Heat and moisture movement and explosive spalling in concrete under fire environment

2010 ◽  
pp. 536-541
Keyword(s):  
Explosive Spalling ◽  
Moisture Movement ◽  
Fire Environment ◽  
Heat And Moisture

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.

Modelling the in Situ Performance of Bentonite-Sand Buffer

1989 ◽  
Vol 176 ◽  
Author(s):  
H.S. Radhakrishna ◽  
K.-C Lau ◽  
B.H. Kjartanson ◽  
S.C.H. Cheung
Keyword(s):  
Boundary Conditions ◽  
Moisture Transport ◽  
Moisture Diffusivity ◽  
Moisture Movement ◽  
Waste Container ◽  
Buffer Material ◽  
Heat And Moisture Transport ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

ABSTRACTIn the Canadian nuclear fuel waste management concept, a number of engineered barriers, such as the bentonite-sand buffer which surrounds the waste container in the emplacement boreholes, are used to inhibit the transport of radionuclides. The buffer material is also required to effectively conduct heat from the fuel-waste containers to the surrounding rock. To a large extent, in situ buffer performance will depend on the degree of moisture within the buffer. The moisture content will in turn depend on temperature, temperature gradients, and buffer initial and moisture flux boundary conditions. Modelling of coupled heat and moisture transport in the buffer before resaturation is necessary to assess in situ buffer performance. This paper describes the results of a parametric study using the Philip and de Vries coupled heat and moisture transport model to assess the effects of variations in the moisture diffusivity parameters and the boundary conditions on buffer performance.The results show that the thermal performance of the buffer is affected by heat-induced moisture movement. In particular, the thermal vapour diffusivity, DTvap, has the most significant effect on thermal drying in a closed system. Work is currently underway to improve our capability to model coupled heat and moisture transport in buffer. Laboratory experiments are in progress to more accurately define the moisture diffusivity parameters and the model is being modified to include the effects of boundary moisture fluxes and pressure potentials so that the resaturation process may be modelled. A full scale buffer/container experiment is currently being planned for conduct in AECL's Underground Research Laboratory to assess further the effects of scale and in situ boundary conditions on buffer performance and to qualify the model.

Temperature and Moisture Distributions in a Clay Buffer Material Due to Thermal Gradients

1992 ◽  
Vol 294 ◽  
Author(s):  
A.M.O. Mohamed ◽  
R.N. Yong ◽  
B. Kjartanson
Keyword(s):  
Temperature Gradients ◽  
Thermal Gradients ◽  
Measured Temperature ◽  
Moisture Movement ◽  
Equilibrium Time ◽  
One Dimensional ◽  
Diffusion Parameters ◽  
Buffer Material ◽  
Heat And Moisture ◽  
Moisture Profiles

ABSTRACTSeveral series of one-dimensional tests were used to investigate the nature of transient heat and moisture movements in a clay buffer under different imposed temperature gradients. The measured temperature and moisture profiles were used to calculate the diffusion parameters governing heat and moisture movement in the buffer material. The diffusion parameters are shown to depend on the moisture content, temperature and moisture equilibrium time.

Experimental Determination of Parameters Governing Heat-Induced Moisture Movement in A Clay Buffer

1991 ◽  
Vol 257 ◽  
Author(s):  
A.P.S. Selvadurai
Keyword(s):  
Experimental Determination ◽  
Nuclear Waste ◽  
Experimental Evaluation ◽  
Thermal Parameters ◽  
Moisture Movement ◽  
Engineered Barrier ◽  
Coupled Heat And Moisture ◽  
Determination Of Parameters ◽  
Heat And Moisture

ABSTRACTThis paper discusses the experimental evaluation of the hygro-thermal parameters governing coupled heat and moisture movement within a moist clay buffer, which is developed as an engineered barrier for the isolation of heat emitting nuclear waste containers in either a borehole environment or in an in-room emplacement scheme.

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