制取流体冰新方法及高效冰蓄冷研究

冰蓄冷空调能够有效地将日间部分高峰用电负荷转移到夜间低谷时段，是我国当前积极推广和鼓励的一项重要“削峰填谷”措施。制取块冰、壳冰存在的共同问题是：当冰在固体制冷面形成后，因冰的导热系数很小，将造成很大的传热热阻，并且随冰层厚度的增加而急剧增大，因此制冰能耗高。流体冰(或称为冰浆，Ice Slurry)由于制冰过程中在固体传热面上无冰层产生，实现流动换热，因此制冰过程传热温差小，制取流体冰的热力性能系数可比制取块冰提高近一倍。但现有流体冰制取方法用于冰蓄冷还存有问题，为克服所存在的不足和使制取流体冰的方法更为简单、高效，文中提出了一种制取流体冰的新方法．采用水与非相溶液体接触换热结冰来取代以往水与固体壁面换热结冰，通过将水雾化成细小水滴而大大增加水结冰过程的传热面积，有效地减小了冰层热阻。该种新型制冰方法可使冰蓄冷措施更为经济有效。     

电厂真空冷凝器自动除垢及传热强化技术

本文介绍了真空冷凝器清洗技术现状,阐述了塑料纽带自动清洗技术的优越性,并对其强化传热功效进行了实验研究,传热系数可以提高10％以上。     

真空法制取冰浆的实验分析与研究

本文通过分析总结,构建真空法制取冰浆实验的总体布局,建立可视化的真空法制取冰浆的实验台。通过改变水滴初温与真空罐内初始压力,对真空制取冰浆的方法进行了实验研究。实验表明,初始压力对冰浆生成率的影响更大。     

真空闪蒸对R718旋流喷雾影响研究

为研究真空状态下闪蒸对于旋流喷雾的雾化角、轴向速度和液滴粒径的影响,搭建真空闪蒸试验台,采用高速摄影、相位多普勒粒子分析仪(PDPA)等进行流场测试。结果表明:当控制旋流喷嘴两端压差为常见值时(0.5～0.7 MPa),通过降低喷嘴出口背压或升高液相温度引起闪蒸,雾化角显著增加,增幅超过20。;闪蒸使喷雾轴向速度由3.06 m/s增加至6.79 m/s;闪蒸工况下雾化角与出口背压和液相温度均呈二次方关系,而在一定范围内轴向速度与液相温度呈线性关系,闪蒸对液滴粒径影响不大。     

冰浆技术及其应用进展

冰浆是一种良好的载冷和储冷介质,也是安全廉价的高效换热介质,因其独特性而在众多领域有很好的应用前景。本文综述了冰浆技术的发展简史,并对各冰浆制取技术的研发和应用现状进行了介绍,对工程化应用过程的技术难点和关键技术进行了阐述。     

立式真空钎焊炉设计

快冷真空钎焊炉的研发，温度控制精度高，极限真空度高，惰性气体快速循环冷却，实现PLC程序控制／手动控制切换，电热效率提高，适合真空开关管的大批量生产，达到生产过程全自动化。     

Experimental research on titanium dioxide nanofluid in vacuum flash evaporation

This study is purposed to conduct experimental investigation into the characteristics of vacuum flash evaporation with nanofluid under adsorption conditions, with the effects of nanoparticle concentration, surfactant concentration, and nanofluid stability taken into consideration. By measuring absorbency, solute concentration, and sedimentation graph, a new nanofluid with excellent dispersion was developed for the vacuum ice-making system. It has been demonstrated that the low concentration of additive is conductive to not only the maintenance of vacuum but also the generation of binary ice. For nanofluid, there are two distinct freezing stages in the process of vacuum flash evaporation. The supercooling stage of nanofluid is delayed with the increase of surfactant concentration, whereas the TiO₂ nanofluid applied to the vacuum ice-making system under adsorption shows stability. Moreover, it is indicated that, for the vacuum ice-making system with TiO₂ nanofluid, the pH level is around 8.5, the surfactant is sodium dodecyl benzene sulfonate-span 60 (SDBS-SPAN), the ratio of SDBS to SPAN is about 10:7, the concentration of TiO₂ nanoparticle is around 0.20 wt%, and the ratio of TiO₂ nanoparticle to SDBS-SPAN is about 10:5. Compared with pure water, undercooling is reduced by 77.92%; the ice packing factor and thermal conductivity are increased by 40.61% and 67.27%, respectively. The results of test and analysis can be applied to conduct further research on vacuum flash evaporation.     

常减压蒸馏装置节能技术优化

从常减压蒸馏装置实际情况出发,对运行中暴露的问题,尤其对加热炉进料温度偏低的问题进行分析,依此提出换热网络优化的必要性。通过实施该优化项目,加热炉进料温度由270℃提高到300℃,大幅度降低了燃料消耗。     

Recent progress in the adsorption heat pump technology

吸附热泵是一种以低品位热能驱动的节能环保型热泵技术,利用吸附剂与吸附质间的吸附热实现制冷或制热效果,从文献检索结果来看该技术越来越受到广泛关注,国内外相关学者开展了大量的研究工作.本文首先介绍了开展吸附热泵相关研究的课题组和其主要研究方向,进而简要介绍了吸附式热泵技术;其次,着重描述了吸附热泵技术的国内外研究现状,对吸附工质的研究,床层的传热传质强化,热泵新技术及商业化热泵产品等进行了详细的叙述;最后,叙述了吸附式热泵当前存在的主要问题,指出了吸附热泵发展存在的挑战性问题和未来的发展方向.     

