| 1. |
|
|
| 2. |
- Elustondo, Diego, et al.
(författare)
-
Drying with superheated steam : Maximum drying rate as a linear function of pressure
- 2002
-
Ingår i: Chemical Engineering Journal. - 1385-8947 .- 1873-3212. ; 86:1-2, s. 69-74
-
Tidskriftsartikel (refereegranskat)abstract
- Drying with superheated steam (SS) as heating agent is controlled through three operative variables, the steam temperature, the recycle velocity, and the system pressure. Once the other conditions are fixed, there is an optimum pressure at which drying rate reaches its maximum value. The exact optimum conditions can be found through a differential mass and energy balance over the heat exchange area, resulting in two equations. The first one to calculate the drying rate as function of the operating conditions and the second one to find the values of those conditions which make the operation optimum. Then, using these equations, this paper shows that the relationship between maximum drying rate and pressure can be rewritten in a unique linear equation. Experiments were performed in a model system to obtain a family of drying rates versus pressure curves, and in accordance with the predicted behaviour, it was observed that all maximum drying rates lay on a straight line
|
|
| 3. |
- Elustondo, Diego, et al.
(författare)
-
Mathematical modeling of moisture evaporation from foodstuffs exposed to subatmospheric pressure superheated steam
- 2001
-
Ingår i: Journal of Food Engineering. - 0260-8774 .- 1873-5770. ; 49:1, s. 15-24
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a reduced expression to calculate the drying rate of foodstuffs being dried with low pressure superheated steam is developed. It is based on a theoretical drying mechanism which assumes that water removal is carried out by evaporation in a moving boundary making the vapor to flow through the dry layer built as drying proceeds. The theoretical model can be applied to any form and features dimensionless parameters to allow for the influence of form, shrinking effect and boiling point rise. To make the application easier, a simplified expression was derived, which has only two experimentally determined parameters and allows the calculation of the drying rate of a given product. Different foodstuffs were dried with this technique and the empirical parameters were calculated from the experimental data fitting equation. Interestingly, those parameters can be considered constant within the 10000-20000 Pa pressure range and the 60-90°C temperature range
|
|
| 4. |
- Elustondo, Diego, et al.
(författare)
-
New thermal conductivity probe design based on the analysis of error sources
- 2001
-
Ingår i: Journal of Food Engineering. - 0260-8774 .- 1873-5770. ; 48:4, s. 325-333
-
Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity determination by means of the thermal probe is a classical non-stationary method, suitable for foodstuffs because of the relatively short period of time and the small temperature rise required during experimental measurements. Even though its simplicity, this method has theoretical and practical implicit errors, their main sources being evaluated in this paper. The theoretical analysis shows that experimental errors can be kept within acceptable values, if the testing time period is within certain limits, out of which the errors grow quite rapidly. The error arising from the calculation of the thermal conductivity by means of an approximate equation is studied and a new way to express it is presented. Also, testing times were calculated for different probe dimensions. Finally, on the basis of two former probe which exhibits some advantages upon each other, a new probe design is proposed which recoveries those features.
|
|
| 5. |
- Vasco, Diego A., et al.
(författare)
-
Kinematic characterization of the pressure-dependent PCM impregnation process for radiata pine wood samples
- 2018
-
Ingår i: European Journal of Wood and Wood Products. - : Springer. - 0018-3768 .- 1436-736X. ; 76:5, s. 1461-1469
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the properties of Pinus radiata wood impregnated with an organic phase change material (O-PCM). The tests are aimed at characterizing the kinetics of impregnation (rates, flows, and fronts) and the thermophysical properties (thermal conductivity and specific heat). In particular, a paraffin type O-PCM (octadecane) is used to impregnate dry radiata pine wood in the tangential flow direction at four manometric pressures (0, 1, 2, and 3 bar) and constant temperature of 50 °C. The wood is sapwood from 12-year old P. radiata growing in the Bío-Bío region and dimensioned according to Chilean standard for treated wood sample extraction. The results show that it is viable to impregnate P. radiata wood with O-PCM to improve its thermophysical properties with the purpose of passive conditioning.
|
|
| 6. |
- Ahmed, Sheikh Ali, et al.
