Study on ground temperature response of multilayer stratums under operation of ground-source heat pump

Zhou, Shiyu; Cui, Wenzhi; Tao, Jiaxiang; Peng, Qingyuan

doi:10.1016/j.applthermaleng.2016.02.130

Cited by 35 publications

(7 citation statements)

References 14 publications

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“…Assuming that the liquid flow is a piston flow, the values of the liquid temperature at the borehole outlet may be considered as ones corresponding to temperatures at various depths in the ground. Another method for the determination of the temperature profile in the ground consists in the introduction of temperature sensors at various depths into a filled (e.g., with a liquid) U-tube of the exchanger, which was described in papers by, among others, Yu et al [7] and Zhou et al [8].…”

Section: Heat Balance On the Surface Of The Groundmentioning

confidence: 99%

Undisturbed Ground Temperature—Different Methods of Determination

2017

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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.

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Section: Heat Balance On the Surface Of The Groundmentioning

confidence: 99%

Undisturbed Ground Temperature—Different Methods of Determination

2017

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“…The change in the soil type strongly affected the thermal properties of the soil and therefore influenced the thermal radius of the BHE. For the effects of soil type on thermal radius during the 168 h discharging process, the detailed thermophysical properties of three kinds of typical soils, including clay [24], sand (the TRT experiment), and sandstone (Li et al, 2018) [25], are given in Table 4. The simulated results are shown in Figure 10.…”

Section: The Influence Of Soil Type On Thermal Radiusmentioning

confidence: 99%

Numerical Investigation of the Influence of Precooling on the Thermal Performance of a Borehole Heat Exchanger

Zhu

Sun²,

Zhong

et al. 2021

Energies

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Ground source heat pumps (GSHPs), a high-efficiency and energy-saving air-conditioning technology that utilizes shallow geothermal resources for both heating and cooling, are a vital green energy system for residential and commercial buildings. Improving the performance of such a system was the focus of the current research. As soil temperature and thermal radius are two important aspects that affect the performance of ground source heat pump systems, we conducted a new numerical simulation to capture the changes in sensitive factors and propose the optimized paths. The numerical simulation analyzed the thermal characteristics of a borefield under different pre-cooling times and soil types. The results indicated the following: (1) The rate of the ground temperature change with pre-cooling during the discharging period had a faster rise than in the case without pre-cooling. The longer the precooling time was, the smaller the thermal radius became. In particular, when the precooling time was longer than 14 days, the decrease in the thermal radius rate percentages was less than 4%. (2) Among the three kinds of soils compared, the soils with lower thermal conductivity and thermal diffusivity best suppressed the thermal interference effects. (3) Using a multivariate nonlinear function regression model, a simulation formula was proposed to predict- the thermal radius, which considered the factors of thermal diffusivity, precooling time, and discharging time. The prediction deviation was within 14.8%.

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“…Numerical simulations further indicated that the borehole thermal resistance could be determined using the data of a combination of recovery and heat injection. Zhou et al (2016) analyzed ground temperature response of multilayer strata under operation of a GSHP system. A numerical model was developed according to the field ground geological configuration, and a long term operation was simulated.…”

Section: Introductionmentioning

confidence: 99%

Comparison of ground temperature response of energy pile and borehole heat exchanger during thermal response tests

et al. 2016

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Thermal migration of ground heat exchanger (GHE) in subsurface is crucially important to the efficiency and sustainability of ground source heat pump systems. In order to investigate heat transfer efficiency of GHE, ground temperature response during system operation should be analyzed. In this paper, two types of GHEs operate under heating operating condition are simulated by thermal response test. A set of parameters including fluid temperature, borehole wall and ground temperature are monitored with duration of 148 h. The analysis of thermal performance shows that the energy pile has specific thermal rates of 147 W/m which is 230% higher than that of borehole heat exchanger with 56 W/m. Furthermore, heat flux per unit area of the contacting area at borehole wall (q, W/m 2 ) is analyzed. The monitored temperature development at the borehole wall for both types of GHEs can be perfectly explained by q. The finding of this study indicates that the parameter is useful in estimating ground thermal accumulation of GHEs. The larger the q is, the higher the possible of ground thermal accumulation and unstable performance of GHEs would be.

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Study on ground temperature response of multilayer stratums under operation of ground-source heat pump

Cited by 35 publications

References 14 publications

Undisturbed Ground Temperature—Different Methods of Determination

Undisturbed Ground Temperature—Different Methods of Determination

Numerical Investigation of the Influence of Precooling on the Thermal Performance of a Borehole Heat Exchanger

Comparison of ground temperature response of energy pile and borehole heat exchanger during thermal response tests

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