BVH型全焊板式热交换器在热电联产机组中的应用

本文介绍了BVH型全焊板式热交换器的特点及其在热电联产机组中的应用。将其与传统管壳式热交换器进行对比分析。结果表明,BVH型全焊板式热交换器是一种新型结构紧凑高效的热交换器,可在多个工况中替代管壳式热交换器,在热电联产机组中有着广泛的应用优势和市场。     

基于摄影测量技术的板式换热器静态变形试验研究

从摄影测量所属学科门类的角度对摄影测量的概念进行描述,详细阐述摄影测量的基本原理及与经常使用的编码标志技术。通过对板式换热器结构、原理介绍,提出采用国内自主研发的XJTUSD三维光学摄影测量系统对BR1.9型板式换热器静态变形测试。测试结果得到了换热器的固定压紧板和活动压紧板的静态变形：固定压紧板的最大变形发生在1.2MPa,最大变形值为1.38mm。活动压紧板的最大变形发生在1.8MPa,最大变形值为3.29mm。     

翅片热板散热器的传热数值模拟研究

采用有限元法,应用ANSYS软件的热分析功能对翅片热板散热器的传热性能进行了数值模拟,并计算出该散热器表面的瞬态温度变化曲线,与实验测试结果吻合得较好.最后的研究结果表明:所研制的新型功率电子元器件翅片热板散热器散热性能良好,具有良好的启动性能和等温性能.     

可拆式板式换热器的腐蚀分析及防护措施

分析某钢厂可拆式板式换热器发生腐蚀的原因,提出了相关的防护措施。认为通过建立交换介质监控,控制交换介质温度,机械加工中的应力释放完全,从而达到防止和降低腐蚀情况,提高设备寿命和降低设备的维护成本。     

管壳式换热器管束与管板连接问题的探讨

就管壳式换热器在使用过程中，管束经常出现的几个问题进行了分析，提出了在设计、制造管束的过程中，易出现的问题并采取应对措施加以防范，避免换热器在使用中出现泄漏，以满足生产装置安、稳、长、满、优运行的需要。     

翅片热板散热器的传热研究

在已设计的翅片热板散热器基础上进行了传热性能实验,对于充装不同工质、工质充装量、翅片热板散热器的工作方式等因素都进行了较深入的传热测试,分析这些因素对翅片热板散热器传热性能的影响.同时对翅片热板散热器的瞬态和稳态传热性能也进行了实验测试,分析了瞬态、稳态表面温度变化曲线,并进行了传热性能比较分析,讨论了工质充装量、倾斜角度等对翅片热板散热器传热性能的影响.     

基于正交试验的钎焊板式换热器优化设计

按钎焊板式换热器设计制造要求,本文选择波纹深度、波纹倾角、波距为影响钎焊板式换热器换热性能的主要因素,以传热系数为目标函数设计正交试验方案,基于Fluent仿真软件分析了各参数对换热性能的影响。由极差分析得到各结构参数对换热性能影响的主次关系,波纹深度是影响换热器换热性能的最主要因素,最后得到了一组优选参数。     

Air to air fixed plate enthalpy heat exchanger, performance variation and energy analysis

The thermal performance of a Z shape enthalpy heat exchanger utilising 70 gsm Kraft paper as the heat and moisture transfer surface has been investigated. Effects of different inlet air humidity ratio conditions on the heat exchanger effectiveness and on the energy recovered by the heat exchanger have been the main focus of this investigation. A typical air conditioning cooling coil which incorporates an enthalpy heat exchanger has been modelled for tropical climate. Under test conditions, results have shown that latent effectiveness and the moisture resistance coefficient have strong dependency on the inlet air humidity ratio. Moreover, the latent effectiveness has been found to be strongly dependent on the moisture resistance coefficient rather than the convective mass transfer coefficient. Finally, annual energy analysis for Singapore weather conditions have also shown that energy recovered under variable inlet air conditions is 15% less than that recovered under constant inlet air conditions for the same heat exchanger.     

Experimental studies on domestic refrigeration system with brazed plate heat exchanger as condenser

Journal of Mechanical Science and Technology - In view of Kyoto protocol, there is a pressing need to reduce the energy consumption and environmental impacts of domestic appliances. In the total...     

