Effect of Tube Pitch on Heat Transfer in Sprinkled Tube Bundle

abstrakt

angličtina

Water flowing on a sprinkled tube bundle forms three basic modes: It is the Droplet mode (liquid drips from one tube to another), the Jet mode (with an increasing flow rate droplets merge into a column) and the Membrane (Sheet) mode (with further increasing of falling film liquid flow rate columns merge and create sheets between the tubes. With sufficient flow rate sheets merge at this state and the tube bundle is completely covered by a thin liquid film). There are several factors influencing the individual mode types as well as heat transfer. Beside the above mentioned falling film liquid flow rate they are for instance tube diameters, tube pitches in a tube bundle or a physical condition of a falling film liquid. This paper presents a summary of data measured at atmospheric pressure at a tube bundle consisting of copper tubes of 12 milimeters diameter and of the studied tube length one meter. Tubes are situated horizontally one above another at 15 to 30 mm pitch and there is a distribution tube placed above them with water flowing through apertures of 1.0 mm diameter at 9.2 mm span. Two thermal conditions were tested with all pitches. I.e. 15 to 40 and 15 to 45, where 15 degrees Celsius was the temperature of the falling film liquid at the distribution tube input which was heated during the flow through the exchanger, and 40 degrees Celsius, alternatively 45 degrees Celsius, was the temperature of the heating liquid at the exchanger input with a constant flow rate of approx. 7.2. litres per minute. The values measured were used to compile criterial equations for the heat transfer coefficient at the surface of sprinkled tubes for various sprinkled surface types

sprinkled, tube bundle, heat transfer, tube pitch

KRACÍK, P.; COPEK, T.; POSPÍŠIL, J.

23. 4. 2014

Brno University of Technology

Brno

978-80-214-4931-2

Proceedings of Abstracts

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48

48

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