|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | Principle of equipartition of entransy dissipation for heat exchanger design显示文摘In the present work,a principle of equipartition of entransy dissipation(EoED) for heat exchanger design is established,which says that for a heat exchanger design with given heat duty and heat transfer area,the total entransy dissipation rate reaches the minimum when the local entransy dissipation rate is uniformly distributed along the heat exchanger.When the heat transfer coefficient is unfixed,the total entransy dissipation obtained by the EoED principle is less than that obtained by the principle of equipartition of temperature difference(EoTD).Furthermore,the exchanger effectiveness obtained by the EoED principle is larger than that obtained by the EoTD principle.When the heat transfer coefficient is fixed,the EoED principle is equivalent to the EoTD principle.We show that the equipartition of entropy production(EoEP) and EoED principles give rise to difference in entropy generation and entransy dissipation for a heat exchanger optimization design.The discrepancies are caused by distinct features of entropy production minimization and entransy dissipation minimization principles,the former is to optimize the design of heat exchanger by making the lost available work minimum,while the latter is not involved with heat-work conversion.It is found that the entropy generation number is not suitable for evaluating heat exchanger performance,since it directly depends on the inlet and outlet temperatures of working fluids.On the contrary,the entransy dissipation number is not directly related to the inlet and outlet temperatures of working fluids.Therefore,the entransy dissipation number is more suitable for serving as a criterion to evaluate heat exchanger performance. | GUO JiangFeng,XU MingTian & CHENG Lin Institute of Thermal Science and Technology,Shandong University,Jinan 250061,China | 2010 | Science China(Technological Sciences)2010，53，5： | 46 |
| 2 | Modeling on Heat and Mass Transfer in Stored Wheat during Forced Cooling Ventilation显示文摘A mathematical model based on the theory of heat and mass transfer in porous media was developed to simulate the evolution of grain temperature and moisture content in a wheat storage bin during ventilation with cooling air at the constant temperature and humidity.Unlike the previous works on this aspect,the present work was not focused on cooling the stored grain by ventilation with ambient air,but with the refrigerated air.Validation was performed by comparing between predicted and measured grain temperature and grain moisture content for two cases.Predicted data were in reasonable good agreement with measured ones.The model and the parameter values used in the model are applicable for predicting temperature and moisture of stored grains under ventilation conditions. | Yuancheng WANG,Haifeng DUAN,Hao ZHANG and Zhaohong FANG College of Thermal Energy Engineering,Shandong Jianzhu University,Jinan 250101,China | 2010 | Journal of Thermal Science2010，19，2： | 27 |
| 3 | Comparative analysis of CO_2-based transcritical Rankine cycle and HFC245fa-based subcritical organic Rankine cycle using low-temperature geothermal source显示文摘A detailed thermodynamic and techno-economic comparison is presented for a CO2-based transcritical Rankine cycle and a subcritical organic Rankine cycle (ORC) using HFC245fa (1,1,1,3,3-pentafluoro-propane) as the working fluid driven by the low-temperature geothermal source,in order to determine the configuration that presents the maximum net power output with a minimum investment.The evaluations of both Rankine cycles have been performed based on equal thermodynamic mean heat rejection temperature by varying certain system operating parameters to achieve each Rankine cycle's optimum design at various geothermal source temperature levels ranging from 80oC to 120oC.The results obtained show that the optimum ther-modynamic mean heat injection temperatures of both Rankine cycles are distributed in the scope of 55% to 65% of a given geothermal source temperature level,and that the CO2-based transcritical Rankine cycle presents 3% to 7% higher net power output,84% reduction of turbine inlet volume flow rate,47% reduction of expansion ratio and 1.68 times higher total heat transfer capacity compared with the HFC245fa-based subcritical ORC.It is also indicated that using the CO2-based transcritical system can reduce the dimension of turbine design.However,it requires larger heat transfer areas with higher strength heat exchanger materials because of the higher system pressure. | GUO Tao,WANG HuaiXin & ZHANG ShengJun Department of Thermal Energy and Refrigeration Engineering,Tianjin University,Tianjin 300072,China | 2010 | Science China(Technological Sciences)2010，53，6： | 26 |
