scholarly journals Thermal effects due to air flow and vapor transport in dry snow

1992 ◽  
Vol 38 (129) ◽  
pp. 273-281 ◽  
Author(s):  
M. R. Albert ◽  
W. R. Mcgilvary
Keyword(s):  
Heat Conduction ◽  
Temperature Gradient ◽  
Flow Rate ◽  
Thermal Effects ◽  
Air Flow ◽  
Vapor Transport ◽  
Snow Sample ◽  
Dry Air ◽  
Flow Through

AbstractThe thermal effects of air flow forced through a snow sample are investigated numerically. A new method for calculating vapor transport in snow is presented which allows for the determination of the effects of sublimation. In this method, the snow is not assumed to be saturated with water vapor. Results of the model show very good agreement with analytical and experimental results. The effects of heat conduction, heat advected by the dry air and heat associated with sublimation are examined in a comprehensive theory, and then each effect is isolated to determine its overall contribution. It is demonstrated that the heat transfer associated with vapor transport is significant in the determination of the overall temperature profile of a ventilated snow sample but that the major effects are controlled by the heat carried by the dry air flow through the snow and heat conduction due to the temperatures imposed at the boundaries. The thermal effects of ventilation of snow are more likely to be observed when there is a smaller temperature gradient over the entire snowpack and a greater flow rate of air in the snow than would be observed when there is a greater overall temperature gradient and lesser air-flow rate.

scholarly journals Thermal effects due to air flow and vapor transport in dry snow

1992 ◽  
Vol 38 (129) ◽  
pp. 273-281 ◽  
Author(s):  
M. R. Albert ◽  
W. R. Mcgilvary
Keyword(s):  
Heat Conduction ◽  
Temperature Gradient ◽  
Flow Rate ◽  
Thermal Effects ◽  
Air Flow ◽  
Vapor Transport ◽  
Snow Sample ◽  
Dry Air ◽  
Flow Through

AbstractThe thermal effects of air flow forced through a snow sample are investigated numerically. A new method for calculating vapor transport in snow is presented which allows for the determination of the effects of sublimation. In this method, the snow is not assumed to be saturated with water vapor. Results of the model show very good agreement with analytical and experimental results. The effects of heat conduction, heat advected by the dry air and heat associated with sublimation are examined in a comprehensive theory, and then each effect is isolated to determine its overall contribution. It is demonstrated that the heat transfer associated with vapor transport is significant in the determination of the overall temperature profile of a ventilated snow sample but that the major effects are controlled by the heat carried by the dry air flow through the snow and heat conduction due to the temperatures imposed at the boundaries. The thermal effects of ventilation of snow are more likely to be observed when there is a smaller temperature gradient over the entire snowpack and a greater flow rate of air in the snow than would be observed when there is a greater overall temperature gradient and lesser air-flow rate.

Numerical Investigation on the Strategies for Reducing the Cell Temperature Gradient of an Indirect Internal Reforming Tubular SOFC

2004 ◽  
Author(s):  
Takafumi Nishino ◽  
Hiroshi Iwai ◽  
Kenjiro Suzuki
Keyword(s):  
Temperature Gradient ◽  
Distribution Pattern ◽  
Flow Rate ◽  
Air Flow ◽  
Maximum Temperature ◽  
Air Flow Rate ◽  
Internal Reforming ◽  
Average Temperature ◽  
Reforming Catalyst ◽  
Catalyst Distribution

Strategies to reduce the temperature gradient of the cell have been numerically examined by using a comprehensive analytical model of an indirect internal reforming tubular SOFC, the first generation of which was presented at the last conference in 2003 (1st ICFCSET). In particular, how the air flow rate, gas inlet temperature and density distribution of reforming catalyst affect the thermal field in the cell has been examined. Based on the calculated results, it has been confirmed that larger air flow rate reduces the maximum temperature and accordingly the temperature gradient of the cell, while lower inlet temperatures of gases reduce only the average temperature of the cell. For the reforming catalyst distribution, it has been determined that the temperature gradient of the cell can be fairly reduced by adjusting the amount and allocation of the catalyst. In addition, it has been revealed that the distribution pattern of the catalyst has little effect on the average temperature, so that the power generation performance of the cell is not affected by the adjustment of the catalyst distribution pattern substantially.

scholarly journals Jeffery-Hamel slip flow in a convergent microchannel with uniform wall temperature and streamwise heat conduction

2019 ◽  
Vol 286 ◽  
pp. 08010
Author(s):  
Mohammed Niagui ◽  
Youssef Haddout ◽  
Abdelaziz Oubarra ◽  
Jawad Lahjomri
Keyword(s):  
Heat Conduction ◽  
Analytical Solution ◽  
Slip Flow ◽  
Thermal Characteristics ◽  
Three Dimensions ◽  
Uniform Wall Temperature ◽  
Uniform Wall ◽  
Flow Through ◽  
Laminar Forced Convection

