Mutual Influence Between Tunnel Structures and Heat Exchange Pipes of Ground Source Heat Pump in Tunnel

Abstract:

Tunnel heating system using heat pump was introduced for the first time at Zhadun River tunnel in Inner Mongolia Autonomous Region of China to prevent freezing damage in cold region tunnels. Tunnel heating system consists of the heating section, absorbing section, heat pump, collector, and distributor line. This system can be used for heating lining and insulation ditch in tunnel portal. The heat exchange pipes are laid between first lining and second lining in series of longitudinal arrangement. By calculating the decreased ratio of area and moment of inertia of carrying cross section within heat exchange pipes, the results show that the influence of heat exchange pipes on the carrying capacity of tunnel lining is so small that it can be ignored. Tunnel structure includes anchors, waterproof boards and steel arches. The influences of each component on the heat transfer of heat exchange pipes were analyzed by establishing single factor comparison model. The results show that: ① The influence of anchors on the heat transfer of heat exchange pipes is not obvious, only 2.3% at most; ② The disadvantageous influence of waterproof boards on the heat transfer of heat exchange pipes should be considered at the prophase, but it can be ignored after long running; ③ The advantageous influence of steel arches on the heat transfer of heat exchange pipes is obvious at the prophase, but it tends to be not obvious after long running.

Key words:tunnel in cold region; ground source heat pump; heat exchange pipe; mutual influence