Pressure drop in D shaped cylindrical headers of parallel flow MCHXs: Pressure loss coefficients for single phase flow

This paper presents the investigation of the pressure drop in headers and development of the correlation for pressure loss coefficient for single phase flow through D shaped cylindrical headers of parallel MCHXs. D shaped headers are becoming more popular compared to conventional round cylindrical types due to reduction in charge and pressure drop, despite complexity at difficulties in handling higher pressures. The working fluid was compressed air flowing through header with 1-20 m/s based on smallest cross section while the velocity through microchannels was in the range 4-25 m/s. The experimental results indicate that the pressure loss coefficient of inlet header is a linear function of the ratio of velocities through microchannel tube and header, except for the first two microchannel tubes; the pressure loss coefficient of outlet header is a quadratic function of the ratio of velocities through microchannel tube and header, and decreases as the velocities through upstream microchannel tubes increase. Correlations for predicting pressure drop of inlet header and outlet header are developed and agreement for 98% of experimental data is within ±15 Pa.