scholarly journals Artificial ground freezing using solar-powered thermosyphons

2021 ◽  
Author(s):  
Anna Wagner ◽  
Jon Maakestad ◽  
Edward Yarmak ◽  
Thomas Douglas
Keyword(s):  
Solar Array ◽  
Freeze Ground ◽  
Passive Mode ◽  
Frozen Ground ◽  
Air Temperatures ◽  
Ground Freezing ◽  
Refrigeration Unit ◽  
Artificial Ground Freezing ◽  
Solar Powered ◽  
The 1960S

Thermosyphons are an artificial ground-freezing technique that has been used to stabilize permafrost since the 1960s. The largest engineered structure that uses thermosyphons to maintain frozen ground is the Trans Alaska Pipeline, and it has over 124,000 thermosyphons along its approximately 1300 km route. In passive mode, thermosyphons extract heat from the soil and transfer it to the environment when the air temperature is colder than the ground temperature. This passive technology can promote ground cooling during cold winter months. To address the growing need for maintaining frozen ground as air temperatures increase, we investigated a solar-powered refrigeration unit that could operate a thermosyphon (nonpassive) during temperatures above freezing. Our tests showed that energy generated from the solar array can operate the refrigeration unit and activate the hybrid thermosyphon to artificially cool the soil when air temperatures are above freezing. This technology can be used to expand the application of thermosyphon technology to freeze ground or maintain permafrost, particularly in locations with limited access to line power.

Effect of Freeze Pipe Eccentricity in Selective Artificial Ground Freezing Applications

2021 ◽  
pp. 1-33
Author(s):  
Ahmad Zueter ◽  
Ali Madiseh ◽  
Ferri Hassani ◽  
Agus Pulung Sasmito
Keyword(s):  
Energy Consumption ◽  
Radiation Heat Transfer ◽  
Conservation Equation ◽  
Underground Mines ◽  
Frozen Ground ◽  
Two Phase ◽  
Ground Freezing ◽  
1D Model ◽  
Artificial Ground Freezing ◽  
Conjugate Model

Abstract Building concentric tubes is one of biggest practical challenges in the construction of freeze-pipes of selective artificial ground freezing (S-AGF) applications for underground mines. In this study, the influence of tubes eccentricity on phase-front expansion (i.e., expansion of the frozen body) and energy consumption of S-AGF systems is analyzed. A 1+1D semi-conjugate model that solves two-phase transient energy conservation equation is derived based on the enthalpy method. The 1+1D model is firstly validated against experimental data and then verified with a fully-conjugate model from our previous work. After that, the 1+1D model is extended to a field-scale of typical underground mines to examine the effect of freeze-pipe eccentricity. The results show that concentric freeze-pipes form the desired frozen ground volume 15% faster than eccentric freeze-pipes. Also, the geometrical profile of the phase-transition-front of the frozen ground is found to be significantly influenced by the freeze-pipe eccentricity. Furthermore, in the passive zone, where S-AGF coolants are isolated from the ground to reduce energy consumption, freeze pipe eccentricity can increase the coolant heat gain by 20%. This percentage can increase up to 200 % if radiation heat transfer is minimized.

Effect of Freeze Pipe Eccentricity in Artificial Ground Freezing Applications

2020 ◽  
Author(s):  
Ahmad F. Zueter ◽  
Minghan Xu ◽  
Mahmoud A. Alzoubi ◽  
Agus P. Sasmito
Keyword(s):  
Energy Consumption ◽  
Radiation Heat Transfer ◽  
Conservation Equation ◽  
Underground Mines ◽  
Phase Front ◽  
Two Phase ◽  
Ground Freezing ◽  
Deep Underground ◽  
Artificial Ground Freezing ◽  
Conjugate Model

Abstract Building concentric tubes is one of biggest practical challenges in the construction of freeze-pipes of artificial ground freezing (AGF) applications for deep underground mines. In this study, the influence of tubes eccentricity on phase-front expansion (i.e., expansion of the frozen body) and energy consumption of AGF systems is analyzed. A 1+1D semi-conjugate model that solves two-phase transient energy conservation equation is derived. The model is firstly validated against experimental data and then verified with a fully-conjugate model from the literature. After that, the model is extended to a field scale of typical deep underground mines to study freeze-pipe eccentricity. The results show that an eccentric freeze pipe can reduce the phase-front expansion by around 25%, as compared with a concentric one. Also, the geometrical profile of the phase-front is significantly influenced by the freeze-pipe eccentricity. Furthermore, in the passive zone, where AGF coolants are isolated from the ground to reduce energy consumption, freeze pipe eccentricity can increase the coolant heat gain by 10%. This percentage can increase up to 200% if radiation heat transfer is minimized.

scholarly journals REVIEW DAN ANALISIS PERKEMBANGAN PLTS PADA SARANA TRANSPORTASI LAUT

2021 ◽  
Vol 4 (2) ◽  
pp. 105-118
Author(s):  
Made Puji Dwicaksana ◽  
I Nyoman Satya Kumara ◽  
I Nyoman Setiawan ◽  
I Made Aditya Nugraha
Keyword(s):  
Online Survey ◽  
Solar Power ◽  
Solar Array ◽  
Production Volume ◽  
Solar Pv ◽  
Passenger Transportation ◽  
Battery Capacity ◽  
Array Structure ◽  
Solar Powered ◽  
Fixed Array

This paper aims to review the current development of vessels with solar power to reference the research and development of solar power vessels in Indonesia. The research method is a systematic literature review on the development of solar-powered vessels and includes an online survey of vessels using solar PV. This study found 86 solar-powered vessels consisting of boats, utility boats, ferries, houseboats, research, vehicle carriers, dive boats, and yachts developed from 1988 to 2020. These solar-powered vessels were built for various functions such as competitions, cleaning the environment, passenger transportation, and water tourism.  Production of solar-powered vessels is increasing in terms of production volume, PV capacity, and battery capacity. In terms of PV configuration, the solar array is dominated by a fixed array structure. However, there have been innovations using sun-tracking, wind tracking airfoils, and expandable channels to increase PV capacity.

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