| 4 | Investigation of heavy metal partitioning influenced by flue gas moisture and chlorine content during waste incineration显示文摘The impact of moisture on the partitioning of the heavy metals including Pb,Zn,Cu and Cd in municipal solid waste (MSW) was studied in a laboratory tubular furnace.A thermodynamic investigation using CHEMKIN software was performed to compare the experimental results.Simulated waste,representative of typical MSW with and without chlorine compounds,was burned at the background temperature of 700 and 950°C,respectively.In the absence of chlorine,the moisture content has no evident effect on the volatility of Pb,Zn and Cu at either 700 or 950°C,however,as flue gas moisture increasing the Cd distribution in the bottom ash increased at 700°C and reduced at 950°C,respectively.In the presence of chlorine,the flue gas moisture reduced the volatility of Pb,Zn and Cu due to the transformation of the more volatile metal chlorides into less volatile metal oxides,and the reduction became significant as chlorine content increase.For Cd,the chlorine promotes its volatility through the formation of more volatile CdCl 2.As a result,the increased moisture content increases the Pb,Zn,Cu and Cd concentrations in the bottom ash,which limits the utilization of the bottom ash as a construction material.Therefore,in order to accumulate heavy metals into the fly ash,MSW should be dried before incineration. | Qinghai Li,Aihong Meng,Jinyan Jia,Yanguo Zhang Department of Thermal Engineering,Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education of China,Tsinghua University,Beijing 100084,China. | 2010 | Journal of Environmental Sciences2010，22，5： | 24 |
| 5 | Investigations on an Axial Flow Fan Stage subjected to Circumferential Inlet Flow Distortion and Swirl显示文摘The combined effects of swirl and circumferential inlet flow distortion on the flow field of an axial flow fan stage are reported in this paper. The study involves measurements at the inlet of the rotor and exit of the rotor and stator at design and off design now conditions. The study indicated that at the design flow condition, swirl had caused deterioration of the performance in addition to that caused by distortfou. Pressure rise imparted in the distortion zone is higher than in the free zone. The attenuation of distortion is high in the presence of swirl. | M. Govardhan K. Viswanath (Thermal Turbomachines Laboratory Department of Mechanical Engineering, Indian Institute of Technology, Madras 600 036, India ) | 1997 | Journal of Thermal Science1997，6，4： | 20 |
| 6 | Emission characteristics of dioxins,furans and polycyclic aromatic hydrocarbons during fluidized-bed combustion of sewage sludge显示文摘Pre-dried sewage sludge with high sulfur content was combusted in an electrically heated lab-scale fluidized-bed incinerator. The emission characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polycyclic aromatic hydrocarbons (PAHs) were studied. Coal and calcium oxide (CaO) were added during the sewage sludge combustion tests to optimize combustion conditions and control SO2 emission. The results indicated that the flue gases emitted during mono-combustion of sewage sludge were characterized by relatively high concentrations of SO2, NOx and organic pollutants, due to the high sulfur, nitrogen, and volatile matter content of sewage sludge. The total 16 USEPA priority PAHs and 2,3,7,8-substituted PCDD/Fs produced from sewage sludge combustion were found to be 106.14 μg/m3 and 8955.93 pg/m3 in the flue gas, respectively. In the case of co- combustion with coal (msludge/mcoal = 1:1), the 16 PAHs and 2,3,7,8-substituted PCDD/Fs concentrations were markedly lower than those found during mono-combustion of sewage sludge. During co-combustion, a suppressant effect of CaO on PCDD/Fs formation was observed. | DENG Wenyi, YAN Jianhua, LI Xiaodong, WANG Fei, CHI Yong, LU ShengyongState Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China. | 2009 | Journal of Environmental Sciences2009，21，12： | 17 |
| 7 | Hydraulic design and pre-whirl regulation law of inlet guide vane for centrifugal pump显示文摘A new hydraulic design method of three-dimensional guide vane for centrifugal pump is proposed on the assumption that the fluid at the outlet of guide vane satisfies the uniform velocity moment condition.The geometry of blade is controlled by the distributed rule of blade angles along the meridional streamline which is described by a fourth-order polynomial.Experiment results demonstrate that the designed guide vane can overcome the drawback of two-dimensional guide vane,enlarge the high efficiency scope and improve the hydraulic performance of centrifugal pump on the off-design operation conditions.In comparison with the performance of the centrifugal pump without inlet guide vane,the peak value of efficiency can be enhanced by 2.13% after the three-dimensional guide vane was being installed.The three-dimensional entire flow field of the centrifugal pump with inlet guide vane is simulated,and the basic principle and mechanism of inlet guide vane pre-whirl regulation are analyzed.The validity of design method has been proved. | TAN Lei ,CAO ShuLiang&GUI ShaoBo State Key Laboratory of Hydroscience and Engineering,Department of Thermal Engineering,Tsinghua University,Beijing 100084,China | 2010 | Science China(Technological Sciences)2010，53，8： | 14 |
