TWO-PHASE FLOW METERING OF MALDISTRIBUTION INSIDE A HEADER BY MEAN OF VENTURI FLOWMETER SOLELY

Abstract

In evaporators, the distribution of the liquid and vapor phases among the channels is a complex prob- lem, depending on a wide range of parameters. However, maldistribution causes important loss of performances. Most of the experimental investigations of multiphase flow distribution are measur- ing the liquid and vapor quantities in the channels through a phase separation process, increasing the test duration and complexity. Therefore, the amount of parameters usually investigated is limited. In the present work, an air/water mixture was used as fluid. The distribution of the two phases in eight channels connected to a header was investigated. The inlet mass flow rates considered ranged from 0 to 0.2kg/s for the water, and from 0 to 0.04kg/s for the air. Consequently, qualities x up to 0.3 and void fractions α up to 0.9 were reached. Finally, to allow a continuous measurement process, the mass flow rates in each channel were measured thanks to venturi flowmeter calibrated on a separate line. Since no void fraction meter was coupled, a new iterative methodology, based on the venturi pressure drops measurement solely, was developed and is proposed here. It proved to successfully predict the vapor and liquid phases flow rates in each channel.