ASTM A517 Grade E
2011年5月4日 by admin
【Abstract】 Hydronic Ice-Snow Melting (HISM) system is a new kind of Hot Melting De-Icing technology, by using the heat collecting in summer to melt the snow and ice on the road in winter, which can improve road safety. While in the hot summer, it uses the road to absorb solar radiation and stores it to the ground for winter use. This technology not only can realize the seasonal application of renewable energy, but also can effectively reduce the pavement surface temperature in hot summer, reduce the rate of heat corrosion and extend the life of the pavement adequately.Road surface, as a basic structure in HISM system, bears the thermodynamic process of winter ice-snow melting and heat absorption process of summer solar radiation, which is the basic heat transfer process of heat release and heat collection. Therefore, this paper will focus on road ice-snow melting in winter and slab solar collection in summer by combining with experimental investigation and analog simulation, to explore the heat transfer and mass transfer characteristic in ice-snow melting and variation of surface condition and time-varying feature of underground soil, to discover the mechanism of heat transfer and mass transfer in road ice-snow melting process and slab solar collection for technological improvement of road ice-snow melting.The main works of this paper are consisted of the analysis of the process, characteristics researches and simulation of HISM system and the study of heat absorption process of solar radiation. At first, based on different snow falling and melting process on road, the basic heating characteristics was studied systematically, and presented basic processes of static snow melting, dynamic snow melting and preheating snow melting process, to reveal their inside variation rules of temperature, energy character, relative heat character and the difference of influences; At second, depending on the experiment of variable load heating surface, the ice melting characteristic in the process of surface ice melting was studied systematically, to discuss the ice melting characteristics and impacts for getting the relation of load character; At third, basic heat transfer analysis was carried out systematically on HISM system, on the base of resolving the process of HISM unit objectively, heat transfer control equations presenting the basic thermal phenomena was brought up, and based on MATLAB-Simulink, a model of HISM was built to form a fundamental module of the integrated system, and from this module, surface temperature and energy characteristics in the process of HISM were analyzed further, so it provided a powerful method for the research of integrated HISM system and its control strategy, and an analog simulation of this integrated system was taken for a further research of HISM system with several dynamic snow melting method available; At fourth, as to heat absorption of solar radiation on road in summer, by using thermodynamic analysis and spectral analysis, heat absorption experiments with different road materials and different road morphology and heat collection experiment of solar radiation were carried out.The snow melting process can be divided into static melting and dynamic melting, and the latter one can be divided into preheating melting and non preheating melting. Therefore, a set of experimental system of road snow melting was built by using electric heating hot fluid with controlled temperature, instead of heat pump heating devices in practical engineering to study the three processes with different snowfalling characteristics. Depending on surface condition and surface temperature, the ability of road snow melting was evaluated, and depending on energy consumption of snow melting, the utilization efficiency of energy and heat exchange capacity was evaluated. So, it provides an important basis of the design of HISM system.Because of the icy road, that will heavily reduce the surface friction, it becomes necessary to study the characteristics of road ice melting. In this paper, by using a scaled down stimulant, a set of experimental facility was built, which used controllable electric heating carbon fiber, for the study on the characteristics of ice melting and heat transfer and mass transfer characteristic. Depending on ice melting rate and the variation of ice-layer temperature, ice melting characteristics was analyzed. Meanwhile, the effect of heating load, thickness of ice-layer, ice water flowing, spacing of heating pipe and aSTM A517 Grade Errangement of pipe on ice melting were analyzed. So, it provides an important guidance to the design of ice melting system.Road ice-snow melting system of winter is a complex heat and mass transfer process with phase transformation. By writing S function to build various simulation modules by myself, including road ice-snow melting module, heat pump module, circulating pump module, GLHE module and controller module, etc, an integrated HISM system was set up. Snow free area ratio and surface temperature that are feature parameters to measure the system capacity were analyzed through single snow melting process and whole winter process. And meanwhile, two economic indicators of the system, COP of heat pump and energy consumption, were presented. By comparing different snowfall, different outdoor air temperatures and different initial underground temperature, an anlysis were done on the economic evaluation of the system. The results indicated that raising the temperature of underground soil can effectively improve the performance of the system. And the way to raise the temperature of underground soil can be realized by heat collection in summer. Therefore, the study on slab solar collection seems to be necessary.It is important of slab solar radiation collection to road ice-snow melting of winter. However, different absorbability of solar radiation and heat collecting performance are arisen on different material slabs and different configuration slabs. Therefore, in this paper, these two kinds of slabs were studied. From the view of temperature and reflection spectrum, the absorbability of solar radiation was analyzed mainly to explore the characteristic of temperature variation and the capacity of heat transmission. Meanwhile, for different configuration slabs, the performance of heat collection under solar radiation was studied, and the characteristic of heat quantity per unit area and heat collecting efficiency were analyzed for further application of practical engineering.STM A517 Grade E
Tags: ASTM A517 Grade E steel A517 Gr.E A517 GRF
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