锅炉运行工况对热管换热器安全运行的影响

本文通过计算实例，讨论了变负荷、变过量空气系数及积灰引起的烟温变化对热管换热器最高允许工作温度的影响、对最后几排热管低温腐蚀的影响以及对热管换热器流动阻力的影响，对热管换热器的安全使用和设计有一定的意义。     

同轴径向热管换热器壳程流场数值模拟

基于多孔介质模型和分布阻力方法,引入Al-sanea和Taborek两种阻力关系式模拟同轴径向热管换热器壳程的流场。结果表明:换热器壳程静压沿烟气流动方向呈线性分布;随入口烟气速度的增加,换热器阻力损失增大、压降增大;且随入口烟气速度的增加,压降增加的速率增大。     

气液两相流冲刷水平管束的阻力特性研究

本文对水平布置的、壳管式换热器中的气液两相流冲刷管束时的流动阻力进行了实验研究。实验段采用壳管式换热器模型，沿长度方向用三块折流板将管束分成四个冲刷流程。当气液两相流从一端进入并冲刷管束时，分别测量摩擦阻力和局部阻力，并用分相流动模型进行分析，得到良好的计算关联式。图６参９     

空-空热管式中冷器设计与热力性能试验研究

依据热管式换热器的特点,编制了空-空热管式中冷器的设计程序,并设计了试验用热管式换热器样件对该设计程序进行试验验证。利用通用的传热系数计算公式程序所得的计算值与试验所得的实测值变化趋势基本一致,说明所编制的计算程序是实用和可靠的。根据试验结果对设计程序进行了修正,热空气出口温度最大偏差为0.5℃,热流量最大偏差为7W,表明修正后程序的计算结果与试验结果吻合较好。用试验数据分析了欧拉数与雷诺数的关系,拟合得到适合空-空热管式换热器的阻力计算的准则方程式,压降修正结果与实测值最大偏差为31.39Pa,误差不超过6%,说明在中冷器设计程序中可以利用拟合公式较好的分析压降。     

气流两相流冲刷水平管束的阻力特性研究

本文对水平布置的、壳管式换热器中的气液两相流冲刷管束时的流动阻力进行了实验研究。实验段采用壳管式换热器模型，沿长度方向用三块折流板将管束分成四个冲刷流程。当气液两相流从一端进入并冲刷管束时，分别测量摩擦阻力局部阻力，并用分相流动模型进行分析，得到良好的计算关联式。图６参９     

热管和内螺纹管在低温空气预热器中的应用

结合目前低温空气预热器存在的问题和实际应用的结果，通过对光管、内螺纹管和热管的传热，流动阻力以及壁温（低温腐蚀）性能进行对比分析，阐述了内螺纹管和热管换热器作为空气预热器的优点，并说明了它们的适用条件。     

双壳程管壳式换热器的传热和阻力特性

针对弓形折流板管壳式换热器流动死区大,压降高的不足,提出外螺旋折流板内斜百叶折流板的双壳程管壳式换热器结构,外螺旋角为15°～40°,内斜百叶折流板倾角为45°。通过三维数值模拟,研究其传热和阻力特性,获得其局部流场,并与传统弓形折流板换热器进行了对比,同时分析了外壳程螺旋折流板不同倾角对其性能的影响。结果表明:双壳程管壳式换热器的壳侧流场分布均匀,流动死区减小,综合性能高于相同壳径和管束布置的弓形折流板管壳式换热器,外螺旋角为30°时,单位压降下的传热系数平均提高了24. 4%。当外螺旋角为20°时,该换热器具有最好的综合性能。     

重力式热管换热器的设计程序

<正> 随着热管换热器在节能技术中的应用增多,合理设计重力式热管换热器成为一个重要问题。本文根据研究和应用经验给出重力式热管换热器的系统设计程序,兼补充和阐述《节能》1982.2期“重力式热管换热器的设计计算”一文之不足。     

板壳式换热器流动与传热的数值模拟

基于计算流体力学方法对板壳式换热器内部流场进行模拟,建立了板壳式换热器流动及换热计算的模型,模拟了换热器内部流动和换热情况,分析了流道内温度场和压力场及流线的分布情况,对流体的流动和传热进行了详细的描述,分析了换热器内流体流动和传热特性,对实际工程具有一定的指导意义。     

