Thermal−hydraulic characteristics of R32 and R410A flow boiling in plate heat exchangers with 1 mm chevron depth

Brazed plate heat exchanger (BPHE) has gained more advantages of refrigerant inventory reduction and high efficiency due to smaller chevron channel. This paper experimentally investigates the heat transfer and pressure drop of R32 and R410A flow boiling in BPHEs with 1 mm chevron depth and W– and V– chevron patterns. Variations in heat transfer coefficient (HTC) and frictional pressure drop (FPD) with mass flux (15 − 40 kg m⁻² s⁻¹ for R32 and 25 − 60 kg m⁻² s⁻¹ for R410A) and imposed heat flux (from 6 − 14 kW m⁻²) are analyzed for each combination of the two refrigerants and two types of plate patterns. The HTC of R32 is approximately 10 % and 30 % higher than that of R410A at same mass flux in W– and V–shaped plates, respectively, which has an equivalent friction factor. The V–shaped plate is found more suited for R32 compared to the W–shaped plate. The existing available transition criterions fail to predict the flow boiling heat transfer mechanism in microscale channel, and convective boiling seems dominant in 1 mm chevron depth channel under the present working conditions, particularly for R32. The HTC correlations of Hsieh and Lin, and Palmer et al. fit the measured data relatively well with 96 and 80 % data within the deviation of ±20 %, respectively. Huang et al. correlation exhibits fare predictability for FPD, with more than 80 % data within the deviation of ±25 %.