浅谈“流体力学与传热”之间的关系

本文主要从流体不同的流动状况和不同的流动方向所产生不同的传热效果来进行分析．指出传热速率的快慢主要与边界层的厚度有关。一般来说，加大流速，不断改变流体的流动方向是减薄边界层，强化传热的有效途径。同时也描述了边界层形成的内外因素，分析了边界层是传热的主要阻力，联系工程实际，理论与实践相结合，进一步阐述流体流动与传热有着必然的关系。不同的流动方式，传热质素就不同。     

《相变传热》课程过程性评价教学方法研究

过程性评价是近些年来备受大家关注的一种评价方式,有着评价体系全面、注重提高学生学习能力和提高教学质量等优点。文章结合本校能源与动力工程类专业课《相变传热》课程的建设与改革,采取过程性评价方法对原有的课程评价体系进行了改革,改革后的评价体系更注重对学生学习能力的培养,评价体系更加完善。     

板式换热器性能实验台的研制与性能分析

为探究板式换热器的换热性能,根据工程热力学、传热学、热工测试技术等基本测试原理和方法,结合现行的国家标准与规范要求,研制了板式换热器性能实验台。此实验台安装有高精度的传感器,并研发了基于STM32为主芯片的高精度数据采集板和上位机软件。上位机软件利用Visual Studio2008的开发环境,用C#编程语言编写完成,并结合了动态Flash、SQL Sever数据库、虚拟仪器等相关技术。根据实测数据,计算出板式换热器的性能参数和传热关联式。实验结果表明,该实验台具有自动化程度高、控制精度高、可操作性强等特点,为理论研究提供了可靠的实验依据和数据支撑。     

热管技术在热能工程中的应用

热管的应用越来越广泛,热管技术也受到越来越多的人们重视.热管技术发展到现在,在热能工程中取得了很大的成效并与热能工程技术相互促使彼此不断发展.本文将对热管技术的基础知识及其在热能工程中的应用作出介绍,以望能对热管技术及热能工程的研究者有所帮助.     

空气载能辐射孔板温度集总参数模型及温度特性分析

本文分析了空气载能辐射空调系统末端的传热特性,并运用热阻分析法建立了辐射孔板的平均温度以及夏季最低温度和冬季最高温度的集总参数模型,通过CFD模拟与实验对该模型进行验证,并基于该模型分析辐射孔板表面温度的均匀性。结果表明,本文提出的模型准确性较高,且空气载能辐射孔板与传统的金属辐射板相比,表面温度分布较均匀,供冷/热效果更好。     

啤酒工业的发展与水资源的高效利用

通过分析啤酒生产过程中水的使用情况和现状,探讨为保护环境而节约用水的方式方法。     

揭开人造卫星的“外衣”

人人都有这样的体会:夏天穿单薄、浅色的衣服最好,冬天以厚实、深色的着装为佳。这是日常生活中保持体温常见的一个例子。其实,一切幸存下来的生物,动物也好,植物也罢,都是由于它们有随季节变化的适应能力,才能在地球上得以繁衍。     

Numerical study on heat transfer enhancement for use of corrugated,nodal and horizontal grain tubes

With isopentane as working fluid, the heat transfer performances for corrugated, nodal and horizontal grain tubes are simulated. The structural parameters of the three kinds of tubes are compared with those of the plain tube. The numerical results using computational fluid dynamics are validated with theoretical values. For the corrugated, nodal and horizontal grain tubes, the heat transfer enhancements(HTEs) are 2.31—2.53, 1.18—1.86 and 1.02—1.31 times of those of the plain tube, respectively. However, the improved HTEs are at the expense of pressure losses. The drag coefficients are 6.10—7.09, 2.06—11.03 and 0.53—1.83 higher, respectively. From the viewpoint of comprehensive heat transfer factor, the corrugated tube is recommended for engineering applications, followed by the horizontal grain tube.     

Coupled models of heat transfer and phase transformation for the run-out table in hot rolling

Mathematical models are been proposed to simulate the thermal and metallurgical behaviors of the strip occtLrring on the run-out table （ROT） in a hot strip mill. A variational method is utilized for the discretization of the governing transient conduction-convection equation, with heat transfer coefficients adaptively determined by the actual mill data. To consider the thermal effect of phase transformation during cooling, a constitutive equation for describing austenite decomposition kinetics of steel in air and water cooling zones is coupled with the heat transfer model. As the basic required inputs in the numerical simulations, thermal material properties are experimentally measured for three carbon steels and the least squares method is used to statistically derive regression models for the properties, including specific heat and thermal conductivity. The numerical simulation and experimental results show that the setup accuracy of the temperature prediction system of ROT is effectively improved.     

Coupled seepage and heat transfer intake model

In the beach well intake system, heat is transferred from soil to fluid when seawater is filtered through the aquifer, providing higher temperature source water to the seawater source heat pump (SWHP) system in winter. A 3-D coupled seepage and heat transfer model for studying beach well intake system is established by adopting the computer code FLUENT. Numerical results of this model are compared with the experimental results under the same conditions. Based on the experiment-verified coupled model, numerical simulation of the supply water temperature is studied over a heating season. Results show that the minimum temperature of supply water is 275.2 K when this intake system continuously provides seawater with flow rate of 35 m3/h to SWHP. Results also indicate that the supply water temperature is higher than seawater, and that the minimum temperature of supply water lags behind seawater, ensuring effective and reliable operation of SWHP.