Jökull - 01.12.2007, Blaðsíða 83

A hot water drill with built-in sterilization
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APPENDIX
To calculate the curves in Figures 4 and 5, we use for-
mulas (10) and (11) derived below. The following pa-
rameters are used in the calculations, see also Figure
6 for explanations.
Figure 6. Schematic drawing of the borehole, hose
and drill tip, indicating some of the parameters used
in the calculations. – Skýringarmynd er sýnir nokkra
hluta borsins sem notaðir eru í reikningum í viðauka.
T0 = initial temperature of drilling water in the hose
at surface
T = temperature of drilling water at the drill tip
Tf = pressure melting point of ice, assumed to be =
0!C over the pressure range considered
t = time (s)
mw/t = mass flow rate through the drill tip
mice/t = rate of ice melting at the bottom of the bore-
hole
lice = latent heat of fusion of ice = 334 kJkg"1
cpw = heat capacity of water at constant pressure =
4190 Jkg"1K"1
!ice = density of the ice = 900 kgm"3 (appropriate
value for bubbly, temperate ice)
Vice = volume of borehole drilled in time t
S = mean cross sectional area of borehole drilled in
time t
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