Abstract
Thermo-active piles are widely utilised for low carbon heating and cooling, and their uses are further encouraged in cities where there are obligations for developments larger than a certain threshold to generate a portion of their estimated energy use on site in a renewable manner. It is therefore important to model accurately the thermal performance of the designed thermo-active piles to ensure that such obligations are complied with. In this paper, the thermal performance of a thermo-active pile is quantified by the evolution with time of the power that can be harnessed from the pile, obtained from 3D thermo-hydro-mechanically coupled finite element analyses which include the simulation of a hot fluid flowing through heat exchanger pipes. Different pipe arrangements are considered in this study, in order to demonstrate the potential gains in efficiency arising from the installation of multiple U-loops within the pile. Furthermore, detailed analysis of the heat fluxes resulting from pipe-pile-soil interaction is carried out, illustrating the contribution of the different components of the system (concrete, near-field and far-field) to the overall storage of thermal energy.
Highlights
Thermo-active piles differ from conventional piles in a way that heat exchanger pipes are embedded within them, which allow the circulation of a hot or cold fluid in order to promote the exchange of heat with the ground
In order to ensure that such an obligation is complied with during the design of thermoactive piles, it is important to model its thermal performance accurately, which is quantified in this paper by the evolution of power with time that can be harnessed from the pile, as well as the storage of energy in different components of the system, namely in the pile itself, near-field and farfield in the soil
The rate of energy transfer between the heat exchanger pipes and the pile at a time instant t, P t, can be evaluated using Equation (1): P t = ρC ∙ Q ∙ T t − T t where Q is the flow rate of the fluid, T t is the temperature of fluid entering the pile at t and T t is the temperature of fluid leaving the pile at t
Summary
Thermo-active piles differ from conventional piles in a way that heat exchanger pipes are embedded within them, which allow the circulation of a hot or cold fluid in order to promote the exchange of heat with the ground. The fact that thermo-active piles function both as a ground source heat pump (GSHP) system to provide low carbon heating and cooling and as a foundation to provide structural stability justifies their growing popularity in recent years. [1]), further encourage the use of thermo-active piles, as these are often the only viable option to produce renewable energy in dense urban settings. In order to estimate the evolution of temperature in the ground due to a borehole heat exchanger, which has a much larger aspect ratio (pile length to diameter ratio) than a thermo-active pile, [2] proposed the use of temperature response functions (G-functions). In order to estimate the evolution of temperature in the ground due to a borehole heat exchanger, which has a much larger aspect ratio (pile length to diameter ratio) than a thermo-active pile, [2] proposed the use of temperature response functions (G-functions). [3,4,5] provided new G-functions for thermo-active piles, which can account for their transient behaviour and the energy
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
