Determination of interface temperatures at scaled borehole heat exchanger physical models using distributed temperature sensing

Abstract. This paper describes a method to correct for the effect of solar radiation in atmospheric Distributed Temperature Sensing (DTS) applications. By using two cables with different diameters, one can determine what temperature a zero diameter cable would have. Such virtual cable would not be affected by solar heating and would take on the temperature of the surrounding air. The results for a pair of black cables and a pair of white cables were very good. The correlations between standard air temperature measurements and air temperatures derived from both colors had a high correlation coefficient (r2 = 0.99). A thin white cable measured temperatures that were close to air temperature. The temperatures were measured along horizontal cables but the results are especially interesting for vertical atmospheric profiling.

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Fiber optic distributed temperature sensing for the determination of the nocturnal atmospheric boundary layer height

Atmospheric Measurement Techniques ◽

10.5194/amt-4-143-2011 ◽

2011 ◽

Vol 4 (2) ◽

pp. 143-149 ◽

Cited By ~ 26

Author(s):

C. A. Keller ◽

H. Huwald ◽

M. K. Vollmer ◽

A. Wenger ◽

M. Hill ◽

...

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Fiber Optic ◽

Temperature Inversion ◽

Nocturnal Boundary Layer ◽

Temperature Sensing ◽

Temperature Profiles ◽

Distributed Temperature Sensing ◽

Boundary Layer Height

Abstract. A new method for measuring air temperature profiles in the atmospheric boundary layer at high spatial and temporal resolution is presented. The measurements are based on Raman scattering distributed temperature sensing (DTS) with a fiber optic cable attached to a tethered balloon. These data were used to estimate the height of the stable nocturnal boundary layer. The experiment was successfully deployed during a two-day campaign in September 2009, providing evidence that DTS is well suited for this atmospheric application. Observed stable temperature profiles exhibit an exponential shape confirming similarity concepts of the temperature inversion close to the surface. The atmospheric mixing height (MH) was estimated to vary between 5 m and 50 m as a result of the nocturnal boundary layer evolution. This value is in good agreement with the MH derived from concurrent Radon-222 (222Rn) measurements and in previous studies.

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Fiber optic distributed temperature sensing for the determination of the nocturnal atmospheric boundary layer height

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-3-2723-2010 ◽

2010 ◽

Vol 3 (3) ◽

pp. 2723-2741 ◽

Cited By ~ 2

Author(s):

C. A. Keller ◽

H. Huwald ◽

M. K. Vollmer ◽

A. Wenger ◽

M. Hill ◽

...

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Fiber Optic ◽

Temperature Inversion ◽

Nocturnal Boundary Layer ◽

Temperature Sensing ◽

Temperature Profiles ◽

Distributed Temperature Sensing ◽

Boundary Layer Height

Abstract. A new method for measuring air temperature profiles in the atmospheric boundary layer at high spatial and temporal resolution is presented. The measurements are based on Raman scattering distributed temperature sensing (DTS) with a fiber optic cable attached to a tethered balloon. These data were used to estimate the height of the stable nocturnal boundary layer. The experiment was successfully deployed during a two-day campaign in September 2009, providing evidence that DTS is well suited for this atmospheric application. Observed stable temperature profiles exhibit an exponential shape confirming similarity concepts of the temperature inversion close to the surface. The atmospheric mixing height (MH) was estimated to vary between 5 m and 50 m as a result of the nocturnal boundary layer evolution. This value is in good agreement to the MH derived from concurrent Radon-222 (222Rn) measurements and in previous studies.

