This paper presents the results of an experimental investigation of convective heat transfer, friction factor and also overall heat transfer coefficient of double pipe heat exchanger with wire-coil insert for following geometrical characteristics: helical pitch 14 mm, wire diameter 1 mm and helical angle 60°. The test were conducted on a two concentric double-pipe heat - exchangers of counter-flow type, constructed with copper tubes 26 mm and 16 mm inner diameter. The heat exchangers were instrumented for measurement of a bulk fluid temperatures and wall temperatures for computerized data-acquisition and data-processing. All temperatures were measured using iron-constantan ("Omega Engineering, INC", J-type, ISO 9001) thermocouples. Voltage (do) output from thermocouples was directly fed into the data-acquisition system HP3421A and computer HP35731B. The fluid flow rates were estimated by measuring fluid pressure drop along short copper tube 10 mm inner diameter, with U-tube manometer. Fluid pressure drop along test sections were measured by U-tube manometer.
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