Liquid-film thickness during flow boiling of pure hydrocarbons and their mixtures

Author(s)

Baptistella, Victor Eduardo Corte ; Moreira, Tiago Augusto ; Ribatski, Gherhardt

• Document type: Journal article
• Source: EXPERIMENTAL THERMAL AND FLUID SCIENCE; v. 144, p. 17-pg., 2023-02-24.

Abstract

The present study concerns an experimental investigation of the liquid-film thickness and void fraction during flow boiling of hydrocarbons and their zeotropic mixtures. High-speed flow images were also gathered. Exper-iments were performed for R600a, R290, R1270, R600a/R290 (70/30 M fraction) and R600a/R1270 (75/25 M fraction) in a horizontal stainless-steel tube with an internal diameter of 9.43 mm. Liquid-film thickness and flow footage were gathered in an adiabatic section, 50 mm downstream the heating section. The saturation tem-perature was kept at 5 degrees C, mass velocities ranged from 50 to 250 kg/m2s, vapor qualities from 0.07 to 0.81, and heat fluxes from 5 to 80 kW/m2. The experimental data comprehends annular flows, including results for the intermittent dryout-rewetting phenomenon. The rewetting front was found to be composed of a two-stage wave. Initially it approached the dry wall, increasing the film thickness sharply until reaching a peak. Downstream the wave-peak the liquid-film thickness and its interfacial roughness decreased smoothly. Ripples were observed on top of the rewetting wave and their velocity and amplitude decreased at the wake of the wave. Additionally, footage showed that the entrained droplets flow within intermittent clusters and not homogeneously distributed along the vapor core. The void faction was estimated based on the liquid-film thickness measurements and compared with prediction methods available in the literature. In general, reasonable agreement between experimental data and their predictions was found. (AU)

• FAPESP's process: 16/16849-3 - THEORETICAL AND EXPERIMENTAL ANALYSIS OF HEAT TRANSFER COEFFICIENT, PRESSURE DROP AND FLOW PATTERNS DURING CONDENSATION OF HYDROCARBONS ZEOTROPIC MIXTURES INSIDE TUBES
• Grantee: Tiago Augusto Moreira
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 20/10923-2 - Evaluation of the hydrodynamic behavior and the heat transfer mechanisms during flow boiling in microchannels under conditions close to the surface dryout
• Grantee: Victor Eduardo Corte Baptistella
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 18/06057-8 - Extend and assessment of the accuracy of current liquid film thickness measurement technique for flat surfaces to a curved geometry
• Grantee: Tiago Augusto Moreira
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 19/08577-1 - Multi-User Equipment approved in grant 16/09509-1: high speed video camera phantom V2012
• Grantee: Gherhardt Ribatski
• Support Opportunities: Multi-user Equipment Program