共查询到20条相似文献，搜索用时 156 毫秒
1.
朱津裘 《中山大学学报论丛》1992,(2)
设计与制造了重力式和水平式的热二极管元件,并对所制得的元件进行了正反向工作时,冷凝端温度随时间变化的T-t曲线、冷凝端热流密度随时间变化的q-t曲线及各元件升温速率的测试。结果表明,重力式或水平式的热二极管都能实现其单向高速传热的待性,并且热二极管的性能与该管的结构参数、工质种类、工质数量以及管内真空度等有着强烈的依赖关系。 相似文献
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《实验室研究与探索》2016,(3)
建立了一套蒸发式冷却器实验装置,模拟实际工况下喷淋密度、风量及复合管热阻对蒸发式冷却器传热性能的影响,研究了复合管替代碳钢管应用于该冷却器的可行性。实验结果表明,模拟工况为湿空冷时,复合管传热性能与普通碳钢管接近,增加配风量能够提高蒸发式冷却器的传热性能,并存在最佳喷淋密度。通过实验得到了复合管管外水膜传热传质系数关联式,为工业应用提供了可靠依据。 相似文献
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赵巍陈琴珠王学生石仲璟 《实验室研究与探索》2016,(3):70-72
建立了一套蒸发式冷却器实验装置,模拟实际工况下喷淋密度、风量及复合管热阻对蒸发式冷却器传热性能的影响,研究了复合管替代碳钢管应用于该冷却器的可行性。实验结果表明,模拟工况为湿空冷时,复合管传热性能与普通碳钢管接近,增加配风量能够提高蒸发式冷却器的传热性能,并存在最佳喷淋密度。通过实验得到了复合管管外水膜传热传质系数关联式,为工业应用提供了可靠依据。 相似文献
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丁科 《唐山师范学院学报》1997,(5)
1.问题的提出 全国高师专科统编教材“化学工艺学”传热过程这一章中,有一节“对流传热”。其主内容是:对流传热机理分析→引出牛顿冷却定律→分析定理中的给热系数α→介绍两个在特定条件下可以计算给热系数α的半经验的准数关联式。 相似文献
8.
张实斌 《辽宁科技学院学报》2010,12(3):15-16
文章探讨了采用箱型重力式挡土墙处理15m～20m高挡土墙的问题,克服了传统挡土墙应用的局限性,利用挡土墙箱内的填土来平衡外部土体压力,既减小了结构构件的截面尺寸又相应增加了重力式挡土墙的适用高度。 相似文献
9.
本文采用连续流不可逆卡诺热泵模型,以总传热面积为目标函数,导出不可逆卡诺热泵的最佳传热面积比以及最小传热面积与泵热系数和泵热率间的关系。并由此讨论了不可逆卡诺热泵与传热面积有关的各种优化性能。 相似文献
10.
殷玲 《呼伦贝尔学院学报》2005,13(6):75-77
在重力式挡土墙底加谩墙趾台阶增大基底面积,降低档土墙对地基承栽力的要求;将基底做成逆坡,利用滑动面上部分反力来抗滑;对较大高度的档土墙通过在重力式挡土墙底部设钢筋混凝土底板,使重力式挡土墙的挡土高度显著增加,同时也使该种形式的挡土墙能适应较差的地基,这种形式的挡土墙能同时做到较重力式挡土墙经济且较钢筋混凝土悬壁式或扶壁式档土墙施工方便。 相似文献
11.
Numerical investigation on the phase change of water-saturated porous media with thermosyphon 总被引：1，自引：0，他引：1
Numerical investigations were carried out to determine the coupled heat transfer of water-saturated porous media with a two-phase
closed thermosyphon for soil freezing, and to examine the characteristics of the freezing heat transfer in the water-saturated
porous media. The whole control volume includes the thermosyphon and the porous media. The two-dimensional governing equations
for the water-saturated porous media are used.
The conjugation of heat transfer between the thermosyphon and porous media is reflected through thermal balance between the
thermosyphon and the porous media.
The finite-difference method was used to solve the two-dimensional goverming equation, for the water-saturated porous media
and the heat transfer characteristics of the thermosyphon, obtain the flow fields and the temperature distributions in the
soil. This paper deals mainly with the effect of some factors (such as soil properties, climate and thermosyphon dimensions)
on the heat transfer rate of the thermosyphon and the growth of the freezing front. The predictions of the present study agree
well with the measured data. 相似文献
12.
Rafael Cortell 《浙江大学学报(A卷英文版)》2008,9(5):648-653
In this paper a numerical analysis is carried out to obtain the temperature distribution within a single fin. It is assumed that the heat transfer coefficient depends on the temperature. The complete highly non-linear problem is solved numerically and the variations of both, dimensionless surface temperature and dimensionless surface temperature gradient as well as heat transfer characteristics with the governing non-dimensional parameters of the problem are graphed and tabulated. 相似文献
13.
Heat transfer between gas-solid multiphase flow and tubes occurs in many industry processes, such as circulating fluidized
bed process, pneumatic conveying process, chemical process, drying process, etc. This paper focuses on the influence of the
presence of particles on the heat transfer between a tube and gas-solid suspension. The presence of particles causes positive
enhancement of heat transfer in the case of high solid loading ratio, but heat transfer reduction has been found for in the
case of very low solid loading ratio (M
s of less than 0.05 kg/kg). A useful correlation incorporating solid loading ratio, particle size and flow Reynolds number
was derived from experimental data. In addition, thek-∈ two-equation model and the Fluctuation-Spectrum-Random-Trajectory Model (FSRT Model) are used to simulate the flow field
and heat transfer of the gasphase and the solid-phase, respectively. Through coupling of the two phases the model can predict
the local and total heat transfer characteristics of tube in gas-solid cross flow. For the total heat transfer enhancement
due to particles loading the model predictions agreed well with experimental data.
