Pavement Heating Research Articles

Energy foundations and other thermo-active ground structures

Energy foundations and other thermo-active ground structures, energy wells, and pavement heating represent an innovative technology that contributes to environmental protection and provides substantial long-term cost savings and minimised maintenance. The paper focuses on earth-contact concrete elements that are already required for structural reasons, but which simultaneously work as heat exchangers. Absorber pipes filled with a heat carrier fluid are installed within conventional structural elements (piles, barrettes, diaphragm walls, basement slabs or walls, tunnel linings), forming the primary circuit of a geothermal energy system. The natural ground temperature is used as a heat source in winter and for cooling in summer. Hence no additional elements have to be installed below surface. The primary circuit is then connected via a heat pump to a secondary circuit within the building. ‘Free cooling’ may even run without a heat pump. The paper describes heat transfer in the ground, and between absorber fluid and concrete/soil. Temperature-induced changes of soil properties or of foundation behaviour are also discussed, and recommendations for design and operation are given. Pilot research projects and case histories bridge the gap between theory and practice, and special applications reveal the wide field of geothermal geotechnics.

A Model for Simulating the Performance of a Pavement Heating System as a Supplemental Heat Rejecter With Closed-Loop Ground-Source Heat Pump Systems

The thermal loads of commercial and institutional buildings are generally cooling-dominated. When such buildings use ground source heat pump systems (GSHP) they reject more heat to the ground-loop heat exchanger than they extract over the annual cycle. In these situations, supplemental heat rejecters can be used to reduce the required size of the ground-loop heat exchanger, thereby reducing the first cost of the system. This paper describes the development, validation, and use of a design and simulation tool for modeling the performance of a hydronic pavement heating system as a supplemental heat rejecter in ground-source heat pump systems. The model uses a finite difference method to solve the transient two-dimensional heat conduction equation and has been formulated for use in component based system simulation. Full-scale experiments were conducted concurrently with the development of the model, the results of which have been used for validation purposes. An example application simulation is presented to demonstrate the use of the model as well as the viability of the use of pavement heating systems as supplemental heat rejecters in GSHP systems. [S0199-6231(00)00404-4]