(författare)
-
Anatomical properties and process parameters affecting blister/blow formation in densified European aspen and downy birch sapwood boards by thermo-hygro-mechanical compression
- 2013
-
Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 48:24, s. 8571-8579
-
Tidskriftsartikel (refereegranskat)abstract
- Approximately, 13.5 % of the standing volume of productive forest land in Sweden is covered by birch and aspen, which provides the vast potential to produce value-added products such as densified wood. This study shows whether it is possible to densify those species with a thermo-hygro-mechanical (THM) process using heat, steam, and pressure. In this process, transverse compression on thin European aspen (Populus tremula) and downy birch (Betula pubescens) boards was performed at 200 ºC with a maximum steam pressure of 550 kPa. To obtain a theoretical 50 % compression set, the press’s maximum hydraulic pressure ranged from 1.5 to 7.3 MPa. Preliminary tests showed that ~75 % of the birch boards produced defects (blisters/blows) while only 25 % of the aspen boards did. Mainly, radial delamination associated with internal checks in intrawall and transwall fractures caused small cracks (termed blisters) while blows are characterized by relatively larger areas of delamination visible as a bumpy surface on the panel. Anatomical investigations revealed that birch was more prone to those defects than aspen. However, those defects could be minimized by increasing the pre-treatment time during the THM processing.
|
|
| 7. |
- Ananías, Rubén A., et al.
(författare)
-
Collapse of Eucalyptus nitens Wood after Drying Depending on the Radial Location Within the Stem
- 2014
-
Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 32:14, s. 1699-1705
-
Tidskriftsartikel (refereegranskat)abstract
- Collapse is almost certain to occur in the industrial drying of Eucalyptus nitens, and as such this prevents the lumber manufacturing industry in Chile from producing commercial solid wood products from this species. This problem is still unsolved, and different studies to reduce collapse are currently underway. In this exploratory study, shrinkage and collapse after drying of Eucalyptus nitens was measured for boards cut from different radial locations within the stem (core, transition and outer wood from pith to bark) and having different annual ring orientation (flat-sawn and quarter-sawn). Even though exploratory, the results appear to confirm that pieces that were cut from the center of the trees were less susceptible to collapse than the pieces cut from the transition zone between the center and the periphery. On average, collapse in transition wood was approximately 50% higher than the collapse observed in wood cut from the central zone of the trees.
|
|
| 8. |
- Ananías, Rubén A., et al.
(författare)
-
Drying Schedules for Canelo Wood
- 2013
-
Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 31:3, s. 282-285
-
Tidskriftsartikel (refereegranskat)abstract
- Canelo wood is a highly valued native species in Chile that shows delicate marbling patterns with a pinkish soft silver luster. Due to its decorative qualities, canelo wood is dried for the manufacture of furniture and musical instruments. However, canelo wood lacks vessels cells that typically transport the water in hardwoods. Per its drying behavior, canelo wood is considered a transition species between hardwoods and softwoods. Therefore, this article reports drying schedules that were developed for drying 25-mm and 50-mm canelo lumber. In addition, this article reports experimental overall mass transfer coefficients, so that drying times for each of the drying stages can be easily estimated
|
|
| 9. |
|
|
| 10. |
- Ananías, Rubén A., et al.
(författare)
-
Energy Consumption in Industrial Drying of Radiata Pine
- 2012
-
Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 30:7, s. 774-779
-
Tidskriftsartikel (refereegranskat)abstract
- This article reports the results of an exploratory study designed to reduce heat and electricity consumption in industrial drying of radiata pine. The experiments were performed with slight modifications of the standard drying schedules used by the sawmill to dry radiata pine in 100-m 3 industrial kilns. The heat and electricity consumption were determined with data collected during the drying runs and calculations based on mathematical models. The results showed that depending on the case, heat and power consumption were respectively reduced by up to 14 and 35%.
|
|
| 11. |
- Ananías, Rubén A., et al.
(författare)
-
Kiln schedule certification for industrial drying of radiata pine
- 2013
-
Ingår i: Wood and Fiber Science. - 0735-6161. ; 45:1, s. 98-104
-
Tidskriftsartikel (refereegranskat)abstract
- This is a summary of a study carried out in Chile to certify industrial kiln drying of radiata pine to comply with the international phytosanitary standard ISPM 15. The drying tests were performed in 100-m3 industrial kilns located at four different sawmills of the VIII region in Chile. The objective was to develop a standard protocol to certify industrial drying of radiata pine depending on the drying schedule and wood thickness. In part, the results were used to develop a multiple regression equation that permits sawmills to select their drying schedules in such a way that the lumber can be officially stamped as both kiln-dried and heat-treated for international trade.
|
|
| 12. |
- Ananías, Rubén A., et al.
