Development of freezing-prevention on Road by Using Thermal Energy

本研究的目的是开发北陆和山阴地区的道路防冻系统。该系统期望使用自然能，即热能，并且由长2 m、直径0.1m的铝棒组成。用0.01m厚、直径0.6m的铝板与铝棒连接，放入混凝土板中，假定为路面。该混凝土板为圆柱形，直径为0.7m，厚度为0.1m。该装置设置在福井大学。用30对热电偶测量了铝棒和混凝土板周围土壤的温度分布。用照相机记录冻结过程，然后在试验地点附近同时获得由于电风扇引起的蒸发速率、空气温度和湿度。该系统的有效性在2月的清晨得到了证明，然后在含铝混凝土上没有观察到冻结。然而，不含铝的混凝土上的水在试验开始两小时后冻结。蒸发率比自然蒸发率高出约6倍，从凌晨4点开始，气温保持在零度以下3小时。铝板混凝土的温度始终比不加铝板的混凝土高1 ~ 2 ℃。土壤中垂直方向的温度梯度与沿沿着铝棒方向的温度梯度基本相同。结果表明，铝是非常有效的介质，把热能拉到路面上，所提出的系统也是有效的道路上的防冻。

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.