Evaporation heat transfer characteristics of falling film in small diameter fabricated tubes of absorption refrigeration system: An experimental investigation

•Newly developed fabricated tubes are used to improve the wettability and reducing the uneven distribution of falling film evaporator.•Finned tube shows the better performance than the corrugated tubes.•Transition Reynolds number is an important criteria to get the best performance from falling film evaporator.•New empirical Nusselt correlations are obtained for the fabricated tubes which shows an agreement within ±20%.