Development and Validation of Mathematical Model for Tailrace Tunnel Ventilating Process in Hydropower Station

2011 ◽  
Vol 71-78 ◽  
pp. 4069-4073
Author(s):  
Yan Shun Yu ◽  
Pu Hua Qian ◽  
Shao Fan Zhang
Keyword(s):  
Mathematical Model ◽  
Moisture Transfer ◽  
Water Vapor Pressure ◽  
Three Dimensional ◽  
Hydropower Station ◽  
Tunnel Wall ◽  
Cold Source ◽  
Thermodynamic Conditions ◽  
Tailrace Tunnel ◽  
Heat And Moisture

When outdoor air flowing through the tailrace tunnel, it will be handled and its thermodynamic conditions will change under the differences of temperature and water vapor pressure between air and water surface, air and tunnel wall. Utilizing the handled air for space cooling in hydropower station is an energy saving, environmental protection and renewable application of natural cold source. In this paper, a detailed quasi-three-dimensional mathematical model of heat and moisture transfer of tailrace tunnel ventilating was developed and validated against the field test data from Yingxiuwan hydropower station, and the validation shows that the model predicts the test results very well. The model can be used to predict the heat and moisture performance of tailrace tunnel ventilating system.

A comprehensive mathematical model of heat and moisture transfer for wood convective drying

Holzforschung ◽  
2017 ◽  
Vol 71 (5) ◽  
pp. 425-435 ◽  
Author(s):  
Jingyao Zhao ◽  
Yingchun Cai
Keyword(s):  
Mathematical Model ◽  
Fluid Flow ◽  
Moisture Transfer ◽  
Three Dimensional ◽  
Convective Drying ◽  
Heat And Moisture Transfer ◽  
Initial Stage ◽  
Heat And Moisture ◽  
Velocity Pressure ◽  
Current Circulation

Abstract The focus of this study is the development of a specific drying model for the design and operation of drying systems for stacked lumber in drying chambers. Namely, a comprehensive three-dimensional (3D) mathematical model of heat and moisture transfer in stacked wood has been developed, where the wood was subjected to convective drying that accounts for the effect of the surrounding fluid flow. In developing the model, the characteristics of wood and fluid flow, i.e. velocity, pressure, temperature, relative humidity (RH) and moisture content (MC) are described by the conservation equations of mass, momentum and energy as well as thermodynamic relations. The model presented was solved numerically by means of the commercial software COMSOL Multiphysics. The simulation results were validated against experimental data under laboratory conditions. Air current circulation was found to be non-uniform during drying, which accounts for the different rates of temperature and MC in wood. At the initial stage of drying, this difference was relatively large but reduced gradually with the drying process. Meanwhile, the transient gathered phenomenon related to humidity around the stacked wood in the chamber was observed in response to air current circulation and evaporation rate of moisture. Finally, sources of error incurred in numerical calculations and actual detection were identified and discussed.

Mathematical Models of Papermaking

2001 ◽  
Vol 6 (1) ◽  
pp. 9-19 ◽  
Author(s):  
A. Buikis ◽  
J. Cepitis ◽  
H. Kalis ◽  
A. Reinfelds ◽  
A. Ancitis ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Initial Value Problems ◽  
Moisture Transfer ◽  
Bound Water ◽  
Drying Process ◽  
Initial Value ◽  
First Order ◽  
Heat And Moisture ◽  
The Mathematical Model ◽  
The Web

The mathematical model of wood drying based on detailed transport phenomena considering both heat and moisture transfer have been offered in article. The adjustment of this model to the drying process of papermaking is carried out for the range of moisture content corresponding to the period of drying in which vapour movement and bound water diffusion in the web are possible. By averaging as the desired models are obtained sequence of the initial value problems for systems of two nonlinear first order ordinary differential equations. 

scholarly journals Numerical Network Modeling of Heat and Moisture Transfer through Capillary-Porous Building Materials

