Optimization Design of Refuse-Incinerating Power Plant With Air-Cooled Heat Exchanger

As a newly developed industry, refuse incinerating power plants with air-cooled heat exchanger (ACHE) systems benefit both environment and energy savings. Since the exhaust steam of power plant is cooled in the atmosphere, the pressure of the exhaust steam fluctuates with variation of air temperature. As a result, the generated electric power of a power plant with an ACHE system is considerably influenced by meteorological conditions in the region where this type of power plant is built. The present work studies three different designs of a refuse-incinerating power plant with ACHE for a real project. Under the local meteorological conditions, the overall flow and temperature fields of the air in the whole power plant, especially around the air-cooled heat exchanger, are numerically investigated with the commercial computational fluid dynamics (CFD) code FLUENT and the feasibility of the project is then evaluated. In addition, a comparison of these three designs is also provided, including the performance of the exchangers and the fans, the collocation of the exhaust gas pipe, and the costs of the ACHE system.     

Heat Transfer Characteristics of a Quadratic Koch Island Fractal Heat Exchanger

Heat exchangers are widely used in the air conditioning and refrigeration industries, and any increase in their efficiency will have a positive effect on the industry as well. A new design of heat exchanger is proposed that will increase the heat transfer area significantly. The heat transfer area was increased by the use of fractals. Three techniques were used to investigate the heat transfer increase; analytical, numerical, and experimental methods. The results showed that the fractal heat exchanger has a higher heat transfer to overall volume ratio than a conventional tube-in-tube heat exchanger.     

废热锅炉的设计

废热锅炉是国内某合成氨/尿素工程项目中的主要设备,这台设备的工艺包及工艺计算为国外某知名废热锅炉制造商提供,哈锅负责对其进行强度设计及产品制造。本文对废热锅炉的选材、结构设计、设计计算以及制造等问题进行较详细的论述和分析。     

折流杆换热器的设计

为了解决传统折流板换热器流体阻力大、易发生换热管震动与破坏等缺点,开发了一种新型换热器——折流杆换热器.介绍了折流杆换热器的结构特点、设计方法,着重阐述了折流杆换热器的选材、折流杆结构的设计、堆焊技术要求,为以后设计类似产品提供参考.     

Evolution of Heat Exchanger Design Techniques

The principles of ‘ rating’ and ‘ design ’ of shell-and-tube heat exchangers are described as they developed from manual type methods to computerized applications. Criteria for initial design considerations, identification of limiting cases, and analysis of intermediate and final designs are described in sufficient detail to serve as a guide for heat exchanger designers. Future developments in the art and techniques of exchanger design are discussed.     

锯齿型内翅式传热管热交换器的研发

介绍了某型柴油机配套滑油冷却器的改进设计,采用新型锯齿型内翅式传热管冷却器替代原扁管式滑油冷却器,性能试验证明:改进设计后的滑油冷却器的主要性能均优于前者,解决了原扁管式滑油冷却器使用寿命短,可靠性差的问题。     

Costs of Irreversibilities in Heat Exchanger Design

Abstract

An operationally convenient methodology is presented for relating economic costs to entropy generation. This methodology, in the hands of the heat exchanger designer, allows an interaction with the system designer to gain insights into the trade-offs allowed between the thermodynamic irreversibilities of flow friction, heat transfer, heat leakage, and mixing. The methodology starts with a recognition of the appropriate individual irreversibilities, then relates the individual costs to system rating and energy penalties by thermodynamic arguments. The analysis loop is closed by considerations related to reduction of the individual irreversibilities in a cost-effective way. In contrast, the usual energy or “exergy” analysis provides an answer for the overall costs of the collective irreversibilities. This does not provide the engineer with the insight needed to minimize the individual irreversibilities in a cost-effective manner,     

Thermo-Mechanical Calculation of Printed Circuit Heat Exchanger Using Homogenization

The Finite-Element Method(FEM) is mainly used to design Compact Heat Exchanger structures. However, the narrow channel structures require fine mesh to accurately compute stress and strain. Combined with the dimensions of the overall component, this leads to an excessively large numerical model and therefore long computing time. This is especially true for transient thermal analyses, which require taking into account the full geometry. It is therefore interesting to reduce the size of the mesh. P...     

U-Tube Assembly Heat Exchanger Performance Analysis Using Cyclic Iteration

This article outlines a technique to predict the performance of the convection passes of pulverized coal boilers, where the heat exchangers are typically comprised of assemblies of U-tube elements. Therein a heat exchanger comprised of n U-tubes per assembly is modeled as 2n rows in the product gas flow direction, and the portions of the straight tubes making up each assembly are considered to be distinct passes in crossflow. It is assumed that in each pass the tube-side fluid is unmixed and the gas-side fluid is mixed, and likewise the gas-side fluid is mixed between passes. The model employs a straightforward approach to predict the performance of a single pass as a building block to predict the performance of the overall assembly.     

