Study on the Influence of Neighbour Room Heat Transfer on the Indoor Thermal Environment in a Heating Room

2014 ◽  
Vol 1070-1072 ◽  
pp. 2006-2009
Author(s):  
Ye Wang ◽  
Tong Zou ◽  
Wen Ting Hu
Keyword(s):  
Heat Transfer ◽  
Temperature Difference ◽  
Thermal Environment ◽  
Internal Surface ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Indoor Thermal Environment ◽  
Average Temperature ◽  
Nusselt Numbers ◽  
Temperature Filed

To obtain the influence of the neighbour room heat transfer on the radiator heat transfer characteristics and indoor thermal environment, a new k-ε model is used to numerically simulate the radiator surface heat transfer ability, indoor velocity field and temperature filed at different neighbour room heat transfer temperature differences. The results indicate that both the radiator surface temperature and the average Nusselt numbers on radiator surface are approximately increasing with the increasing neighbour room heat transfer temperature differences when the indoor average temperature is up to 18°C. At the same neighbour room heat transfer temperature difference, the local heat transfer ability is decreasing gradually from the bottom to the top of the radiator surface. The temperature gradient close to the floor is decreasing with the increasing neighbour room heat transfer temperature difference and the indoor temperature is tending to be more homogeneous. And the velocity gradients close to the ceiling and the internal surface of east wall are higher for the case that the neighbour room heat transfer is considered.

Local Heat Transfer Distribution in a Rotating Serpentine Rib-Roughened Flow Passage

1993 ◽  
Vol 115 (3) ◽  
pp. 560-567 ◽  
Author(s):  
N. Zhang ◽  
J. Chiou ◽  
S. Fann ◽  
W.-J. Yang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Performance ◽  
Height Ratio ◽  
Nusselt Numbers ◽  
Rayleigh Numbers ◽  
Rib Roughened

Experiments are performed to determine the local heat transfer performance in a rotating serpentine passage with rib-roughened surfaces. The ribs are placed on the trailing and leading walls in a corresponding posited arrangement with an angle of attack of 90 deg. The rib height-to-hydraulic diameter ratio, e/Dh, is 0.0787 and the rib pitch-to-height ratio, s/e, is 11. The throughflow Reynolds number is varied, typically at 23,000, 47,000, and 70,000 in the passage both at rest and in rotation. In the rotation cases, the rotation number is varied from 0.023 to 0.0594. Results for the rib-roughened serpentine passages are compared with those of smooth ones in the literature. Comparison is also made on results for the rib-roughened passages between the stationary and rotating cases. It is disclosed that a significant enhancement is achieved in the heat transfer in both the stationary and rotating cases resulting from an installation of the ribs. Both the rotation and Rayleigh numbers play important roles in the heat transfer performance on both the trailing and leading walls. Although the Reynolds number strongly influences the Nusselt numbers in the rib-roughened passage of both the stationary and rotating cases, Nuo and Nu, respectively, it has little effect on their ratio Nu/Nuo.

Heat Transfer in Reciprocating Planar Curved Tube With Piston Cooling Application

2005 ◽  
Vol 128 (1) ◽  
pp. 219-229 ◽  
Author(s):  
Shyy Woei Chang ◽  
Yao Zheng
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Interactive Effects ◽  
Experimental Conditions ◽  
Nusselt Numbers ◽  
Curved Tube ◽  
The Individual ◽  
Cooling Passage ◽  
Piston Cooling

This paper describes an experimental study of heat transfer in a reciprocating planar curved tube that simulates a cooling passage in piston. The coupled inertial, centrifugal, and reciprocating forces in the reciprocating curved tube interact with buoyancy to exhibit a synergistic effect on heat transfer. For the present experimental conditions, the local Nusselt numbers in the reciprocating curved tube are in the range of 0.6–1.15 times of static tube levels. Without buoyancy interaction, the coupled reciprocating and centrifugal force effect causes the heat transfer to be initially reduced from the static level but recovered when the reciprocating force is further increased. Heat transfer improvement and impediment could be superimposed by the location-dependent buoyancy effect. The empirical heat transfer correlation has been developed to permit the evaluation of the individual and interactive effects of inertial, centrifugal, and reciprocating forces with and without buoyancy interaction on local heat transfer in a reciprocating planar curved tube.

