Numerical Study on Thermal Performance of Water Flow in a Twisted Duct Heat Exchanger
This paper presents a numerical study of heat transfer through a downstream annulus using water as the working fluid within the laminar flow region. The annulus consisted of an outer twisted square duct and an inner circular pipe. A three-dimensional formulation was used to solve the Navier-Stokes e...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
University of Zielona Góra
2022-06-01
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| Series: | International Journal of Applied Mechanics and Engineering |
| Subjects: | |
| Online Access: | https://www.ijame-poland.com/Numerical-Study-on-Thermal-Performance-of-Water-Flow-in-a-Twisted-Duct-Heat-Exchanger,166717,0,2.html |
| Summary: | This paper presents a numerical study of heat transfer through a downstream annulus using water as the working fluid within the laminar flow region. The annulus consisted of an outer twisted square duct and an inner circular pipe. A three-dimensional formulation was used to solve the Navier-Stokes equations numerically for the laminar flow system with a low Reynolds number. Three parameters were used in the numerical simulation: the length of the twisted square ( a : 6.6 , 8.2 10.2, 12.6 mm ) the inner diameter of the inner circular pipe ( d : 19, 21, 23 and 25 mm ); and the twist angle (θ: 0 ° (smooth), 45 °, 60 °, and 90 °). Numerical calculations were conducted on sixteen twisted square duct heat exchangers, with water flowing within a Reynolds number range of 220 – 1100 . The results were illustrated as a profile of the thermal enhancement factor, the friction factor and the Nusselt number. The results show that the twisted outer duct of the heat exchanger can create a swirl flow along the length of the heat exchanger. It also caused a boundary layer separation-reattachment on the wall of the inner pipe. Moreover, an increase in the twist angle increased the Nusselt number by 20 %, and the friction factor was also increased as the annular gap of the heat exchanger decreased. |
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| ISSN: | 1734-4492 2353-9003 |