Duct-flow versus external-flow natural convection at a short, wall-attached horizontal cylinder
✍ Scribed by E.M. Sparrow; P. Souza Mendes; M.A. Ansari; A.T. Prata
- Publisher
- Elsevier Science
- Year
- 1983
- Tongue
- English
- Weight
- 751 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0017-9310
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✦ Synopsis
Natural convection heat transfer coefficients were measured at a short horizontal cylinder affixed to an equi-temperature vertical plate for the condiiiofi that the plate and the cylinder form one wall of a vertical duel. The duct was open to the ambient at the top and bottom and, aside from the plate and cylinder, its other walls were not directly heated. It was found that substantially higher cylinder heat transfer coefficients could be attained in the duct-flow mode than in the external-flow mode (i.e. where the plate and cylinder face a large open space). Duct-flow-related enhancements of up to 60% were measured. The enhancement is maximized when the duct is as narrow as possible and when the cylinder is positioned near the lower end of the plate. The radiation surface properties of the unheated walls of the duct also affect the degree of enhancement, with black surfaces bringing about greater enhancement by virtue of their higher buoyancy-creating temperature.