This work is devoted to the determination of the analytical solution of the problem of the laminar forced convection of the Jeffery-Hamel slip flow through a convergent microchannel. The analytical solution is obtained by using a self-adjoint formalism of the functional analysis. The solution represents an extension of the solution obtained in the conventional continuum flow by considering the boundaries slip conditions at the wall and the streamwise heat conduction. This extension has been done by using a new matrix operator of three dimensions in the Hilbert space. The results show that the thermal characteristics are strongly influenced by the Reynolds, Prandtl and Knudsen numbers, the aperture angle of the channel and the streamwise heat conduction.

scholarly journals Measurement and Determination of Friction Characteristic of Air Flow through Porous Media

Metals ◽  
2015 ◽  
Vol 5 (1) ◽  
pp. 336-349 ◽  
Author(s):  
Wei Zhong ◽  
Xin Li ◽  
Guoliang Tao ◽  
Toshiharu Kagawa
Keyword(s):  
Porous Media ◽  
Air Flow ◽  
Flow Through Porous Media ◽  
Friction Characteristic ◽  
Flow Through

Determination of optimal air flow rate in air drilling

1992 ◽  
Vol 8 (1) ◽  
pp. 1-11
Author(s):  
Michael A. Adewumi ◽  
Shifeng Tian
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Air Flow Rate ◽  
Air Drilling

scholarly journals Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers

2015 ◽  
Vol 47 (1) ◽  
pp. 69-85 ◽  
Author(s):  
Marek Kalenik
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Air Flow ◽  
Operating Conditions ◽  
Water Delivery ◽  
Air Flow Rate ◽  
Analysis Of Results ◽  
Delivery Pipe ◽  
Air Lift

Abstract: Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers. The paper presents the analysis of results of the investigations concerning the influence of various constructive solutions of the air-water mixers on hydraulic operating conditions of the air lift pump. The scope of the investigations encompassed the determination of characteristics of delivery head and delivery rate for three types of air-water mixers applied in the constructed air lift pump. Using the obtained results, the efficiency of the three types of air-water mixers applied in this air lift pump was determined. The analysis was carried out and there was checked whether the improved analytical Stenning-Martin model can be used to design air lift pumps with the air-water mixers of these types. The highest capacity in the water transport was reached by the air lift pump with the 1st type air-water mixer, the lowest one – with the 3rd type air-water mixer. The water flow in the air lift pump increases along with the rise in the air flow. The lower are the hydraulic losses generated during flow of the air flux by the air-water mixer, the higher is the air lift pump capacity. Along with the rise in the water delivery head, the capacity of the air lift pump decreases. The highest efficiency is reached by the air lift pump with the 1st type air-water mixer, the lowest – with the 3st type air-water mixer. The efficiency of the air lift pump for the three investigated types of air-water mixers decreases along with the rise in air flow rate and water delivery head. The values of submergence ratio (h/L) of the delivery pipe, calculated with the use of the improved analytical Stenning-Martin model, coincide quite well with the values of h/L determined from the measurements.

Standardized On-line Method to Quantify the Air Flow Rate for Determination of Emissions in a Broiler House

2005 ◽  
Author(s):  
R. Kosch ◽  
R. Neumeier ◽  
H. Arnold ◽  
A. Schwarz ◽  
H. Van den Weghe
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Air Flow Rate ◽  
Line Method ◽  
On Line ◽  
Broiler House

scholarly journals Aeration of the premises of the dairy cows keeping in the light weight design in the warm period of the year

2020 ◽  
pp. 45-47
Author(s):  
Darya Viktorovna Abramkina
Keyword(s):  
Dairy Cows ◽  
Flow Rate ◽  
Significant Contribution ◽  
Air Flow ◽  
Warm Period ◽  
Light Weight ◽  
Exchange Flow ◽  
Weight Design ◽  
Flow Through ◽  
Air Exchange

The purpose of the article is to conduct multivariate calculations of aeration in a building at dairy cows keeping in order to identify the most effective way of ensuring normal air exchange in the stall house. According to the results of studies, it was found out that the supply air flow through the external gate makes a significant contribution to the overall air exchange of the stall house. Keywords: aeration; cowshed; ventilation; air exchange; flow rate.

scholarly journals Fluid mechanical valving of air flow in bird lungs

1988 ◽  
Vol 136 (1) ◽  
pp. 1-12 ◽  
Author(s):  
D. O. Kuethe
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
Pressure Difference ◽  
Air Flow ◽  
Low Pressure ◽  
Physical Models ◽  
Unidirectional Flow ◽  
Air Sacs ◽  
Caudal Portion ◽  
Flow Through

The unidirectional flow through the gas-exchanging bronchi of bird lungs is known to be effected by (1) the structure of the major bronchi and (2) a pressure difference between the cranial and caudal air sacs. To study the effects of bronchial structure, simple physical models of bird lungs were constructed. They suggested that, to achieve unidirectional flow, air in the caudal portion of the primary bronchus must be directed towards the orifices of the mediodorsal bronchi. To study the effect of air sac pressures, a controllable pressure difference was produced between the air sac orifices of fixed duck lungs. The cranial orifices had a higher pressure than the caudal ones during inhalation and vice versa during exhalation. There was a set of pressure differences for which the paleopulmo received the same flow rate during inhalation as during exhalation. High pressure differences caused more flow in the paleopulmo during exhalation than during inhalation; low pressure differences had the converse effect.

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