能量桩桥面除冰融雪的能源需求与供给能力案例分析

Case Studies on Energy Demand and Capacity of Bridge Deck Deicing and Snow Melting Technology Based on Energy Piles

基于能量桩的桥面除冰融雪技术,克服了传统融雪剂对桥面板结构的腐蚀问题,且具有节能环保等技术经济优势。能源需求与能量桩供热能力的计算是能量桩桥面除冰融雪系统设计的关键。为达到除冰融雪目的,桥面板表面温度需维持在0℃以上;基于桥面板的热响应试验与除冰试验得到桥面板温度与换热效率、流体温度的关系,根据热传导定律,推导出桥面除冰融雪所需的换热效率与流体温度的计算公式;探讨了能量桩热泵系统的供热能力。计算得到换热管埋深和间距分别为14 cm和25 cm的桥面板,在环境温度为-1℃~0℃时,系统的热有效率(有效热流密度与换热效率的比值)约为50%,系统的热有效率随着环境温度的降低而降低。选取3座具有不同板桩比(桥面板面积与能量桩总长比值)的桥梁为案例,进一步分析了环境温度-10℃~0℃,降雪量水当量0.1~1.0 mm·h^(-1)范围内,能量桩的供热比,以及满足融雪需求入口流体温度的计算表达式。结果表明:能量桩的供热比与环境条件和桥梁的板桩比有关,板桩比为0.7 m2·m^(-1)时,环境温度为-5℃,降雪量不大于0.4 mm·h^(-1)(暴雪),能量桩供热可满足融雪需求;板桩比为1.5 m2·m^(-1)条件下,环境温度为-1℃时,降雪量不大于0.3 mm·h^(-1),能量桩供热可满足融雪需求;板桩比为2.0m2·m^(-1)时,环境温度-1℃时,降雪量不大于0.2 mm·h^(-1),能量桩供热可满足融雪需求。

Bridge deck deicing and snow melting technology based on energy piles can overcome issues of corrosion associated with the use of traditional snow melting agents,and provides technical and economic advantages including energy savings and environmental protection.The accurate calculation of the energy demand and heating capacity of an energy pile is the critical factor in the successful design of associated bridge deck deicing and snow melting systems.The temperature of the bridge deck surface should be kept above 0℃during snow melting process.An equation for the heat exchange rate and fluid temperature required of the bridge deck deicing and snow melting system was accordingly derived based on the relationships between the temperature of the bridge deck,the heat exchange rate,and the fluid temperature obtained through the thermal response and deicing tests.Furthermore,the heating capacity of the energy pile heat pump system was discussed.When the buried depth and spacing of heat exchange tubes were 14 cm and 25 cm,respectively,and the ambient temperature was-1℃-0℃,the thermal efficiency(ratio of the effective heat flux to the heat exchange rate)of the system was approximately 50%.The thermal efficiency of the system decreases with the decrease of the ambient temperature.Three bridges with different deck-pile ratios(defined as the bridge deck area divided by the total length of the energy piles)were selected as examples to analyze the heating ratio of energy piles under an ambient temperature range of-10℃-0℃with a snowfall water equivalent of 0.1-1.0 mm·h^(-1).Furthermore,the calculation of inlet fluid temperature required to meet the snowmelt requirement was analyzed.The heating ratio of the energy pile was found to be related to the environmental conditions and the deck-pile ratio of the bridge:the energy pile heating system was shown to meet the snowmelt demand without an external heat source when the deck-pile ratio was 0.7 m~2·m^(-1),the ambient temperature was-5℃,and the snowfall rate was less than 0.4 mm·h^(-1)(blizzard);when the deck-pile ratio was 1.5 m~2·m^(-1),the ambient temperature was-1℃,and the snowfall rate was less than 0.3 mm·h^(-1);and when the deck-pile ratio was 2.0 m~2·m^(-1),the ambient temperature was-1℃,and the snowfall rate was less than 0.2 mm·h^(-1).