(författare)
-
Testing New In-Kiln Meter for Monitoring Lumber Moisture Content during Drying
- 2013
-
Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 31:3, s. 277-281
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to test a new in-kiln sensor for monitoring lumber moisture content during industrial drying. The theoretical foundation of the technology was already known, because it is based on electrical conductivity, but the mechanism of implementation was new and required validation. For this reason, the technology was compared with two other widely used methods for assessing lumber moisture content, namely, the oven-drying and electrical capacitance methods. The tests were performed in a 120-m3 industrial kiln operated by a sawmill in the eighth region of Chile, and the results showed that the average moisture content at the end of drying was satisfactorily determined by the new in-line sensor. As predicted by theory, the sensor was not able to accurately measure moisture content above 25%, but it was still able to provide the equivalent of a drying curve for monitoring of the drying process
|
|
| 13. |
- Bajraktari, Agron, et al.
(författare)
-
Weathering protection for beech wood in Kosovo
- 2013
-
Ingår i: International Journal of Current Engineering and Technology. - 2277-4106. ; 3:2, s. 331-333
-
Tidskriftsartikel (refereegranskat)abstract
- Beech wood (Fagus sylvatica L.) is one of the most important timber species produced in Kosovo. About 33% of the trees in our country are beech and most of the wood products are from this kind of timber. The color difference between red heart wood and white wood of the beech is significant. Adequate protection against weathering (snow, rain and low temperature) and leaching of preservative components into the environment are the main problems faced by wood companies in Kosovo as coatings defects may become apparent after only one year of outside exposure. The aim of this study was to assess the best way to protect beech wood products from weathering with available types of commercial wood coatings: film forming, non film forming, transparent stain and semi transparent penetrating stain. We concluded that the film forming and semitransparent penetrating stain are the best painting methods for beech woodproducts protection, according to weathering performance and coating properties.
|
|
| 14. |
- Couceiro, José, et al.
(författare)
-
Implementation of Computer Aided Tool for Non-Destructive X-Ray Measurement of Moisture Content Distribution in Wood
- 2015
-
Ingår i: Pro Ligno. - 1841-4737 .- 2069-7430. ; 11:4, s. 330-336
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports recent attempts for implementing non-destructive measuring of moisture contentin wood based on computed tomography technology. The study focus onan image analysis method that has been already proposed and validated in the literature, but ithas not been tested for measuring low moisture content variations below fibre saturation point.The computed tomography method was tested against the oven-dry method.The results show thatit is possible to apply this technology to measure low levels of moisture content based on a regression model, where therootmean square error of the modelwas 1,4percentage points of moisture content. The method can still be improved because the density differences between samples are relatively small in relation to the experimental error and the computed tomography precision.
|
|
| 15. |
- Elustondo, Diego, et al.
(författare)
-
A method for optimizing lumber sorting before kiln-drying
- 2009
-
Ingår i: Forest Products Journal. - 0015-7473. ; 59:9, s. 45-50
-
Tidskriftsartikel (refereegranskat)abstract
- Drying lumber can be quite challenging when uniformity and consistency are required. Over-drying and under-drying are common causes for lower grade recovery and dimensional stability problems. It is known that both over-drying and underdrying can be reduced by sorting green lumber into different moisture content groups. Additionally, sorting also offers the opportunity to redesign drying schedules. In this study, a new methodology was designed and tested to optimize kiln-drying of lumber by implementing green sorting coupled with modified drying schedules. The methodology was applied to optimize the drying of 114 by 114 mm2 hem-fir lumber sorted with an NMI capacitance type meter. It was found that in comparison to unsorted lumber, sorting into three groups reduced the drying time by approximately 7 percent and recovered around threequarters of the under-dried lumber
|
|
| 16. |
- Elustondo, Diego, et al.
(författare)
-
Comparative analysis of three methods for stochastic lumber drying simulation
- 2005
-
Ingår i: Drying Technology. - 0737-3937 .- 1532-2300. ; 23:1-2 Spec. issue, s. 131-142
-
Tidskriftsartikel (refereegranskat)abstract
- This article describes a novel stochastic model designed to simulate systems that cannot be analyzed as a unit, but as a collection of a large number of similar components. In order to state advantages and disadvantages, the proposed method is compared with two other published models. The first is a symbolic mathematical relationship designed to predict average moisture content and standard deviation after conventional drying of lumber. Since this model is exact, it was used as reference to evaluate the accuracy of the other approximate numerical methods. The second model is entirely random, and it emulates a real system behavior in which the parameters and conditions randomly change from one component to the other. The proposed method is based on numerical integration of the parameter's frequency distribution curves, which always produce the same and most probable result for the same parameters and conditions. The three methods were applied for simulation of conventional lumber drying, and the results were compared both qualitatively and numerically
|
|
| 17. |
|
|
| 18. |
- Elustondo, Diego, et al.
