Development of freezing-prevention on Road by Using Thermal Energy

这项研究的目的是开发北国和萨宁地区的道路防冻系统。该系统需要使用一种自然能源，即热能，由长2m、直径0.1m的铝棒组成。将厚度0.01m、直径0.6m的铝板与铝杆连接，放入混凝土板中，作为路体。该混凝土板为柱状，直径为0.7m，厚度为0.1m。这台仪器是在福井大学安装的。用30个热电偶测量了铝棒和混凝土板周围土壤的温度分布。用静止摄像机记录了冻结过程，同时获得了试验点附近电风扇的蒸发速率、空气温度和湿度。该系统的有效性在2月的凌晨得到了验证，随后未观察到加铝混凝土的冻融现象。然而，不含铝的混凝土上的水在两个小时后从测试开始就冻结了。蒸发速率大约是自然蒸发速率的6倍，从凌晨4点开始，气温就一直保持在零下3个小时。有铝板混凝土的温度比无铝板混凝土的温度高1~2ﾟC。土壤中垂直方向的温度梯度与铝棒上的温度梯度基本相同。结果表明，铝是一种非常有效的将热能拉升到路体上的介质，所提出的系统对道路防冻也是有效的。

The purpose of this study is the development of freezing-prevention system on road for Hokuriku and Sanin areas. This system has been desired to use a natural energy, i.e. thermal energy and is composed of aluminum rod 2m in length and 0.1m in diameter. An aluminum plate 0.01m in thickness and 0.6m in diameter is connected with the aluminum rod and is put into a concrete plate, assumed as a road body. This concrete plate has a columnar shape and its diameter and thickness are 0.7m and 0.1m, respectively. This apparatus was set in Fukui University. Temperature profiles in soil arround the aluminum rod and concrete plate were measured by thirty thermocouples. The freezing process was recorded by a still camera and then the evaporation rate due to an electric fan, air temperature and humidity were simultaneously obtained near the test site. The validity of thes system was demonstrated in the early morning in February and then the freezing was not observed on the concrete with aluminum. The water on the concrete without aluminum, however, was freezed two hours later from the beginning of test. The evaporation rate was about six times higher than the natural evaporation rate, and the air temperature kept the sub-zero temperature for three hours since 4 a.m.. The temperature in concrete with aluminum plate always was 1 - 2ﾟC higher than that without aluminum plate. The temperature gradient in the vertical direction in soil was almost same as that along the aluminum rod. It was confirmed that the aluminum is very effective as the media to pull up the thermal energy up to the road body and the proposed system was also effective for the freezing-prevention on road.