Friday, 14 March 2008

Failure analysis of the Loch Avie Cryogenic Seasonal Support Engine

Nicholas K, Bellambi E. Failure analysis of the Loch Avie Cryogenic Seasonal Support Engine (CSSE). Proc Royal Soc 1898;3.

The Loch Avie Cryogenic Seasonal Support Engine (CSSE) unexpectedly failed in February 1898, with resultant thermal destabilisation of the terrain. This analysis was conducted to determine the cause of failure, as well as to identify other potential failure modes of the engine. The root cause appears to be geothermal anomalous events triggered by plate tectonic movements. Various preventative strategies are discussed.

The CSSE was implemented during the current winter season in Caledon to support and enhance the ground and air temperature cooling needed to ensure persistent snow cover (maximum -3.5 degrees Centigrade) and precipitation occurring as snow (maximum -2.2 degrees C.) The system exhibited a meta-effect of allowing shallow-water ice to form to depths of up to 1 metre. (Fig. 1.)

The system was controlled from a certain location within Loch Avie. Electromagnetic relays were used to control various aspects of the system. Coolant temperature, flows, and hydraulic pressure were measured at the control panel. (Fig. 2.)

At various locations around the Loch, coolant pipes were exposed to the water and atmosphere to enable convective heat exchange to occur. Figure 3 demonstrates one such submerged pipe.

Note that the combination of the amount of dissolved solutes and particulate matter in the Loch water have dropped the freezing point to below the coolant temperature, as no ice build-up is seen. (Fig. 3a.)

Figure 4 demonstrates one of the above-ground heat-exchange mechanisms, which were used in tandem with the exposed pipe apparatus used for submersible cooling.

The details of the design of the cryogenic plant itself, and the method for dissipating heat from the system remain classified, as they were commissioned originally for The Security Service (Box 500, Loch Avie, Caledon).

System failure.
During the week of February 21, ambient air temperatures and soil temperatures began climbing by an average of 0.17 degrees C. per day, from their prior stable baselines of -3.5 and -2.2 degrees C. respectively. Snow cover began to dissipate immediately due to solar heating, and new precipitation fell as rain and freezing rain by February 26. By the first week in March, existing snow cover had vanished, and there was no contiguous ice remaining on the Loch.

During the warming event, the cryogenic fluid production remained constant, with nominal temperatures. (Fig. 5.) Readings from the heat dissipation system showed increasingly-warmer effluent.

Flow and pressure monitors recorded no pressure drops or coolant leaks. (Fig. 6.)

The data support that the system encountered increased ambient heat which could not be effectively dissipated, resulting in increasingly less-efficient cooling. While available readings from surrounding areas are scant, the data suggest increased energy deposition into the air, water, and soil. Electromagnetic (EM) sensors did not indicate any change in background EM or radio-frequency energies. Seismic readings, though, showed low-level activity beginning and increasing in a temporally-associated fashion with the warming event. One hydrothermal vent which is routinely monitored indicated increased output of geothermal energy.

The CSSE failure was a result of its heat-exchanging system being overwhelmed by an unusual increase in hydrothermal energy. The increase in seismic activity in the area is the most likely etiology. The CSSE operated as designed, without any loss of system integrity . Based on the system design, and the observed mode of failure, the CSSE failed safely. The design could not have been modified on-line to accomodate the increased need for heat dissipation. The authors recommend that the system, now off-line, be re-engineered to increase heat transfer and dissipation, and that seismic monitoring be instituted to allow for better prediction of the need for increased efficiency. Finally, a further study of the unusual seismic events should be undertaken, as the increased geothermal activity provides demonstrable evidence of a change in tectonic interactions.

No comments: