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Showing papers by "Ephraim M Sparrow published in 1980"






Journal ArticleDOI
TL;DR: In this paper, the authors investigated the effect of the thermal boundary conditions and on the role of radiation as an enhancement mechanism on heat transfer in a vertical parallel plate channel of finite height, and compared the heat transfer from a single isothermal vertical plate with that for a plate that is shrouded by an adiabatic wall.
Abstract: Numerical finite-difference solutions enabled the determination of heat transfer rates for pure natural convection and for Interacting natural convection and radiation in a vertical parallel plate channel of finite height. Attention was focused on the effect of the thermal boundary conditions and on the role of radiation as an enhancement mechanism. The results also enabled comparisons of the heat transfer from a single isothermal vertical plate with that for a plate that is shrouded by an adiabatic wall situated parallel to the plate. For pure convection and at intermediate and large Grashof numbers, the rate of heat transfer for a channel with two Isothermal equt-temperature walls exceeds by more than a factor of 2 that for a channel with one isothermal wall and one adiabatic wall (note that the ratio of active heat transfer areas for the two cases Is equal to 2). At lower Grashof numbers, the heat transfer rates differ only slightly. Radiation effects were explored for the case of a channel having one ...

43 citations



Journal ArticleDOI
TL;DR: In this paper, an analytical study is made of the laminar flow and heat transfer in ducts whose cross section is bounded by a wall with periodic corrugations distributed across the span; the other bounding wall is parallel to the corrugated wall and is plane.

19 citations


Journal ArticleDOI
TL;DR: In this paper, an analysis of laminar forced-convection heat transfer in a horizontal pipe was performed for the case in which the flowing fluid loses heat to the external environment by natural convection and radiation.

16 citations


Journal ArticleDOI
TL;DR: In this paper, the basic heat transfer results for natural convection in an array of vertical in-line plate segments were obtained by numerical finite-difference solutions and tabulated along with previously computed results for staggered and continuous-plate arrays.
Abstract: Basic heat transfer results for natural convection in an array of vertical in-line plate segments were obtained by numerical finite-difference solutions and are tabulated along with previously computed results for staggered and continuous-plate arrays. These results were employed as the basis of three performance comparisons Involving alt three types of arrays, with the continuous-plate array serving as a baseline case. In the first of these comparisons, it was found that the discrete-plate arrays can enhance the heat transfer rate by as much as 80-90% for fixed values of the wall-to-ambient temperature difference and heat transfer surface area. Furthermore, the use of discrete plates affords the possibility of reducing the wall-to-bulk temperature differences by as much as 35-40% at a fixed heat load and surface area. Reductions in the height of the array of up to 50% can also be achieved for conditions of fixed heat load and fixed wall-to-bulk temperature difference. The attainment of enhanced heat tran...

14 citations





Journal ArticleDOI
TL;DR: In this article, the authors analyzed flow and heat transfer for a duct in which there are cross-sectional nonuniformities, consisting of a spanwise-periodic array of rectangles.
Abstract: Laminar fully developed flow and heat transfer have been analyzed for a duct in which there ore cross-sectional nonuniformities. The nonuniformity consists of a spanwise-periodic array of rectangul...



Journal Article
TL;DR: In this paper, 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