隧道地源热泵供热系统加热段隔热层厚度及热负荷计算

 为解决寒区隧道冻害问题，首次将地源热泵供热系统应用于内蒙古博牙高速林场隧道中。系统由取热段、加热段、热泵和分、集水管路组成。加热段位于隧道洞口处，由位于二衬和保温隔热层之间的供热管对隧道进行加热。将复杂的隧道加热段热传导问题转化为便于求解的圆形复合介质热传导问题，利用有限积分变换法获得其温度场解析解。利用考虑隔热层材料造价和耗能的经济计算模型，计算分析隧道全寿命周期30 a的隔热层厚度和供热负荷。计算结果表明：随着隔热层厚度的增加，隔热层材料费呈线性增加，供热消耗的电费呈递减趋势，材料费与电费之和呈递减趋势。建议林场隧道保温隔热层厚度取8 cm，年供热负荷取580 MJ/m2。

CALCULATION OF INSULATION LAYER THICKNESS AND HEATING LOAD OF HEATING SECTION OF TUNNEL HEATING SYSTEM USING HEAT PUMP

In order to solve the freezing damage problem of tunnel in cold region,an innovative heating system-tunnel heating system using heat pump was introduced for the first time to Linchang tunnel in Inner Mongolia Autonomous Region of China.Tunnel heating system consists of heating section,absorbing section,heat pump,collector and distributor line.The heating section is at the portal of tunnel and heated by the heating pipes located between secondary lining and insulation layer.The heat conduction of heating section is transformed to the heat conduction of composite medium in the cylindrical coordinate system.Its analytical solution was obtained using the finite integral transfer method.The yearly heating load is calculated by using the analytical solution under steady periodic conditions at different insulation layer thicknesses.These loads are used as inputs to an economic model including the cost of insulation material and the present value of energy consumption cost lifetime of 30 years of tunnel to determine the optimum insulation layer thickness.The investigation is carried out for Linchang tunnel in Inner Mongolia Autonomous Region of China.Results show that the energy costs decrease with the increasing insulation layer thickness;the cost of insulation material increases linearly with the increasing insulation layer thickness.Total cost,which is sum of insulation material cost and energy cost,decreases with the increasing insulation layer thickness.The optimum insulation layer thickness is obtained to be 8 cm;the yearly heating load is 580 MJ/m2.