【作者】 李翠敏；

【导师】 赵加宁；

【作者基本信息】 哈尔滨工业大学 ， 供热、供燃气、通风及空调工程， 2012， 博士

【摘要】 降低以供暖为主的建筑能耗，利用工业余热和可再生能源等低温能源供暖，实现能源的梯级利用是目前建筑能源领域的重点课题。我国的低温能源极其丰富，能够提供大量的可用于供暖的低温热水。但是，目前针对低温供暖末端设备的研究相对较少，产品种类单一且具有一定的适用局限性。重力循环供暖末端设备以毛细管网为换热芯，可使用30℃的热水进行采暖，从而对其他类型供暖末端设备难以使用的低品位热源加以利用。设备从概念提出到应用于实际工程，有很多问题需要解决，例如，该设备中的毛细管尺寸介于常规管与微细管之间，其阻力特征的基本规律描述尚不清楚；设备换热时，存在着对流换热和辐射换热，特别在增加蓄热相变板而进行蓄放热时，还同时存在着导热和相变换热，换热机理非常复杂；另外，设备的整体换热及流动阻力等性能参数也均是空白。本文首先对设备运行特性进行研究。通过毛细管单管层流向湍流转变的临界雷诺数和阻力特性的实验，得到了其从层流向湍流转捩的临界雷诺数，表明其流动阻力特性与典型的常规管相吻合。进一步，对试制样机的阻力特性、散热特性、供冷特性和传热规律等进行实验研究。阻力实验表明设备阻力较大，设备设计中毛细管网宽度不应超过1m；供冷特性实验得到了样机利用温度较高的冷冻水供冷时的供冷能力数据，为设备的进一步优化研究提供了基础；传热规律的分析结果表明样机运行时内部温度场和进、出风口处的温度场在宽度方向上具有一致性，可依据此特点简化计算模型。在设备结构参数优化研究中，本文通过数值模拟的方法得到了设备内部温度分布的特性和散热量，分析并优化了设备外罩高度、厚度、进风口尺寸、出风口尺寸和毛细管网间距等结构参数，并将各参数对散热量的影响近似拟合成关于Ra数的关系式。为验证优化结果，将优化设备安装在实际工程中，并对应用现场的散热效果进行实验测试。测试结果表明设备结构合理，应用效果良好，能够满足房间耗热量需求。在此基础上，根据设备运行特点和供暖效果提出了标准工况和经济性指标。在设备的供暖和供冷特性研究以及工程应用中发现，该设备适合与热泵热源联合使用，如果设备增加蓄热功能，能够在间歇运行的建筑内充分利用电网的峰谷特性，对电网起到削峰填谷的作用。为开发并研究设备的蓄热特性，试制了蓄热材料并将其与设备结合。蓄热材料以有机材料癸酸和高聚乙烯为原料，具有相变温度低、蓄热时不流动等特点，并且均匀性和稳定性良好，相变性能明显改善。本文以铝合金板为框架材料，与上述材料结合形成相变板，并提出了相变板与设备的结合方式。在对设备蓄热特性的研究中发现，带有相变板的重力循环供暖末端设备蓄放热机理及特性非常复杂，对流换热、辐射换热、导热和相变换热同时发生。为研究并优化设备的蓄热性能，本文依据设备运行特点建立数学模型，通过程序计算得到设备蓄热时的运行特性，并以蓄热时间为限制因素优化与设备结合的相变板厚度。为了研究设备蓄热功能的地区适用性，本文通过对数学模型的求解，分别得到夏热冬冷地区和寒冷地区的设备运行特点。研究结果表明设备的蓄热功能应用在夏热冬冷地区更为适合，基于以上结果本文提出了设备在该地区的运行方案及经济性分析。重力循环供暖末端设备可采用低温热水供暖、高温冷水供冷，并具有蓄热的能力。该设备的研发为低温末端的应用提供了一种新的选择，拓展了低温热源用于供暖的空间。本文所做的工作，为该新型低温供暖末端设备的进一步研究和应用提供了理论和实践基础，将促进该设备更快地走向工程应用。更多还原

