增强节能意识 抓好基础管理与技术进步

随着能源供应的紧张,能源价格的上涨,对节能和环保要求愈来愈严格的形势下,对铝线材连铸连轧新工艺装备中原燃煤手烧式冲天熔铝炉和电保温炉进行了技术改造。改造的内容是(1)新装一台2.4M水套式煤气发生炉,(2)改造手烧式冲天熔铝炉为热煤气燃烧式冲天熔铝炉,(3)熔铝保温炉由电保温改造成热煤气燃烧保温。从今年初开始投入使用,节能效果显著,现将改造前、后经济效益对比如下:     

煤气循环水系统的合理设计

本文对太重煤气站洗涤煤气循环水改造前后状况进行分析,通过理论计算与实际运行比较得出,在煤气工程设计中,将煤气循环水系统冷,热分开发设计是合理的。     

锻造加热炉的改造与节能

一、加热炉改造问题的提出我厂锻工车间1982年拥有6台煤气加热炉和两台烧燃加热炉,用来加热机床产品等锻压零件,毛坯加热温度要求在1200℃左右。这些炉子虽经多次大修,结构一直比较陈旧。能耗居全厂第四位。其中67.3%为煤和煤气。白煤106吨,占全厂煤耗2.7%,煤气耗用45万米~3,占全厂煤气的70%,所以我们优先改造煤气加热炉。1982年5月对一台1.3米~3煤气和热炉进行了热平衡测试,测试结果,热效率只有5.41%,效率之低,浪费之大是非常惊人的,已到了非改造不可的地步。     

安钢的节能与供热

对安钢高炉煤气放散、锅炉供热以及热负荷分配现状进行了全面分析，并介绍了3＃、4＃锅炉纯煤气的改造经验和7．5t/h锅炉实现热电联产的情况，最后提出了今后节能和供热工作的努力方向。     

节能投资重点领域

1 .热电联产及三联产 (热、电、煤气或热、电、冷 )。 2 .集中供热及工业锅炉改造。 3.工业窑炉改造及余热利用。4.城市煤气及放散气回收。 5 .型煤及配煤。 6 .节能建筑物。7.冶金炉窑改造及压差发电。 8.煤炭洗选取及综合利用。9.化工工艺改造。 10 .炼油工艺改造。 11.轻工工艺改造及环保项目。 12 .建材工艺改造及新型墙体材料。 13.新型机电产品及节能仪器仪表。 14.重要通用设备 (如电机拖动系统 ,流化床锅炉 ,非晶态金属变压器、高效电光源、疏水阀等 )。 15 .风力发电 ,太阳能发电等新能源项目。节能投资重点领域…     

煤气余能电站的建设与效益

在钢铁企业的冶炼生产过程中,副产的焦炉煤气、高炉煤气等是优质燃料,是宝贵的能源财富,对这些煤气的综合利用,特别是对过去不太重视的高炉煤气的利用,化废为宝,是节约能源、改善环境的重要课题,全国已有许多钢铁企业在这方面做了大量工作,收到了显著的效果.例如:利用煤气作锅炉燃料来生产蒸汽供热发电.利用煤气显热用余热锅炉来生产蒸汽、高炉炉顶煤气余压发电装置等等.均取得了较好的经济、社会效益及环境效益。徐州钢钢铁总厂在利用煤气来生产蒸汽供热发电方面也作了尝试.收到了一定的效果.已改造建成     

均热炉采用蓄热燃烧技术的节能分析及应用

从燃料热利用率分析出发，对均热炉改造的方案进行了节能情况分析，用于指导均热炉的改造实施，从分析得知采用空气单蓄热、煤气预热的方案可以实现节能约16％，通过实际运行对计算结果进行了验证，该方案的成功实施对周期性的室式炉节能改造具有良好的指导意义。     