板式换热器性能的数值模拟

建立了人字形板式换热器冷热双流道的流体流动与传热计算模型,利用计算流体力学软件对5组不同速度工况下换热器内流体的流动和传热进行了数值模拟,分析了换热器流道内的速度场、温度场和压力场.结果表明:数值模拟得到的板式换热器进、出口温差和压降与试验测量值的误差均小于6%;换热器内流体的流动和传热存在明显的不均匀性,导致其进、出口的另一侧出现明显的传热"死区";换热器的总传热系数和流道阻力均随着流体流速的增大而增大.     

余热回收用热管及热管式换热器的研究

简要介绍了热管及热管式换热器的工作原理,热管式换热器在工业余热回收中的应用,以及热管式换热器运行过程中防止积灰和低温腐蚀等问题的有效措施。     

On the steady‐state modelling of a two‐stage evaporator system

We develop and validate against experimental measurements a steady‐state two‐stage flooded refrigerant evaporator model for a heat pump drying system. A prototype two‐stage heat pump dryer test facility was designed, built and instrumented to provide the required measurements for the validation of the model. Repeatability and data quality tests were conducted to evaluate the accuracy of measurements. Experimental data could be reproduced to within ±6.5 per cent of replicated air and refrigerant side measurements for the same evaporator's air inlet conditions while the discrepancy of energy balance at the air‐side and refrigerant‐side was observed to be within ±8.9 per cent. The two‐stage evaporator model predicted the air‐side total heat and latent heat transfer of the two‐stage evaporator to within (?6.3 per cent, 7.6 per cent) and (?11.5 per cent, 9.5 per cent), respectively. On the refrigerant‐side, the model enabled the calculation of the degree of superheat to within (?10.6 per cent, 1.7 per cent). The model has shown that there is significant improvement in the heat recovered from a two‐stage evaporator system compared to a single evaporator system. In addition, the model demonstrated that the improvement in total heat recovery could be as high as 40 per cent over its base‐value when the latent to total load at the two‐stage evaporator is increased. Copyright © 2001 John Wiley & Sons, Ltd.     

显热储热材料的制备及性能研究

采用水泥作为材料的胶凝剂,添加热容、热导率大的物质作为骨料来制备混凝土储热材料。研究表明:当铝酸盐水泥含量为10%时,材料的抗压、抗折强度能满足工业需求;材料的比热容随温度的升高先增大,在500℃时达到最大,后随着温度的升高反而降低;材料的热导率随着石墨粉含量的增加几乎成直线上升,当石墨含量为5%时材料的热导率大于1.7W/(m·K)。     

间歇式热处理炉传热计算与分析

建立了台车式热处理炉炉膛传热数学模型和辐射换热器工作模型,分析了换热器的传热特性（空气预热温度、壁温、传热系数）随炉况的变化。结果表明,辐射换热器的传热特性随炉子的升温及保温过程变化而波动很大,因而对炉子的热工性能产生了影响。     

Quantification of the European industrial heat demand by branch and temperature level

We present the first comprehensive estimate of the final energy demand for heat in all EU28 member states for the reference year 2012, differentiated by temperature levels, comparing two different approaches. Two different calculation approaches based on different data sets yielded estimates of the total final energy demand for heat in the EU28 of 8150 PJ and 8518 PJ in 2012, respectively. Approach 1 distinguishes between three different process heat (PH) temperature levels and results in final energy demand for heat <100°C: 2077 PJ, 100–400°C: 2214 PJ and >400°C: 3859 PJ. The second approach distinguishes between low temperature space heat and hot water (<100°C: 1161 PJ) and four different PH temperature levels with a resulting energy demand of <100°C: 1027 PJ, 100–500°C: 1785 PJ, 500–1000°C: 1679 PJ and >1000°C: 2865 PJ. The high share of high‐temperature heat illustrates the limits to the potential decarbonisation of industrial thermal processes with renewable energy sources such as (non‐concentrating) solar thermal, geothermal or environmental heat. Therefore specific information on required temperature levels is of the essence. This, in turn, points out the relevance of renewable electricity and synthetic fuels based on renewable power for a significant reduction of CO₂ emissions from the industry sector in Europe. Considering current data quality, it is recommended to develop a consistent, comprehensive methodology to significantly improve the data basis on industrial heat demand. Copyright © 2015 John Wiley & Sons, Ltd.     

