scholarly journals Ventilation of window interpane cavity aimed at a higher temperature of the inner pane

2002 ◽  
Vol 6 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Mikhail Diomidov ◽  
Mikhail Nizovtsev ◽  
Viktor Terekhov
Keyword(s):  
Experimental Study ◽  
Heat Flux ◽  
Air Flow ◽  
Winter Season ◽  
Climatic Chamber ◽  
Flow Rates ◽  
Ventilated Cavity ◽  
Wide Range ◽  
Internal Cavities ◽  
Higher Temperature

An experimental study of the thermal performance of an air-flow window with triple glazing is described. The measurements were carried out in a climatic chamber under conditions close to a winter season. In the experiments, the temperature and heat-flux distributions on each pane surface, and also the air-temperature distribution over the window height at the middle of the ventilated cavity were determined. The thermal performances of forced and naturally ventilated windows with internal cavities of various thicknesses are reported for a wide range of air-flow rates.

scholarly journals Experimental Study of Forced- Convection from Horizontal Rectangular Fins Array into Air Duct

2019 ◽  
Vol 15 (1) ◽  
pp. 35-45
Author(s):  
Saad Najeeb Shehab
Keyword(s):  
Experimental Study ◽  
Heat Flux ◽  
Flow Velocity ◽  
Forced Convection ◽  
Surface Heat Flux ◽  
Rectangular Cross Section ◽  
Air Flow ◽  
Surface Heat ◽  
Wide Range ◽  
Air Flow Velocity

    In this work, an experimental study has been done to expect the heat characteristics and performance of the forced-convection from a heated horizontal rectangular fins array to air inside a rectangular cross-section duct. Three several configurations of rectangular fins array have been employed. One configuration without notches and perforations (solid) and two configurations with combination of rectangular-notches and circular-perforations for two various area removal percentages from fins namely 18% notches-9% perforations and 9% notches-18% perforations are utilized.  The rectangular fins dimensions and fins number are kept constant. The fins array is heated electrically from the base plate with five different magnitudes of power-inputs. Five several air flow velocity into a duct are utilized. The influence of fin geometry, air flow velocity, Reynolds number and the surface heat flux on the heat-performance of forced heat convection have been simulated and studied experimentally. The experimental data indicates that the combination of 18% rectangular-notched and 9% circular-perforated rectangular fins array gave best forced heat performance in terms of average heat transfer coefficient about (25% - 45%) and (7% - 20%) compared than solid and 9% notches with18% perforations fins array respectively. Five empirical correlations to predict the average Nusselt number for the 18% notches with 9% perforations rectangular fins array at wide range of surface heat flux are deduced. The present data are compared with previous works and a good closeness in behavior is noticed.

Nitrogen Removal from Anaerobically-Treated Leachate

1984 ◽  
Vol 19 (1) ◽  
pp. 87-100
Author(s):  
D. Prasad ◽  
J.G. Henry ◽  
P. Elefsiniotis
Keyword(s):  
Nitrogen Removal ◽  
Air Flow ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Flow Rates ◽  
Anaerobic Filter ◽  
Ph Values ◽  
Wide Range ◽  
Ammonia Desorption ◽  
Effects Of Ph

Abstract Laboratory studies were conducted to demonstrate the effectiveness of diffused aeration for the removal of ammonia from the effluent of an anaerobic filter treating leachate. The effects of pH, temperature and air flow on the process were studied. The coefficient of desorption of ammonia, KD for the anaerobic filter effluent (TKN 75 mg/L with NH3-N 88%) was determined at pH values of 9, 10 and 11, temperatures of 10, 15, 20, 30 and 35°C, and air flow rates of 50, 120, and 190 cm3/sec/L. Results indicated that nitrogen removal from the effluent of anaerobic filters by ammonia desorption was feasible. Removals exceeding 90% were obtained with 8 hours aeration at pH of 10, a temperature of 20°C, and an air flow rate of 190 cm3/sec/L. Ammonia desorption coefficients, KD, determined at other temperatures and air flow rates can be used to predict ammonia removals under a wide range of operating conditions.

Evaluation of Boiling Expectation Time in Falling Wavy Liquid Films on Nonsteady Heat Release

2013 ◽  
Vol 8 (3) ◽  
pp. 71-81
Author(s):  
Andrey Chernyavskiy ◽  
Aleksandr Pavlenko
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Flux Density ◽  
Heat Flux Density ◽  
Reynolds Numbers ◽  
Liquid Films ◽  
Time Dependency ◽  
Flow Rates ◽  
Nonsteady Heat ◽  
Wide Range

Mathematical model which allows to calculate the boiling expectation times in falling wavy liquid films on nonsteady heat release has been developed. The process of wave formation in the falling films of liquid nitrogen has been simulated numerically for different inlet Reynolds numbers. The calculation of boiling expectation time dependency on heat flux density and heater surface inertia rate in conditions of fast heat growing has been done. The satisfactory agreement of numerical simulation results with experimental data in the wide range of heat flux density and different flow rates has been shown

Experimental Study of Low Concentration Sand Transport in Multiphase Air–Water Horizontal Pipelines

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Kamyar Najmi ◽  
Alan L. Hill ◽  
Brenton S. McLaury ◽  
Siamack A. Shirazi ◽  
Selen Cremaschi
Keyword(s):  
Experimental Study ◽  
Gas Flow ◽  
Intermittent Flow ◽  
Sand Transport ◽  
Physical Parameters ◽  
Internal Diameter ◽  
Flow Rates ◽  
Minimum Flow ◽  
Wide Range ◽  
Sand Size

