Figure 3
The top panel, Panel A, plots outlet temperature minus inlet temperature against time in days. The horizontal axis extends to 360 days on a logarithmic scale, and the vertical axis ranges from 0 to 20 degrees Celsius. Curves begin between about 0.5 and 19 degrees Celsius and generally decline, with most approaching about 1 to 6 degrees Celsius by 360 days. The accompanying scale represents initial temperature minus inlet temperature from 2 to 20 degrees Celsius. Panel B plots wall temperature difference against time in months on a logarithmic scale from 0.001 to beyond 1,000 months. The vertical axis ranges from 0 to minus 40 degrees Celsius. Curves remain near 0 initially, then decline at different rates, with most ending between about minus 5 and minus 25 degrees Celsius and a few reaching nearly minus 40 degrees Celsius. Panel C plots outlet temperature difference over the same time scale. Its vertical axis ranges from 0 to minus 50 degrees Celsius. The curves decline earlier and more strongly than in Panel B, with most ending between about minus 5 and minus 30 degrees Celsius and several approaching minus 50 degrees Celsius. The scales beside Panels B and C represent heat flux from 0 to minus 80 watts per square metre.Evolution of (a) the difference between outlet and inlet (constant) temperatures, (b) the wall-averaged temperature, and (c) the outlet temperature, over time for all samples in the database