TWO-PHASE FLOW DISTRIBUTION IN A HEADER OF A PARALLEL FLOW HEAT EXCHANGER
The air and water flow distribution are experimentally studied for a heat exchanger composed of round headers and ten flat tubes. The effects of tube protrusion depth as well as mass flux, and quality are investigated. The flow at the header inlet is annular. For the downward flow configuration, the water flow distribution is significantly affected by the tube protrusion depth. For flush-mounted geometry, significant portion of the water flows through frontal part of the header. As the protrusion depth increases, more water is forced to the rear part of the header. The effect of mass flux or quality is qualitatively the same as that of the protrusion depth. Increase of the mass flux or quality forces the water to rear part of the header. Similar trends had been obtained for thirty channel tests. For the upward flow configuration, different from the downward configuration, significant portion of the water flows through the rear part of the header. The effect of the protrusion depth is the same as that of the downward flow. As the protrusion depth increases, more water is forced to the rear part of the header. However, the effect of mass flux or quality is opposite to the downward flow case. As the mass flux or quality increases, more water flows through the frontal part of the header. Compared with the previous thirty channel data, the present ten channel data show much stronger effect of tube protrusion depth, mass flux and quality. Possible explanation on the flow distribution is provided from the flow visualization results.