The present paper reports local heat transfer coefficients measured during condensation of
R1234yf within a single circular 0.96 mm diameter minichannel and compares them to the
ones of R134a.
This experimental work is carried out in a unique test apparatus which allows to determine
the local heat flux extracted from the condensing fluid from the temperature profile of the
coolant. For this purpose, the temperatures of the coolant and of the wall are measured
along the test section. The saturation temperature is determined from the saturation
pressure which is measured at inlet and outlet of the test channel.
Condensation tests are carried out at mass fluxes ranging between 200 and 1000 kg m2 s1
and the heat transfer coefficients result to be lower as compared to the ones of R134a. Since
the saturation temperature drop directly affects the heat transfer rate, the pressure drop
during adiabatic two-phase flow of R1234yf is also measured and compared to R134a