Project supported by National Natural Science Foundation for Distinguished Young Scholars (No. 50025618) 相似文献
14.
Numerical study of heat transfer characteristics of downward supercritical kerosene flow inside circular tubes 总被引：3，自引：0，他引：3
The heat transfer characteristics of China RP-3 aviation kerosene flowing in a vertical downward tube with an inner diameter of 4 mm under supercritical pressures are numerically studied. A ten-species surrogate model is used to calculate the thermophysical properties of kerosene and the re-normalization group (RNG) k-ε turbulent model with the enhanced wall treatment is adopted to consider the turbulent effect. The effects of mass flow rate, wall heat flux, inlet temperature, and pressure on heat transfer are investigated. The numerical results show that three types of heat transfer deterioration exist for the aviation kerosene flow. The first type of deterioration occurred at the tube inlet region and is caused by the development of the thermal boundary layer, while the other two types are observed when the inner wall temperature or the bulk fuel temperature approaches the pseudo-critical temperature. The heat transfer coefficient increases with the increasing mass flow rate and the decreasing wall heat flux, while the inlet bulk fluid temperature only influences the starting point of the heat transfer coefficient curve plotted against the bulk fluid temperature. The increase of inlet pressure can effectively eliminate the deterioration due to the small variations of properties near the pseudo-critical point at relatively high pressure. The numerical heat transfer coefficients fit well with the empirical correlations, especially at higher pressures (about 5 MPa). 相似文献
15.
MALIK Pravin KADOLI Ravikiran GANESAN N. 《浙江大学学报(A卷英文版)》2007,8(7):1044-1052
Numerical exercises are presented on the thermally induced motion of internally heated beams under various heat transfer and structural boundary conditions. The dynamic displacement and dynamic thermal moment of the beam are analyzed taking into consideration that the temperature gradient is independent as well as dependent on the beam displacement. The effect of length to thickness ratio of the beam on the thermally induced vibration is also investigated. The type of boundary conditions has its influence on the magnitude of dynamic displacement and dynamic thermal moment. A sustained thermally induced motion is observed with progress of time when the temperature gradient being evaluated is dependent on the forced convection generated due to beam motion. A finite element method (FEM) is used to solve the structural equation of motion as well as the heat transfer equation. 相似文献
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17.
王寒栋 《深圳职业技术学院学报》2012,11(5):3-10
在一种太阳能驱动、采用喷雾吸收器并以板式换热器作为主要换热部件的LiNO3-NH3-He三工质扩散吸收式制冷系统中,根据试验测得的运行参数,以溶液的p-t-x西方程及物性方程、传热基础理论等为依据,提出了计算溶液换热器中溶液流量的方法,并利用综合传热系数k、传热单元数N_TU与换热器效率s研究了板式换热器作为LiN03-NH3-He扩散吸收式制冷系统发生器、冷凝器、溶液热交换器、溶液冷却器时的换热性能．试验与分析表明,板式换热器的换热面积及其内部流道中的流量（流速）对其综合传热性能具有较大影响;在介质流量一定时,板式换热器不宜考虑过大的面积预留量;板式溶液换热器内部流道宜采用多流程布置形式以强化传热、提高换热效率． 相似文献
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以水一水换热为实验对象,研究了螺旋隔板单管换热器的传热与流阻性能。实验结果表明,在相同的Re值下,螺旋隔板花瓣管单管换热器的壳程传热准数Nu是螺旋隔板光滑管单管换热器的2—4倍,压降只是它的1．4—1．8倍,证明花瓣管具有十分优越的强化传热性能,其与螺旋隔板搭配构成的换热器具有良好的传热与压降性能。在实验范围内,花瓣管翅片高度的增加、翅间距的减少都有利于传热强化性能的提高。 相似文献
19.
蒙永寅 《南宁师范高等专科学校学报》2010,(5):29-31
采用试差法,参考换热器传热系数的大致范围,假设一个传热系数值,利用热量衡算和传热速率方程估算传热面积,初选换热器型号,最后校核传热系数和传热面积。 相似文献
20.
Arrangement strategy of ground heat exchanger with groundwater 总被引：2，自引：2，他引：0
The orientation strategy of side pipe and the heat transfer performance of six ground heat exchangers(GHEs) were optimized by numerical simulation,with soil being treated as a porous medium.An experiment on the heat transfer of four GHEs was carried out in 2010.Results indicate that the velocity field is disturbed by GHEs.The optimal orientation strategy of side pipe is that the upward pipe is located upstream and the downward pipe downstream.The space between GHEs should be appropriately adjusted,depending on the direction and flow velocity.Groups of GHEs should be installed perpendicular to the mainstream in a single row,but if the acreage does not meet the requirements,GHEs should be installed in staggered multiple rows.Fewer GHEs parallel to the mainstream strengthen the heat transfer.Moreover,numerical results agree well with the test data,with the maximum relative error being less than 7.7%. 相似文献