Forced convection heat transfer characteristics by controlling concurrent flow rates of a NanoPCM emulsion/water through outer annulus/inner tube of a concentric double-tube duct

Abstract

In present study demonstrates via heat transfer experiments complementary with numerical simulations the feasibility of achieving enhanced forced convection heat transfer of laminar water flow in an isoflux heated circular tube by inserting a concentric circular tube and controlling the concurrent flow distribution through the resulting concentric double-tube duct In the experiment copper was used as the material of the round tube and the outer tube size was: length 1250 mm outer diameter 10 mm inner diameter 9 1 mm The inner tube has a length of 2060 mm an outer diameter of 8 mm and an inner diameter of 7 4 mm The inner and outer tube gap is 1 1mm A tightly wound nickel-chromium resistance coil is provided in the heating section of the copper tube to provide iso-flux heating conditions In the experimental conditions of fixed total flow and heating power the heat transfer gain is proportional to the flow ratio If the working fluid is a nanoemulsion the higher the heat transfer effect will be higher than the pure water In the fixed total flow rate the nanoemulsions with concentration of 2% and 5% are respectively in the heating power 110W flow ratio 0 7 and the heating power 110W flow ratio 0 27 and the convection has the best gain of 1 32 times and 1 88 times Key words: Concentric double tube Nano-PCM emulsion Phase change material Laminar forced convection

Date of Award	2019
Original language	English
Supervisor	Ching-Jenq Ho (Supervisor)