管式换热器对流给热的强化措施

介绍了管式换热器无相变时强化对流给热的措施。     

高效特型管换热器在石油化工中的应用

结合设计、生产和推广高效换热器的经验,分析了高效特型管换热器在石化、化工等领域中的应用及其在节能中的优势.用设计实例说明了高效特型管换热器与普通光管换热器相比,不但可以提高换热器的换热能力,而且同时可以节约大量能量.     

管壳式换热器管板与换热管焊接常见质量问题的预防

管壳式换热器在使用中常出现因换热管和管板焊接接头质量差而泄漏的问题 ,通过合理的制造工艺可有效防止。     

Heating and cooling of flocculated and non-flocculated slurries in tubular heat exchangers

The distinctly different turbulent heat transfer characteristics of flocculated kaolin slurries are compared with nonflocculated coal slurries via modified J-factor correlation forms for tubular exchangers. Both slurry types were statistically best-fitted with the approximate solution Bingham plastic flow model in preference to the local shear power law. In addition, the first known turbulent slurry heat transfer cooling results are presented along with the heating results. No distinction was made between heating and cooling correlation forms because of a random scatter of experimental points. Experimental results were interpreted as follows A. Flocculated kaolin slurries J_H = (h/C_pG) (C/K₁)^2;3= 0.027(DVρ/μLe^B?)^0.2 11%ω < %ω Solids < 24%ω Maximum Deviations: + 19.3%, ? 17.8% B. Non-flocculated coal slurries J_w = (h/C_pG)(C_pμLe^B?/k_w)^2/3e^?B?/4) =0.0285 (DVρ/ μLe^B?)^?0.2 13%_w > %w Solids < 33.5%. Maximum Deviations: + 17.8%, - 11.1%     

Modeling of the heat transfer in cross-flow heat exchangers

The heat transfer in plate heat exchangers with cross flows of heat-transfer media is considered. At constant values of thermophysical parameters using a model of a one-dimensional flow in cach channel, analytical expressions for the temperature and heat flux distributions are obtained. The efficiency of heat exchangers at different values of dimensionless parameters is estimated. A model is proposed to take into account the two-dimensional flow of heat-transfer media in channels on the basis of empirical relations for the flow resistance and the heat transfer in flat channels.     

Dynamics of convection heat exchangers

A mathematical model is developed for heat exchangers with condensing vapors on one side which includes the effects of variations in the local film heat transfer coefficients and allows for energy accumulation and conduction in the tube wall. A numerical integration scheme for the flow forced case is presented. The model is tested against experimental steady state and transient data for a steam-water exchanger. It was necessary to modify the standard correlations of heat transfer coefficients to get a match of the overall steady state heat flux actually obtained in the apparatus. With these modified heat transfer coefficients, the model proved capable of predicting flow forced transients. These results are contrasted with transients predicted by a simple lumped parameters model employing empirically fit overall heat transfer coefficients. The lumped parameters model is shown quite adequate for predicting transient behavior under the specific conditions studied. The reasons for and limitations on the success of this very simple model are explored.     

螺旋扁管换热器

螺旋扁管换热器是一种新型的管壳式换热器。螺旋扁管换热器比传统的管壳式换热器具有压降小 ,传热效率高 ,不易结垢易清洗 ,无折流板 ,无震动 ,成本低等一系列优点。     

Simulation of air-cooled heat exchangers

An algorithm is presented for the simulation of air-cooled finned tubes heat exchangers with topological configuration which preclude the use of method based on overall coefficients and mean temperatures differences. It is a generalization of the step by step method arising when the transfer area of each tube is divided into a finite number of elements. The heat transfer rate equations and the energy balances corresponding to all the elements of all tubes constitute a system of linear equations which is solved iteratively.     

