Thermal design of automotive HVAC condensers for mixed flow regimes in minichannels

The air cooled automotive condensers under study are of brazed aluminium tube and center, consisting of one row array of horizontal parallel multi-port flat tubes with corrugated louver fins on the air side. Each tube is with a number of smooth parallel minichannels for internal flow of refrigerant. The analysis uses decomposition of the condenser along refrigerant flow path into specific different zones as follows: two single phase zones, namely: superheated and subcooled, and a few zones of two phase flow that can appear along some specific condensation paths to be: annular/intermittent/bubble or annular/annular-wavy/intermittent/bubble or annular/wavy/stratified. The approach presented is based on two phase flow regimes and corresponding experimental correlations for heat transfer and pressure drop. The heat transfer prediction is performed using [epsilon] - NTU[o] methodology.Results of the analysis refer to variations in the flow regimes and vapour quality along the condensation path, overall heat transfer rate, and for particular zones: contributed thermal resistances, heat transfer effectivenesses, flow lengths, heat transfer rates.