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Modeling water and heat transfer in soil-plant-atmosphere continuum applied to maize growth under plastic

Meng DUAN, Jin XIE, Xiaomin MAO

《农业科学与工程前沿（英文）》 2019年第6卷第2期页码 144-161 doi: 10.15302/J-FASE-2019258

摘要：

Based on our previous work modeling crop growth (CropSPAC) and water and heat transfer in the soil-plant-atmosphere continuum (SPAC), the model was improved by considering the effect of plastic film mulching applied to field-grown maize in North-west China. In CropSPAC, a single layer canopy model and a multi-layer soil model were adopted to simulate the energy partition between the canopy and water and heat transfer in the soil, respectively. The maize growth module included photosynthesis, growth stage calculation, biomass accumulation, and participation. The CropSPAC model coupled the maize growth module and SPAC water and heat transfer module through leaf area index (LAI), plant height and soil moisture condition in the root zone. The LAI and plant height were calculated from the maize growth module and used as input for the SPAC water and heat transfer module, and the SPAC module output for soil water stress conditions used as an input for maize growth module. We used , the representation of evaporation resistance, instead of the commonly used evaporation resistance to reflect the change of latent heat flux of soil evaporation under film mulching as well as the induced change in energy partition. The model was tested in a maize field at Yingke irrigation area in North-west China. Results showed reasonable agreement between the simulations and measurements of LAI, above-ground biomass and soil water content. Compared with the original model, the modified model was more reliable for maize growth simulation under film mulching and showed better accuracy for the LAI (with the coefficient of determination = 0.92, the root mean square of error RMSE= 1.23, and the Nush-Suttclife efficiency E = 0.87), the above-ground biomass (with = 0.96, RMSE= 7.17 t·ha and E = 0.95) and the soil water content in 0–1 m soil layer (with = 0.78, RMSE= 49.44 mm and E = 0.26). Scenarios were considered to simulate the influence of future climate change and film mulching on crop growth, soil water and heat conditions, and crop yield. The simulations indicated that the change of LAI, leaf biomass and yield are negatively correlated with temperature change, but the growing degree-days, evaporation, soil water content and soil temperature are positively correlated with temperature change. With an increase in the ratio of film mulching area, the evaporation will decrease, while the impact of film mulching on crop transpiration is not significant. In general, film mulching is effective in saving water, preserving soil moisture, increasing soil surface temperature, shortening the potential growth period, and increasing the potential yield of maize.

关键词： film mulching growth stage leaf area index maize growth water and heat transfer

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Heat and mass transfer of ammonia-water in falling film evaporator

Xianbiao BU, Weibin MA, Huashan LI

《能源前沿（英文）》 2011年第5卷第4期页码 358-366 doi: 10.1007/s11708-011-0161-y

摘要： To investigate the performance of heat and mass transfer of ammonia-water during the process of falling film evaporation in vertical tube evaporator, a mathematical model of evaporation process was presented, the solution of which that needed a coordinate transformation was based on stream function. The computational results from the mathematical model were validated with experimental data. Subsequently, a series of parameters, such as velocity, film thickness and concentration, etc., were obtained from the mathematical model. Calculated results show that the average velocity and the film thickness change dramatically at the entrance region when <100 mm, while they vary slightly with the tube length in the fully developed region when >100 mm. The average concentration of the solution reduces along the tube length because of evaporation, but the reducing tendency becomes slow. It can be concluded that there is an optimalβrelationship between the tube length and the electricity generated. The reason for the bigger concentration gradient in the direction is that the smooth tube is chosen in the calculation. It is suggested that the roll-worked enhanced tube or other enhanced tube can reduce the concentration gradient in the film thickness direction and enhance the heat and mass transfer rate.

关键词： falling film evaporation ammonia-water heat and mass transfer

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Heat transfer with water flowing upward in a tube for pressures up to supercritical region

Yuzhou CHEN, Chunsheng YANG, Shuming ZHANG, Minfu ZHAO, Kaiwen DU,

《能源前沿（英文）》 2010年第4卷第3期页码 358-365 doi: 10.1007/s11708-009-0071-4

摘要： A heat transfer experiment was conducted in a tube of 6.07mm in diameter with water flowing upward, covering the ranges of pressure of 10―23MPa, mass flux of 288―1298kg/(m·s), local water temperature of 78°C―270°C, heat flux of 0.23―1.18MW/m and Reynolds number of 5.5×10―3.9×10. The experimental results were compared with the predictions of the Dittus-Boelter correlation, Jackson correlation, Bishop correlation, Swenson correlation and Yamagata correlation. Significant deterioration in heat transfer was observed in both subcritical and supercritical region due to the effect of buoyancy force, but it was not predicted reasonably by the existing correlations.