| 8 | Transient Free Convection and Thermal Stratification in Uniformly-Heated Partially-Filled Horizontal Cylindrical and Spherical Vessels显示文摘Anintegral approach has been used to analyze the development of the free convection boundary layer on heated concave surfaces,such as those in horizontal cylinders or a sphere,Based on the non-dimensional laminar and turbulent velocity and temperature profiles closed form expressions for the boundary layer thickness,velocity scale as well as the boundary layer commencement after the point of instability are obtained.In addition,the mass flowrate to the thermal stratified rgeion is given. | C.M.Yu Professor,Department of Thermal Engineering,University of Science and Technology Beijing,Beijing 100083,ChinaN.U.Aydemir Atomic Energy of Canada Limited,Whiteshell Nuclear Research Establishment,Pinawa,Manitoba,ROE 1LO,CanadaJ.E.S.Venart Fire Science Centre,University of New Brunswick,P.O.Box 4400,Fredericton,NB E3B 5A3,Canada | 1992 | Journal of Thermal Science1992，1，2： | 13 |
| 9 | 我国城市集中供热发展概况显示文摘概述了中国城市热电联产、集中供热锅炉房和供热输配系统的现状,对集中供热规模、能源利用率和热电联产的发展提出了一些建议。 | Thermal Engineering Specialized Committee of the Chinese Power Engineering Society. . | 1997 | 动力工程1997，17，5： | 10 |
| 10 | Self-aggregation of vapor-liquid phase transition显示文摘The concept of the molecular free path is introduced to derive a criterion distinguishing active molecules from inactive molecules in liquid phase. Based on molecular self-aggregation theory a concept of the critical aggregation concentration (CAC) of active molecules is proposed to describe the physical configuration before the formation of the nuclei in the process of vapor-liquid phase transition. All active molecules exist in the form of the monomer when the concentration of active molecules is lower than CAC, while the active molecules will generate aggregation once the concentration of the active molecules reaches CAC. However, these aggregates with the aggregation number N smaller than 5 can steadily exist in bulk phase. The other excess active molecules can only produce infinite aggregation and form a critical nucleus of vapor-liquid phase transition. Without outer perturbation the state point of CAC corresponds to the critical superheated or supercooled state in the process of vapor-liquid phase transition. With the aggregate property, the interfacial tension between the bulk phase and the tiny new phase is predicted and a correction is made for the classical nucleation rate in a quite good agreement with experimental results. | WANG Xiaodong, TIAN Yong and PENG Xiaofeng(Department of Thermal Engineering, Tsinghua University, Beijing 100084, China) | 2003 | Progress in Natural Science:Materials International2003，13，6： | 9 |
| 11 | THE METHOD OF SEMI-FALSE TRANSIENT FOR COMPUTING THE FLOW INTO POROUS MEDIUM IN THE CIRCULAR PIPE显示文摘The method of semi-false transient was used to numerically compute the incompressible steady flow into the porous medium in this paper. The fundamental equations were established and numerically solved in the united flow field, which included the space region and the porous region. The non-equidistant non-orthogonal semi-staggered mesh system was used in the method of semi-false transient. The computational results of two problems concerning the flow into porous medium from space region, in which there was the backward flow besides main flow, were obtained and discussed. It is seen from the results that the backward flow is generally not present in the porous medium as the osmotic resistance is very large. | Chen Jin-e Department of Thermal Power Engineering, Shanghai University of Electric Power, Shanghai 200090, China Jiang Jin-liang Department of Information and Computing Science, Shanghai University of Electric Power, Shanghai 200090, China | 2002 | Journal of Hydrodynamics2002，14，2： | 7 |
| 12 | Experimental and Numerical Investigation of Enhancement of Heat and Mass Transfer in Adsorbent Beds显示文摘ExperimentalandNumericalInvestigationofEnhancementofHeatandMassTransferinAdsorbentBedsLiuZhenyan;FuZhuman;GeXinshi;SuYuehong;... | Liu Zhenyan Fu Zhuman Ge Xinshi Su Yuehong Wang Yongtang (Department of Thermal Science and Energy Engineering, University of Science and Technology of China,Hefei, Anhui, 230026, China) | 1994 | Journal of Thermal Science1994，3，3： | 7 |
