||Two-phase flow in ammonia risers
||Atlason, Guðmundur Freyr
||Elmegaard, Brian (Termiske Energisystemer, Institut for Mekanisk Teknologi, Danmarks Tekniske Universitet, DTU, DK-2800 Kgs. Lyngby, Denmark)
Kærn, Martin Ryhl (Termiske Energisystemer, Institut for Mekanisk Teknologi, Danmarks Tekniske Universitet, DTU, DK-2800 Kgs. Lyngby, Denmark)
Reinholdt, Lars (Dansk Teknologisk Institut)
||Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
||Models simulating two-phase flow of ammonia in a vertical riser have been made along
with a model simulating a refrigeration system with a flooded evaporator. Simulations
using five frictional pressure loss correlations and four void fraction correlations were
made using the program Engineering Equations Solver. These correlations are
explained briefly and their pressure drop results compared. The correlations are then
compared with data collected from a test setup. This setup was built by DTI in Århus,
Denmark to simulate two-phase ammonia flow in various riser diameters.
A literature search suggests that El-Boher & Lesin correlation is most suitable for
modeling void fraction for vertical flow with large diameters. Comparing the considered
correlations with data from the test setup shows that Müller, Steinhagen & Heck
correlation for frictional pressure drop predicts the measured data the best.
Various literatures suggest that minimum pressure loss is achieved within the
annular flow regime. It was shown that gravitational pressure drop has a steeper
pressure drop gradient than frictional one.
Further experiments would be ideal to better test the validity of the models in this
project. Constructing a flow map using the test setup in Århus would be of great
interest as such a map has not been made for vertical ammonia flow. The map could
then be used to test the validity of flow pattern models.
||Technical University of Denmark (DTU) : Kgs. Lyngby, Denmark
Creation date: 2009-11-05
Update date: 2010-10-28