Experimental Investigation of Cross Flow Staggered Elliptic Tube Heat Exchanger at 45⁰ Angle of Attack
5 Pages Posted: 22 Jan 2018
Date Written: December 21, 2017
Thermal and hydraulic of performance of cross flow heat exchanger using elliptical shape tube in staggered arrangement at 45˚ angle of attack is carried out. Hot water is passed in a zigzag manner through 25 tubes of length 0.15 m and cold air is flowing over the tubes in cross flow heat exchanger of size 1×0.15×0.165 m^3. Elliptic shaped tubes array is having transverse and longitudinal pitches of 0.052 m with 45º angle of attack and minor to major axis ratio of 0.5. From the literature it was observed that the selected 45º angle of attack gives the highest thermal performance for a heat exchanger. Effect of varying mass flow rate of air on Nusselt number, Reynolds number, Prandtl number, coefficient of heat transfer, friction factor and pressure drop is calculated. Thermal performance of elliptical shape tube heat exchanger increases 30% - 75% as compare to circular shape tubes in the Reynolds number range 4500 - 14500. Friction factor (f) decreases from 1.96 to 1.38 as Reynolds number increased. The new correlation is developed for staggered tube array as, 〖Nu〗_a=0.106×〖Re〗_a^(0.773)×〖Pr〗_a^(0.36).
Keywords: A-A - Section of 3 tube in column, B-B - section of 2 tube in column, CFD- Computational Fluid Dynamics, Staggered tube array, Thermal- hydraulic performance.
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