热脏发生炉煤气的工业应用

从多年的经验出发,介绍了热脏发生炉煤气的使用背景和现状。分析亍热脏煤气的性能,重点介绍了热脏煤气系统中的各种设备及其使用注意事项,最后介绍了流化床煤气发生炉。     

75T/h煤粉锅炉全燃煤气改造

根据湘潭钢铁公司高炉煤气热值低、流量大可有效利用特点,对现有热电厂的75t/h煤粉炉进行了3个方面的全烧煤气改造,并取得了良好的改造效果。     

某管式炉改烧高炉煤气的改造思路及数值模拟

为了能减少高炉煤气的放散,充分利用高炉煤气资源,对某钢厂的管式加热炉提出添加高炉煤气作为燃料的改造方案。提出了在原管式炉下方区域增加圆筒形绝热燃烧室,采用焦炉煤气与高炉煤气两用燃烧器以及侧喷切圆燃烧技术等手段来保证改造成功,同时针对改造方案进行了一系列数值模拟。模拟结果表明改造方案切实可行,采用侧喷切圆燃烧方式能显著提高燃烧室出口截面温度均匀性。即使完全燃烧低热值的高炉煤气,也能保证燃烧室中气体的稳定燃烧。     

The photochemical heat pipe

The performance of a solar collector system for high temperature heat delivery based on a photochromic reaction is discussed. The system consists of a non-focusing collector and a reactor integrated into a flow system. In the collector, kept close to ambient temperature, the chemical potential of the photochromic system is increased through an endothermic photochemical reaction and is used to drive the reverse thermal reaction taking place in the reactor at a high temperature. No separation of the photoproducts is involved. Accordingly, the highest temperature at which heat can be delivered from the reactor is determined by the maximum attainable photostationary state in the collector and not, as in a conventional flat-plate collector, by heat-loss from the collector to the surroundings. Accordingly, the highest temperature at which heat can be delivered from the reactor is determined by the maximum attainable photostationary state in the collector and not, as in a conventional flat-plate collector, by heat-loss from the collector to the surroundings. The functioning of the device is exemplified by calculations for a model system utilizing the photodissociation of gaseous nitrosylchloride. The results show that it should be possible to build a system which, on a clear day, delivers about 100 W heat at temperature above 200°C for each m² collector area. A tenfold reduction in the radiation flux density of the incident light will only slightly reduce output efficiency.     

Modulated wick heat pipe

In heat pipes, modulation of evaporator wick thickness provides extra cross-sectional area for enhanced axial capillary liquid flow and extra evaporation surface area, with only a moderate increase in wick superheat (conduction resistance). This modulated wick (periodic stacks and grooves over a thin, uniform wick) is analyzed and optimized with a prescribed, empirical wick superheat limit. A thermal-hydraulic heat pipe figure of merit is developed and scaled with the uniform wick figure of merit to evaluate and optimize its enhancement. The optimal modulated wick for the circular and flat heat pipes is found in closed-form expressions for the viscous-flow regime (low permeability), while similar results are obtained numerically for the viscous-inertial flow regime (high permeability which is also gravity sensitive). The predictions are compared with the experimental result of a prototype (low permeability, titanium/water pipe with the optimal design) heat pipe which gives a scaled figure of merit of 2.2. Good agreement is found between the predicted and measured performance. The maximum enhancement is limited by the pipe inner radius (tapering of the stacks), the wick effective thermal conductivity, and the prescribed wick superheat limit.     

Closed-loop pulsating heat pipe

Flow visualization was conducted for the closed-loop pulsating heat pipe (PHP) using a charge coupled device (CCD). It was observed that during the start-up period, the working fluid oscillates with large amplitude, however, at steady operating state, the working fluid circulates. The direction of circulation for the working fluid is consistent once circulation is attained, but the direction of circulation can be different for the same experimental run. Phenomena such as nucleation boiling, coalescence of bubbles, formation of slug and propagation of inertia wave were observed in the closed-loop PHP. The findings showed that the meandering bends, uneven slug and plug distribution and non-concurrent boiling at the evaporator contributed to the driving and restoring forces for fluid circulation and oscillations.     

Experimental research on heat transfer of pulsating heat pipe

Experimental research was conducted to understand heat transfer characteristic of pulsating heat pipe in this paper, and the PHP is made of high quality glass capillary tube. Under different fill ratio, heat transfer rate and many other influence factors, the flow patterns were observed in the start-up, transition and stable stage. The effects of heating position on heat transfer were discussed. The experimental results indicate that no annular flow appears in top heating condition. Under different fall ratios and heat transfer rate, the flow pattern in PHP is transferred from bulk flow to semi-annular flow and annular flow, and the performance of heat transfer is improved for down heating case. The experimental results indicate that the total heat resistant of PHP is increased with fill ratio, and heat transfer rate achieves optimum at filling rate 50%. But for pulsating heat pipe with changing diameters the thermal resistance is higher than that with uniform diameters.     

