Boiling Manhole Heat-Loss Calculations

Abstract : Military facilities that maintain and operate underground heat distribution systems (UHDS) need to make proper, cost-effective decisions concerning maintenance and repair. A poorly maintained manhole can become flooded from rainwater runoff, infiltrating ground water, or other sources. A flooded manhole will experience boiling, producing steam and causing a significant, and avoidable, increase in energy use. This report presents a method to estimate the amount of heat loss from a boiling manhole in a wide variety of situations. A set of correlations is developed to estimate manhole heat loss given a minimum of input parameters. Estimates of the energy cost for several sample calculations of typical manholes are included. Using current Army "Red Book" energy costs, typical flooded manholes can cost the DoD between $50,000 and $125,000 per year if they remain unrepaired.