【作者】 徐慧宁；

【导师】 谭忆秋；

【作者基本信息】 哈尔滨工业大学 ， 道路与铁道工程， 2011， 博士

【摘要】 路面积雪结冰是我国大部分地区常见的现象,及时有效地清除路面冰雪对于保障交通安全和提高道路通行能力具有重要的意义。流体加热道路融雪系统以其可控性强、热能来源广、绿色无污染、能源利用率高等优势而备受各国道路工作者推崇。但是,现有的流体加热道路融雪模型忽略了融化雪水在道路结构中传递对道路材料热物理参数的影响致使融雪模型预测精度不高;另一方面,流体加热道路融雪系统由于缺少实测数据的支持,在一定程度上制约了融雪模型的发展。针对上述问题,本文开发了真实环境流体加热道路融雪试验系统;考虑了融化雪水在道路结构中的传递对道路材料热物理参数的影响,开展了流体加热道路融雪系统温—湿耦合融雪模型的研究;在此基础上,借助仿真分析的方法探讨流体加热道路融雪系统的融雪特性与融雪效果,制定了融雪系统运行过程控制方法,提出了针对我国不同地区不同融雪目标的流体加热道路融雪系统设计热负荷。主要研究内容及成果概括如下:首先,采用太阳能和土壤源热能作为融雪系统能量来源,建立了真实环境下的流体加热道路融雪试验系统。依托试验系统开展试验研究,分析了融雪过程热泵系统工作特性及路面温变特性,验证了试验系统的稳定性与可靠性,并探讨了液体流速、管间距、管埋深、环境因素对路面温变特性的影响,揭示了流体加热道路融雪系统良好的环境适应性。其次,综合考虑融化雪水在道路结构中的传递对道路材料热物理性质的影响,利用含水量作耦合项,建立了流体加热道路融雪系统温—湿耦合融雪模型。运用计算语言编制模型子程序,将其嵌入HVACSIM+仿真环境,完成了流体加热道路融雪系统仿真的实现。在此基础上,采用不同融雪方式流体加热道路融雪试验数据,验证了流体加热道路融雪系统温—湿耦合融雪模型的准确性与合理性,对比分析了温—湿耦合融雪模型与温度场单场融雪模型对融雪过程预测精度的差别,揭示了融化雪水在道路结构中的传递对融雪过程的影响。随后,基于建立的温—湿耦合融雪模型,以发生于路表的各种热流密度为研究对象,分析了其随时间的变化规律,研究了流体加热道路融雪系统融雪特性,明确了融雪过程的三个阶段即待融阶段、融雪阶段及融后蒸发阶段。采用“待融时间”、“融雪过程平均固—液相变热流密度”、“融后5小时平均液—汽相变热流密度”分别表征上述三阶段的融雪特性,分析了融雪条件(环境因素、系统运行参数)对流体加热道路融雪系统融雪特性的影响。基于显著影响融雪特性的因素,建立了针对融雪过程不同阶段的流体加热道路融雪系统运行过程控制图,并据此提出了流体加热道路融雪系统的运行过程控制方法(即运行策略),为流体加热道路融雪系统的运行过程控制提供参考。最后,基于本文建立的温—湿耦合融雪模型,采用“针对某一融雪目标的无雪时间比”表征流体加热道路融雪系统的宏观融雪效果,分析了地点、系统运行参数、系统设计参数、环境参数等因素对流体加热道路融雪系统融雪效果的影响,并探讨了融雪目标及模型计算深度对流体加热道路融雪系统融雪效果评价的影响。在此基础上,依据我国降雪分布特点及近30年气象数据,选择代表性城市作为研究对象,基于融雪效果提出了针对我国不同地区不同融雪目标的流体加热道路融雪系统设计热负荷,为今后我国流体加热道路融雪系统的设计提供依据。本文在流体加热道路融雪试验系统开发、温—湿耦合融雪模型研究、流体加热道路融雪系统的运行策略及设计热负荷等方面开展了一系列工作,将促进流体加热道路融雪系统研究的发展及此项技术在我国的推广应用。更多还原

【Abstract】 In winter, traffic accidents occur frequently during snowfall, sleet andfreezing rain. Therefore, preventing ice formation and snow accumulation onroad surface is of high priority to improve the safety of driving. In recent years,due to certain inherent advantages, such as, high energy efficiency, strong systemcontrollability, convenient installation and wide energy source, hydronic heatingis the most promising candidate to be practically applied for the applications ofpavement snow melting. But the neglection of melted water on the thermalparperties of pavement material is the main reason for low prediction precisionof snow melting model. On the other hand, the lack of test data also restricts thedevelopment of snow melitng model.In this paper, a large-scale hydronic snow melting test system has been built.And a 2-dimensional snow melting model coupling the thermal and hydrologicalprocess is developed. A research implementation of this model has been used insnow melitng characteristic study and snow melting performance study.Operation strategy for hydronic snow melting system is suggested, and requiredheat fluxes for hydronic snow melting system in China is proposed. The mainresearch contents and achievements are summarized in the following:Firstly, a large-scale hydronic snow melting test system has been developed.In this test system, both solar energy and ground thermal energy are adopted asenergy source. Heat pump with inverter, pavement structure with differentembeded pipe depth and pipe spacing make up the multiple operating conditions.The system reliability and stability is validated by the data collected fromsolar-ground source coupled snow-melting test systems for pavement. Besides,the factors which have an impact on temperature distribution characteristic arealso investigated. It indicates that this system could be used in a widetemperature range.Secondly, a two dimensional snow melting model coupling the heat andmass transfer process is developed, which accounts for the effect of melted waterpenetration into pavement. A Fortran code is written and numerical implementedin HVACSIM+ simulation environment. The collection of operating data, and corresponding weather data, from the snow melting test system (Achievement 1)is used in the model validation. The prediction difference between the heat andmass coupled snow melting model and heat only snow melting model iscompared. The role of melted moisture transport to pavment is discussed.Thirdly, based on the heat and mass coupled snow melting model, snowmelting characteristic for hydronic heated system for pavement is analyzed. It isindicated that idling period, snow melting period and after-snow period are thethree periods during the snow melting process. The snow melting characteristicduring snow melting process are represented by waiting time, averagesolid-liquid phase change heat flux during snow melting process, and averageliquid-steam phase change heat flux within the first 5 hours in after-snow process,respectively. The factors which have an impact on snow-melting characteristicare also investigated. Based on the results above, operation strategy for hydronicsnow melting system is suggested. The proposed method will give a lot ofsuggestion in the operation of hydronic heated system for pavementAt last, based on the heat and mass coupled snow melting model, thepercentage of snow-free hours during snowfall is adopted to represent the snowmelting performance of hydronic snow melting system. The effect of idling time,heat fluxes, pipe spacing, embeded pipe depth, pipe material, thermal property ofmaterial, meteorological condition and control strategy on the snow meltingperformance have been discussed. The effect of the snow melting aim andcalculation depth of the model on the snow melting performance evaluation isalso studied. According to the research on snow hazard regionalization in China,different locations have been chosen to represent a range of climates andsnowfall characteristics. According to the weather data corresponding to snowevent from 1981 to 2010 in representative cities, the limit snowfall conditions ata 95% confidence level is proposed. Based on the limit snowfall conditions at a95% confidence level , required heat fluxes for hydronic snow melting system inChina is suggested. The proposed heat fluxes will give a lot of suggestion in thedesignation of hydronic heated system for pavement in China.A series of creative researches, such as the development of hydronic snowmelting test system, the development of a heat and mass coupled snow meltingmodel for hydronic heated pavement, the operation strategy and required heat for hydronic snow melting system, were carried out in this paper. Theseresearches will promote the development and application of hydronic heatedpavement in China.更多还原