-types of heat sources. According to our new catalog, 71% of EGS sites host mantle-origin heat sources. The temperature logging curves indicate that EGS sites which host mantle-origin magma heat sources have the highest temperature. Therefore, high heat flow(>100 m W/m^(2)) regions with mantle-origin magma heat sources should be highlighted for the future exploration of EGS. The principle to identify the heat source is elucidated by applying geophysical and geochemical methods including noble gas isotope geochemistry and lithospheric thermal structure analysis. This analytical work will be helpful for the future exploration and assessment of HDR geothermal resources.
基金National Key Project of Fundamental Research u SCSMEX" the Research Fund for the Doctoral Program of Higher Education:" Stud
文摘The apparent heat sources (?Q1 ?) and moisture sinks (?Q2 ?) are calculated based on the reanalyzed data of the South China Sea Monsoon Experiment (SCSMEX) from May 1 to August 31, 1998. It is found that the formation and distribution of the atmospheric heat sources are important for the monsoon onset. The earlier onset of the SCS monsoon is the result of enduring atmospheric heating in the Indo–China Peninsula and South China areas. The atmospheric heating firstly appears in the Indo–China Peninsula area and the sensible heat is the major one. The 30–50 day periodic oscillation of atmospheric heat sources between the SCS area and the western Pacific warm pool has a reverse phase distribution before the middle of July and the low frequency oscillation of heat sources in SCS area has an obvious longitudinal propagation. The 30–50 day low frequency oscillation has vital modificatory effects on the summer monsoon evolution during 1998. Key words Apparent heat sources - Apparent moisture sinks - The South China Sea monsoon - Diagnostic Study Sponsored by the National Key Project of Fundamental Research “ SCSMEX” and the Research Fund for the Doctoral Program of Higher Education: “ Study of the Air-sea Interaction in the SCS Monsoon Region”.
基金supported by the the National Natural Science Foundation of China (Grants 91337216 and 41175070)and the Open Project of the Key Laboratory of Meteorological Disaster of Ministry of Education (Grant KLME1309)
文摘As a huge,intense,and elevated atmospheric heat source(AHS) approaching the mid-troposphere in spring and summer,the Tibetan Plateau(TP) thermal forcing is perceived as an important factor contributing to the formation and variation of the Asian summer monsoon.Despite numerous studies devoted to determine the strength and change of the thermal forcing of the TP on the basis of various data sources and methods,uncertainties remain in quantitative estimation of the AHS and will persist for the following reasons:(1) Routine meteorological stations cover only limited regions and show remarkable spatial inhomogeneity with most distributed in the central and eastern plateau.Moreover,all of these stations are situated at an altitude below 5000 m.Thus,the large area above that elevation is not included in the data.(2) Direct observations on heat fluxes do not exist at most stations,and the sensible heat flux(SHF) is calculated by the bulk formula,in which the drag coefficient for heat is often treated as an empirical constant without considering atmospheric stability and thermal roughness length.(3) Radiation flux derived by satellite remote sensing shows a large discrepancy in the algorithm in data inversion and complex terrain.(4) In reanalysis data,besides the rare observational records employed for data assimilation,model bias in physical processes induces visible errors in producing the diabatic heating fields.
基金supported by the National Natural Science Foundation of China(Grant Nos. 40633018 and 40675036)
文摘NCEP/NCAR reanalysis data and a 47-year precipitation dataset are utilized to analyze the relationship between an atmospheric heat source （hereafter called 〈 Q1 〉） over the Qinghai-Xizang Plateau （QXP） and its surrounding area and precipitation in northwest China. Our main conclusions are as follows： （1） The horizontal distribution of 〈 Q1 〉 and its changing trend are dramatic over QXP in the summer. There are three strong centers of 〈 Q1 〉 over the south side of QXP with obvious differences in the amount of yearly precipitation and the number of heat sinks predominate in the arid and semi-arid regions of northwest China （NWC）, beside the northern QXP with an obvious higher intensity in years with less precipitation. （2） In the summer, the variation of the heat source＇s vertical structure is obviously different between greater and lesser precipitation years in eastern northwest China （ENWC）. The narrow heat sink belt forms between the northeast QXP and the southwestern part of Lake Baikal. In July and August of greater precipitation years, the heating center of the eastern QXP stays nearly over 35°N, and at 400 hPa of the eastern QXP, the strong upward motion of the heating center constructs a closed secondary vertical circulation cell over the northeast QXP （40~ 46~N）, which is propitious to add precipitation over the ENWC. Otherwise, the heating center shifts to the south of 30°N and disappears in July and August of lesser precipitation years, an opposite secondary circulation cell forms over the northeast QXP, which is a disadvantage for precipitation. Meanwhile, the secondary circulation cell in years with more or less precipitation over the ENWC is also related to the heat source over the Lake Baikal. （3） The vertical structure of the heat source over the western QXP has obvious differences between greater and lesser precipitation years in western northwest China in June and July. The strong/weak heat source over the western QXP produces relatively strong/weak ascending motion and correspondingly constructs a secondary circulation cell in lesser/greater precipitation years.