Efficiency of mixed-flow heat exchangers

It has been shown that studies are aimed at improving existing apparatuses and their elements in the agitating zone of liquids. A great deal of attention is devoted to investigating heat exchange upon stirring, the problem of the intensification of which has not been solved completely. For this reason, apparatuses with vertical heat-exchange units are considered to be promising. A model that allows for the assumption of the effect of the features of the design of agitator and heat-exchange units designed as vertical tubes on the heat-exchange efficiency in the stirring apparatus has been suggested. Results of experimental investigations of hydrodynamics and heat exchange in the apparatuses under study have been given and their high heat effectiveness has been demonstrated. The effectiveness of heat transfer has been compared in the blocks with parallel and series-connected tubes at identical flow rates of the heat carrier in the pipes of each block. No difference in the effectiveness of heat transfer is observed in the entire range of the rotation frequency of a stirrer. At higher water consumption, a block with parallel-connected pipes provides a higher amount of heat flow due to the larger driving force of heat transfer. Experimental data are generalized based on the theoretical dependence for calculating the coefficient of heat withdrawal from the agitated medium. The possibility of increasing coefficients of heat withdrawal from the agitated medium is only restricted by the supplied mechanical energy. An example of the calculation of apparatuses has been given.     

Analysis of the model of tube-in-tube heat exchangers

The operation of a tube-in-tube heat exchanger with cocurrent and countercurrent flows of heat-transfer agents is analyzed in the steady state mode on the basis of the traditional model. The characteristics of the given flow modes of heat-transfer agents are compared. A number of inequalities, whose proof have not been developed in the literature or containing errors, are proven for the parameters characterizing the operation of a heat exchanger in the cocurrent and countercurrent modes.     

多壳程换热器设计方法

对１－２型多壳程换热器的设计准则进行了分析，并修正了系数，提出了优化设计的新准则，给出了该类换热器优化设计的三种新方法。     

钛材换热器的结构设计

讨论了氯碱工业用钛材换热器中几个关键连接部位的设计方案,包括换热管与管板、复合板之间、衬筒接管与复合板筒体、复合板筒体和衬筒高颈对焊法兰衬里、衬筒接管和高颈对焊接管法兰衬里、钛制筒体与活套设备法兰、钛接管与平焊环松套管法兰等。     

Computer-aided design of tube-bundle heat exchangers

Based on a paper by Hein, a dimensioning program for tube-bundle heat exchangers with straight tubes and fixed tube sheets has been developed. The equipment to be dimensioned is tested at 14 critical points, with regard to permissible stresses. The optimum thickness of the tube sheet, the shell and channel are subsequently selected on the basis of economic criteria. Compared to dimensioning according to AD-data sheet, it is possible to save between 10 and 25% of production costs. With the aid of a finite-element (FE) program, complex structures such as heat exchangers can be calculated accurately. Several mesh-generation programs were written for the data input. The structure of a tube-bundle heat exchanger with straight tubes is generated with 3/D elements with only some geometrical data. An FE-calculation of a heat exchanger is explained with the aid of an example and stress analysis is presented.     

换热器的技术经济评价

在综合考虑原材料购置、设备磨损、电力消耗等相关因素的基础上,提出了采用总投资费用法,运行成本费用法,年计算费用法,费用现值与费用年值法等4种方法对多种换热器投资方案进行分析,便于对不同选型方案进行经济性分析,以达到技术上可行、经济上合理的目标.     

板式换热器的检修

本文介绍了大型板式换热器解体大修的方法和注意事项等。     

热管换热器的发展和应用

阐述了热管换热器的结构特征、材质和工质选择、应用进展以及在化工行业的应用实例     

板翅式换热器参数化绘图

针对板翅式换热器的基本结构 ,阐述了板翅式换热器的参数化设计过程和尺寸间的约束关系 ,并以芯体为例 ,分析了板翅式换热器零件尺寸与驱动尺寸之间的关系 ,为板翅式换热器参数化设计奠定了基础     

非金属换热器及其应用

详细介绍了国外非金属换热器的种类、结构以及发展和应用现状。