Temperature distribution in beech wood during vacuum drying

2021 ◽  
Vol 116 ◽  
pp. 111-122
Author(s):  
Ewa Dobrowolska ◽  
Andrzej Klimczak
Keyword(s):  
Temperature Distribution ◽  
Beech Wood ◽  
Absolute Pressure ◽  
Vacuum Drying ◽  
Wood Moisture ◽  
Wood Structures ◽  
Anatomical Structures ◽  
Direct Measurements ◽  
Subsurface Layers ◽  
Drying Rates

Temperature distribution in beech wood during vacuum drying. The temperature distribution and changes in humidity in beech wood in the form of friezes during drying in a vacuum were analysed. The intensity of the occurring phenomena of desorption and the volumetric flow of moisture through the anatomical structures of the wood, depending on the absolute pressure and the temperature of the process, was determined. It was found that the fastest temperature increase took place in the subsurface layers directly adjacent to the heating plates. The introduction of conditioning between the drying phases made it possible to even out the humidity and temperature distribution in the entire element. On the basis of the analysis of changes taking place between the volumes of the three components of wood, it was found that the volume of moisture in the form of vapor removed in the initial phase of drying is over 20 times greater than the volume of voids in wood structures, and in the following phases it decreases to 0.27. The average volume of vapour removed from 1 m3 of wood at the temperature of 55℃ is 13.9 m3/h, decreasing in the following phases to 9.1 m3/h at the drying temperature of 60℃ and then 3.1 m3/h at the temperature of 65℃. The drying rates for these phases reach the value of 0.15%/h, 0.17%/h and 0.075%/h, respectively. Direct measurements of wood moisture, made during the experimental course of the drying process at an absolute pressure of 150 hPa, follow the equivalent moisture, determined on the basis of the Hailwood-Horrobin model, taking into account the appropriate calculation factors.

Dry Characteristics and Kinetics of Explosion Puffing Dried Crispy Winter Jujube at Different Vacuum Drying Temperature

2011 ◽  
Vol 236-238 ◽  
pp. 2505-2509
Author(s):  
Xin Yi He ◽  
Jin Fu Liu ◽  
Li Li Cheng ◽  
Bu Jiang Wang
Keyword(s):  
Moisture Diffusivity ◽  
Percentage Error ◽  
Vacuum Drying ◽  
Drying Temperature ◽  
Thin Layer Drying ◽  
Relative Percentage Error ◽  
Drying Rates ◽  
Predicted Values ◽  
Drying Curves

Drying characteristics of crispy winter jujube dried by explosion puffing drying at different vacuum drying temperature were investigated. Selection of the best model was examined by comparing the determination of coefficient (R2), root means square error (RMSE), and mean relative percentage error (P) between the experimental and predicted values. As expected, higher drying rates were obtained with higher vacuum drying temperature. The results showed that the Modified Henderson and Pabis model provided better simulation of drying curves for crispy winter jujube according to thin-layer drying theory. The effective moisture diffusivity of crispy winter jujube dried by explosion puffing drying with higher vacuum drying temperature was higher than the others.

Dehydration and Rehydration of Cooked Mussels

2016 ◽  
Vol 12 (2) ◽  
pp. 173-180 ◽  
Author(s):  
G. Tribuzi ◽  
J. B. Laurindo
Keyword(s):  
Freeze Drying ◽  
Continuous Monitoring ◽  
Vacuum Drying ◽  
Drying Methods ◽  
Processing Temperature ◽  
Sample Weight ◽  
Freeze Dried ◽  
Drying Rates ◽  
Drying Curves ◽  
Water Holding

Abstract The objective of this study was to investigate different drying methods (oven-drying, vacuum-drying, and freeze-drying) applied to cooked mussels meat and the resulting rehydration and water-holding capacity. Drying curves were obtained using an online weighting system that allows continuous monitoring of sample weight during processing. The influence of the processing temperature on the drying rates and on the properties of dehydrated samples was assessed. In the studied conditions, freeze-drying presented higher drying rates and less structure alterations compared to the other drying methods investigated. The equilibrium rehydration capacity of oven-dried and vacuum-dried mussels was about 37 % lower than rehydration capacity of freeze-dried samples for the rehydration performed at 20 °C and about 21 % lower for rehydration performed at 80 °C.

Mapping of temperature distribution in pharmaceutical microwave vacuum drying

2006 ◽  
Vol 162 (2) ◽  
pp. 133-137 ◽  
Author(s):  
Á. Kelen ◽  
S. Ress ◽  
T. Nagy ◽  
E. Pallai ◽  
K. Pintye-Hódi
Keyword(s):  
Temperature Distribution ◽  
Vacuum Drying ◽  
Microwave Vacuum Drying

scholarly journals Alkylimidazolium Ionic Liquids Absorption and Diffusion in Wood

2021 ◽  
Vol 11 (16) ◽  
pp. 7640
Author(s):  
Catalin Croitoru ◽  
Ionut Claudiu Roata
Keyword(s):  
Surface Tension ◽  
Ionic Liquids ◽  
Diffusion Coefficients ◽  
Beech Wood ◽  
Bulk Diffusion ◽  
Longitudinal Direction ◽  
Wood Structures ◽  
Sorption Ability ◽  
Penetration Ability ◽  
Good Penetration