| 13 | An exploration for the macroscopic physical meaning of entropy显示文摘The macroscopic physical meaning of entropy is analyzed based on the exergy (availability) of a combined system (a closed system and its environment), which is the maximum amount of useful work obtainable from the system and the environment as the system is brought into equilibrium with the environment. The process the system experiences can be divided in two sequent sub-processes, the process at constant volume, which represents the heat interaction of the system with the environment, and the adiabatic process, which represents the work interaction of the system with the environment. It is shown that the macroscopic physical meaning of entropy is a measure of the unavailable energy of a closed system for doing useful work through heat interaction. This statement is more precise than those reported in prior literature. The unavailability function of a closed system can be defined as T0S and p0V in volume constant process and adiabatic process, respectively. Their changes, that is, AiTgS) and A (p0V) represent the unusable parts of the internal energy of a closed system for doing useful work in corresponding processes. Finally, the relation between Clausius entropy and Boltzmann entropy is discussed based on the comparison of their expressions for absolute entropy. | WU Jing1 & GUO ZengYuan2 1 College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China 2 Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, School of Aerospace, Tsinghua University, Beijing 100084, China | 2010 | Science China(Technological Sciences)2010，53，7： | 6 |
| 14 | Numerical study on optical and electric-thermal performance for solar concentrating PV/T air system显示文摘Hybrid photovoltaic/thermal(PV/T)system with solar concentrator is an effective way to improve solar energy conversion efficiency.In this work,a single-pass PV/T air system with a three-trough compound parabolic concentrator(CPC)of concentration ratio 2.0 is designed and the solar incident distributions at the solar cell surface are calculated by ray tracing method.Based on energy balance,the heat transfer models of all main components in this system are developed.The effects of some main designing and operational parameters on the electric-thermal performance of the system are analyzed. The results show that the solar radiation intensity can be higher than 1200 W/m 2 at most area of the cell surface.The temperature of the air and cell surface increases along the length of the system.Thus the system efficiency of the CPC is higher than that of the system without the CPC.The thermal efficiency, exergy and electrical efficiency of this CPC system increase with increasing of the air mass flow rate and the length of the system.With increasing packing fraction the electrical efficiency increases,but the thermal efficiency decreases.The exergy efficiency increases slightly with the packing fraction rising.The data obtained in this work are valuable for the design and operation for this kind of solar concentrating PV/T systems. | SUN Jian 1,2 &SHI MingHeng 1 1School of Energy and Environment,Southeast University,Nanjing 210096,China 2Department of Thermal Energy Engineering,Jingdezhen Ceramic Institute,Jingdezhen 333001,China | 2009 | Science China(Technological Sciences)2009，52，12： | 5 |
| 15 | Experimental study on drying of typical MSW under incinerator-like conditions显示文摘In this paper, a series of experiments were conducted to investigate the drying of typical municipal solid wastes (MSW) in a muffle incinerator. From the experimental drying characteristic curves, the effects of temperature on drying process were observed to be more obvious in the low temperature region than in the high tem- perature region in muffle incinerator. At a specified drying temperature, drying time was highly dependent upon the packed waste thickness, having an exponent rela- tion with the thickness. When the drying temperature increased or the thickness of potato bulks was diminished, the maximum drying rate reduced. Based on the first-order reaction, activation energy (Ea), and factor A of potato and cabbage were determined. | ZHANG YanGuo1, CHEN MeiQian2, MENG AiHong1, LI QingHai1 & CHEN YunXuan2 1 Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China 2 School of Mechanical, Electronical and Control Engineering, Beijing Jiaotong University, Beijing 100044, China | 2007 | Science China(Technological Sciences)2007，50，5： | 5 |
| 16 | A Cold Model Experimental Study on the Flow Characteristics of Bed Material in a Fluidized Bed Bottom Ash Cooler in a CFB Boiler显示文摘A cold model experimental study on the flowing characteristics of bed material between a fluidized bed ash cooler and a furnace of CFB boiler were discussed in this paper. The research results showed that flowing status of the bed material in a bubbling bed, which was run with a circulating fluidized bed together in parallel operation, was influenced by the pressure difference between the CFB and the bubbling bed, the switch status of unlocking air, and the structure of the exit of the bubbling bed. There was a circulating flow of bed material between CFB and bubbling bed. | Lu Xiaofeng,Li Yourong (Institute of Thermal Energy Engineering, Chongqing University, Chongqing, 400044, China) | 2000 | Journal of Thermal Science2000，9，4： | 5 |
