Gas flow rate distributions in parallel minichannels for polymer electrolyte membrane fuel cells: Experiments and theoretical analysis

In the present work, instantaneous gas flow rates in each of two parallel channels of gas-liquid two-phase flow systems were investigated through measurements of the pressure drop across the entrance region. Liquid flow rates in two branches were pre-determined through liquid injection independently into each channel. Experiments were conducted in two different manners, i.e., the gas flow rate was varied in both ascending and descending paths. Flow hysteresis was observed in both gas flow rate distributions and the overall pressure drop of two-phase flow systems. Effects of liquid flow rates on gas flow distributions were examined experimentally. The presence of flow hysteresis was found to be associated with different flow patterns at different combinations of gas and liquid flow rates and flow instability conditions. A new and simple method was developed to predict gas flow distributions based on flow regime-specific pressure drop models for different experimental approaches and flow patterns. In particular, two different two-phase pressure drop models were used for slug flow and annular flow, separately. Good agreement was achieved between theoretical predictions and our experimental data. The developed new method can be potentially applied to predict gas flow distributions in parallel channels for fuel cells.