HEAT TRANSFER DURING POOL BOILING OF WATER, METHANOL, AND R141B ON POROUS COATED HORIZONTAL TUBE BUNDLES

摘要

This paper presents the results of experimental investigation of water, methanol, and R141b refrigerant boiling on horizontal porous coated tube bundles supposed to represent a flooded-type evaporator. Experiments were carried out for a bundle of 19 tubes in triangular layout for two pitch-to-diameter ratio values-1.7 and 2.0-in atmospheric and subatmospheric pressure conditions. Average heat transfer coefficients-both local, row-specific, and for the whole bundle-were determined. The boiling process on a bundle was visualized with a charge-coupled device camera and laser sheet technique. A Nusselt-type correlation equation allowing the calculation of the average heat transfer coefficient for boiling on porous coated tube bundles has been proposed.