Geometry effects in nucleate boiling of halocarbon refrigerants in horizontal tubes

Author(s)

Evandro Fockink da Silva

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2005-09-16

Examining board members

Jose Maria Saiz Jabardo; Enio Pedone Bandarra Filho; Luben Cabezas Gómez; Helio Aparecido Navarro; Celso Luiz da Silva

• Advisor: Jose Maria Saiz Jabardo

Abstract

The research reported herein is a theoretical and experimental investigation of nucleate boiling heat transfer in an isolated tube and a row of three horizontal tubes. The literature review provided enough information to raise the intervening physical parameters and several correlations. The experimental bench has been developed and adapted to perform experiments with several refrigerants, three different tube diameters, and to accommodate a row of three parallel tubes. The experiments have been carried out with refrigerants R-11, R-123 and R-134a. Heating of the brass tubes has been provided by tubular electrical heaters inserted inside the tubes. The heat flux varied from 1 to 40 kW/'M POT.2'. Experiments have been carried out by successively heating two and three tubes. Effects of boiling in tubes underneath (lower level) have been investigated. Finally a correlation for the heat transfer coefficient in successive tubes of a tube bank has been developed. The correlation presents good accuracy with respect to data from the present investigation. (AU)