(författare)
-
Development of method for surface modification of wood
- 2015
-
Ingår i: Proceedings of the Eighth European Conference on Wood Modification. - Helsinki : Aalto University, School of Chemical Engineering. ; , s. 137-140
-
Konferensbidrag (refereegranskat)abstract
- This study concerns the development of a method for surface modification based on the hot-and-cold bath process. In the experiments the wooden boards were first heated in an oven and after that they were immediately soaked in a cold chemical solution. This procedure allowed the chemicals to penetrate partially into the wood without using pressure equipment. In this study copper, furfuryl alcohol and phenol formaldehyde based solutions were used. The impregnation resulted in modified layers below the wood surfaces representing a trade- off between the full-bulk modification and surface coating of wood. It is concluded that the method can be developed further for potential industrial use to produce e.g. flooring, cladding or decking.
|
|
| 19. |
- Elustondo, Diego, et al.
(författare)
-
Drying Western Red Cedar with Superheated Steam
- 2014
-
Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 32:5, s. 550-556
-
Tidskriftsartikel (refereegranskat)abstract
- This exploratory study evaluated the possibility of drying 50-mm-thick western red cedar with superheated steam. Since there are no industrial facilities in Canada drying western red cedar with superheated steam, the study was designed to explore the potential of this technology in terms of lumber quality, moisture content distribution, and drying time. The experiments showed that the 50-mm-thick product can be dried in less than three days without jeopardizing lumber quality (in comparison with the two weeks that is currently required in conventional kilns), and the percentage of pieces that remained wet after drying was within the 10% to 15% range that is typically tolerated in industry.
|
|
| 20. |
- Elustondo, Diego, et al.
(författare)
-
Estimation of green moisture content distribution in hemfir timber by stochastic simulation
- 2004
-
Ingår i: Holzforschung. - 0018-3830 .- 1437-434X. ; 58:4, s. 413-417
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes an improved stochastic model designed to simulate systems, such as green timbers, that cannot be analyzed as a unit but as a collection of a large number of similar components. The stochastic model provides a piecewise green moisture content frequency distribution curve by using nondestructive measurements such as of timber weight. A new, relatively simple two-parameter function was designed to describe the log-normal moisture concentration distribution above the fiber saturation point, and the parameters of this function were determined by fitting the experimental timber weights with the results of the stochastic model. The simulated green moisture content distributions showed good agreement with the experimental data for Pacific coast hemlock (hemfir) timbers, thus providing a piece of information that is indispensable for applying stochastic simulation to industrial drying of timbers.
|
|
| 21. |
- Elustondo, Diego, et al.
(författare)
-
Evaluation of three semi-empirical models for superheated steam vacuum drying of timbers
- 2003
-
Ingår i: Drying Technology. - 0737-3937 .- 1532-2300. ; 21:5, s. 875-893
-
Tidskriftsartikel (refereegranskat)abstract
- Superheated steam drying at sub-atmospheric pressure (SSV) has been successfully employed in Europe and Asia for drying some types of timbers, showing that drying time could be reduced by 50% with respect to conventional drying without significant losses in the quality of the final product. This reduction is the consequence of a different heat and mass transfer control mechanism. Since SSV drying is carried out in absence of gaseous air, diffusion of the generated vapor is not a limiting factor and drying rate becomes more dependent on heat transference. Therefore, classical interpretation of timber drying as a process based on moisture migration control is not applicable to SSV. This work is targeting the development and validation of a simplified semi-empirical model for SSV drying of timbers. Mathematical representation of the proposed model is uncomplicated and straightforward to apply, and the comparison between model predicted and experimental data showed a high degree of agreement under variable drying conditions.
|
|
| 22. |
|
|
| 23. |
- Elustondo, Diego, et al.
(författare)
-
Industrial evaluation of re-dry stragegy for softwood lumber
- 2005
-
Ingår i: MADERAS. - 0717-3644 .- 0718-221X. ; 7:2, s. 65-78
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents an experimental evaluation of the first commercial scale dry-sort-redry (DSRD) strategy for drying of 2x4 Pacific coast hemlock (PCH) lumber. The DSRD strategy is a methodology designed to reduce final moisture content variability in kiln dried lumber by complementing conventional drying with radio frequency vacuum (RFV) drying technology. The strategy′s objective is to avoid producing over-dried lumber in conventional drying by setting the target moisture content to a value much higher than those usually used in industry. Then, RFV drying technology is implemented to quickly and efficiently re-dry the lumber that remains wet (under-dried) after the first conventional pass. Six experimental tests were performed in an industrial sawmill with the intention of studying the effect of target moisture content on the properties and quality of the dried lumber. In all cases, the first drying pass was performed in a 260m3 industrial heat-and-vent conventional kiln, and the re-drying of wets was performed in a 75m3 RFV kiln. Additionally, a mathematical model developed for prediction of data dispersion in lumber drying was calibrated with experimental data, and used to simulate the DSRD strategy under other hypothetical conditions. The results of the study demonstrate that the DSRD strategy reduces drying time, shrinkage and kiln drying degrade in comparison with a single conventional pass.
|
|
| 24. |
- Elustondo, Diego, et al.