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Fiber optic distributed temperature sensing for the determination of air temperature

Atmospheric Measurement Techniques ◽

10.5194/amt-8-335-2015 ◽

2015 ◽

Vol 8 (1) ◽

pp. 335-339 ◽

Cited By ~ 25

Author(s):

S. A. P. de Jong ◽

J. D. Slingerland ◽

N. C. van de Giesen

Keyword(s):

Air Temperature ◽

Urban Areas ◽

Fiber Optic ◽

Solar Heating ◽

Temperature Sensing ◽

Temperature Measurements ◽

Distributed Temperature Sensing ◽

Air Temperatures ◽

Different Diameters

Abstract. This paper describes a method to correct for the effect of solar radiation in atmospheric distributed temperature sensing (DTS) applications. By using two cables with different diameters, one can determine what temperature a zero diameter cable would have. Such a virtual cable would not be affected by solar heating and would take on the temperature of the surrounding air. With two unshielded cable pairs, one black pair and one white pair, good results were obtained given the general consensus that shielding is needed to avoid radiation errors (WMO, 2010). The correlations between standard air temperature measurements and air temperatures derived from both cables of colors had a high correlation coefficient (r2=0.99) and a RMSE of 0.38 °C, compared to a RMSE of 2.40 °C for a 3.0 mm uncorrected black cable. A thin white cable measured temperatures that were close to air temperature measured with a nearby shielded thermometer (RMSE of 0.61 °C). The temperatures were measured along horizontal cables with an eye to temperature measurements in urban areas, but the same method can be applied to any atmospheric DTS measurements, and for profile measurements along towers or with balloons and quadcopters.

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Novel Experimental Device to Monitor the Ground Thermal Exchange in a Borehole Heat Exchanger

Energies ◽

10.3390/en13051270 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1270 ◽

Cited By ~ 1

Author(s):

Cristina Sáez Blázquez ◽

Laura Piedelobo ◽

Jesús Fernández-Hernández ◽

Ignacio Martín Nieto ◽

Arturo Farfán Martín ◽

...

Keyword(s):

Heat Exchanger ◽

Borehole Heat Exchanger ◽

Physical Processes ◽

Geothermal Resources ◽

Thermal Exchange ◽

Heating And Cooling ◽

Ground Source ◽

Grouting Material ◽

Polyethylene Container

Ground source heat pump (GSHP) systems are becoming popular in space heating and cooling applications. Despite this fact, in most countries, the role of this energy is not as important as it should be nowadays according to its capabilities for energy generation without CO2 emissions, mainly due to the lack of technical knowledge about GSHP performance. The analysis of the physical processes that take part in the geothermal exchanges is necessary to allow the optimal exploitation of the geothermal resources. For all the above, an experimental geothermal device was built in the laboratory to control the phenomena that take place in a borehole heat exchanger (BHE). A 1-m high single-U heat exchanger was inserted in the center of a polyethylene container which also included granular material (surrounding ground) and the grouting material. Temperature sensors were situated in different positions of the experimental setup. Physical processes are evaluated to finally validate the model. Numerous applications can be developed from the experimental BHE. In this research, the determination of the thermal conductivity of the material used as medium was carried out. Results of this parameter were also compared with the ones obtained from the use of the KD2 Pro device.

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Analysis of novel shallow geothermal system in coastal fractured limestone aquifer

10.5194/egusphere-egu21-12377 ◽

2021 ◽

Author(s):

Nicola Pastore ◽

Claudia Cherubini ◽

Concetta Immacolata Giasi

Keyword(s):

Heat Exchanger ◽

Heat Exchangers ◽

Industrial Area ◽

Physical Models ◽

Experimental Investigations ◽

Geothermal System ◽

Geothermal Systems ◽

Borehole Heat Exchanger ◽

Limestone Aquifer ◽

Fractured Limestone

In shallow geothermal systems natural and forced groundwater movement as well as the temperature driven flow plays an important role on the borehole heat exchanger efficiency.The analysis of the efficiency of innovative heat exchangers installed in a fractured limestone aquifer was carried out through three-dimensional numerical simulations and experimental investigations on physical models.The coastal fractured limestone aquifer of the industrial area of Bari (Italy) was chosen as benchmark field site in order to identify the aquifer parameter range and the respective combinations. The role of seawater intrusion on the borehole heat exchanger efficiency was deepen .The results disclosed that the efficiency of the innovative heat exchangers is strictly dependent on the aquifer transmissivity and groundwater flow under natural and forced groundwater conditions.Discussion on the performance of the seasonal heat storage and the occurrence of the thermal interference between the borehole heat exchanger was presented.

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