长距离环路热管传热性能实验研究

基于航空航天等领域对环路热管长距离传热的需求,设计制造了一套传热距离8.1m的圆柱型蒸发器环路热管,试验了不同加热功率、不同冷凝温度下该环路热管的启动和变工况运行性能,并对其热阻及最大传热能力进行了分析。研究结果表明：当其他条件一致、初始气液分布相同和不同时,加热功率由100W增大至160W后,本研究中的环路热管启动时间和启动温升均发生一定程度的下降;加热功率100W时,冷凝温度由10℃降低至-10℃使得环路热管启动时间增加,加热功率160W时,冷凝温度由10℃降至-10℃对环路热管的启动时间影响不大。在冷凝温度0℃下,该环路热管在100~500W范围内均能稳定运行,且200W时环路热管传热效率最高,传热温差最小,稳定运行温度最低;另外,由于系统传输距离较长,每个工况达到稳定所需要的时间也较长,分布于1000至3500S内。随着加热功率的增大,环路热管热阻先减小后逐渐增大,该环路热管传热热阻最大不超过0.09℃/W,最小为0.024℃/W;随着传热距离的增大,管路的热损失增加,总压降和热阻也变大。当传热距离基本相同时,蒸发器容积的大小、冷凝器的冷凝能力及气液管线的布置形状均在一定程度上影响环路热管的最大传热能力。     

脉动热管的研究综述

自从上世纪九十年代初期脉动热管问世以来,对它的研究主要是建立数学模型的理论研究,还有关于运行机理的可视化,以及充液率、管径、加热端与冷却端相对位置、工质、不凝性气体等参数对脉动热管的热性能影响的实验研究。对于脉动热管优化和设计的完整方案还需要进一步的研究。文中主要介绍了有关脉动热管研究的近期进展,并对脉动热管的进一步研究和在电子冷却中的应用做了展望。     

Design of miniature loop heat pipe

In the present study, the loop heat pipe (LHP) was miniaturized for application to electronic cooling. According to the capillary limitation, the wick structure parameters that would affect the heat transfer capacity were analyzed theoretically. Among the various wick parameters, this study especially investigated the effect of wick thickness, which has rarely been mentioned in the literature. Here, various thicknesses were analyzed theoretically and then tested experimentally. The results showed that the temperature on the evaporator wall dropped with decreasing wick thickness. This effect would lead to the raising of heat transfer capacity and the descending of thermal resistance. According to the analysis and the practical demand for electronic cooling, a miniature LHP was fabricated with the evaporator outer diameter of 13 mm and the evaporator length of 50 mm. The testing results showed that, at the allowable working temperature of 80 °C, the maximum heat transfer capacity was up to 200 W and the thermal resistance was 0.17 °C/W. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(1): 42–52, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10133     

回路热管的热力特性分析

对回路热管稳定运行的动力和热力特性进行了分析,指出整个循环要顺利完成,主毛细芯产生的毛细压差必须具备的条件以及换热条件.并进而在合理的简化和假设条件下,对该热管建立了热力分析数学模型.用简单的代数运算代替了复杂的微积分计算,在精确度要求不高时,能够简便快速的进行热力分析.应用所提模型和计算方法对两个给定的回路热管进行了热力分析,得出了关键节点的压力、温度,分析了工作温度、环境温度和毛细芯厚度等对回路热管传热性能的影响.     

A novel miniaturized loop heat pipe

The research on a novel miniaturized loop heat pipe (LHP) consisted of an evaporator, a condenser, vapor and liquid lines is presented in this paper. In the LHP, the evaporator was separated into two parts of boiling and suction chambers by a vapor separator, which drove vapor to one-way flow to vapor line. Moreover, the bottom of evaporator was connected as the cycle channel of refrigerant. Thin copper plates with micro-fins as enhanced structures fabricated by the ploughing–extrusion (P–E) method were embedded in the boiling chamber. Accordingly, the copper fiber sintered felt fabricated by the solid-phase sintering of copper fibers with rough surface, was filled in the suction chamber of evaporator as the wick to provide the capillary force. In addition, the integral rhombic-shaped pillars fabricated by the milling, behaved as intensified condensation structures in the condenser. The startup and operation characteristics of LHP were tested under different heat loads and refrigerants. The experimental results showed that the highest temperature of evaporator reached 93.2 °C under the maximum heat load of 150 W.