(författare)
-
Localized wood surface modification, Part I : Method characterization
- 2017
-
Ingår i: BioResources. - : North Carolina State University. - 1930-2126. ; 12:1, s. 283-295
-
Tidskriftsartikel (refereegranskat)abstract
- This study assesses the potential of an open process for treatment of European Scots pine (Pinus sylvestris) with chemicals that could potentially make the surfaces stronger, more dimensionally stable, or more durable, depending on the treatment solution. The method provides an intermediate solution between full volume impregnation by pressure treatment and superficial surface treatment by dipping. Figuratively speaking, the process creates the equivalent of a layer of coating applied below the wood surfaces rather than above. Two different techniques were compared, namely, heating-and-cooling (H & C) and compression-and-expansion (C & E). Taking into account that commercial suppliers recommend 0.15 to 0.25 L/m2 of coating in sawn wood and 0.1 to 0.15 L/m2 in planed wood surfaces, then this study demonstrates that the H & C method can impregnate an equivalent amount of solution under the surfaces in less than 15 min using treatment temperatures below 150 °C. © 2017 North Carolina State University.
|
|
| 25. |
- Elustondo, Diego
(författare)
-
Lumber quality model : The theory
- 2010
-
Ingår i: Wood Material Science & Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 5:3-4, s. 162-172
-
Tidskriftsartikel (refereegranskat)abstract
- A new model for predicting moisture content, distortion and shrinkage distribution after lumber drying has been designed, implemented and tested. The model was implemented using Monte Carlo simulation, and it involves three empirical equations that were developed on the basis of experimental data. The model is referred as the Lumber Quality Model, and it is designed to be calibrated by knowing the initial and final moisture content, distortion and shrinkage distribution for a reference drying run. After calibration, the model can be used to predict the same information for other hypothetical drying scenarios. The present study explains the theoretical aspects of the model and the methodology for implementation. The model was validated with experimental data measured in a laboratory kiln. A full-scale industrial validation will be reported in a future paper.
|
|
| 26. |
- Elustondo, Diego, et al.
(författare)
-
Measuring moisture content and shrinkage during drying of biological materials through CT-scanner technology.
- 2015
-
Ingår i: Proceedings of the 5th European Drying Conference (EuroDrying’2015). - Budapest : Szent István University, Gödöllő. ; , s. 113-119
-
Konferensbidrag (refereegranskat)abstract
- The objective of this study was to investigate the possibility of using X-ray computer tomography (CT) for measuring average moisture content (MC) and shrinkage of biological products that are dried as granular materials. Three different biological materials were dried simultaneously under the same drying conditions, namely, spruce sawdust and two species of mushrooms. The results showed that moisture content values within approximately ±1% of the oven-dry values and linear relationships between shrinkage and MC can be obtained without any calibration factor and a limited number of CT-images.
|
|
| 27. |
- Elustondo, Diego, et al.
(författare)
-
Model to assess energy consumption in industrial lumber kilns
- 2009
-
Ingår i: MADERAS. - 0717-3644 .- 0718-221X. ; 11:1, s. 33-46
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a kiln energy model was developed with the main objective of assessing energy consumption in industrial lumber kilns. The model simulates kiln energy consumption on the basis of a simplifi ed description of kiln technologies, energy systems and lumber characteristics, and it requires a minimum set of empirical parameters that are calibrated in practice. In this study, the model calibration was performed for a laboratory scale conventional kiln and three experimental drying runs of 50 mm thick spruce-pine lumber. The results of this study illustrate how the kiln energy model is calibrated, compares experimental and simulated MC, energy and water consumption, and describes how the model simulates different components of energy consumption that can be used to evaluate potential energy saving strategies.
|
|
| 28. |
- Elustondo, Diego, et al.
