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.

Measured temperature and moisture profiles during thermal modification of beech (Fagus sylvatica L.) and spruce (Picea abies L. Karst.) wood

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 175-183 ◽  
Author(s):  
Petr Čermák ◽  
Petr Horáček ◽  
Peter Rademacher
Keyword(s):  
Picea Abies ◽  
Fagus Sylvatica ◽  
Soret Effect ◽  
Exothermic Reaction ◽  
Longitudinal Direction ◽  
Thermal Modification ◽  
Measured Temperature ◽  
Moisture Movement ◽  
Chamber Temperature ◽  
Moisture Profiles

Abstract The temperature and moisture profiles during thermal modification of beech (Fagus sylvatica L.) and spruce (Picea abies L. Karst.) wood have been investigated. Specimens with dimensions of 80×80×200 mm3 were heat treated based on ThermoWood technology. Heat transfer was continuously measured by several thermocouples placed into various positions of the samples. In the course of the treatment, samples were removed from the chamber at different times, and their moisture content (MC) was measured by the so-called slicing technique. The complete data of heat and moisture movement during the heat treatment process are presented. Significant temperature gradients occur in the initial and modification stages of the process. In the latter, the chamber temperature was 200°C for 3 h, but exothermic reaction increased the sample temperatures to 240°C (beech) and 215°C (spruce). Thermodiffusion (Soret effect) at the beginning of the process was observed. Therefore, the MC under surfaces (in transverse and in longitudinal direction) was increasing ∼0.5%–3% for 5 h. The results provide a better insight into details of thermal modification of wood.

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.

An Investigation of Thermal Stratification in Horizontal Storage Tanks

1981 ◽  
Vol 103 (4) ◽  
pp. 286-290 ◽  
Author(s):  
M. F. Young ◽  
J. W. Baughn
Keyword(s):  
Thermal Stratification ◽  
Present Model ◽  
Temperature Gradients ◽  
Measured Temperature ◽  
Vertical Temperature ◽  
Makeup Water ◽  
One Dimensional ◽  
Test Conditions ◽  
Axial Temperature ◽  
Horizontal Tank

The thermal behavior of a horizontal storage tank has been investigated numerically and experimentally. The purpose of the present work is to compare a simple, one-dimensional model to the measured temperature stratification in this horizontal tank. For the test conditions used in these experiments, axial temperature gradients were found to be negligible compared to vertical temperature gradients. It was observed that significant mixing of the tank occurred when water was removed unless a diffuser manifold was placed on the makeup water inlet. The numerical model used was one-dimensional (vertical) with some degree of mixing at the inlet and outlet boundaries. The temperatures at the top of the tank were predicted fairly well, but the temperatures at the bottom deviated somewhat from the predictions. It appears that some additional interior mixing, not included in the present model, occurs.

SOIL MOISTURE MOVEMENT UNDER TEMPERATURE GRADIENTS

1973 ◽  
Vol 53 (1) ◽  
pp. 49-57 ◽  
Author(s):  
W. D. JOSHUA ◽  
E. DE JONG
Keyword(s):  
Sandy Loam ◽  
Moisture Flux ◽  
Irreversible Thermodynamics ◽  
Temperature Gradients ◽  
Soil Columns ◽  
Moisture Movement ◽  
Moisture Flow ◽  
Tension Distribution ◽  
Heat And Moisture ◽  
Heat And Moisture Flow

Temperature gradients of 0.5, 1.0, and 1.5 degree C/cm were imposed on sealed soil columns of a fine sandy loam at various moisture contents. When steady state was reached, heat flux, temperature distribution, and moisture content or moisture tension distribution were measured. The coupling between heat and moisture flux was calculated using the theory of irreversible thermodynamics. The coupling between heat and moisture flux was negligible for tensions less than 0.1 bar or higher than 15 bars. Coupling increased as the temperature increased. Within experimental error, Onsager's relation for the interaction between heat and moisture flow was valid. The agreement between the thermodynamic approach and the "series-parallel" theory was satisfactory between 0.3- and 15-bar tension. At tensions above 15 bars or below 0.1 bar, the series-parallel theory predicted more interaction between heat and moisture flow than was observed. It was concluded that the coupling between heat and moisture flow was significant only when the moisture flow occurred in the liquid phase and when soil–water interaction was pronounced.

scholarly journals Influence of rootstock on the quality of sweet cherry fruits in the conditions of the Lower Volga region

2021 ◽  
Vol 845 (1) ◽  
pp. 012063
Author(s):  
OA Nikolskay ◽  
A V Solonkin ◽  
E N Kikteva
Keyword(s):  
Sweet Cherry ◽  
Climatic Conditions ◽  
Lower Volga Region ◽  
One Dimensional ◽  
Qualitative And Quantitative ◽  
Volgograd Region ◽  
Heat And Moisture ◽  
Quantitative Indicators ◽  
Fruit Plantations

Abstract Sweet cherry is a thermophilic and whimsical crop that reacts painfully to unfavorable meteorological conditions, such as frost, drought or high humidity in the air and soil. At the same time, this crop requires a uniform supply of heat and moisture during the growing season. In the climatic conditions of the Volgograd region, stressful situations often arise that can partially or completely reduce the yield of fruit crops, especially those introduced to our region from other regions. To reduce the risk of losing the yield of fruit plantations, including sweet cherry, it is necessary to pay special attention to the choice of the variety, as well as the rootstock on which this variety is grafted. The publication presents the results of studying the influence of rootstocks on the qualitative and quantitative indicators of sweet cherry fruits, such as taste, weight, uniformity, color, and productivity. According to the results of the study in the field (in the garden), varietal-rootstock combinations were identified that have one-dimensional, crack-resistant, large fruits, while maintaining high and stable productivity. According to the results of research, it was found that the rootstock affects not only the strength of growth and the shape of the crown, but also the quality of the fruit. The most dependent of the studied varieties on the type of rootstock is Euphoria, the lowest weight of berries was observed on the rootstock VSL-1. At the same time, this rootstock has a higher percentage of resistance to cracking of the fruit. Based on the conducted research, it can be concluded that with the help of rootstock, it becomes possible to influence the quality indicators of fruits.

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