Avoiding slush for hot-point drilling of glacier boreholes

Hills, Benjamin H.; Winebrenner, D. P.; Elam, W. T.; Kintner, P. M.

doi:10.1017/aog.2020.70

Cited by 5 publications

(4 citation statements)

References 13 publications

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“…In these melt tips, the umbilical cable does not move after it leaves the melt tip and is therefore unaffected by refreezing of the borehole (Aamot, 1967). As the system that we describe here has no mechanism to counter borehole refreezing, such as antifreezing or electrical heating, its maximum theoretical penetration depth depends on outracing the refreezing front within the uppermost, or oldest, portion of the borehole (Suto et al, 2008;Hills et al, 2020).…”

Section: Discussion: Borehole Refreezingmentioning

confidence: 99%

“…In the future, we also envision moving towards an integrated umbilical cable and developing an autonomous drilling feedback loop, whereby winch pay-out varies as a function of winch load. We are also developing ideas about suitable chemical agents to counter borehole refreezing (Zotikov, 1979;Zagorodnov et al, 1994;Hills et al, 2020). In the near term, however, we hope to use the ice-drilling system, as described here, to insert 100 m scale thermistor strings into the Greenland Ice Sheet and/or peripheral ice caps.…”

Section: Summary Remarksmentioning

confidence: 99%

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Design and performance of the Hotrod melt-tip ice-drilling system

Colgan

Shields

Тalalay

et al. 2023

Geosci. Instrum. Method. Data Syst.

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Abstract. We introduce the design and performance of an electrothermal ice-drilling system designed to insert a temperature sensor cable into ice. The melt tip is relatively simple and low-cost, designed for a one-way trip to the ice–bed interface. The drilling system consists of a melt tip, umbilical cable, winch, interface, power supply, and support items. The melt tip and the winch are the most novel elements of the drilling system, and we make the hardware and electrical designs of these components available open-access. Tests conducted in a laboratory indicate that the melt tip has an electrical energy to forward melting heat transfer efficiency of ∼35 % with a theoretical maximum penetration rate of ∼12 m h−1at maximum 6.0 kW power. In contrast, ice-sheet testing suggests the melt tip has an analogous heat transfer efficiency of ∼15 % with a theoretical maximum penetration rate of ∼6 m h−1. We expect the efficiency gap between laboratory and field performance to decrease with increasing operator experience. Umbilical freeze-in due to borehole refreezing is the primary depth-limiting factor of the drilling system. Enthalpy-based borehole refreezing assessments predict refreezing below critical umbilical diameter in ∼4 h at −20 ∘C ice temperatures and ∼20 h at −2 ∘C. This corresponds to a theoretical depth limit of up to ∼200 m, depending on firn thickness, ice temperature, and operator experience.

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Section: Discussion: Borehole Refreezingmentioning

confidence: 99%

Section: Summary Remarksmentioning

confidence: 99%

Design and performance of the Hotrod melt-tip ice-drilling system

Colgan

Shields

Тalalay

et al. 2023

Geosci. Instrum. Method. Data Syst.

View full text Add to dashboard Cite

show abstract

“…umbilical cable does not move after it leaves the melt tip and is therefore unaffected by refreezing of the borehole [Aamot, 1967]. As the system that we describe here has no mechanism to counter borehole refreezing, such as anti-freezing or electrical heating, its maximum theoretical penetration depth depends on outracing the refreezing front within the uppermost, or oldest, portion of the borehole [Suto et al, 2008;Hills et al, 2020].…”

Section: Discussion: Borehole Refreezingmentioning

confidence: 99%

“…In the future, we envision moving towards an integrated umbilical cable and developing an autonomous drilling feedback loop, whereby winch pay out varies as a function of winch load. We are also developing ideas about suitable chemical agents to counter borehole refreezing [Zotikov, 1979;Zagorodnov et al, 1994;Hills et al, 2020]. In the near term, however, we hope to use the ice-drilling system, as described here, to insert 100-m scale thermistor strings into the Greenland ice sheet and/or peripheral ice caps.…”

Section: Summary Remarksmentioning

confidence: 99%

Design and Performance of the Hotrod Melt-Tip Ice-Drilling System

Colgan

Shields²,

Тalalay³

et al. 2022

Preprint

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Abstract. We introduce the design and performance of a melt-tip ice-drilling system designed to insert a temperature sensor cable into ice. The melt tip is relatively simple and low cost, designed for a one-way trip to the ice-bed interface. The drilling system consists of a melt tip, umbilical cable, winch, interface, power supply, and support items. The melt tip and the winch are the most novel elements of the drilling system, and we make the hardware and electrical designs of these components available open access. Tests conducted in a laboratory ice well indicate that the melt tip has an electrical energy to forward melting heat transfer efficiency of ~35 % with a theoretical maximum penetration rate of ~12 m/hr at maximum 6.0 kW power. In contrast, ice-sheet testing suggests the melt tip has an analogous heat transfer efficiency of ~15 % with a theoretical maximum penetration rate of ~6 m/hr. We expect the efficiency gap between laboratory and field performance to decrease with increasing operator experience. Umbilical freeze-in due to borehole refreezing is the primary depth-limiting factor of the drilling system. Enthalpy-based borehole refreezing assessments predict refreezing below critical umbilical diameter in ~4 hours at -20 ˚C ice temperatures and ~20 hours at -2 ˚C. This corresponds to a theoretical depth limit of up to ~200 m, depending on firn thickness, ice temperature and operator experience.

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Heat transfer modelling of thermal anti-freezing method for ice hot-point drilling

Тalalay

Fan

et al. 2022

Case Studies in Thermal Engineering

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Avoiding slush for hot-point drilling of glacier boreholes

Cited by 5 publications

References 13 publications

Design and performance of the Hotrod melt-tip ice-drilling system

Design and performance of the Hotrod melt-tip ice-drilling system

Design and Performance of the Hotrod Melt-Tip Ice-Drilling System

Heat transfer modelling of thermal anti-freezing method for ice hot-point drilling

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