Experimental study of flow patterns and pressure drop during ascending and descending water-air flows in a plate-type heat exchanger

• Grant number: 24/15588-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2024
• End date: November 30, 2025
• Field of knowledge: Engineering - Mechanical Engineering - Transport Phenomena
• Principal Investigator: Gherhardt Ribatski
• Grantee: Bruno de Moura Coelho
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

In general, most applications involving plate-type heat exchangers are based on flow of two fluids as liquid. However, recently, phase change processes in this type of heat exchangers have become common. In such applications, fluid mal-distribution effects to the heat exchanger performance becomes even more relevant than for singlephase fluid flow. These effects depend on the two-phase flow topology along the heat exchanger, which characteristics vary according to the operational conditions and heat exchanger geometry. Two-phase distributions with similar characteristics are known as flow patterns. According to literature, flow patterns influence both heat transfer and pressure drop. In this context, the objective of this study is to identify the flow patterns and the two-phase flow characteristics in a plate-type heat exchanger model made of acrylic (test section) for adiabatic conditions and upward and downward flows. Images of the two-phase flow will be captured through a high-speed video camera. Time traces of the signal of the differential pressure along the test section will be also obtained. Then, the flow images and the transient pressure signal will be used to segregate the flow pattern and to develop flow pattern maps. Results for the bubbles velocities will be also obtained using the spatial filter velocimetry technique (SFV). This information is essential to guide future studies concerning the optimization of this type of heat exchangers.