Liquid-liquid direct contact heat exchanger for solar application

In most direct contact liquid-liquid heat exchangers, oil or hydrocarbon with a density less than water is normally used as dispersed working fluid. The main difficulty that arises with this arrangement lies in the control of the interface at the top of the column. When it is closely connected with a solar collector which uses water as its working fluid, the main difficulties arise from the fact that the water can be frozen during winter time. In order to solve these problems and to demonstrate the technical feasibility of a direct contact liquid-liquid heat exchanger, liquids heavier than water with low freezing temperature has been utilized as dispersed phase liquids in a small laboratory scale model made out of pyrex glass. In the present investigation, dimethyl phthalate (C₆H₄(COOCH₃)₂) and diethyl phthalate (C₆H₄(CO₂C₂H₅)₂) are utilized as heavy dispersed phase working fluids. The results of the present investigation support the technical feasibility in the utilization of heavier dispersed working liquid in the spray column liquid-liquid heat exchanger for a solar system. The overall average temperature difference along the column is found to be almost half of the intial temperature difference between the dispersed and the continuous phase. Despite the fact that the two phthalates tested in the experiment differ significantly in some of their physical properties, the volumetric heat transfer coefficients in terms of dispersed fluid superficial velocities were found to be similar for both phthalates tests.     

Combined heat and mass transfer analysis during the dehumidification process within a plate type heat exchanger

Liquid desiccant systems have been paid attention because of its advantages in energy saving and an environmental friendliness. The use of liquid desiccant systems offers design and performance advantages over the solid desiccant systems, especially when solar energy is used for regeneration. The objective of this paper is to analyze the simultaneous heat and mass transfer characteristics of lithium chloride aqueous solution for the plate type dehumidification system. The effects of process air and solution inlet conditions on the dehumidification performance are studied in this study. It is found that the heat transfer coefficient of the air side gives much more significant effect on the absorption rate and dehumidification effectiveness than those of the solution and the coolant sides while the mass transfer coefficient of the solution side gives more significant effect than that of the air side. It is also found that the solution concentration is the most important factor for absorption performance improvement during the dehumidification process.     

Effect of adsorption and desorption cycle time allocation on the performance of an adsorption chiller

Journal of Mechanical Science and Technology - Most previous studies on adsorption chillers were conducted using the same adsorption and desorption times. Instead, this study analyzed various...     

Life prediction of brazed plate heat exchanger based on several accelerated life test data

This paper presents a life prediction method based on several accelerated life test data for brazed plate heat exchanger. For this purpose, accelerated life tests were performed with pressure cycle and fluid temperature as accelerating stresses. Statistical analyses of the two test data sets and their combination were conducted. As a result, the shape parameter of Weibull distribution, the accelerating index of pressure cycle, the activation energy, and the life cycles under normal use conditions for the brazed plate heat exchanger were obtained.     

组合涡发生器在螺旋板式换热器上的强化传热研究

在螺旋板式换热器螺旋通道内设置三角翼和椭圆柱组合涡发生器,利用流体计算软件Fluent进行三维数值模拟。研究了Re为4000～7000内组合涡发生器对通道平均Nu和平均阻力系数f的影响,并应用场协同原理进行了分析。与只加装椭圆柱涡发生器的螺旋板式换热器进行对比,结果表明,纵向涡发生器产生的二次流能改善螺旋通道内的速度场与温度场的协同性,起到强化换热作用。在正三角形排列方式下,组合涡发生器通道的平均Nu比椭圆柱涡发生器的平均Nu增大8.7%,阻力因子f减小23.7%,强化换热的效果较好。     

Effect of the switching time on the performance of an adsorption chiller

The switching time is an important operating condition that must be correctly anticipated for an effective adsorption cooling system. Before the adsorption (or desorption) process begins, time is required to cool down (or heat up) the bed temperature so that the bed pressure reaches the evaporator pressure (or condenser pressure). During the switching time, the supplied heat is reduced and pressure overload conditions can be avoided. The switching time cannot be estimated early on, and an improper switching time degrades the system performance. Thus, this study provides guideline with which to determine the required time to open this valve, i.e., the switching time, and carefully examines the thermo-physical behavior in the adsorption bed during this period. A two-dimensional numerical method with the composite sorbent of SWS-1L and a water pair is applied to a fin-tube type adsorption chiller. Three cases of no switching time, the optimal switching time and a double the optimal switching time are examined. The results show that no consideration of the switching time overestimates the performance of the adsorption cooling system in terms of the Coefficient of performance (COP) and the Specific cooling power (SCP). On the other hand, if the switching time exceeds the optimal value, the performance of the adsorption cooling system is also reduced compared to that when using the optimal switching time. The dependency of the optimal switching times on various design parameters, such as the fin pitch, fin height and heating temperature, is also examined.