(författare)
-
Modeling a timber "dry/sort/re-dry" strategy using combined conventional and dielectric technologies
- 2002
-
Konferensbidrag (refereegranskat)abstract
- In this work, a numerical stochastic model is presented and utilized to study the dry/sort/re-dry (DSRD) strategy for 116-mm square ,timbers ,by using ,combined conventional,and ,radio frequency ,vacuum ,(RFV) drying ,technologies. The model parameters are calibrated with experimental timber drying data of mixed western hemlock and amabilis fir, and the total percentages of on-grade, over-dried and under-dried timbers are simulated for different conventional and RFV target moisture content situations. The results of the simulated percentages of timbers are presented in 2-D level curves, and the ranges of target that should be used ,in order ,to obtain ,maximum ,on-grade timbers are analyzed.
|
|
| 29. |
- Elustondo, Diego, et al.
(författare)
-
Moisture content target optimization in lumber drying
- 2011
-
Ingår i: Wood Material Science & Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 6:4, s. 190-195
-
Tidskriftsartikel (refereegranskat)abstract
- A Lumber Quality Model developed to predict lumber grade after drying was applied and validated in industry. The model was calibrated with a 198-piece lumber package that was dried at a local sawmill in British Columbia, Canada, and 30 sawmill grade reports were recorded from 2008 to 2010. The calibrated model was then used to predict the target moisture content that would result in the maximum lumber value. It was predicted that lumber value should increase by approximately 17 CAD (Canadian dollars) m -3 if the target moisture content were reduced from the historic 17% to an optimum of approximate 13%. The sawmill implemented the recommendations and the predictions were validated with another seven industrial drying runs
|
|
| 30. |
|
|
| 31. |
- Elustondo, Diego, et al.
(författare)
-
New methodology to optimize sorting in wood drying
- 2010
-
Ingår i: MADERAS. - 0717-3644 .- 0718-221X. ; 12:2, s. 79-91
-
Tidskriftsartikel (refereegranskat)abstract
- One important problem in lumber drying is to maintain the lumber moisture content distribution within certain minimum and maximum values. Over-drying and under-drying are common causes for lower grade recovery and dimensional stability problems. It is known that both over-drying and underdrying can be reduced by sorting green lumber into different moisture content groups and sorting also offers the opportunity to redesign drying schedules. In this study, a new methodology was designed and tested to optimize kiln drying of lumber by implementing green sorting coupled with modified drying schedules. The methodology was applied to optimize the drying of 114 by 114mm 2 hem-fir lumber sorted with an NMI capacitance type meter at a local sawmill. It was found that in comparison to unsorted lumber, sorting into three groups can reduce the drying time by 7% approximately and recover around 3/4 of the under-dried lumber. The experimental data on lumber degrade and moisture gradients measured after drying were also reported in this paper.
|
|
| 32. |
- Elustondo, Diego, et al.
(författare)
-
Non-deterministic description of wood radio frequency vacuum drying
- 2003
-
Ingår i: Holzforschung. - 0018-3830 .- 1437-434X. ; 57:1, s. 88-94
-
Tidskriftsartikel (refereegranskat)abstract
- A numerical method is proposed to predict the stochastic dispersion of data that unavoidably occurs in a real drying process. The method is based on the use of discrete frequency distribution curves to predict a random variation on some parameters of the process and is applied to the case of radio frequency vacuum (RFV) drying of wood. Experimental data of RFV drying of western hemlock timbers were used to obtain the numeric values of the stochastic parameters and their standard deviation. A mathematical model was designed to simulate the final moisture content dispersion on hypothetical examples. Results were quantified using three indices: average, range and standard deviation.
|
|
| 33. |
- Elustondo, Diego, et al.
(författare)
-
Opportunities to reduce energy consumption in softwood lumber drying
- 2006
-
Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 24:5, s. 653-662
-
Tidskriftsartikel (refereegranskat)abstract
- While a few years ago the cost and availability of energy was not an important issue for the Canadian lumber industry, this situation has recently changed. Today, companies that have operated trouble-free for many years using the same technologies and practices may now have to adapt to the rising cost of fossil fuels and concerns about greenhouse gas emissions. This article addresses this problem for the particular case of the softwood lumber industry. The study describes the most important sources of energy losses in conventional drying and proposes a number of strategies and technologies to reduce kiln energy demand
|
|
| 34. |
- Elustondo, Diego, et al.
