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SUMMARY:Some considerations of underground heat transferring in GSHP coupl
 ed thermal foundations: pipe heat flows\, heating capacities and response 
 test - He Qi\, CUED
DTSTART:20141204T170000Z
DTEND:20141204T180000Z
UID:TALK54241@talks.cam.ac.uk
CONTACT:Anama Lowday
DESCRIPTION:For new building and infrastructure developments\, it is possi
 ble to incorporate the mechanism for heat transfer between the building an
 d the ground through the foundation elements (e.g. piles and diaphragm wal
 ls). This geothermal underground infrastructure approach is considered as 
 potentially cost-effective due to small additional installation cost and l
 ess occupied land/underground space. For its implementation\, it is of sig
 nificance to discuss the impact to the ground source heat pump (GSHP) perf
 ormance from the foundation itself as well as other underground structures
  in the planning period. This study describes a case of a combined thermal
  pile and wall system installed at a recently constructed underground stat
 ion box. The following three potential impacts emerged while investigating
  the case study\; (1) a nearby underground tunnel which has been in operat
 ion for more than 100 years\, and (2) the station box and new tunnel itsel
 f when the commercial service begins. Finite element simulations were cond
 ucted to investigate the magnitude of the issues. Results show that\, the 
 heat generated from both nearby underground tunnel and the station box its
 elf can influence the performance of GSHP. In this case study\, the amount
  of heat extracted increased several times of the original design when the
  heat supply from the existing underground infrastructure is considered. A
 t the same time the overall changes in the ground temperature after many y
 ears of GSHP operation is discussed.\nIn the other part\, it was doubted t
 hat the conductivity value of the soil estimated by classic thermal respon
 se test (TRT) methodology is not proper in the pile/wall. A detailed compu
 tational fluid dynamics (CFD) model was conducted to illustrate this inacc
 uracy. Results shows: (1) the classic TRT results should be over-evaluated
  due to the heat transfer co-efficient across the pipe walls. (2) the diff
 erent heat transfer co-efficient due to the friction to the liquid at the 
 wall interface\, and (3) water flow rate is a key in the difference of TRT
  results. An acceptable compensatory method is to apply velocity-related h
 eat transfer co-efficient calculation in linear-sourced model to simulate 
 the heat transfer process. \n
LOCATION: Cambridge University Engineering Department\, Lecture Room 6
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