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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Experimental Investigation of Dimples as a Heat Transfer Enhancement Feature in Narrow Diverging and Converging Channels

Srinivasan, Shreyas 22 August 2013 (has links)
Detailed heat transfer coefficient distributions have been obtained for narrow converging and diverging channels with and without enhancement features. The enhancement feature considered for this study is dimples (inline and staggered) on the main heat transfer surfaces. All the measurements are presented at Reynolds numbers of 3500, 8900, 18000, and 7000, 14000, 28000 for converging and diverging channels respectively. Pressure drop measurements for the overall channel are also presented to evaluate the heat transfer enhancement geometry with respect to pumping power requirements. The test models were studied for wall heat transfer coefficient measurements using the transient liquid crystal technique. The modeled wall inner surfaces were sprayed with thermochromic liquid crystals, and a transient test was used to obtain the local heat transfer coefficients from the measured color change. Analysis of results shows that dimples, in general, have very good enhancement capabilities and staggered dimpled surfaces provide considerably higher heat transfer coefficients and a reasonable pressure drop compared to inline dimpled configuration. Additionally, this study was extended to understand the effect of strategic placement of dimples (staggered) at various locations along the channel to understand regions that contribute significantly to the overall enhancement. / Master of Science
52

Augmentation of single phase heating and subcooled boiling by internally finned tubes

Mani, Mortaza January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
53

A study of heat transfer from cylinders in turbulent flows by using thermochromic liquid crystals

Wiberg, Roland January 2004 (has links)
<p>In gas quenching, metal parts are rapidly cooled from hightemperatures, and the convection heat transfer coefficientdistributions are of importance for the hardness and thedistortion (the shape nonuniformities) of the quenched parts.Thermochromic liquid crystals (TLC) and a thin foil techniques,were investi- gated and used for studies of a circular cylinderin axial flows, affected and not affected by upstream owmodifying inserts. Quadratic prisms in cross ows were alsostudied, a single prism, two prisms arranged in-line, and forfour prisms arranged in a square pattern. In this study,particle image velocime- try (PIV) was used for visualizationof the flow, giving physical insight to the convection heattransfer data. Further, relations of the type<i>Nu</i>=<i>CRe</i><i>e</i>were established. The TLC and thin foil techniques werealso used to indicate the dimensions of separated flowregions.</p><p><b>Descriptors:</b>Fluid mechanics, wind-tunnel, turbulence,gas quenching, con- vection heat transfer, thermochromic liquidcrystals, calibration, temperature measurement errors, thinfoils, particle image velocimetry, cylinder in axial flow, flowmodifying inserts, quadratic prisms in cross flow</p>
54

An enquiry into the mechanism of the pressure drop in the regenerator of the Stirling cycle machine

Su, C-C. January 1986 (has links)
No description available.
55

Mathematical modelling of interactions between a hot liquid and a cold horizontal substrate

Bashforth, Pauline S. January 1995 (has links)
No description available.
56

Heat transfers from district heating pipes

Neale, Antony John January 1987 (has links)
Experimental and numerical investigations were carried out on air-filled cavities containing heated inner cylinders. The effect of varying the position of radial spacers on a single cylinder was studied. It was concluded that for central positioning of the cylinder within the cavity. the rate of heat-transfer was minimised at a radial spacer angle of 480 (measured from the vertically downwards radius vector). When the cylinder was positioned at displacement ratio of 0.7, the rate of heat-transfer was minimised at a corresponding spacer angle of 520. The corresponding reductions in the total rate of heat-transfer were found to be 25% and 31% less than that obtained for the system with no spacers at a cylinder displacement ratio of zero. Following this research investigation, the behaviour of a two-pipe arrangement, consisting of a hot supply and cooler return pipe within a rectangular sectioned cavity, was studied. Eccentric positioning of both supply and return pipes showed that minimum rates of heat-transfer occur at supply and return pipe displacement ratios of 0.45 and -0.33 respectively. This value of heat-transfer is approximately 20% less than that obtained for a system where supply and return pipe displacement ratios are 0.7 and zero respectively. As experimental testing has proved to be excessively time consuming (e. g. due to having to wait until a steady-state ensued before measurments were taken) and laborious, a finite-element numerical model was developed and used to predict the heat-transfer between a heated inner cylinder and a cooled outer square duct. This study investigated eccentricity effects on the rate of heat-transfer for different ratios of duct height to cylinder radius. Solutions were obtained for Rayleigh numbers 1 to 300 and optimal pipe eccentricity for minimum heat-transfer was predicted. These predictions were in good agreement with previous experimental results.
57

Finite elements in incompressible viscous flow including heat transfer

Ijam, A. Z. January 1977 (has links)
No description available.
58

Thermofluid effects of lubricating oil in heat pump systems

Cawte, Howard January 1989 (has links)
No description available.
59

An investigation into fluid to particle heat transfer and particle mixing in air and water fluidised beds

Sistern, M. I. January 1987 (has links)
No description available.
60

The near-wall structure of the thermal turbulent boundary layer over riblets

Orchard, D. M. January 1996 (has links)
No description available.

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