(författare)
-
Optimum operating conditions in drying foodstuffs with superheated steam
- 2002
-
Ingår i: Drying Technology. - 0737-3937 .- 1532-2300. ; 20:2, s. 381-402
-
Tidskriftsartikel (refereegranskat)abstract
- It is inferred from experimental data that in drying foodstuffs with superheated steam, the initial drying rate has a direct effect on the rate at which the overall drying takes place. That is, the faster the initial drying rate, the shorter the overall drying time. This criterion is very convenient because at the beginning, water moistens the sample external surface so evaporation does not depend on internal sample characteristics, but only on external convective heat and mass transfer rates. Mass and energy balance equations are solved and the result converted into a general initial drying rate equation, in which all dryer characteristics are grouped into one dimensionless parameter. The initial drying rate equation is mathematically maximized and the optimum working conditions determined. The result shows that initial drying rate always increase with increases of either the superheated steam temperature or velocity, but once these two variables are fixed, there exists at least one "optimum" pressure at which the initial drying rate is a maximum. Finally, the initial drying rate and optimum condition equations are applied to three model dryers, a dryer for a flat sheet, a fixed bed dryer and a rotary dryer. In each case, numeric values are computed and plotted as drying rate versus pressure curves, in which the optimum drying rate is also included. Also presented is a chart to compare the optimum pressures as functions of temperature and steam velocity for the three dryers.
|
|
| 35. |
- Elustondo, Diego, et al.
(författare)
-
Predicting thermal efficiency in timber radio frequency vacuum drying
- 2004
-
Ingår i: Drying Technology. - 0737-3937 .- 1532-2300. ; 22:4, s. 795-807
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, the efficiency of transforming dielectric energy into evaporated water is analyzed for the case of timber radio frequency vacuum drying. Based on well-known heat and mass transfer equations, a simplified mathematical model is proposed that estimates the drying efficacy in regards to the thermo-physical properties of wood. Although not exact, the theoretical results are close to the experimental observations and elucidate some phenomena like the tendency of the timber to dry from inside to outside, and the drying rate increase with the rise of the timber gas permeability. The theoretical efficiency model also predicts a range of wood permeability values for which the drying efficiency changes from 100 to 0%, thus providing a quantitative scale for classifying the spectrum of "difficult-to-dry" all the way to "easy-to-dry" wood species when using radio frequency vacuum technology
|
|
| 36. |
- Elustondo, Diego, et al.
(författare)
-
Rfv drying schedule development for thick western red cedar timbers
- 2008
-
Ingår i: International Wood Products Journal. - : Informa UK Limited. - 0020-3203. ; 18:2, s. 68-74
-
Tidskriftsartikel (refereegranskat)abstract
- Radio frequency vacuum drying of timbers could result in internal checking (honeycombing) due to elevated internal temperatures and pressures that is believed to be associated to the level of applied power density, but it might be also related to the way electric power is applied during the drying process. In this exploratory study the relationship between power density and wood damage for thick western red cedar dried in a laboratory RFV dryer was evaluated. Two different types of drying strategies were assessed and the results were used to identify apparent trends and thus recommend the drying schedule that appears to minimize internal and surface checking.
|
|
| 37. |
- Elustondo, Diego, et al.
(författare)
-
Simulated comparative analysis of sorting strategies for RFV drying
- 2003
-
Ingår i: Wood and Fiber Science. - 0735-6161. ; 35:1, s. 49-55
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a numerical stochastic model is used to compare three possible sorting strategies in radio frequency vacuum (RFV) drying of thick timbers, namely, moisture content based pre-sorting (MCPS), batch dry/sort/redrying (b-DSRD) and continuous or retro-feed dry/sort/redry (c-DSRD). The model parameters were calibrated with experimental data of western hemlock dried in a commercial RFV dryer, and the results of the simulations were compared to a single pass base case (SPBC). The numerical results clearly demonstrated the differences among these strategies. The MCPS showed no significant improvement in final timber quality as defined by average timber moisture content, but there is an evident improvement in both b-DSRD and c-DSRD. The comparison was based on the increment of the percent of the on-grade wood (within moisture content range) and the reduction of overdried and underdried (wets) percentages. Furthermore, it was also shown that the effective drying time is roughly independent of the drying strategy
|
|
| 38. |
- Elustondo, Diego, et al.
(författare)
-
Stochastic numerical model for conventional kiln drying of timbers
- 2003
-
Ingår i: Journal of Wood Science. - : Springer Science and Business Media LLC. - 1435-0211 .- 1611-4663. ; 49:6, s. 485-491
-
Tidskriftsartikel (refereegranskat)abstract
- A numerical model that predicts the stochastic dispersion associated with industrial kiln drying of timber was adapted to conventional drying and evaluated with experimental data. The theoretical aspects of the model are briefly explained, a selection of the calibration parameters was carried out, and a new empirical dispersion factor is proposed to account for all unknown sources of random behavior. The model was calibrated with six experimental runs of western hemlock and amabilis fir (116 mm2 timbers) to an average moisture content (target) of 14%-20%. It was found that with implementation of the dispersion factor, the number of required simulations is considerably reduced, the calibration results are consistent for all the experimental runs, and the target moisture content along with its standard deviation can be well reproduced using the all-run average parameters.
|
|
| 39. |
- Elustondo, Diego, et al.
