Numerical simulation and sensitivity study of double-layer Slinky-coil horizontal ground heat exchangers

Fujii, Hikari; Yamasaki, Shohei; Maehara, Takahiro; Ishikami, Takashi; Chou, Naokatsu

doi:10.1016/j.geothermics.2013.02.006

Cited by 54 publications

(33 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The heat flux resulting from an algebraic summation of the listed fluxes qcond is transported into the ground (mainly by conduction) or in the opposite direction, depending on its minus/plus sign. The heat balance on the surface of the ground taking into account convection, radiation, and moisture evaporation has the following form [13][14][15][16][17][18][19][20][21]:…”

Section: Heat Balance On the Surface Of The Groundmentioning

confidence: 99%

Undisturbed Ground Temperature—Different Methods of Determination

2017

View full text Add to dashboard Cite

Methods for the calculation of the undisturbed ground temperature (UGT) are presented. Heat fluxes occurring on the surface of the ground and their influence on the UGT are described. Correlation equations for the calculation of the undisturbed ground temperature based on the meteorological data averaged in the yearly cycle are proposed. These equations are of a semi-empirical character and they are based on the heat flux balance. The determined coefficients of these equations, particularly the convection heat transfer coefficient, are consistent with the values specified by other methods.

show abstract

Section: Heat Balance On the Surface Of The Groundmentioning

confidence: 99%

Undisturbed Ground Temperature—Different Methods of Determination

2017

View full text Add to dashboard Cite

show abstract

“…It can be concluded that the average COP of the horizontal-coupled GCHP was 2.5 and there was no significant difference in the heat extraction of the slinky heat exchanger at different coil diameters. Fujii et al [22,23] compared the heat exchange rates of double-layer slinky-coil horizontal GHEs and single-layer horizontal GHEs by long term cooling and heating tests. The results showed that the heat exchange rate per unit land area is obviously improved by using double-layer horizontal GHEs.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigations and Numerical Simulation of Thermal Performance of a Horizontal Slinky-Coil Ground Heat Exchanger

Zhang

Yang

et al. 2017

Sustainability

View full text Add to dashboard Cite

Abstract:A model test system of horizontal slinky coil ground heat exchanger (HSCGHE) was established according to the similarity theory. A 2-D mathematical model of HSCGHE was built and experimentally validated. Experimental and numerical investigations of effects of different parameters on the thermal behavior of HSCGHE were undertaken. The results show that the heat release rate of the slinky coil and soil temperature around it increase as the inlet fluid temperature of coil increases. The soil temperature operated in intermittent mode can get a recovery, and thus the heat release rate of the coil can be improved effectively. For a given condition, reducing the coil central interval distance can increase the heat release rate of the HSCGHE, but also results in the decrease of the heat release rate per unit length of the coil. Therefore, the coil central interval distance cannot be decreased without limit. At the same time, the thermal performance of HSCGHE is related to the ground surface wind velocity. The heat release rate in the sandstone is the largest, followed by sand, the lowest for clay. Additionally, with the increase of buried depth of coil, the heat release rate increases, but the increase degree gradually becomes small. Thus, the buried depth cannot be too deep and should be determined by thermal performance, excavation cost and safety requirements.

show abstract

“…Even so, the use of horizontal GHEs can reduce installation cost and minimize the compromise between increase in efficiency and cost [19][20][21]. Horizontal GHEs are usually installed in a trench approximately 1.5-3 m deep, and their thermal efficiency is affected by pipe configuration, type of pipe, trench depth and ground thermal properties [22][23][24][25]. Among them, Congedo et al [23] analyzed the thermal efficiency of different types of horizontal GHEs using numerical analysis method.…”

Section: Introductionmentioning

confidence: 99%