关键词： heat transfer deterioration buoyancy supercritical water

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Natural convection heat transfer of water in a horizontal circular gap

SU Guanghui, WU Yingwei, Kenichiro Sugiyama

《能源前沿（英文）》 2007年第1卷第2期页码 167-173 doi: 10.1007/s11708-007-0021-y

摘要： An experimental study on the natural convection heat transfer on a horizontal downward facing heated surface in a water gap was carried out under atmospheric pressure conditions. A total of 700 experimental data points were correlated using Rayleigh versus Nusselt number in various forms, based on different independent variables. The effects of different characteristic lengths and film temperatures were discussed. The results show that the buoyancy force acts as a resistance force for natural convection heat transfer on a downward facing horizontal heated surface in a confined space. For the estimation of the natural convection heat transfer under the present conditions, empirical correlations in which Nusselt number is expressed as a function of the Rayleigh number, or both Rayleigh and Prandtl numbers, may be used. When it is accurately predicted, the Nusselt number is expressed as a function of the Rayleigh and Prandtl numbers, as well as the gap width-to-heated surface diameter ratio; and uses the temperature difference between the heated surface and the ambient fluid in the definition of Rayleigh number. The characteristic length is the gap size and the film temperature is the average fluid temperature.

关键词： function diameter different independent different characteristic horizontal downward

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Augmentation of natural convective heat transfer by acoustic cavitation

Jun CAI, Xiulan HUAI, Shiqiang LIANG, Xunfeng LI,

《能源前沿（英文）》 2010年第4卷第3期页码 313-318 doi: 10.1007/s11708-009-0064-3

摘要： An experimental study was conducted to investigate the effects of acoustic cavitation on natural convective heat transfer from a horizontal circular tube. The experimental results indicated that heat transfer could be enhanced by acoustic cavitation and had the best effect when the head of the ultrasonic transducer was over the midpoint of the circular tube, and the distance between the head and the tube equaled 15 mm. The augmentation at low heat flux was better than that in the case of high heat flux. Based on experimental results, the correlation formula of Nusselt number for water was obtained.

关键词： heat transfer enhancement augmentation acoustic cavitation acoustic streaming convective heat transfer

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Experimental study of heat transfer coefficient with rectangular baffle fin of solar air heater

Foued CHABANE,Nesrine HATRAF,Noureddine MOUMMI

《能源前沿（英文）》 2014年第8卷第2期页码 160-172 doi: 10.1007/s11708-014-0321-y

摘要： This paper presents an experimental analysis of a single pass solar air collector with, and without using baffle fin. The heat transfer coefficient between the absorber plate and air can be considerably increased by using artificial roughness on the bottom plate and under the absorber plate of a solar air heater duct. An experimental study has been conducted to investigate the effect of roughness and operating parameters on heat transfer. The investigation has covered the range of Reynolds number from 1259 to 2517 depending on types of the configuration of the solar collectors. Based on the experimental data, values of Nusselt number have been determined for different values of configurations and operating parameters. To determine the enhancement in heat transfer and increment in thermal efficiency, the values of Nusselt have been compared with those of smooth duct under similar flow conditions.

关键词： Nusselt number flow rate heat transfer heat transfer coefficient thermal efficiency forced convection

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Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over

Krishnendu Bhattacharyya

《化学科学与工程前沿（英文）》 2011年第5卷第3期页码 376-384 doi: 10.1007/s11705-011-1121-0

摘要： In this paper, an investigation is made to study the effects of radiation and heat source/sink on the unsteady boundary layer flow and heat transfer past a shrinking sheet with suction/injection. The flow is permeated by an externally applied magnetic field normal to the plane of flow. The self-similar equations corresponding to the velocity and temperature fields are obtained, and then solved numerically by finite difference method using quasilinearization technique. The study reveals that the momentum boundary layer thickness increases with increasing unsteadiness and decreases with magnetic field. The thermal boundary layer thickness decreases with Prandtl number, radiation parameter and heat sink parameter, but it increases with heat source parameter. Moreover, increasing unsteadiness, magnetic field strength, radiation and heat sink strength boost the heat transfer.