     

逆向工程技术在板式换热器研发中的应用

由于板式换热器板片具有复杂的几何形状,快速、精确得到各种板型的CAD模型对板式换热器的开发过程具有十分重要的意义。介绍了国内板式换热器开发过程中所面临的问题以及逆向工程所起到的作用,对板片表面几何数据的获取、点云的平滑处理以及数字化模型重构做了详细的阐述。获取的板片数字化模型具有良好的精确性,大大加快了板式换热器的研发过程。     

双管板换热器的设计、制造及应用

换热器是一种实现物料之间热量交换的节能设备,它广泛应用于国民经济的各个领域。在生产中为了防止腐蚀和污染,以及满足工艺流程、劳动保护、安全生产等方面的要求,通常采用双管板换热器来解决。论述了双管板换热器的用途、结构、设计等方面需注意的问题,并把它与单管板换热器进行了对比,指出双管板换热器的管程壳程间泄漏量变得很小,受力状况也更好。同时也论述了双管板换热器的壳体、管板、折流板等的制造工艺方法、管板预装、管板与换热管的连接方法、以及压力试验等方面的技术问题。     

Evaporation heat transfer and pressure drop characteristics of r-134a in the oblong shell and plate heat exchanger

The evaporation heat transfer coefficienthr and frictional pressure drop δp_f of refrigerant R-134a flowing in the oblong shell and plate heat exchanger were investigated experimentally in this study. Four vertical counterflow channels were formed in the oblong shell and plate heat exchanger by four plates of geometry with a corrugated sinusoid shape of a 45° chevron angle. Upflow of refrigerant R-134a boils in two channels receiving heat from downflow of hot water in other channels. The effects of the refrigerant mass flux, average heat flux, refrigerant saturation temperature and vapor quality of R- 134a were explored in detail. Similar to the case of a plate heat exchanger, even at a very low Reynolds number, the flow in the oblong shell and plate heat exchanger remains turbulent. The results indicate that the evaporation heat transfer coefficienthr and pressure drop Δp_f increase with the vapor quality. A rise in the refrigerant mass flux causes an increase in theh _r and Δp_f. But the effect of the average heat flux does not show significant effect on the h_r and Δp_f. Finally, at a higher saturation temperature, both theh _r and Δp_f are found to be lower. The empirical correlations are also provided for the measured heat transfer coefficient and pressure drop in terms of the Nusselt number and friction factor.     

Experimental measurement and numerical computation of the air side convective heat transfer coefficients in a plate fin-tube heat exchanger

The air-side forced convective heat transfer of a plate fin-tube heat exchanger is investigated by experimental measurement and numerical computation. The heat exchanger consists of a staggered arrangement of refrigerant pipes with a diameter of 10.2 mm and a fin pitch of 3.5 mm. In the experimental study, the forced convective heat transfer was measured at Reynolds numbers of 1082, 1397, 1486, 1591 and 1649 based on the diameter of the refrigerant piping and on the maximum velocity. The average Nusselt number for the convective heat transfer coefficient was also computed for the same Reynolds number by using the commercial software STAR-CD with the standard k - ɛ turbulent model. It was found that the relative errors of the average Nusselt numbers between the experimental and numerical data were less than 6 percent in a Reynolds number range of 1082∼1649. The errors between the experiment and other correlations from literature ranged from 7% to 32.4%. However, the literature correlation of Kim et al. is closest to the experimental data within a relative error of 7%. This paper was recommended for publication in revised form by Associate Editor Man-Yeong Ha Jin-Gi Paeng recieved a bachelor’s degree in Aero Mechanical Engineering from Gyeong-sang National University in 2000. He then went on to recieve his M.S. degrees from Changwon National University in 2004. Currently, he completed the doc-tor’s course and a doctoral dissertation in 2007 and 2008, respectively. He will take a doctorate in 2008.     

管壳式换热器查漏工装卡具的设计与应用

由于化工行业管壳式换热器应用广泛，在生产中泄漏问题时有发生，查漏困难，成为生产的一大难题，为此设计了管壳式换热器的工装卡具。本文介绍了管壳式换热器工装卡具的特点、应用范围、使用方法、应用实例及设计要点。