Heat pump dryer Part 1: Simulation of the models

Heat pump dryer is a complex system because of the interaction of heat and mass transfer of the working fluids. Since the system cannot be completely close, ambient conditions (temperature and humidity) influence the performance of the system. To investigate the performance of the heat pump dryer thoroughly, simulation models of heat pump dryer components have been developed. The finite-difference method was employed in the simulation to examine the state of the working fluids and heat and mass transfer. The simulation of each component can be used to construct different system configurations the results of which are reported in Part 2.     

国内分离式热管概况与热环研究的小结及展望

本文对我国分离式热管技术的研究进行了简要概况,针对工程中热源在上,冷源在下及冷热源相距较远时的热量传递问题,在分析了一般分离式热管及“水回路”等技术的基础上,对一种新型分离式热管－泵或风机驱动的动力型分离式热管（简称热环）的研究进行了小结和展望。     

Field test of a novel combined system of a high-efficiency heating/cooling heat pump and a clathrate cool storage unit

The Research Laboratory of Kyushu Electric Power Co., Inc. (KEPCO) installed a novel system in March 1992 which is a combination of a super heat pump with about twice the performance of a conventional one and a compact chemical storage-type clathrate cool storage unit. A field test was implemented by integrating these units into an actual air-conditioning system. As a result of the test, system performance was determined and the effectiveness of the system was confirmed. © 1998 Scripta Technica. Heat Trans Jpn Res, 26(6): 410–418, 1997     

Heat-spreading analysis of a heat sink base embedded with a heat pipe

A simplified model predicting the heat transfer performance of a heat sink base with a high thermal conductivity was developed. Numerical analysis was performed using the commercial software FLUENT. The investigation indicates that for heat sink bases with a high effective thermal conductivity, such as the base embedded with a typical heat pipe, the entire heat sink can be modeled as a flat plate with a uniform temperature and an effective convection heat transfer coefficient. This simplified model can be used to determine the heat transfer performance of a heat sink embedded with a typical heat pipe or vapor chamber.     

Augmentation of heat transfer through passive techniques

The thermal performance of energy preservation systems is greatly improved by increasing miniaturization and boosting. These are imaginative (or Promethean) techniques to enhance heat transfer. Enhancement methods of heat transfer draw great attention in front of the industrial sector because of their ability to provide energy savings and raise the economic efficiency of thermal systems. Three techniques these methods are categorized; those are active, passive, and compound. Different types of components are used in passive methods because of the transfer/working fluid flow path to the enhancement of the heat transfer rate. In this article, the subject of the review was the passive heat transfer enhancement methods including inserts (conical strips, winglets, twisted tapes, baffles), porous materials, coil/helical/spiral tubes, rough surfaces (corrugated/ribbed surfaces), extended surfaces (fins) and nanofluids (mono and hybrid nanofluid). Recent passive heat transfer enhancement techniques are studied in this article as they are cost-effective and reliable, and also comparably passive methods do not need any extra power to promote the energy conversion systems' thermal efficiency than active methods. In the passive approaches, various components are applied to the heat transfer/working fluid flow path to improve the heat transfer rate. The passive heat transfer enhancement methods studied in this article include inserts (twisted tapes, conical strips, baffles, winglets), extended surfaces (fins), porous materials, coil/helical/spiral tubes, rough surfaces (corrugated/ribbed surfaces), and nanofluids (mono and hybrid nanofluid). From the pioneers' research work, it is clear that a lower twist ratio and lower pitch, lesser winglet angles can provide more heat transfer rate and a little bit more friction factor. In the case of nanofluids, a little bit of pumping power is enhanced. Finally, heat transfer enhancement is compared with the thermal performance factor, which is more than unity.