MEASUREMENT OF THE LOCAL HEAT TRANSFER COEFFICIENT DURING CONDENSATION OF SATURATED WATER VAPOR ON THE SURFACE OF A HORIZONTAL PIPE
E.R. Zainullina, V.Yu. Mityakov, S.Z. Sapozhnikov
Peter the Great St. Petersburg Polytechnic University, Saint Petersburg, Russia
Keywords: local heat transfer coefficient, film condensation, gradient heat flux thermometry, GHFT, saturated water vapor, horizontal pipe
Abstract
A new approach to measuring the local heat transfer coefficient during condensation of saturated water vapor on the surface of a horizontal pipe is proposed. The heat transfer coefficient values are determined from direct measurements of the heat flux density using gradient heat flux thermometry and of the pipe surface temperature using thermocouples. Results are presented for a test section supplied with saturated water vapor at a temperature close to 100 °C and a flow rate varying from 4 to 10 kg/h; the cooling water flow rate was 130 kg/h. Angular distributions of temperature, heat flux density, and heat transfer coefficient during condensation are constructed. Depending on the vapor flow rate, either mixed or film condensation is found to develop on the surface. The proposed approach provides a relative uncertainty in the local heat transfer coefficient of less than 8 %.
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