Experiments on Void Fraction of CO2 Flow Boiling in a Horizontal Micro-fin Tube
Abstract
This paper deals with an experimental investigation on the void fraction of CO2 flow boiling in a horizontal micro-fin tube. The mean void fraction in the insulated 400 mm length sampling section, which is located next to the test evaporator, has measured by the quick closing valve method. The experimental data have been obtained in mass flux range of 200 to 455 kg/(m2s) and the refrigerant pressure range of 3.5 to 5.0 MPa. It is confirmed that the relation between void fraction and quality is affected by both mass flux and pressure. The experimental results are also compared with two previous correlations for horizontal smooth tubes, which are proposed by Butterworth and Smith. The present data satisfactorily agreed with Butterworth's correlation in the range of quality from 0.03 to 0.99. However, Smith's correlation is found to predict slightly higher than present data. As a trial, the empirical correlation of void fraction, based on the experimental slip ratios, is proposed.
- Publication:
-
Transactions of the Japan Society of Refrigerating and Air Conditioning Engineers
- Pub Date:
- 2011
- Bibcode:
- 2011TRACE..25...55K
- Keywords:
-
- Void fraction;
- Micro-fin tube;
- Carbon dioxide;
- Flow boiling;
- Experiment