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Showing papers by "Ephraim M Sparrow published in 1981"


Journal ArticleDOI
TL;DR: In this article, a finned vertical tube with either conduction in the solid or natural convection in the liquid was used to study freezing on a paraffin phase change medium with a fusion temperature of 36.4°C.

119 citations



Journal ArticleDOI
TL;DR: In this paper, a methodology is presented for numerical solution of transient two-dimensional diffusion-type problems (e.g., heat conduction) in which one of the boundaries of the solution domain moves with time.

67 citations


Journal ArticleDOI
TL;DR: In this article, the conjugate phase change convection problem was solved using the solution methodology developed in the preceding paper, which was amplified, adapted, and then employed to solve the conjUGATE phase change.

51 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured heat transfer coefficients for melting about a heated vertical cylinder embedded in a solid phase-change medium whose temperature was either at the melting point or was subcooled below the melting value.

35 citations




Journal ArticleDOI
TL;DR: In this article, a conjugate internal-external natural convection problem was solved numerically for Grashof numbers between 103 and 107 and for a Prandtl number of 0.7.

25 citations






Journal ArticleDOI
TL;DR: In this paper, the authors investigated the heat transfer response to framing the thermally active cover surface of a flat plate solar collector with adiabatic co-planar extension surfaces, and found that the wind-related heat transfer coefficients can be substantially lower when the collector is framed than when it is unframed.
Abstract: The heat transfer response to framing the thermally active cover surface of a flat plate solar collector with adiabatic co-planar extension surfaces has been investigated by wind tunnel experiments. Various framing patterns were employed (leading edge and/or trailing edge and/or side edge framing), along with frames of different width. The experiments were performed for various angles of inclination of the plate surface relative to the oncoming airstream and for a range of Reynolds numbers. It was found that the wind-related heat transfer coefficients can be substantially lower when the collector is framed than when it is unframed. An estimate of the possible reduction of the average heat transfer coefficient can be obtained from the equation h/h +- = (L/sub c//L/sub f/)/sup 1/2/, where h and h +- respectively denote the coefficients in the presence and in the absence of the frame. The quantity L/sub c/ is a dimension that is characteristic of the thermally active area of the cover surface, while L/sub f/ is a characteristic of the outer edges of the frame. With respect to the reduction of the heat transfer coefficient, framing along the side edges appears to be more beneficial than framing along the leading and trailingmore » edges, as is framing along the trailing edge compared with framing along the leading edge.« less

Journal ArticleDOI
TL;DR: In this paper, the authors measured forced convection heat transfer coefficients at a plane surface pierced by an aperture (or tube inlet) of diameter d into which fluid flows from a large upstream space.



Journal ArticleDOI
TL;DR: In this paper, the authors performed both heat transfer measurements and flow visualization for turbulent flow in a square duct whose cross section was partially obstructed by a centrally positioned transverse blockage.


Journal ArticleDOI
TL;DR: In this paper, the upper-plate heat transfer response to a lateral offset of the plate from a position of precise alignment with a lower plate was investigated. And the lateral offset was varied parametrically, as was the vertical separation distance between the plates.
Abstract: Numerical solutions have been obtained for the upper-plate heat transfer response to a lateral offset of the plate from a position of precise alignment with a lower plate. Both plates are vertical and are at the same uniform temperature above ambient. The lateral offset was varied parametrically, as was the vertical separation distance between the plates. Relative to an aligned plate, offsetting tends to reduce the local heat flux in the initial portion of the plate and to enhance the flux at larger downstream distances. The extent of the initial-region heat flux reduction is greater for larger vertical separation distances, while the extent of the downstream-region enhancement Is diminished. For short plates and for large vertical separation distances, the surface-integrated heat transfer for an offset plate Is less than that for an aligned plate. Offsetting can lead to an enhancement of the surface-integrated heat transfer for small separation distances and for intermediate and long plates.

01 Jan 1981
TL;DR: In this article, the authors describe fundamental heat transfer processes which occur in phase-change thermal storage systems, including both melting and freezing, and include both experiment and analysis, and the status of four research problems is discussed.
Abstract: Research on fundamental heat transfer processes which occur in phase-change thermal storage systems is described. The research encompasses both melting and freezing, and includes both experiment and analysis. The status of four research problems is discussed. One of the freezing problems was focused on investigating, via experiment, the extent to which freezing can be enhanced by the attachment of fins to the external surface of a cooled vertical tube situated in a liquid phase-change medium. Very substantial enhancements were encountered which neutralize the degradation of freezing due to the thermal resistance of the frozen layer and to natural convection in the liquid phase. The second of the freezing problems was analytical in nature and sought to obtain solutions involving both the phase-change medium and the heat transfer fluid used either to add heat to or extract heat from the medium. For freezing on a plane wall, it was possible to obtain a closed-form analytical solution, while for freezing about a coolant-carrying circular tube, a new numerical methodology was devised to obtain finite-difference solutions. For melting, quantitative design-quality heat transfer coefficients were determined experimentally for melting adjacent to a heated vertical tube. These experiments explored the effects of solid-phase subcooling andmore » of open versus closed top containment on the coefficients. A dimensionless correlation enables these results to be used for a wide range of phase-change media. Studies on melting of a phase-change material situated within a circular tube are in progress.« less