Modelling water and heat transport in subsurface reservoirs of cold and warm water

Jeroen Wille

Supervisor: Fred Vermolen and Jennifer Ryan
Site of the project:
Delft University of Technology

start of the project: November 2008

In March 2009 the Interim Thesis has been appeared and a presentation has been given.

The Master project has been finished in July 2009 by the completion of the Masters Thesis and a final presentation has been given.

For working address etc. we refer to our alumnipage.

Summary of the master project:
Since heating and cooling of large buildings is very energy consuming, one tries to find alternative, more efficient ways to heat or cool such buildings. A novel technique, which is applied nowadays to the building of the faculty EWI at the Delft University of Technology, is based on subsurface storage of heat and cold. The situation is as depicted in Figure 1, where a subsurface reservoir of warm and cold water is sketched. This reservoir is separated from the earth surface by a layer of well-insulating shale with a thickness of 10 meters approximately. The underground reservoir, itself, consists of grannular silicon. The communication between the building and the reservoir is by the use of wells (see Figure 1).

Figure 1: Schematic of the subsurface reservoir of cold and warm water. The situation for the summer is depicted here.

During summer warm water from the steerings of the building is injected via the well into the reservoir in order to have warm water that can be used for heating during the next winter, whereas from an other well cold water is abstracted for airconditioning from the reservoir by the use of an other well. During winter cold water is injected into the reservoir in order to have cold water for the cooling of the building for the next summer, whereas warm water is restrained from an other well for the heating of the building. This provides a cheap and efficient use of energy resources.


One remarkable observation is that in order to have the same volumetric flow of the injected water and extracted water is that the magnitude of the extraction pressure is larger than the injection pressure. One of the aims of the aims of the project is to find an explanation of this observation.

Work Proposed:

For this purpose, a model is developed, which takes into account the flow of cold and hot water in the porous medium (convection and Darcy's Law). Further, temperature variations of the density of the sandstone are taken into account. This leaves us with an equation of state for the density of the sandstone as a function of temperature and an additional equation describing heat transport. To compute the solution of the system of equations a Finite Element Method is used. For this purpose the Finite Element package SEPRAN can serve as a basis. Further, the obtained numerical solution is tested by the use of a semi-analytical solution for the equations.

This will be done by the following steps:

(a) literature survey,
(b) mahematical formulation,
(c) numerical implementation.

Contact information: Kees Vuik

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