The ultimate goal of this work is to determine the minimum flow rates necessary for effective transport of sand in a pipeline carrying multiphase flow. In order to achieve this goal, an experimental study is performed in a horizontal pipeline using water and air as carrier fluids. In this study, successful transport of sand is defined as the minimum flow rates of water and air at which all sand grains continue to move along in the pipe. The obtained data cover a wide range of liquid and gas flow rates including stratified and intermittent flow regimes. The effect of physical parameters such as sand size, sand shape, and sand concentration is experimentally investigated in 0.05 and 0.1 m internal diameter pipes. The comparisons of the obtained data with previous studies show good agreement. It is concluded that the minimum flow rates required to continuously move the sand increases with increasing sand size in the range examined and particle shape does not significantly affect sand transport. Additionally, the data show the minimum required flow rates increase by increasing sand concentration for the low concentrations considered, and this effect should be taken into account in the modeling of multiphase sand transport.

scholarly journals Impact of radiation on hygrothermal behavior of ventilated cavity wall

2019 ◽  
Vol 282 ◽  
pp. 02014
Author(s):  
Thibaut Colinart ◽  
Mathieu Bendouma ◽  
Patrick Glouannec
Keyword(s):  
Experimental Study ◽  
Heat Flux ◽  
Moisture Transfer ◽  
Measured Data ◽  
Transfer Model ◽  
Hygrothermal Behavior ◽  
Ventilated Cavity ◽  
Oceanic Climate ◽  
Ventilated Facade ◽  
Heat And Moisture

This work deals with the performance of a high school building renovated with prefabricated ventilated façade elements through a field experimental study under oceanic climate. Temperature, relative humidity and heat flux were measured at different points of the renovated façade and are analyzed as function of the exterior boundary conditions. The measured data are compared to numerical results. For this purpose, two models are considered: an energy balance is made for the cladding, while a heat and moisture transfer model is solved within the insulation materials. In this study, particular attention is paid in the influence of the radiative exchanges in short and long wavelengths on the hygrothermal behavior of the retrofitted wall.

A Numerical Investigation of Turbulent Non-Premixed Nozzle-Mixed Industrial Burner

2002 ◽  
Author(s):  
Per Stralin ◽  
Achintya Mukhopadhyay ◽  
Ishwar K. Puri
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Velocity Ratio ◽  
Flame Stabilization ◽  
Flame Height ◽  
Flow Rates ◽  
Fuel Ratio ◽  
Fuel Flow ◽  
Annular Jet ◽  
Wide Range

Nozzle-mix burners are widely used in heat treatment and non-ferrous melting furnaces, and other applications, where temperature uniformity is required. These burners are stable over a wide range of air-fuel ratios from very lean to rich (up to 50% of excess fuel), high turndown ratio and low NOX emissions at all air-fuel ratios. Here, the fuel is generally transported by a central jet and air through an annular jet. The separation between the fuel jet and the air annulus and confining wall are crucial for flame stabilization. The objective of the present work is to investigate the flow and flame characteristics of a nonpremixed nozzle-mix burner through a detailed parametric study. The inferences from this study will provide useful information for designers, regarding choice of parameters. The burner is modeled as an axisymmetric arrangement of fuel duct at the center, surrounded by a coaxial annular duct of air. The ducts discharge into a confined environment, formed by a chimney, placed coaxially with the ducts. The results of the numerical simulation show that for a given air-fuel ratio, as the fuel flow rate increased, the location of the flame base shifted from near the fuel nozzle towards the oxidizer nozzle. Similar shift in flame position was also observed for higher air velocities for a given fuel velocity. High fuel and air flow rates and small separation between fuel and air jets tend to destabilize the flame. For a given air-fuel ratio, flame height increased with increase in fuel flow rates, but the change became insignificant at higher flow rates. For a given fuel velocity, flame height decreased with increase in air flow rate for both buoyancy-controlled and momentum-controlled regimes. The air-to-fuel velocity ratio was found to be the most significant parameter in determining the flame height.

Flow Patterns and CHF in a Locally Heated Liquid Film Shear-Driven in a Minichannel

2010 ◽  
Author(s):  
D. V. Zaitsev ◽  
O. A. Kabov
Keyword(s):  
Heat Flux ◽  
Liquid Film ◽  
Gas Flow ◽  
Liquid Films ◽  
Vapor Flow ◽  
High Heat Flux ◽  
Film Rupture ◽  
Space Applications ◽  
Flow Rates ◽  
Wide Range

Thin and very thin (less than 10 μm) liquid films driven by a forced gas/vapor flow (stratified or annular flows), i.e. shear-driven liquid films in a narrow channel is a promising candidate for the thermal management of advanced semiconductor devices in earth and space applications. Development of such technology requires significant advances in fundamental research, since the stability of joint flow of locally heated liquid film and gas is a rather complex problem. The paper focuses on the recent progress that has been achieved by the authors through conducting experiments. Experiments with water in flat channels with height of H = 1.2–2.0 mm (mini-scale) show that a liquid film driven by the action of a gas flow is stable in a wide range of liquid/gas flow rates. Map of isothermal flow regime was plotted and the length of smooth region was measured. Even for sufficiently high gas flow rates an important thermocapillary effect on film dynamics occurs. Scenario of film rupture differs widely for different flow regimes. It is found that the critical heat flux for a shear driven film can be 10 times higher than that for a falling liquid film, and exceeds 400 W/cm2 in experiments with water for moderate liquid flow rates. This fact makes use of shear-driven liquid films promising in high heat flux chip cooling applications.

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