Modal Effects on the Local Heat Transfer Characteristics of a Vibrating Body

1999 ◽  
Vol 122 (2) ◽  
pp. 233-239 ◽  
Author(s):  
K. D. Murphy ◽  
T. A. Lambert,
Keyword(s):  
Heat Transfer ◽  
Structural Response ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Vibration Modes ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Nusselt Numbers ◽  
Transverse Vibrations ◽  
Resonance Frequencies

This is an experimental investigation of the effects of forced transverse vibrations on the local heat transfer characteristics of a heated, pinned-pinned beam. In particular, the response of a cylindrical beam near its first two natural frequencies, corresponding to the first two vibration modes, is considered. The results show that there is a strong spatial variation in the local Nusselt number and that these variations are closely related to the mode shape of the response. Because the heat transfer measurements were taken at the resonance frequencies, where the structural response was greatest, the measured Nusselt numbers provide an upper bound for the increased convection due to flexible body vibrations, i.e., in the absence of any rigid-body mode. The possibility of large-amplitude nonlinear vibrations are discussed (though they were not witnessed experimentally) in a theoretical framework. [S0022-1481(00)01702-3]

Local Heat Transfer Downstream of Abrupt Circular Channel Expansion

1970 ◽  
Vol 92 (1) ◽  
pp. 53-60 ◽  
Author(s):  
P. P. Zemanick ◽  
R. S. Dougall
Keyword(s):  
Heat Transfer ◽  
Experimental Work ◽  
Local Heat Transfer ◽  
Reynolds Numbers ◽  
Local Heat ◽  
Working Fluid ◽  
Published Data ◽  
Circular Channel ◽  
Nusselt Numbers ◽  
Channel Expansion

Experimental work was performed to determine local Nusselt numbers in the region beyond an abrupt expansion in a circular channel. Three expansion geometries, ratios of upstream-to-downstream diameter of 0.43, 0.54, and 0.82, were tested with air as the working fluid. Data are shown for Reynolds numbers from 4000 to 50,000–90,000 depending on geometry. Selected comparisons with previously published data for air and water are included.

The Effect of Support Grid Features on Local, Single-Phase Heat Transfer Measurements in Rod Bundles

2004 ◽  
Vol 126 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Mary V. Holloway ◽  
Heather L. McClusky ◽  
Donald E. Beasley ◽  
Michael E. Conner
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Enhancement ◽  
Nusselt Numbers ◽  
Loss Coefficients ◽  
Effect Of Support ◽  
Support Grid

Locally averaged heat transfer measurements in a rod bundle downstream of support grids with and without flow-enhancing features are investigated for Reynolds numbers of 28,000 and 42,000. Support grids with disk blockage flow-enhancing features and support grids with split-vane pair flow enhancing features are examined. Grid pressure loss coefficients and feature loss coefficients are determined based on pressure drop measurements for each support grid design. Results indicate the greatest heat transfer enhancement downstream of the support grid designs with disk blockages. In addition, the local heat transfer measurements downstream of the split-vane pair grid designs indicate a region of decreased heat transfer below that of the hydrodynamically fully developed value. This decreased region of heat transfer is more pronounced for the lower Reynolds number case. A correlation for the local Nusselt numbers downstream of the standard support grid designs is developed based on the blockage of the support grid. In addition, a correlation for the local Nusselt numbers downstream of support grids with flow-enhancing features is developed based on the blockage ratio of the grid straps and the normalized feature loss coefficients of the support grid designs. The correlations demonstrate the tradeoff between initial heat transfer enhancement downstream of the support grid and the pressure drop created by the support grid.

Heat Transfer to an Airfoil in Oscillating Flow

1971 ◽  
Vol 93 (4) ◽  
pp. 461-468 ◽  
Author(s):  
J. A. Miller ◽  
P. F. Pucci
Keyword(s):  
Heat Transfer ◽  
Oscillation Frequency ◽  
Leading Edge ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Oscillating Flow ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Consequent Increase

Local heat transfer coefficients to an airfoil in an oscillating stream have been measured for a range of frequencies and oscillation amplitudes. Results at moderate angles of attack are in agreement with previously reported findings. However, at large angles of attack, including those associated with stall in steady flow, a strong periodic starting vortex shed from the leading edge leads to a dramatic reattachment of the flow and consequent increase in local Nusselt Numbers of as much as five-fold. These effects are shown to be amplified by increasing oscillation frequency and amplitude.

