Flow Characteristics of Nitrogen (N2) in Micro-Channels of Printed Circuit Heat Exchanger (PCHE)

Abstract

Experiment and simulation studies were performed to investigate the flow characteristics of pressure-driven Nitrogen flow in the micro-channels of Printed Circuit Heat Exchanger (PCHE). The core of the PCHE was made using diffusion bonding method with ten stainless steel 316L plates, where hemispherical 1 mm in diameter channels were chemically etched. On one of the plates, four-teen more channels, 1 mm in diameter, were milled to make pressure taps to measure local pressure drops. Then, one inlet tube and four-teen tubes for pressure tabs were attached by welding on the top and sides of PCHE core, respectively. The PCHE was connected to Nitrogen tank with pressure regulator, Coriolis flowmeter and differential pressure gauge, and data was acquired with DAQ system. By varying the velocity of Nitrogen gas from 1 to 35 m/s, differential pressure drops were measured between two different locations. The local pressure drops were analyzed theoretically and pressure loss coefficients could be calculated in straight and serpentine channels, respectively. In addition, simulation work using ANSYS Fluent was also performed to understand flow characteristics especially at corners of channels.