A Numerical Study on Natural Convection Heat Transfer of Handheld Projectors with a Fin Array

This study numerically investigates the effects of the number of bottom openings and the fin spacing on both the natural convection heat transfer and airflow field of the handheld projector with various orientations. The horizontally-oriented 120 mm × 53 mm × 19 mm handheld projector, which had 11 bottom openings and was installed with either 7 plate fins or 13 rows of square pin, was considered as the primary case. The fin number varied from 6 plates to 13 plates or from 7 pin rows to 16 pin rows, while the bottom openings varied from 11 to 15 in this study with handheld projector held at a specified inclination ranging from −90° to 90°. The results showed that the heat transfer coefficient of a specific surface of the plate-fin array installed in the primary handheld projector increased from 6 to 7 W/m2·K as the heating power increased from 2 W to 7 W. The optimal fin spacing in the handheld projector possessing 11 bottom openings was 2.875 mm and 3.375 mm for the plate-fin and pin-fin, respectively, at a heating power of 7 W. Although the velocity magnitude of the airflow between fins increased as the bottom opening increased, it was not able to offset the reduction of the airflow velocity resulting from the fin spacing reduction.

[1]  W. Elenbaas.  Heat dissipation of parallel plates by free convection , 1942 .

[2]  Piotr K. Smolarkiewicz,et al.  On spurious vortical structures , 2001 .

[3]  S. Churchill,et al.  Correlating equations for laminar and turbulent free convection from a vertical plate , 1975 .

[4]  H. Gurney.  Heat Transmission , 1909, Nature.

[5]  Mehdi Mehrtash,et al.  Natural convection heat transfer from inclined plate-fin heat sinks , 2013 .

[6]  Jin-Cherng Shyu,et al.  Thermal performance of passively cooled pico projector equipped with a fin array , 2016 .

[7]  Jin-Cherng Shyu,et al.  Thermal management of pico projector using a piezoelectric fan , 2015 .

[8]  Avram Bar-Cohen,et al.  Fin Thickness for an Optimized Natural Convection Array of Rectangular Fins , 1979 .

[9]  M. Mobedi,et al.  A three dimensional numerical study on natural convection heat transfer from short horizontal rectangular fin array , 2003 .

[10]  H. Yüncü,et al.  Optimum fin spacing of rectangular fins on a vertical base in free convection heat transfer , 2007 .

[11]  S. Ostrach.  An analysis of laminar free-convection flow and heat transfer about a flat plate parallel to the direction of the generating body force , 1953 .

[12]  A. Kraus,et al.  Design of Optimum Plate-Fin Natural Convective Heat Sinks , 2003 .

[13]  D. W. Van de Pol,et al.  Free Convection Nusselt Number for Vertical U-Shaped Channels , 1973 .

[14]  Hyun-Jung Kim,et al.  Experimental Study of Natural Convection Cooling of Vertical Cylinders with Inclined Plate Fins , 2016 .

[15]  Witold M. Lewandowski,et al.  Heat transfer by free convection from an isothermal vertical round plate in unlimited space , 2001 .

[16]  E. Radziemska,et al.  Heat transfer by natural convection from an isothermal downward-facing round plate in unlimited space , 2001 .

[17]  Dimitris Drikakis,et al.  Qualitative assessment of RANS models for Hypervapotron flow and heat transfer , 2009 .

[18]  Jonghun Kim,et al.  Savings in Cooling Energy with a Thermal Management System for LED Lighting in Office Buildings , 2015 .

[19]  Hideaki Imura,et al.  Natural-convection heat transfer from a plate with arbitrary inclination , 1972 .

[20]  M. J. Shilston,et al.  Heat exchanger: Optimal separation for vertical rectangular fins protruding from a vertical rectangular base , 1985 .

[21]  W. Rohsenow,et al.  Thermally Optimum Spacing of Vertical, Natural Convection Cooled, Parallel Plates , 1984 .

[22]  H. Yüncü,et al.  An experimental investigation on performance of rectangular fins on a horizontal base in free convection heat transfer , 1998 .

[23]  Alan Burns,et al.  Computational modelling of the HyperVapotron cooling technique , 2012 .