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1819
Author(s):  
Borys Basok ◽  
Borys Davydenko ◽  
Anatoliy M. Pavlenko
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
Three Dimensional ◽  
Total Pore Volume ◽  
Equivalent Diameter ◽  
Average Pore ◽  
The Difference ◽  
Three Dimensional Coordinate ◽  
Solid Liquid ◽  
Heat And Moisture

The article presents the modeling of the dynamics of the vapor-gas mixture and heat and mass transfer (sorption-desorption) in the capillary structure of the porous medium. This approach is underpinned by the fact that the porous structure is represented by a system of linear microchannels oriented along the axes of a three-dimensional coordinate system. The equivalent diameter of these channels corresponds to the average pore diameter, and the ratio of the total pore volume to the volume of the entire porous material corresponds to its porosity. The entire channel area is modeled by a set of cubic elements with a certain humidity, moisture content, pressure and temperature. A simulation is carried out taking into account the difference in temperatures of each of the phases: solid, liquid and gas.

scholarly journals Strain-Stress Formation and Deformation of Molded Materials by Drying-Induced Shrinkage

2018 ◽  
Vol 248 ◽  
pp. 01011
Author(s):  
Yoshinori Itaya
Keyword(s):  
Mass Transfer ◽  
Moisture Transfer ◽  
Three Dimensional ◽  
Internal Strain ◽  
Stress Generation ◽  
Heat And Moisture Transfer ◽  
Internal Heating ◽  
Strain Stress ◽  
Stress Formation ◽  
Heat And Moisture

Drying-induced strain-stress and deformation was modeled for molded materials such as ceramics and foods. The transient three-dimensional problem of strain-stress and heat and moisture transfer was solved simultaneously by the finite element method. The behaviors of internal strain-stress formation and deformation are compared among three modes of hot air heating, intermittent heating and internal heating for a ceramic slab. The concepts of the mass transfer potential and a linear viscoelasticity were introduced to consider the different sorption isotherm for layered foods consisting of two ingredients and creep phenomenon. The tensile and compressive stresses fluctuate and fall remarkably during lower heating period when the slab is heated intermittently. In the internal heating mode, drying proceeds fastest as well as stress formation is maintained at the lowest level in the three modes. This effectiveness of the internal heating is investigated experimentally by employing the microwave heating as well. The combination of different foods influences significantly not only the drying characteristic but also the internal strain-stress generation. The drying behavior could be analyzed with a high accuracy even if only heat and moisture transfer were solved without strain-stress analysis. This fact results in that heat and mass transfer and strain-stress are not always necessary to be analyzed simultaneously for saving the CPU time.

A Numerical and Experimental Study of Heat and Moisture Transfer With Phase Change and Mobile Condensates in Fibrous Insulation

2003 ◽  
Author(s):  
Jintu Fan ◽  
Xiaoyin Cheng
Keyword(s):  
Phase Change ◽  
Moisture Absorption ◽  
Moisture Transfer ◽  
Water Vapor Pressure ◽  
Heat And Moisture Transfer ◽  
Moisture Movement ◽  
Saturation State ◽  
New Model ◽  
Fibrous Insulation ◽  
Heat And Moisture

This paper reports on an improved model of coupled heat and moisture transfer with phase change and mobile condensates in fibrous insulation. The new model considered the moisture movement induced by the partial water vapor pressure, a super saturation state in condensing region as well as the dynamic moisture absorption of fibrous materials and the movement of liquid condensates. The results of the new model were compared and found in good agreement with the experimental ones. Numerical simulation was carried using the model to investigate the effect of various material parameters on the transport phenomena.

Heat and moisture transfer from skin to environment through fabrics: A mathematical model

2007 ◽  
Vol 50 (25-26) ◽  
pp. 5292-5304 ◽  
Author(s):  
Kyunghoon Min ◽  
Yangsoo Son ◽  
Chongyoup Kim ◽  
Yejin Lee ◽  
Kyunghi Hong
Keyword(s):  
Mathematical Model ◽  
Moisture Transfer ◽  
Heat And Moisture Transfer ◽  
Heat And Moisture
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