Experimental Study of a Vertical Channel Solar Chimney with Uniform Heat Flux for Natural Ventilation in Buildings

2011 ◽  
Vol 374-377 ◽  
pp. 585-589
Author(s):  
Hai Wei Jing ◽  
An Gui Li
Keyword(s):  
Experimental Study ◽  
Heat Flux ◽  
Velocity Field ◽  
Natural Ventilation ◽  
Vertical Channel ◽  
Heated Wall ◽  
Uniform Heat Flux ◽  
Airflow Rate ◽  
Optimum Ratio ◽  
Solar Chimney

A experimentally study has been carried out to predict airflow rate, temperature field and velocity field for different chimney gap and heat flux. Results showed that, for veritical solar chimney,there is an optimum ratio of chimney width-to height to achieve a maximum airflow rate. The optimum ratio is about 1：2. Meanwhile,temperature and velocity field of solar chimney channel were analyzed. The air temperature and the velocity approaching to the surface of the heated wall are higher than that away from the surface of the heated wall.

Experimental Investigation of Using Solar Chimney to Induce Natural Ventilation

2014 ◽  
Vol 672-674 ◽  
pp. 109-112 ◽  
Author(s):  
Cai Xia Hao ◽  
Hai Ping Zhang ◽  
Min Xia Hao
Keyword(s):  
Heat Flux ◽  
Experimental Investigation ◽  
Velocity Field ◽  
Boundary Layers ◽  
Natural Ventilation ◽  
Heated Surface ◽  
Experimental Results ◽  
Solar Chimney ◽  
Air Velocity ◽  
Radiant Intensity

The vertical panels of solar chimney have internal dimensions of 2000mm height、1000mm length. Under the condition of heat flux and chimney gap variety, we research chimney interior velocity field. Experimental Results show that airflow increased with chimney gap augmentation, the airflow and air velocity augment with the increase of solar radiant intensity, and air velocity decreases with the increase of solar chimney gap. Air velocity is higher near the heated surfaces than it in the middle chimney. Meanwhile velocity boundary layers form near the heated surface.

A Nondimensional Analysis of Boiling Dry a Vertical Channel with a Uniform Heat Flux

1981 ◽  
Vol 103 (4) ◽  
pp. 667-672 ◽  
Author(s):  
K. H. Sun ◽  
R. B. Duffey ◽  
C. Lin
Keyword(s):  
Heat Flux ◽  
Nuclear Power ◽  
Closed Form Solution ◽  
Vertical Channel ◽  
Form Solution ◽  
Uniform Heat Flux ◽  
Two Phase ◽  
Drift Flux ◽  
Rod Bundle ◽  
Uniform Heat

A thermal-hydraulic model has been developed for describing the phenomenon of hydrodynamically-controlled dryout, or the boil-off phenomenon, in a vertical channel with a spatially-averaged or uniform heat flux. The use of the drift flux correlation for the void fraction profile, along with mass and energy balances for the system, leads to a dimensionless closed-form solution for the predictions of two-phase mixture levels and collapsed liquid levels. The physical significance of the governing dimensionless parameters are discussed. Comparisons with data from single-tube experiments, a 3 × 3 rod bundle experiment, and the Three Mile Island nuclear power plant show good agreement.

Natural-Ventilation Flow in a 3-D Room Fitted With Solar Chimney

2012 ◽  
Author(s):  
B. P. Huynh
Keyword(s):  
Heat Flux ◽  
Flow Pattern ◽  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation Rate ◽  
High Heat Flux ◽  
Solar Chimney ◽  
Solar Heat ◽  
Solar Heat Flux ◽  
Inlet Opening

Natural-ventilation flow induced in a real-sized rectangular-box room fitted with a solar chimney on its roof is investigated numerically, using a commercial CFD (Computational Fluid Dynamics) software package. The chimney in turn is in the form of a parallel channel with one plate being subjected to uniform solar heat flux. Ventilation rate and air-flow pattern through the room are considered in terms of the heat flux for two different locations of the room’s inlet opening. Chien’s turbulence model of low-Reynolds-number K-ε is used in a Reynolds-Averaged Navier-Stokes (RANS) formulation. It is found that ventilation flow rate increases quickly with solar heat flux when this flux is low, but more gradually at higher flux. At low heat flux, ventilation rate is not significantly affected by location of the inlet opening to the room. On the other hand, at high heat flux, ventilation rate varies substantially with the opening’s location. Location of the inlet opening to the room also affects strongly the air-flow pattern. In any case, ample ventilation rate is readily induced by the chimney.