Analysis of characteristics of water flash evaporation under low‐pressure conditions

The relation between the maximum heat transfer coefficient and the saturation temperature of vapor for water flash evaporation under low‐pressure conditions is theoretically analyzed. The optimum evaporation time is introduced by analytical consideration to reflect the experimental result of the linearity of the super heat flux and the unknown constant included in the optimum evaporation time is determined by the experiment. The analytical result is compared with experimental data and shows a good agreement. The analysis also gives information regarding the optimum spray condition among the spray flow rate, particle diameter, and the intermittent spray time to achieve the maximum heat transfer coefficient under low‐pressure conditions. © 1999 Scripta Technica, Heat Trans Asian Res, 29(1): 22–33, 2000     

Enhancement of boiling heat transfer in restricted spaces in compact horizontal tube bundles

ln desalinization devices and some heat exchangers making use of low‐quality heat energy, both wall temperatures and heat fluxes of heated tubes are quite low and generally cannot cause boiling in flooded‐type tube bundle evaporators with a large tube spacing. But when the tube spacing is very small, boiling in restricted spaces can occur and induce a higher heat transfer than that of a falling film or pool boiling at the same heat flux. This study investigated experimentally the effects of tube spacing, positions of tubes, and heating status of tubes as well as surface status (smooth and roll‐worked) on boiling in restricted spaces in compact horizontal tube bundle evaporators under atmospheric pressure. The experimental results provide a restricted space boiling database for water in smooth and enhanced surface tube bundles. Of particular importance is information concerning the influence of tube spacing of flooded‐type tube bundle evaporators, especially for the case of zero pitch, when the neighboring tubes are contacting each other. © 2001 Scripta Technica, Heat Trans Asian Res, 30(5): 394–401, 2001     

Melting of ice slurry in a tube‐in‐tube heat exchanger

One of the main components of a closed ice slurry system is the heat exchanger in which ice slurry absorbs heat resulting in the melting ice crystals. Design calculations of heat exchangers are mainly based on heat transfer coefficient and pressure drop data. But experiments presented in this paper show the effect of ice slurry mass flux on heat transfer rate and heat transfer coefficient during melting. For the experiments, ice slurry was made from 6.5% ethylene glycol–water solution, flowing through a 16.91mm internal diameter, 1500mm long horizontal copper tube. The ice slurry was heated by hot water circulated at the annulus gap of the heat exchanger. Experiments of the melting process were conducted with changing the ice slurry mass flux and the ice fraction from 800 to 3500kgm^?2s^?1 and 0 to 25%, respectively. During the experiment, it was found that the measured heat transfer rates increase with the mass flow rate and ice fraction; however, the effect of ice fraction appears not to be significant at high mass flow rate. At the region of low mass flow rates, a sharp increase in the heat transfer coefficient was observed when the ice fraction was more than a certain value. Experiments were also conducted to investigate the effect of hot water temperature on the heat transfer coefficient. Copyright © 2006 John Wiley & Sons, Ltd.     

蒸发冷却空调技术在住宅建筑中的研究进展

介绍蒸发冷却空调技术在住宅领域的研究进展。主要包括:直接蒸发冷却空调技术在住宅建筑的应用、间接蒸发冷却在住宅建筑的应用以及蒸发冷却与其他技术相结合在住宅建筑领域的应用几个部分。参考国内外相关文献及其专利,得出蒸发冷却空调技术在部分地区住宅领域应用效果较好的结论,特别是将蒸发冷却空调技术与其他技术相结合的应用过程中,这项技术能够提高整个机组的运行能效比,使机组运行更加节能、环保。在广阔的农村住宅领域以及"干空气能"丰富的部分地区,蒸发冷却空调技术值得被大力推广。     

高效传热技术的研究现状及进展

简要介绍了多种高效传热技术,并分析了其传热机理、性能与构造特点。阐述了强化传热元件的开发与应用。通过分析总结可知采用高效传热技术,对于改善传热性能和节能降耗有着现实意义。     

Numerical study of the evaporative cooling of liquid film in laminar mixed convection tube flows

A numerical study is reported to investigate the evaporative cooling of liquid film falling along a vertical tube. A marching procedure is employed for solution of the equation of mass momentum, energy and concentration in the flow. Numerical results for air-water system are presented. The effects of flow conditions on the film cooling mechanism are discussed. Results show that a better liquid film cooling is noticed for a system having a higher inlet liquid temperature T_L0, a higher gas flow Reynolds number Re or a lower liquid flow rate Γ₀. Additionally, the results indicate that the convection of heat by the flowing water film becomes the main mechanism for heat removal from the interface.