Numerical Simulations of a Ground Source Heat Pump System With Pile Heat Exchangers

Oguma, Masahito; Matsumoto, Takeshi; Kakizaki, Takao

doi:10.1115/1.4028343

Cited by 1 publication

(4 citation statements)

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“…A numerical analysis is performed to determine the underground temperature over a period of several years, and the predicted and measured annual underground temperature fluctuations are found to be in good agreement [9]. In the case of no steel pipe, thermal transfer is in the vertical direction only, and the basic formula for the underground section is (1) In the presence of the steel pipe, heat transfer occurs only by conduction in the pipe wall, so the basic formula is 1…”

Section: Numerical Analysis Modelmentioning

confidence: 99%

“…results without a steel pipe for a year using Koriyama City standard annual temperature data. The value of a g given in Table 1 was used for the thermo-physical properties of the soil [9]. For depths of greater than 10 m, the temperature becomes constant at 12.8 °C, and is uninfluenced by temperature fluctuations on the ground surface.…”

Section: Numerical Analysis Modelmentioning

confidence: 99%

“…Such pipes can have internal diameters as large as 140-200 mm leading to good workability. However, this method involves measuring the temperature of shallow soil that has a temperature profile [8], using a thermometer encased in a steel pipe that has a high thermal conductivity in comparison to the surrounding soil. As such, the measurement accuracy is expected to decrease.…”

Section: David Publishingmentioning

confidence: 99%

“…In this situation, the effect of thermal interference due to collection/ radiation of heat among subterranean heat exchangers, which conventional designs attempt to avoid, is non-negligible. Furthermore, with respect to shallow geothermal heat usage, although a natural heat supply is expected from below the subterranean heat exchangers and from the ground surface [8], the soil heat capacity is not large because of the shallow point of application, and sudden drops in the thermal performance of the system are expected due to factors such as excessive soil cooling, depending on the use of heating and cooling within a residence.…”

mentioning

confidence: 99%

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Evaluation of Measurement Accuracy of Underground Thermometers Using Steel-Pipe Piles

Oguma¹,

Funabiki²,

Endo³

2016

JEPE

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For ground source heat utilization systems, pile heat exchangers are sometimes used. In order for these systems to achieve high performance, control of the system dynamics is important, and the underground temperature must be known. Typically, underground temperature is measured using a thermometer in a borehole. However, in the case of pile heat exchangers, a different method is required, making the system expensive to set up. To overcome this problem, the installation of underground thermometers in the heat exchanger piles themselves is proposed in the present study. The proposed thermometer system consists of thermocouples packed in grout such as silica sand within the piles. However, there is a possibility of measurement errors due to vertical thermal conduction in the steel pipes, and it is important to estimate the measurement accuracy before the development of this system. In the present study, the measurement accuracy is estimated using numerical simulations and then confirmed experimentally. The underground temperature profiles inside and outside the pile are compared. The results indicate that the proposed system offers sufficient accuracy for application to pile heat exchangers.

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Section: Numerical Analysis Modelmentioning

confidence: 99%

Section: Numerical Analysis Modelmentioning

confidence: 99%

Section: David Publishingmentioning

confidence: 99%

mentioning

confidence: 99%

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