Ionic liquids represent a class of highly tunable organic compounds responsible for many applications in the domain of wood-based materials. It has often been emphasized that the use of ionic liquids derives from their high affinity for lignocellulose and their good penetration ability into wood structures. This paper discusses the sorption ability of different types of 1-alkyl-3-methylimidazolium ionic liquids with lateral alkyl chains, ranging from ethyl to hexyl into spruce and beech wood, as a function of their cation molecular mass, anion type (chloride, tetrafluoroborate, acetate), and intrinsic properties (surface tension and kinematic viscosity) at room temperature. All the studied ionic liquids present high relative uptake values at the equilibrium, ranging from 11.2% to 69.7%. The bulk diffusion coefficients of the ionic liquids into the wood range from 2 × 10−3 to 28 × 10−3 mm2/min, being higher in the longitudinal direction for both types of wood. The value of the diffusion coefficients for 1-ethyl-3-methylimidazolium chloride is only 25% lower than that for water, despite the obvious differences in viscosity and surface tension, demonstrating a good penetration ability and the potential for wood industry-related applications (as impregnation compound carriers and preservatives).

scholarly journals Chimneys’ influence on fire risk of solid wood structures in residential buildings in rural Balkan settlements

2020 ◽  
pp. 138-138
Author(s):  
Mirjana Laban ◽  
Meri Cvetkovska ◽  
Ana Trombeva-Gavriloska ◽  
Suzana Draganic ◽  
Marijana Lazarevska ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Cross Sections ◽  
Residential Buildings ◽  
Fire Risk ◽  
Solid Wood ◽  
Rural Settlements ◽  
Mountain Areas ◽  
Wood Structures ◽  
The Cross ◽  
Analyse Data

According to official fire statistics, chimney fires account for almost 20% of all fires that occur in family residential buildings every year in the Balkan region. The high temperature from the chimneys may have an influence on fire spreading to the wooden girders. The objective of the study was to gather and analyse data on timber structure fire incidents occurring in family residential buildings in lowland rural settlements in Serbia (2010-2014) and a mountain settlement in Montenegro (2007-2013) in order to determine the extent to which existing data can be used in fire risk assessment. Additionally, the chimney - timber floor heat transfer mechanism was investigated, namely, the time dependent temperature distribution in the cross section of few types of mostly used chimneys and floor structures were analysed. This research illustrates how the lack of chimney maintenance and social vulnerability of the settlements (aged rural population with low incomes, living in many cases alone in old houses in areas with limited access to distance heating systems or piped gas) could influence the fire risk in timber structures in rural lowland and mountain areas. It is shown that significant differences exist with respect to fire causation over time and the type of wooden structural elements - due to different temperature distribution in the cross sections of the floor structure, both in lowland and mountain settlements.

scholarly journals Paraboloid-Based Spouted Bed Drying of Paddy: Aerodynamics, Temperature Distribution, and Moisture Degradation

2019 ◽  
Vol 1 (2) ◽  
pp. 257-264
Author(s):  
Duygu Evin
Keyword(s):  
Temperature Distribution ◽  
Moisture Content ◽  
Draft Tube ◽  
Initial Moisture Content ◽  
Spouted Bed ◽  
Drying Time ◽  
Pressure Drops ◽  
Rate Period ◽  
Drying Rates ◽  
Draft Tubes

Aerodynamics, temperature variations in the annulus, and the moisture reduction of paddy in a paraboloid-based spouted bed (PBSB) dryer without draft tube and with solid and porous draft tubes were investigated. Draft tube caused a rapid decrease in the peak pressure drop and minimum spouting velocity when compared with PBSB without a draft tube. Pressure drops with draft tubes were 17 to 30% of the values for the PBSB without a draft tube. Temperature distribution along the bed height in the annular region during drying of paddy was also investigated. Heat-up in the spouted bed without draft tube was more rapid. The experiments were conducted for 70, 90, and 110 °C inlet air temperatures. The required length of drying time to dry the paddy with an initial moisture content of 0.35 db to a moisture content below 0.15 db could be reduced by 50–60% using a temperature of 110 °C instead of 70 °C. No constant rate period was observed. Drying took place in the falling rate period. Drying time decreased in the case of porous draft tube rather than the solid one. The highest drying rates were achieved by spouted bed without draft tube. Drying rates were in the range of 0.62–0.1, 0.51–0.06, and 0.37–0.06 (db.min−1) for the spouted bed without draft tube, with porous, and solid draft tubes, respectively.

Prediction of Strength and Elasticity in Oak Beams on the Basis of External Wood Characteristics

2013 ◽  
Vol 778 ◽  
pp. 152-158 ◽  
Author(s):  
Guillermo Riesco Muñoz ◽  
Andrés Remacha Gete
Keyword(s):  
Quercus Robur ◽  
Ring Width ◽  
Axial Direction ◽  
Modulus Of Rupture ◽  
Wood Moisture ◽  
Wood Structures ◽  
Strength Performance ◽  
Wide Range ◽  
Wood Beams ◽  
Northwestern Spain

The purpose of the study was to search external features of timber useful for predicting modulus of rupture (MOR) and modulus of elasticity (MOE), both in axial direction bending, valid for a wide range of beam qualities. For the study, 23 European oaks (Quercus robur L.) were felled in northwestern Spain, where most of the oak stands in the country are located. The trees were sawn and a sample of quarter-sawn planks was selected. Planed and edged specimens (5×10×200 cm) were tested to obtain MOR, MOE, apparent density, wood moisture content, percentage of sapwood, ring width, slope of grain and size and position (faces, upper and lower edge, heads) of external defects. The MOR was correlated with the maximum face and edge knot diameter. However, the correlations were not high enough to justify construction of a predictive model of mechanical behavior on the basis of maximum knot size in the piece. The MOE was correlated with the size of knots and wane. Presence of sapwood did not exhibit significant influence on strength performance. Homogeneity in ring width was negatively related to MOR and mainly to MOE. Subject headings: Bending; Mechanical properties; Stiffness; Wood beams; Wood structures.

Sign in / Sign up

Export Citation Format

Share Document