Experimental and Numerical Investigation on Natural Convection in Horizontal Channels Partially Filled With Aluminium Foam and Heated From Below

2016 ◽  
Author(s):  
Bernardo Buonomo ◽  
Oronzio Manca ◽  
Sergio Nardini ◽  
Alessandra Diana
Keyword(s):  
Heat Flux ◽  
Natural Convection ◽  
Wall Temperature ◽  
Aluminum Foam ◽  
Rectangular Channel ◽  
Lower Surface ◽  
Heated Wall ◽  
Working Fluid ◽  
Bottom Plate ◽  
Uniform Heat Flux

Natural convection in horizontal rectangular channel without or with aluminum foam is experimentally and numerically investigated. In the case with aluminum foam the channel is partially filled. In both cases, the bottom wall of the channel is heated at a uniform heat flux and the upper wall is unheated and it is not thermally insulated to the external ambient. The experiments are performed with working fluid air. Different values of wall heat flux at lower surface are considered in order to obtain some Grashof numbers and different heated wall temperature distributions. Two different aluminum foams are considered in the experimental investigation, one from “M-pore”, with 10 and 30 pore per inch (PPI), and the other one from “ERG”, with 10, 20 and 40 PPI. The numerical simulation is carried out by a simplified two-dimensional model. It is found that the heat transfer is better when the channel is partially filled and the emissivity is low, whereas the heated wall temperature values are higher when the channel is partially filled and the heated bottom plate has high emissivity. The investigation is achieved also by flow visualization which is carried out to identify the main flow shape and development and the transition region along the channel. The visualization of results, both experimental and numerical, grants the description of secondary motions in the channel.

Combined Radiation and Convection in an Asymmetrically Heated Parallel Plate Flow Channel

1964 ◽  
Vol 86 (3) ◽  
pp. 341-350 ◽  
Author(s):  
E. G. Keshock ◽  
R. Siegel
Keyword(s):  
Heat Flux ◽  
Parallel Plate ◽  
Nuclear Reactor ◽  
The Other ◽  
Heated Wall ◽  
Uniform Heat Flux ◽  
Gas Temperature ◽  
Spacing Ratio ◽  
Fluid Properties ◽  
Axial Heat

An analysis is made of the effects of radiation exchanges upon the wall-temperature distributions in a parallel plate channel through which a gas transparent to thermal radiation is flowing. A uniform heat flux is applied at one wall, while the other wall has no imposed heat flux and only receives energy by radiation or convection from the heated wall. This situation approximates that found in the outer passage of a nuclear reactor fuel element where one channel wall is a fuel plate while the other is the support structure. Axial heat conduction is neglected in the channel walls and the gas, and constant fluid properties are assumed. The effects of a number of independent parameters, such as Stanton number, inlet gas temperature, and length-spacing ratio, are illustrated.

Experimental Investigation on the Effect of Longitudinal Aspect Ratio on Natural Convection in Inclined Channels Heated Below

2006 ◽  
Author(s):  
Assunta Andreozzi ◽  
Bernardo Buonomo ◽  
Oronzio Manca ◽  
Sergio Nardini
Keyword(s):  
Heat Flux ◽  
Experimental Investigation ◽  
Natural Convection ◽  
Flow Visualization ◽  
Inclination Angle ◽  
Flow Separation ◽  
Heated Wall ◽  
Uniform Heat Flux ◽  
Heated Plate ◽  
Inclined Channels

In this paper an experimental investigation on natural convection in air in inclined channels with rectangular transversal section and lower wall heated at uniform heat flux is carried out. Wall temperature measurements and flow visualization are presented. The results allow investigating on the effect of the distance between the two principal parallel walls and of the inclination angle. The experiments are accomplished for two channel gap values: 20 and 40 mm. The inclination angle is equal to 80° and 88°. The flow development and the shape of flow transitions along the channel are visualized. Flow visualization allows to describe the secondary motion inside an inclined channel. Flow separation region along the lower heated plate begins at lower axial coordinate as the wall heat flux, the inclination angle and the channel gap are greater. The flow separation depends also on transversal coordinate. The detected secondary structures pass from thermals to plumes and vortices. Along the plane parallel to the heated wall, the visualization shows that thermal plumes split in V-shaped structures. For the largest considered channel gap value the instability phenomena in the channel are stronger and chaotic motion in the channel outlet zone is observed. When the channel gap value increases wall temperatures become lower because the higher distance between the walls determines a greater mass flow rate and an increase in the heat transfer.

The Experimental Study on Magnetic Fluid Flat Plate Heat Pipe as Thermal Spreaders

2009 ◽  
Author(s):  
Ming Zhang ◽  
Zhongliang Liu ◽  
Chen Wang
Keyword(s):  
Experimental Study ◽  
Heat Flux ◽  
Flat Plate ◽  
Heat Pipe ◽  
Magnetic Fluid ◽  
Working Fluid ◽  
Uniform Heat Flux ◽  
Plate Heat ◽  
Evaporation And Condensation ◽  
Flat Plate Heat Pipe

An effective thermal spreader can achieve uniform heat flux distribution and thus enhance heat dissipation of heat sinks. Flat plate heat pipe is one of the highly effective thermal spreaders. Magnetic fluid is a special fluid that can be made flow by traveling force of magnetic field. Therefore, the magnetic fluid is suitable for using as the working fluid of flat plate heat pipes that have a very small gap between evaporation and condensation surfaces. In this paper, we prepared a disk-shaped wickless flat plate heat pipe, and the distance between evaporation and condensation surfaces is 1 mm. From experimental study, the effects of heat flux and working fluid ratio on the performance of the flat plate heat pipe are obtained and the working performance of the magnetic fluid is compared with that of the water flat pate heat pipe of the same geometry structure.

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