Condensation of Butane Vapor in a Gravity-Drained Ice Bed

摘要

Direct condensation of n-butane in ice particle beds was investigated to assess the effect of driving force, bed depth, and ice particle size on operation of a melter-condenser (MC) as part of an overall freezing process for salt water desalination. Ice melting rate for 2-12 inch thick ice particle beds was studied in a 3 foot by 2 or 4 inch inside diameter plastic column, using 0.17 mm diameter ice particles. Studies with the MC indicated that: ice melting rate in shallow ice beds is proportional to the true driving force for driving forces up to at least 0.5F; ice melting rate per ice volume in the MC decreases with increased bed depth and is a function of ice particle size; and that the rate due to axial vapor velocity through the bed is proportional to the vapor velocity to the 1/4 power. The most severe restriction on melting rate of deep ice beds is imposed by liquid and vapor flow limitations through the melting bed. Butane condensation in shallow beds occurs throughout the entire bed, but the topmost ice particles melt faster than those deeper in the bed. Experimentally-determined heat transfer coefficients (for total particle area at 10% melt) for 3 and 12 inch ice beds were about 2/3 and 1/3 of those predicted from theory.