【Abstract】 Reducing energy comsumption from building heating, utilizing industrial wasteheat or renewable energy, and therefore realizing the cascade utilization of energy areseveral major important research subjects in current building energy field. In China, alarge amount of low temperature hot water which is produced from low temperatureresources has a great potential to be reused for building heating. However, current studyon low temperature heating devices is relatively rare, and the products are limited inapplication. The newly developed gravity-powered heating terminal device consists of aseries of capillary tubes in which the running water for heating is as low as30℃, so itcould fully utilize the low-grade heat resoureces which are unusable by other heatingterminal devices. Meanwhile, there are so many subjects should be studied and solvedfor this device from theory to application. For instance, the size of capillary tube isbetween conventional and micro tubes, of which resistance characteristic is unclear. Inadditon, the mechanism of heat transfer is extremly complex especially when thestorage effect has to be considered when the phase change material is added. Lastly, theperformance parameters such as total heat transfer and flow resistance for the wholedevice set are unknown.This thesis studies several operating characteristics of the device firstly. Thecritical Reynolds number in the capillary tube indicating the transition from laminarflow to turbulent flow is obtained by experiment and the flow resistance characteristicof capillary single tube is comparable with typical normal tube. Further, a series ofexperiments on the resistance, heat dissipation, cooling characteristics and heat transferlaw for sample device were conducted. The resistance experiment shows that the devicehas higher resistance, so the width of capillary network should not be more than1m; thecooling characteristic experiment obtains the cooling data when the sample device coolsusing high temperature chilled water, which provides theoretical basis for furtheroptimization; the analysis of heat transfer law shows that the internal temperature fieldand air inlet and outlet have consistency in the width direction during the sample devicerunning, and this characteristic could help to simplify computation model.The characteristics of internal temperature distribution within the device and heatdissipating capacity are obtained through the method of numerical simulation in theparameter optimization research for device structure. Also, this thesis proposes theoptimal parameters such as device enclosure height, enclosure width, inlet size, outletsize, and distance between neighboring capillary tubes, and fits the relations aboutRayleigh number based on these parameters for heat dissipating capacity. Based on theoptimization of structure parameters, an optimal device is designed and applied in the projects to testify the optimization results. Test results show that the improved devicehas reasonable structure, effctive application, and could satisfy the room heatcomsumption. Based on the device operation characterics and heating effect, thestandard condition and ecnomical index are proposed.During the research on device heating and cooling characteristic and application, itindicates that this device is suitable to use by combing with heat pumps. And if storageequipment is added, the device could store heat at night when the power demand is lowand could release heat during daytime when the power demand is high. In this way, thisdevice could balance the power demands, hence reduce cost. This study uses capric acidand high density polyethylene as material, which has the characteristics such as lowerphase change temperature and immobilization during heat storaging, and it has gooduniformity and stability. To integrate the phase change material to gravity-poweredheating terminal device, aluminum alloy plates are used as the frame, and a proto typeof phase change board is fabricated and filled with the device.This thesis studies the heat storage characteristic of the device. The heat storagingand releasing mechanism and characteristics of the gravity-powered heating terminaldevice with phase change plate are extremly complex. Convective heat transfer,radiation, heat conduction and phase change heat transfer occur simultaneously. In orderto study and optimize the device heat storage characteristic, this work obtains theoperation characteristics when the device is storaging heat through mathematicalmodeling and procedure, and optimizes the thickness of phase change plate with theconstraint of heat storage time.In order to study region applicability of the heat storage effect, this thesis studiesthe operating characteristics in hot summer and cold winter regions as well as coldregions through mathematical modeling. Results show that this device is more suitablein hot summer and cold winter regions, and also this study obtains the operation schemeand economical analysis results for this kind of region.Gravity-powered heating terminal device could heat with hot water of lowtemperature and cool with cold water of high temperature, and is capble of storing heat.The development of this device offers a new choice for the application of lowtemperature terminal, and expands the space of the use of low temperature heat sourcefor heating. The works in this thesis provide both theoretical and practical basis for thefurther research and application of new low temperature heating terminal device, andpromote the engineering application of this device.更多还原