关键词： MHD boundary layer unsteady flow heat transfer thermal radiation heat source/sink shrinking sheet suction/injection

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Effect of heat transfer space non-uniformity of combustion chamber components on in-cylinder heat transfer

Jizu LV, Minli BAI, Long ZHOU, Jian ZHOU,

《能源前沿（英文）》 2010年第4卷第3期页码 392-401 doi: 10.1007/s11708-009-0066-1

摘要： Combustion chamber components (cylinder head-cylinder liner-piston assembly-oil film) were treated as a coupled body. Based on the three-dimensional numerical simulation of the heat transfer of the coupled body, a coupled three-dimensional calculation model for the in-cylinder working process and the combustion chamber components was built with domain decomposition and boundary coupling method, which adopts the coupled three-dimensional simulation of in-cylinder working process and the combustion chamber components. The model was applied in the investigation of the influence of space non-uniformity in heat transfer among combustion chamber components on in-cylinder heat transfer. The results show that the effect of wall temperature space non-uniform distribution of combustion chamber components on heat transfer happens mainly at the end of the compression stroke and expansion stroke. Therefore, it can be concluded that wall temperature space non-uniform distribution of combustion chamber components would influence heat transfer during the intake and exhaust stroke obviously.

关键词： heat transfer space non-uniformity soot emission in-cylinder diesel

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Review of the LNG intermediate fluid vaporizer and its heat transfer characteristics

《能源前沿（英文）》 2022年第16卷第3期页码 429-444 doi: 10.1007/s11708-021-0747-y

摘要： The intermediate fluid vaporizer (IFV), different from other liquefied natural gas (LNG) vaporizers, has many advantages and has shown a great potential for future applications. In this present paper, studies of IFV and its heat transfer characteristics in the LNG vaporization unit E2 are systematically reviewed. The research methods involved include theoretical analysis, experimental investigation, numerical simulation, and process simulation. First, relevant studies on the overall calculation and system design of IFV are summarized, including the structural innovation design, the thermal calculation model, and the selection of different intermediate fluids. Moreover, studies on the fluid flow and heat transfer behaviors of the supercritical LNG inside the tubes and the condensation heat transfer of the intermediate fluid outside the tubes are summarized. In the thermal calculations of the IFV, the selections of the existing heat transfer correlations about the intermediate fluids are inconsistent in different studies, and there lacks the accuracy evaluation of those correlations or comparison with experimental data. Furthermore, corresponding experiments or numerical simulations on the cryogenic condensation heat transfer outside the tubes in the IFV need to be further improved, compared to those in the refrigeration and air-conditioning temperature range. Therefore, suggestions for further studies of IFV are provided as well.

关键词： intermediate fluid vaporizer design of structure and intermediate fluid condensation heat transfer

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A new heat transfer correlation for supercritical fluids

Yanhua YANG, Xu CHENG, Shanfang HUANG

《能源前沿（英文）》 2009年第3卷第2期页码 226-232 doi: 10.1007/s11708-009-0022-0

摘要： A new method of heat transfer prediction in supercritical fluids is presented. Emphasis is put on the simplicity of the correlation structure and its explicit coupling with physical phenomena. Assessment of qualitative behaviour of heat transfer is conducted based on existing test data and experience gathered from open literature. Based on phenomenological analysis and test data evaluation, a single dimensionless number, the acceleration number, is introduced to correct the deviation of heat transfer from its conventional behaviour, which is predicted by the Dittus-Boelter equation. The new correlation structure excludes direct dependence of heat transfer coefficient on wall surface temperature and eliminates possible numerical convergence. The uncertainty analysis of test data provides information about the sources and the levels of uncertainties of various parameters and is highly required for the selection of both the dimensionless parameters implemented into the heat transfer correlation and the test data for the development and validation of new correlations. Comparison of various heat transfer correlations with the selected test data shows that the new correlation agrees better with the test data than other correlations selected from the open literature.

关键词： super critical fluids heat transfer circular tubes prediction method

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Analysis of flow and heat transfer characteristics of porous heat-storage wall in greenhouse

OUYANG Li, LIU Wei

《能源前沿（英文）》 2008年第2卷第4期页码 406-409 doi: 10.1007/s11708-008-0094-2

摘要： The flow and heat transfer characteristics of porous heat-storage wall in greenhouse are studied by using the one-dimensional steady energy two-equation model for saturated porous medium. The results show that the heat exchange between the air and the solid matrix of the porous heat-storage wall depends upon the inlet air velocity, the porosity and the permeability of porous medium, and the thermal conductivity of the solid matrix. Because the incidence of solar radiation on the porous heat-storage wall is not uniform, the new composite porous solar wall with different porosity is proposed to reduce the disadvantageous effect.

