Journal of Physics E: Scientific Instruments, 1988
ABSTRACT A systematic study of the effects of heat flux probe design on its thermal characteristi... more ABSTRACT A systematic study of the effects of heat flux probe design on its thermal characteristics and response is reported. The probe considered consists of a metallic film sensor deposited onto a substrate and covered by a thin protective coating. This study considers the case of a constant temperature sensor mounted in an isothermal wall with the sensor maintained at the wall temperature. A two-dimensional, transient numerical analysis for a dynamic heat flux probe was formulated and results reported. Asymptotic response limits were studied by considering idealised probe models and are presented. A non-dimensional relationship between steady-state heat transfer coefficient and sensor power was determined for a range of material properties for the substrate and coating. The steady-state effective probe area was found to remain essentially constant for a broad range of heat flux provided that the probe materials are chosen properly. Probe sensitivity was found to be dependent on probe design and material properties. The transient analysis demonstrated the effect of probe design on probe response and sensitivity.
6th Symposium on Multidisciplinary Analysis and Optimization, 1996
This paper describes the undergraduate curriculum developed by the members of the NASA Multidisci... more This paper describes the undergraduate curriculum developed by the members of the NASA Multidisciplinary Design and Analysis Fellowship program at Clemson. It is a program that is offered to select students who demonstrate interest in the multidisciplinary aspects of their future profession as evidenced by their grades, their commitment to taking directed electives in other disciplines to complement their discipline requirements, and an essay they write at application time. The curriculum is integrated as much as possible in traditional curricula, but targets the selection of humanities electives to deal with teaming issues, and challenge the students to take free and or technical electives in areas that complement their disciplines. Furthermore, their senior projects will consist mainly of industrial multidisciplinary problems submitted to us by our industrial partners.
Heat Transfer and Surface Renewal Dynamics in Gas-Fluidized Beds
Journal of Heat Transfer, 1994
Local instantaneous heat transfer between a submerged horizontal cylinder and a gas-fluidized bed... more Local instantaneous heat transfer between a submerged horizontal cylinder and a gas-fluidized bed operating in the bubble-flow regime was measured and the resulting signals analyzed. Unique to this investigation is the division of particle convective heat transfer into transient and steady-state contact dynamics through analysis of instantaneous heat transfer signals. Transient particle convection results from stationary particles in contact with the heat transfer surface and yields a heat transfer rate that decays exponentially in time. Steady-state particle convection results from active particle mixing at the heat transfer surface and results in a relatively constant heat transfer rate during emulsion phase contact. The average time of contact for each phase is assessed in this study. Signals were acquired using a constant-temperature platinum film heat flux sensor. Instantaneous heat transfer signals were obtained for various particle sizes by varying the angular position of the...
Exergy Approach to Decision-Based Design of Integrated Aircraft Thermal Systems
Journal of Aircraft, 2003
The concept of using an exergy-based approach as a thermal design methodology tool for integrated... more The concept of using an exergy-based approach as a thermal design methodology tool for integrated aircraft thermal systems is introduced. An exergy-based approach was applied to the design of an environmental control system (ECS) of an advanced aircraft. Concurrently, a traditional energy-based approach was applied to the same system. Simplified analytical models of the ECS were developed for each method and compared to assess the ability of each method to suggest optimal design paths. The study identified some roadblocks to assessing the value of using an exergy-based approach: Energy and exergy methods seek answers to different questions, making direct comparisons awkward, and high-entropy generating devices can dominate the design objective of the exergy approach. Nonetheless, exergy methods do approach design differently, providing a ready estimate for efficiency on a component and system basis. Multiobjective optimization tradeoff studies between design weight and entropy generated were used to determine optimal design points. The results from the two analyses provide similar but different decision solutions. The methodology and its implementation are illustrated
A study of the particle convection contribution to heat transfer in gas fluidized beds
Chemical Engineering Science, 1993
ABSTRACT A model for the particle convection heat transfer component of the overall heat transfer... more ABSTRACT A model for the particle convection heat transfer component of the overall heat transfer between a submerged surface and a bubbling fluidized bed is presented. A convective boundary condition combined with surface coverage concepts are introduced to describe the instantaneous wall-to-bed heat transfer. Both thermally lumped and distributed formulations with constant and variable properties for the model are presented and studied. As formulated, the model is not restricted to uniform bed particle size distributions. Experimental measurements obtained from instantaneous local heat flux probes are compared to the model predictions. The thermally distributed, variable property model formulation provides very good agreement with the experimental data over a wide range of particle sizes and fluidization velocities. For particle size beds ranging from 256 to 4000 μm, the model displayed a very accurate trend prediction relative to available data, with magnitude predictions of 2–28% error, depending upon particle size over a wide range of fluidization velocity.
Convective transport : presented at the Winter Annual Meeting of the American Society of Mechanical Engineers, Boston, Massachusetts, December 13-18, 1987
Convection heat transfer and transport prcesses : presented at the Winter Annual Meeting of the American Society of Mechanical Engineers, San Francisco, California December 10-15 1989
Natural convection in enclosures--1988 : presented at the Winter Annual Meeting of the American Society of Mechanical Engineers, Chicago, Illinois, Nov. 27-Dec. 2, 1988
High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion... more High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.
A study into the use of a photon correlation technique in both low and high speed flows
A laser anemometer system using a photon correlation technique in conjunction with a dual beam-Do... more A laser anemometer system using a photon correlation technique in conjunction with a dual beam-Doppler difference optical system was tested. An introduction to the technique is presented. Correlograms were obtained in both low and high speed flows having various degrees of turbulence. Comparisons are made with measurements from a pitot-static tube, a hot-wire anemometer, and a period counter processor. The technique obtained good results even at extremely low light levels with signals of poor signal to noise ratio at velocities up to M = 1.2.
Instantaneous azimuthal heat transfer coefficients from a horizontal cylinder to a mixed particle size air-fluidized bed
Instantaneous, azimuthal heat transfer coefficients were experimentally determined for a heated h... more Instantaneous, azimuthal heat transfer coefficients were experimentally determined for a heated horizontal cylinder immersed in a three dimensional air-fluidized bed. The fluidization conditions covered a range of single and binary particle size mixtures of glass beads in the bubbling flow regime. Instantaneous heat flux measurements were performed using a custom designed, fast responding platinum film heat flux probe capable of withstanding the fluidized bed environment. The instantaneous heat transfer coefficients results along with flow visualization studies were used to evaluate the applicability of current heat transfer models such as the packet model. While the model was found to be adequate in its numerical prediction of the heat transfer coefficient for the tested conditions, this model was not found to be adequate to describe the heat transfer mechanism from an immersed horizontal tube. Flow and heat transfer behavior for such cases are discussed.
Convection transitions within a vertical cylinder heated from below
Physics of Fluids, 1986
ABSTRACT Flow visualization experiments were conducted on a confined vertical column of fluid hea... more ABSTRACT Flow visualization experiments were conducted on a confined vertical column of fluid heated from below. The experiments were performed using a high Prandtl number fluid at Rayleigh numbers up to 118 000 in an apparatus having a height-to-width ratio of unity. An axisymmetric motion was documented at the onset of convection, followed by two distinct three-dimensional motions as the Rayleigh number was increased.
ABSTRACT This book presents the papers given at a conference on heat transfer in buildings. Topic... more ABSTRACT This book presents the papers given at a conference on heat transfer in buildings. Topics considered at the conference included natural convection in enclosures partitioned at different angles, boundary layers, natural convection in rectangular enclosures, Nusselt numbers, porous materials, heating, heat flux, temperature gradients, and walls.
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Papers by R. Figliola