BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI
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<strong>BULETINUL</strong> <strong>INSTITUTULUI</strong> <strong>POLITEHNIC</strong> <strong>DIN</strong> <strong>IAŞI</strong><br />
Publicat de<br />
Universitatea Tehnică „Gheorghe Asachi” din Iaşi<br />
Tomul LVIII (LXII), Fasc. 3, 2012<br />
Secţia<br />
MATEMATICĂ. MECANICĂ TEORETICĂ. FIZICĂ<br />
STUDY OF A SINGLE TUBE BOREHOLE THERMAL ENERGY<br />
STORAGE BY MEANS OF AN IMPLICIT FINITE DIFFERENCE<br />
METHOD<br />
BY<br />
BOGDAN HORBANIUC ∗ , GHEORGHE DUMITRAŞCU and MIHAI ADAM<br />
”Gheorghe Asachi” Technical University of Iaşi,<br />
Department of Mechanical and Automotive Engineering<br />
Received: May 20, 2012<br />
Accepted for publication: June 30, 2012<br />
Abstract. The paper deals with the problem of storing heat provided by a<br />
solar system for the periods when solar energy is not available. In order to level<br />
the primary energy curve so as to secure a quasi constant energy supply, a<br />
thermal storage is mandatory. One of the multiple options is to store heat in the<br />
ground and extract it when necessary. The solution studied in the paper consists<br />
of transporting heat to and from the heat storage represented by the ground, by<br />
means of vertical tubes. In order to study the dynamics of the heat exchange<br />
process, one needs to know the temperature field in the ground that results from<br />
the thermal interaction with the heat transfer tube as well as the heat transferred<br />
to or extracted from the heat storage. This issue is solved by means of an<br />
implicit finite difference scheme assuming that the tube is isothermal<br />
longitudinally. The temperature is plotted versus the radius for selected moments<br />
during the charge/discharge processes of a daily heat storage system and the<br />
transferred heat is calculated. The model is used for a single tube arrangement in<br />
order to get the primary results necessary to refine the model by taking into<br />
consideration the non-isothermal tube and further a structure consisting of<br />
connected tube arrays.<br />
Key words: sensible heat thermal energy storage, borehole thermal energy<br />
storage, isothermal tube, numerical modelling, finite difference method.<br />
∗ Corresponding author: e-mail: bogdan_horbaniuc@yahoo.com