The Intertube Falling Film: Part 2—Mode Effects on Sensible Heat Transfer to a Falling Liquid Film

1996 ◽  
Vol 118 (3) ◽  
pp. 626-633 ◽  
Author(s):  
X. Hu ◽  
A. M. Jacobi
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Local Heat Transfer ◽  
Horizontal Tube ◽  
Local Heat ◽  
Falling Film ◽  
Mode Effects ◽  
Nusselt Numbers ◽  
Transfer Behavior ◽  
Continuous Sheet

When a liquid film falls from one horizontal tube to another below it, the flow may take the form of discrete droplets, jets, or a continuous sheet; the mode plays an important role in the heat transfer. Experiments are reported that explore the local heat transfer behavior for each of these flow patterns, and the results are related to the important features of the flow. Spatially averaged Nusselt numbers are presented and discussed, and new mode-specific design correlations are provided. This research is part of an overall study of horizontal-tube, falling-film flow and heat transfer.

Cross-Flow Heat Transfer in The Freeboard Region of a Fluidized Bed

1996 ◽  
Vol 210 (3) ◽  
pp. 245-253 ◽  
Author(s):  
D B Murray ◽  
P O'Connor ◽  
P Gilroy
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Cross Flow ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Shielding Effect ◽  
Local Concentration ◽  
Nusselt Numbers ◽  
Design Selection ◽  
The Impact

This paper describes an experimental investigation of heat transfer in two tube banks, one in-line and one staggered, located in the freeboard region of a gas fluidized bed. The objectives of this study are twofold. Firstly, examination of the local heat transfer results is used to identify the dominant heat transfer mechanisms. Secondly, the overall heat transfer performance of the two tube configurations is of relevance for the design, selection and siting of heat exchangers for fluidized bed combustors. The experimental results show that the dominant influence on heat transfer is the local concentration of particles, with the impact over the rear of tubes by particles disengaging from the flow having a significant effect on wake heat transfer. The latter mechanism is less important for tubes in the first and second rows of the in-line array, due to the shielding effect of the surrounding tubes. This difference in wake heat transfer contributes to higher mean Nusselt numbers, on average, for the tubes located in the staggered array.

Average Nusselt Number for Pressure and Suction Sides of Squealer Turbine Blade Tip

2011 ◽  
Author(s):  
Chaouki Ghenai
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Cavity Depth ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Blade Tip

Numerical simulations of the flow field and heat transfer of squealer blade tip are performed in this study. The effect of Reynolds number (Re = 10000–40000), the clearance gap to width ratios (C/W = 5%–15%) and the cavity depth to width ratios (D/W = 10%, 20% and 50%) on fluid flow and heat transfer characteristics are obtained. The temperature and velocity distributions inside the cavity, the local heat transfer coefficients, and the average Nusselt numbers for the pressure and suction sides of the turbine blade tip are determined. This paper presents the results of the effects of Reynolds number, clearance gap and width ratios on the Nusslet number for the pressure and suction sides of squealer turbine blade tip. The results show a good agreement with the experimental data obtained by Metzger and Bunker. New correlations for the average Nusselt numbers for turbine blade tip pressure and suction sides are presented.

Heat Transfer in the Oscillating Turbulent Boundary Layer

1969 ◽  
Vol 91 (4) ◽  
pp. 239-244 ◽  
Author(s):  
James A. Miller
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Mean Velocity ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Local Coefficients

Measurements of local heat-transfer coefficients in the fully established oscillating turbulent boundary layer over a flat plate are reported. In the range of frequencies from 0.1 to 200 cps and amplitudes from 8 to 92 percent of the freestream mean velocity, increases in local Nusselt numbers of 3 to 5 percent were found. It is concluded that substantial increases in local coefficients, sometimes reported in oscillating flows of low standing wave ratio, may be traced to reduced transition Reynolds numbers.

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