microchannel, heat transfer, pressure drop, flow pattern, evaporation
This paper presents heat transfer coefficient, pressure drop, and flow visualization of R1234ze(E) and R1234yf measured in the same facility as introduced in Li and Hrnjak (2016). Experiments are conducted on a 24-port microchannel tube with a hydraulic diameter of 0.643 mm. Mass flux varies from 100 to 200 kg m-2s-1. Heat flux varies from 0 to 6 kW m-2. A comprehensive presentation of measurement will be made in this paper. HTC, PD, and flow pattern will be reported in the same figure. The flow pattern results of R1234yf and R1234ze(E) are shown in the previous paper (Li and Hrnjak, 2018). With the capture of flow pattern, discussion of results are enhanced. The pressure drop of R1234ze(E) is higher than R1234yf. Heat transfer coefficient and flow pattern are similar of the two refrigerants. HTC increases as heat flux or mass flux increases. PD increase as mass flux increases or saturation temperature decreases.