Pengujian Karakteristik Aliran Fasa Tunggal Aliran Air Horisontal Pada Annulus Sempit Dari Penukar Kalor Pipa Konsentrik

Abstract

Abstract : This research was conducted to investigate flow characteristics with/without heat exchange of single phase horizontal water flow in narrow annulus of a concentric tube heat exchanger. Test section was a concentric tube heat exchanger. The inner tube was made of aluminium with inside and outside diameters of 17.34 mm and 19.07 mm. The outer tube was made of aluminium with inside and outside diameters of 23.84 mm and 25.14 mm. The pressure measuring length was 1,198 mm. Hydraulic diameter of narrow annulus was 4.77 mm. Flows in the inner tube and in annulus were in opposite directions. Working fluid used in this research was water. For the flow with heat exchange, the water temperature at the inlet of inner tube was maintained at 60 oC. In this research, the water mass flow rate and pressure drop across narrow annulus were measured at steady states. Results of the research were compared with predictions from conventional flow theory. Results of the research shown that the flow characteristics of water through the narrow annulus were different from those in normal pipes. The transition from laminar to turbulent flow was initiated earlier than that in normal pipes, i.e. at a Reynolds number range from 1,400 to 1,800. The flow friction factor of the horizontal flow with heat exchange was larger than that without heat exchange at the Reynolds number lower than 800. The flow friction characteristics in narrow annulus had relations to liquid temperature difference at the inlet and outlet of the annulus. It was concentrated in the laminar flow area.

Keywords : Friction factor, Laminar, Narrow annulus, Reynolds number, Turbulent