Flow rate distribution and pressure drop of an evaporating fluid in small diameter parallel pipes were investigated at steady state and transient conditions. New quantitative experimental results on the transient response of the system to various changes in the inlet flow rate and the heating input are presented. The experimental results are compared with a time dependent model based on the temporal/local flow patterns in the parallel pipes. The experimental results compare fairly well to the theoretical ones. (C) 2015 Elsevier Ltd. All rights reserved.