Use of Chilton-Colburn Analogy to Estimate Effective Plume Chimney Height of a Forced Draft,Air-Cooled Heat Exchanger

An estimation of the effective plume-chimney height above a forced draft, air-cooled heat exchanger operating under natural convection has been carried out by employing Chilton-Colburn and Reynolds analogies of natural convection heat transfer on a flat plate to calculate the differential pressure in driving entrained air from the surrounding air. The results show that the Chilton-Colburn analogy performs closely with the Nusselt number–Equivalence method previously used by Chu [1 Chu, C. M. 2002. A Preliminary Method for Estimating the Effective Plume Chimney Height above a Forced-Draft Air-Cooled Heat Exchanger Operating under Natural Convection. Heat Transfer Engineering, vol. 23(no. 3): 3–12. [CSA][Taylor & Francis Online], [Web of Science ®] , [Google Scholar]] and renders support for its applicability.     

循环流化床锅炉外置式换热器的设计

本文介绍循环流化床锅炉用外置式换热器的结构、性能、设计要点以及实际运行情况。     

Detection of Fouling in a Cross-Flow Heat Exchanger Using Wavelets

Detection of fouling in a heat exchanger experiencing perfect steady-state conditions is not very difficult. But the challenge is to detect fouling when all inputs (inlet temperature of the fluids and the mass flow rates) are simultaneously varying. In this paper it has been considered that the mass flow rates can vary in a ratio of 2, and that the inlet temperatures can vary by about ±20%. This first approach is dedicated to show the feasibility of using the wavelet transform. It has been considered that getting simulated data is the best way. In fact, it is then possible to introduce an arbitrary fouling factor. Thus, in the first part of the paper the model of the heat exchanger is presented. It is developed using Simulink. The validation is carried out on an electrical heater, for which it is possible to find an analytical solution for transient states. It is also shown that steady states are accurately computed over a large range of the number of transfer units and heat capacity rate ratios. Then a brief overview of the wavelet transform is given. Then basic examples show that the wavelet transform can help to find the trend of time series. It is then applied to the analysis of the “wavelet-transformed” effectiveness of the heat exchanger. This analysis is carried out on a sliding observation window (to be able to detect fouling on-line). It is shown that fouling is detected at a very early stage.     

新型螺旋管换热器的设计

螺旋管式换热器适于处理粘度大的流体或含固体颗粒的泥浆，被广泛应用。文章对一种高效、紧凑型的螺旋管换热器的结构设计作了讨论，对螺旋管换热管等具有过冷情况的热力计算方法作了探讨。     

基于遗传算法的热管换热器优化设计

在对热管传热和热阻的关系进行分析的基础上,利用遗传算法进行优化得到了最合适的翅片间距和翅片高度.算例表明这种优化是准确有效的,达到了优化热管换热器性能的目的.     

油-空气换热器设计计算

针对目前工业有机热载体设计计算中常出现偏差较多现象，就油-空气换热器设计计算，提出一些规范与实用的方法，供相关人士参考。     

循环流化床锅炉外置式换热器设计方法的探讨

简要介绍了循环流化术锅炉置式换热器的工作原理,特点及其应用情况,并在冷,热态试验基础上,给出了外置式换热器的设计原则和方法,利用该原则和方法对１台４２０ｔ／ｈ循环流化床锅炉的外置式换器进行了设计。     

城市污水换热器的方案对比与设计

污水换热器是城市污水源热泵系统中的关键设备。针对污水自身的特点,从工程角度总结了污水换热器必须满足的基本要求和特点;介绍并对比分析了几种常见的污水换热器形式,指出宽流道式换热器将带来阻力增大、能耗增加、投资增长,而壳管式换热器是最科学的污水换热器形式。给出了污水换热器设计的基本方程组,总结给出了工程设计中常见的4种技术条件组合下污水换热器的设计方法。本文提出的换热器结构、性能参数与流道尺寸的普适关系,以及污水换热器的设计方法对污水源热泵工程设计和运行具有指导意义。     

螺旋盘管式换热器管板的分析设计

螺旋盘管式换热器的设计标准为ASMEⅧ-1-2010,本文对管板组件进行局部应力分析,按照ASMEⅧ-2进行分析评定。按照标准的规定将管板简化成当量实心圆平板,开孔区设置不同的等效参数。管板组件的应力分析采用两种方法进行,分别为：基于弹性应力分析的应力分类法与基于塑性失效准则的极限载荷分析法。本文旨在促进弹性分析法与极限载荷分析法的联合使用。     

应用遗传算法优化设计紧凑式换热器

应用遗传算法对锯齿型板翅式换热器的结构进行了优化设计.以预定的传热量、两侧压降、体积等设计要求为适应度函数,通过对设计变量构成的种群个体进行适应度评估以及选择、交叉、变异等遗传操作,得到符合设计约束的换热器最优结构参数(如翅高、翅长、间距,以及长、宽、高等).此外,对10次计算得到的设计参数进行了统计分析.结果表明:相关结构参数的不确定度很小,应用遗传算法可以快速方便地对紧凑式换热器的几何结构参数作出符合设计要求的选择.     

分离式液--气热管换热器的设计与应用

文中介绍一种利用工艺中液体冷却放出热量来加热气体的分离式热管换热器.对液--气换热进行了热力分析与强度、结构的设计计算,以及系统的水动力循环分析.同时给出了实际应用实例,充分说明这种联合换热形式的换热器是合理、可靠的.