| 17 | THERMAL CONDUCTIVITY OF THF CLATHRATE HYDRATE FROM 243 K TO 263 K显示文摘Using transient plane source technique, we measured THF hydrate thermal conductivity from 243 K to 263 K. The sample THF solution is over saturated in order to avoid the effect of ice. And also to avoid the effect of crystal anisotropy, the THF hydrate was crushed to measure. In the test temperature value increases with the temperature increasing. | HUANG Duzi~(1,2) and FAN Shuanshi~1(~1Center for Gas Hydrate, Guangzhou Institute of Energy Conversion, CAS, Guangzhou, 510070, Guangdong, China ~2 Department of Thermal Science & Energy Engineering, USTC, Hefei, 230036, Anhui, China) | 2003 | 化工学报2003，54，z1： | 5 |
| 18 | Working fluids of a low-temperature geothermally-powered Rankine cycle for combined power and heat generation system显示文摘A novel combined power and heat generation system was investigated in this study. This system consists of a low-temperature geothermally-powered organic Rankine cycle (ORC) subsystem, an intermediate heat exchanger and a commercial R134a-based heat pump subsystem. The advantages of the novel combined power and heat generation system are free of using additional cooling water circling system for the power generation subsystem as well as maximizing the use of thermal energy in the low-temperature geothermal source. The main purpose is to identify suitable working fluids (wet, isentropic and dry flu-ids) which may yield high PPR (the ratio of power produced by the power generation subsystem to power consumed by the heat pump subsystem) value and QQR (the ratio of heat supplied to the user to heat produced by the geothermal source) value. Parameters under investigation were evaporating temperature, PPR value and QQR value. Results indicate that there exits an optimum evaporating temperature to maximize the PPR value and minimize the QQR value at the same time for individual fluid. And dry fluids show higher PPR values but lower QQR values. NH3 and R152a outstand among wet fluids. R134a out-stands among isentropic fluids. R236ea, R245ca, R245fa, R600 and R600a outstand among dry fluids. R236ea shows the highest PPR value among the recommended fluids. | GUO Tao*, WANG HuaiXin & ZHANG ShengJun Department of Thermal Energy and Refrigeration Engineering, Tianjin University, Tianjin 300072, China | 2010 | Science China(Technological Sciences)2010，53，11： | 4 |
| 19 | Optimization of a serpentine flow field with variable channel heights and widths for PEM fuel cells显示文摘The present study proposes a modified serpentine flow field design in which the channel heights vary along each straight flow path to enhance reactant transport and liquid water removal. An optimization approach, combining a simplified conjugate-gradient method (inverse solver) and a three-dimensional, two-phase, non-isothermal fuel cell model (direct solver), has been developed to optimize the key geometric parameters. The optimal design has tapered channels for channels 1, 3 and 4 and increasing heights for channels 2 and 5 with the flow widths first increasing and then decreasing. The optimal channel heights and widths enhance the efficiency by 22.51% compared with the basic design having all heights and widths of 1 mm. The diverging channels have a greater impact on cell performance than fine adjustments of the channel widths for the present simulation conditions. The channel heights have more effect on the sub-rib convection, while the channel widths affect the uniformity of the fuel delivery more. The reduced channel heights of channels 2–4 significantly enhance the sub-rib convection to effectively transport oxygen to and liquid water out of the diffusion layer. The final diverging channel prevents significant leakage of fuel to the outlet via sub-rib convection. | LIN Lin, ZHANG XinXin, FENG HuTing & WANG XiaoDong Department of Thermal Engineering, School of Mechanical Engineering, University of Science and Technology Beijing, Bejing 100083, China | 2010 | Science China(Technological Sciences)2010，53，2： | 4 |
| 20 | Numerical investigation on hydrogen production by CH_4-Rich combustion in an alumina foam显示文摘The two-phase volume-averaged model with the detailed chemistry reaction mechanism GRI 3.0 was adopted in the quasi-steady-state simulation of hydrogen production by CH4-rich filtration combustion in an alumina foam under fully developed conditions. The relations among the combustion wave velocity, the inlet gas velocity and the equivalence ratio were discussed, and their influences on the distributions of temperature and species in the alumina foam and on H2 yield, CH4 conversion, H2 selectivity and CO selectivity were analyzed in detail. The results show that the combustion wave velocity increases with the increase of equivalence ratio or inlet gas velocity. The H2 yield exceeded 50% with equivalence ratio between 2.0 and 3.0 and combustion wave velocity larger than 0.4 mm/s. The H2 selectivity exceeded 50% with equivalence ratio larger than 2.0 and CO selectivity exceeded 80% with equivalence ratio between 1.8 and 2.0 and combustion wave velocity larger than 0.4 mm/s. | ZHAO PingHui, YE TaoHong, ZHU MinMing, JIANG Hai & CHEN YiLiang Thermal Science & Energy Engineering Department, University of Science & Technology of China, Hefei 230027, China | 2009 | Science China(Technological Sciences)2009，52，10： | 3 |
您所在的机构暂未开通此部分的功能，请联系管理员