关键词： incidence thermal conductivity heat-storage exchange composite

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Heat transfer characteristics of high heat flux vapor chamber

Dongchuan MO, Shushen LU, Haoliang ZHENG, Chite CHIN,

《能源前沿（英文）》 2010年第4卷第2期页码 166-170 doi: 10.1007/s11708-009-0076-z

摘要： To meet the challenge of heat spreading in electronic products, highly efficient high heat flux heat transfer vapor chambers have been manufactured and their heat transfer characteristics have been studied by a fast test system. A solid copper block with the same shape as the vapor chamber is used to compare the performance of the vapor chamber. The result shows that, it will take about 5min to achieve a steady state in the fast test system. The heat transfer characteristics of the vapor chamber are more superior to those of the copper block. In this paper, total thermal resistance of the test system is used to evaluate the heat transfer characteristics of the vapor chamber, because it has already been used to consider both the spreading thermal resistance and the flatness of the vapor chamber.

关键词： high heat flux vapor chamber (VC) heat transfer characteristics fast test

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Heat transfer coefficient of wheel rim of large capacity steam turbines

SHI Jinyuan, DENG Zhicheng, YANG Yu, JUN Ganwen

《能源前沿（英文）》 2008年第2卷第1期页码 20-24 doi: 10.1007/s11708-008-0015-4

摘要： A way of calculating the overall equivalent heat transfer coefficient of wheel rims of large capacity steam turbines is presented. The method and formula to calculate the mean forced convection heat-transfer coefficient of the surface of the blade and for the bottom wall of the blade passage, are introduced. The heat transmission from the blade to the rim was simplified by analogy to heat transmission in the fins. A fin heat transfer model was then used to calculate the equivalent heat transfer coefficient of the blade passage. The overall equivalent heat transfer coefficient of the wheel rim was then calculated using a cylindrical surface model. A practical calculation example was presented. The proposed method helps determine the heat transfer boundary conditions in finite element analyses of temperature and thermal stress fields of steam turbine rotors.

关键词： convection heat-transfer capacity heat-transfer coefficient bottom transmission

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Characteristics of flow and heat transfer of shell-and-tube heat exchangers with overlapped helical baffles

Tingting DU, Wenjing DU

《工程管理前沿（英文）》 2019年第6卷第1期页码 70-77 doi: 10.1007/s42524-019-0005-8

摘要：

The characteristics of flow and heat transfer of shell-and-tube heat exchangers with overlapped helical baffles (STHXsHB) were illustrated through a theoretical analysis and numerical simulation. The ideal helical flow model was constructed to demonstrate parts of the flow characteristics of the STHXsHB, providing theoretical evidence of short-circuit and back flows in a triangular zone. The numerical simulation was adopted to describe the characteristics of helical, leakage, and bypass streams. In a fully developed section, the distribution of velocity and wall heat transfer coefficient has a similar trend, which presents the effect of leakage and bypass streams. The short-circuit flow accelerates the axial velocity of the flow through the triangular zone. Moreover, the back flow enhances the local heat transfer and causes the ascent of flow resistance. This study shows the detailed features of helical flow in STHXsHB, which can inspire a reasonable optimization on the shell-side structure.

关键词： heat exchanger overlapped helical baffle triangular zone helical flow

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Analysis of the radiation heat transfer process of phase change for a liquid droplet radiator in space

Jinying YIN, Linhua LIU

《能源前沿（英文）》 2011年第5卷第2期页码 166-173 doi: 10.1007/s11708-010-0105-y

摘要： The optimization of a space power system is greatly affected by the radiation heat transfer in a liquid droplet radiator (LDR). Radiation heat transfer in a two-dimensional bed of phase-change particle is modeled by solving the radiative transfer equation using the discrete ordinates method and the energy equation using the implicit finite difference method. The Mie theory is used to calculate the radiative properties of the droplet bed, whereas the effective medium theory is used to obtain the optical constants of partial solidification droplets. Multiple factors affect heat flux in the LDR, such as size distribution, flow velocity, phase change of droplets, layer thickness, droplet concentration in the layer, and material type of the work fluid; each of these must be analyzed. Calculations show that once size distribution is neglected, the relative error increases significantly. Size distribution has a remarkably strong effect on heat flux when the flow velocity of the working fluid is above 100 m/s. An increase in flow velocity leads to an increase in the total heat flux for the layer with a fixed volume fraction of droplets. The solidification zone occupies nearly half of the layer, and droplets of different sizes exhibit temperature differences to some extent due to local thermal non-equilibrium among them. Droplet concentration in the layer and the material type of the working fluid have strong effects on heat flux, whereas the thickness of the layer has a mild influence on heat flux.

关键词： radiation heat transfer particle polydispersion liquid droplet radiator phase change