Experimental and theoretical investigation of heat transfer with liquid-vapor phase change in tubes with forced vibrations

• Grant number: 22/07080-9
• Support Opportunities: Research Grants - Initial Project
• Start date: February 01, 2023
• End date: January 31, 2028
• Field of knowledge: Engineering - Mechanical Engineering - Transport Phenomena
• Principal Investigator: Fabio Toshio Kanizawa
• Grantee: Fabio Toshio Kanizawa
• Host Institution: Faculdade de Engenharia Mecânica (FEM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• City of the host institution: Campinas
• Associated scholarship(s): 24/23239-3 - Evaluation of the effects of forced horizontal vibrations during convective boiling in microchannels, BP.MS; 25/01768-7 - Investigation of forced vibration effects during convective condensation, BP.DR

Abstract

This project proposal applies for a grant according to the call Initial Research Project 2022. This project aims to experimentally and theoretically investigate convective flow boiling and condensation inside horizontal round channels subjected to forced vibration. It can be concluded based on the literature review that the number of experimental investigations about active techniques for heat transfer enhancement during convective flow boiling and condensation is limited. The vibration of the tube and/or fluid by pressure pulsation is one of these techniques, however, no experimental investigation has been reported for convective flow boiling and condensation. In the case of refrigeration and power generation systems, the fluid is usually propelled by a compressor or pump, which inherently vibrates during operation, and eventually transmits vibration to the heat exchangers, hence the vibration of the channels is inevitable for several systems. In the case of condensation inside horizontal channels, it is expected that the tube vibration favors liquid film thinning or breaking, which implies an increment of heat transfer coefficient. However, in the case of convective boiling, the reduction of liquid film thickness can imply earlier dryout and heat transfer coefficient reduction. Based on these aspects, the proposed project aims to experimentally determine heat transfer coefficient, pressure drop, and flow patterns during convective flow boiling and condensation inside horizontal channels subjected to forced vibration. It is planned to perform experiments with round channels with internal diameters ranging from 2 to 4 mm, hence comprising micro and transitional scales, during two-phase flow of R134a, R410A, R600a, and R290, at saturation temperature between -5 and 40 °C. Additionally, a mechanical actuator will be used to impose vibrations with frequencies between 20 and 70 Hz, aiming to comprise an operating range of frequency inverter systems, with vertical, horizontal, and compound modes. (AU)