Laminar Heat Transfer Modeling and Investigation of Thermal Dispersion in a Flat Plate Heat Exchanger： Estimating Heat Transfer Coefficient, Heat Flux and Nusselt Number

PHEs （plate heat exchangers） are among the most common thermal equipments in diverse industries particularly in oil and gas companies. This wide usage is obviously due to significant benefits of these heat exchangers over other types. In this article, a behavioral analysis of heat transfer in fiat plates of these heat exchangers in laminar flow situation through CFD （computational fluid dynamics） simulation using FLUENT 6.3.26 software is done. The study reveals results graphically based on fluid＇s behavior in co-current and counter current flows and discusses thermal indexes consisting of heat transfer coefficient, Nusslet and total heat flux in both conditions. Eventually, a comparison via the graphical results is presented between the two types of flow directions.

川西高温水热活动区的地热学分析

川西高温水热活动区地处青藏高原"东构造结"的东北缘,是地中海-喜马拉雅地热活动带的最东端.该区现发现有248个温、热泉点,其中11处温泉口水温超过当地沸点.这些温泉大多沿金沙江断裂、德格-乡城断裂、甘孜-理塘断裂、鲜水河断裂分布,形成北西-南东向条带状高温水热活动区.对此高温水热活动区开展地热学分析,是研究青藏高原"东构造结"深部地球动力学过程、开发利用川西高原地热资源的重要基础,具有重要的科学意义和应用价值.本文利用重、震、磁、氦同位素资料,分析了川西高温水热活动区壳幔热流结构、深部地热特征.结果表明:该区大地热流背景西南高、东北低,地壳热流在地表热流中所占比例低于60%.高温水热活动区与地壳动力学过程相关,沿巴塘-理塘-康定一线,重力反演莫霍面深度"西深东浅",氦同位素估算Q_c/Q_m比值"西大东小",二种不同方法计算的结果具有一致的变化趋势.水热活动区重力水准面比周缘高4~6m,形成相对高值异常"台地",上、中地壳北西-南东向局部张性应力区及上隆构造区与地表水热活动区对应.航磁异常反演得到巴塘、理塘、康定三个热水活动区居里面深度在19.5~22.5km.该区中、下地壳S波速较低,15~30km深度处存在V_s<3.2km s^(-1)的低速圈闭,可能对应温度相对较高的局部熔融,推测其为川西高温水热活动的地壳热源区.分析认为:研究区水热系统可分为巴塘型(Batang-type)和康定型(Kangding-type),二者均主要依靠大气降水、地表水沿断裂带裂隙渗入,经深循环、地壳热源加热后成为地热水.地表热活动的热量主要来自中、下地壳,地下水经深切地壳的断裂渗透到中、下地壳取热,然后回到地表浅层而成为高温泉.