Heat Exchanger Anchors for Thermo-active Tunnels
Event details
| Date | 14.02.2013 |
| Hour | 17:00 › 18:00 |
| Speaker | Thomas Mimouni |
| Location |
GCD0 386, EPFL
|
| Category | Conferences - Seminars |
Shallow geothermal power represents an important energy resource for the heating and cooling of the buildings. Due to relatively low temperature levels
encountered at shallow depths in soils, heat pumps are required to process the extracted heat, forming the so called ground source heat pump system.
Different types of heat exchangers with the ground have been developed in order to optimize the heat exchanges, and recent advances suggest that applying the concept of energy geostructures to tunnel structures could be efficient.
The present study investigates the potential of using tunnel anchors and nails as heat exchangers with the surrounding soil. Two main structures of shallow tunnels were investigated. A cut and cover tunnel, whose diaphragm walls are maintained with long anchors, was modeled first. Thermal influence of the soil surface and unsaturated conditions were taken into account. Nevertheless, mechanical implications of the heat extraction on the cut and cover tunnel were neglected because of the low mechanical confinement observed on the structure. Then, an urban bored tunnel was investigated. Only saturated conditions were
considered and the thermal influence of the surface was neglected but mechanical implications of the heat exploitation were quantified because of the high confinement of the bored tunnel body induced by the soil weight.
Different types of heat production cycles were tested in various soil conditions. The heat extraction was based on the external air temperature to represent a simplified building heat demand. All the exploitation cycles were optimized to reach a temperature threshold in the ground while avoiding freezing. Next, comparisons between extracted and retrieved heat for the different cycles allowed drawing an optimum exploitation method.
encountered at shallow depths in soils, heat pumps are required to process the extracted heat, forming the so called ground source heat pump system.
Different types of heat exchangers with the ground have been developed in order to optimize the heat exchanges, and recent advances suggest that applying the concept of energy geostructures to tunnel structures could be efficient.
The present study investigates the potential of using tunnel anchors and nails as heat exchangers with the surrounding soil. Two main structures of shallow tunnels were investigated. A cut and cover tunnel, whose diaphragm walls are maintained with long anchors, was modeled first. Thermal influence of the soil surface and unsaturated conditions were taken into account. Nevertheless, mechanical implications of the heat extraction on the cut and cover tunnel were neglected because of the low mechanical confinement observed on the structure. Then, an urban bored tunnel was investigated. Only saturated conditions were
considered and the thermal influence of the surface was neglected but mechanical implications of the heat exploitation were quantified because of the high confinement of the bored tunnel body induced by the soil weight.
Different types of heat production cycles were tested in various soil conditions. The heat extraction was based on the external air temperature to represent a simplified building heat demand. All the exploitation cycles were optimized to reach a temperature threshold in the ground while avoiding freezing. Next, comparisons between extracted and retrieved heat for the different cycles allowed drawing an optimum exploitation method.
Practical information
- General public
- Free