scholarly journals Modeling the Temperature Field in the Ground with an Installed Slinky-Coil Heat Exchanger

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4010
Author(s):  
Monika Gwadera ◽  
Krzysztof Kupiec
Keyword(s):  
Temperature Field ◽  
Heat Exchanger ◽  
Surface Temperature ◽  
Ground Surface ◽  
Heat Sources ◽  
Ground Surface Temperature ◽  
Coil Heat Exchanger ◽  
The Relationship ◽  
Temperature Responses ◽  
Coil Heat

In order to find the temperature field in the ground with a heat exchanger, it is necessary to determine temperature responses of the ground caused by heat sources and the influence of the environment. To determine the latter, a new model of heat transfer in the ground under natural conditions was developed. The heat flux of the evaporation of moisture from the ground was described by the relationship taking into account the annual amount of rainfall. The analytical solution for the equations of this model is presented. Under the conditions for which the calculations were performed, the following data were obtained: the average ground surface temperature Tsm = 10.67 °C, the ground surface temperature amplitude As = 13.88 K, and the phase angle Ps = 0.202 rad. This method makes it possible to easily determine the undisturbed ground temperature at any depth and at any time. This solution was used to find the temperature field in the ground with an installed slinky-coil heat exchanger that consisted of 63 coils. The results of calculations according to the presented model were compared with the results of measurements from the literature. The 3D model for the ground with an installed heat exchanger enables the analysis of the influence of miscellaneous parameters of the process of extracting or supplying heat from/to the ground on its temperature field.

scholarly journals RESULTS OF SIMPLIFIED MATHEMATICAL MODELING OF LIQUID TEMPERATURE DISTRIBUTIONIN THE HEAT EXCHANGE CHANNEL OF AN ELECTRIC HEATER WITH AN INTERNAL HEAT SOURCE

2021 ◽  
pp. 117-122
Author(s):  
A.A. Bagaev ◽  
◽  
S.O. Bobrovskiy ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Source ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Heat Sources ◽  
Internal Heat Sources ◽  
Coil Heat Exchanger ◽  
Coil Heat

Indirect electrical resistance heating systems are heat-ers with internal heat sources and are widely used in agri-culture for heating gaseous and liquid media. Such sys-tems are characterized by insufficient intensity of heat ex-change processes. This implies a large heat transfer sur-face area and significant geometric size. Earlier, an attempt was made to solve the problem of increasing the efficiency of heat transfer processes and minimizing the geometric size of the heat exchanger. For this purpose, the heat ex-change characteristics were simulated and the geometric dimensions of three heat exchange systems were deter-mined: “pipe with internal heat sources in a dielectric pipe”, “pipe with an internal heat source -a membraneof heated liquid” and “cylindrical coil -heated liquid”. The analysis of these heat exchange systems has shown that the most promising is a coil-type heat exchanger. This system has the best heat transfer characteristics and the most compact size. To confirm the correctness of the applied method of calculating the heat exchange and geometric parameters of the heat exchanger, the simulation of the temperature dis-tribution of the heated liquid in the channel of the coil heat exchanger is implemented in this work. The verification calculations carried out under the formulated assumptions, using the example of a coil heat exchanger, show that the method for determining the heat exchange and geometric parameters of heat exchangers is correct. As a result of the simulation, it has been found that the error in determining the required channel length of the coil heat exchanger, the number of turns and the height of the coil to reach the liq-uid temperature at the outlet of 75°C does not exceed 4%. A similar conclusion can be made regarding the heat ex-changers of the types “pipe with internal heat sources -heated liquid” and “pipe with an internal heat source -a membraneof heated liquid”.

Relation Between The Ground Surface Temperature

2005 ◽  
Author(s):  
R. Yokoyama ◽  
Chang Ming Zhou ◽  
S. Tanba ◽  
H. Ihara
Keyword(s):  
Surface Temperature ◽  
Ground Surface ◽  
Ground Surface Temperature

scholarly journals Past climate changes and permafrost depth at the Lake El'gygytgyn site: implications from data and thermal modeling

2013 ◽  
Vol 9 (1) ◽  
pp. 119-133 ◽  
Author(s):  
D. Mottaghy ◽  
G. Schwamborn ◽  
V. Rath
Keyword(s):  
Surface Temperature ◽  
Thermal Regime ◽  
Climate Changes ◽  
Ground Surface ◽  
Temperature Data ◽  
Ice Age ◽  
Drilling Process ◽  
Past Climate ◽  
Ground Surface Temperature ◽  
Recent Climate

Abstract. This study focuses on the temperature field observed in boreholes drilled as part of interdisciplinary scientific campaign targeting the El'gygytgyn Crater Lake in NE Russia. Temperature data are available from two sites: the lake borehole 5011-1 located near the center of the lake reaching 400 m depth, and the land borehole 5011-3 at the rim of the lake, with a depth of 140 m. Constraints on permafrost depth and past climate changes are derived from numerical simulation of the thermal regime associated with the lake-related talik structure. The thermal properties of the subsurface needed for these simulations are based on laboratory measurements of representative cores from the quaternary sediments and the underlying impact-affected rock, complemented by further information from geophysical logs and data from published literature. The temperature observations in the lake borehole 5011-1 are dominated by thermal perturbations related to the drilling process, and thus only give reliable values for the lowermost value in the borehole. Undisturbed temperature data recorded over more than two years are available in the 140 m deep land-based borehole 5011-3. The analysis of these observations allows determination of not only the recent mean annual ground surface temperature, but also the ground surface temperature history, though with large uncertainties. Although the depth of this borehole is by far too insufficient for a complete reconstruction of past temperatures back to the Last Glacial Maximum, it still affects the thermal regime, and thus permafrost depth. This effect is constrained by numerical modeling: assuming that the lake borehole observations are hardly influenced by the past changes in surface air temperature, an estimate of steady-state conditions is possible, leading to a meaningful value of 14 ± 5 K for the post-glacial warming. The strong curvature of the temperature data in shallower depths around 60 m can be explained by a comparatively large amplitude of the Little Ice Age (up to 4 K), with low temperatures prevailing far into the 20th century. Other mechanisms, like varying porosity, may also have an influence on the temperature profile, however, our modeling studies imply a major contribution from recent climate changes.

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