(författare)
-
Stochastic numerical model for radio frequency vacuum drying of timbers
- 2002
-
Ingår i: Drying Technology. - 0737-3937 .- 1532-2300. ; 20:9, s. 1827-1842
-
Tidskriftsartikel (refereegranskat)abstract
- A new numeric method to simulate stochastic dispersion (a natural phenomenon that occurs when a magnitude cannot be associated to a specific value, but to the probability of being within a range of values) is proposed and applied to predict Radio Frequency Vacuum (RFV) drying of timber. A theoretical formulation of the method is described and complemented to take into account the frequency distribution of the timber initial moisture content, so that it can be applied to industrial runs. Experimental data obtained from mixed western hemlock and amabilis fir dried in a commercial RFV kiln are used to validate the stochastic model, and the results are compared through moisture content histograms and probability charts. A numerical example is shown in order to provide an idea of the movement of the moisture profiles during RFV drying.
|
|
| 40. |
|
|
| 41. |
- Elustondo, Diego, et al.
(författare)
-
Temperature-drop sensor for determination of drying curves in conventional lumber drying
- 2006
-
Ingår i: Holzforschung. - 0018-3830 .- 1437-434X. ; 60:2, s. 196-200
-
Tidskriftsartikel (refereegranskat)abstract
- Conventional lumber drying is carried out by forcing hot air to flow across a pile of lumber layers separated by wood strips. The airflow provides the heat required to warm up the lumber and produce the moisture evaporation and, in theory, the difference in temperature at each side of the load can be used to estimate the evaporation rate. The main problem with this approach is that typical temperature sensors that are installed in conventional kilns are not accurate enough to measure the temperature drop across the load during periods of low evaporation. In this paper, a new sensor to measure the temperature drop across the load is proposed and tested in three experimental drying runs of 2" X 6" spruce-pine lumber. The results demonstrate that after calibration, the temperature drop across the load can be used to determine drying curves in conventional lumber drying. In the particular case of this study, calibration was performed by multiplying the experimental temperature drop across the load by a constant factor, which was adjusted by identifying the correction factor that best simulated the experimental green moisture content of the three lumber charges.
|
|
| 42. |
- Elustondo, Diego, et al.
(författare)
-
Temperature drop sensor for monitoring kiln drying of lumber
- 2009
-
Ingår i: Holzforschung. - 0018-3830 .- 1437-434X. ; 63:3, s. 334-339
-
Tidskriftsartikel (refereegranskat)abstract
- The main objective of this study was to test a new sensor based on the temperature drop across the load (TDAL). The TDAL sensor was designed to determine the transition point between wet and dry wood without any specific information about the drying process. When additional information is available, the TDAL sensor can also be used to monitor drying rate and estimate the drying end-point. In this study, three potential applications of TDAL sensor for lumber drying were explored, namely, to monitor drying rate, to detect the transition point between wet and dry wood, and for determination of drying end-point after calibration. For the first application, it was demonstrated that the transition point between wet and dry wood coincides with the time at which the TDAL decreases with time at a constant logarithmic slope. For the second application, the TDAL sensor was calibrated with nine experimental drying runs, and the end-points determined with the calibrated TDAL sensor did not show a significant difference with the end-points determined by the in-kiln MC meter. Finally, the TDAL sensor was used to monitor drying rate during drying
|
|
| 43. |
|
|
| 44. |
|
|
| 45. |
- Elustondo, Diego, et al.
(författare)
-
The demonstration of increased lumber value using optimized lumber sorting and radio frequency vacuum drying
- 2005
-
Ingår i: Forest Products Journal. - 0015-7473. ; 55:1, s. 76-83
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents an experimental evaluation of the first commercial scale dry/sort/re-dry (Q-Sift®) strategy for drying of 2 by 4 Pacific Coast hemlock lumber using combined conventional and radio frequency vacuum drying technologies. The strategy was evaluated through six experimental tests in which lumber loads were dried to different final average moisture content in an industrial heat-and-vent conventional kiln, and measured for initial and final moisture content distribution, shrinkage, and drying degrade. Additionally, a stochastic model especially developed for this strategy was calibrated with the measured data and used to simulate the results of the strategy under different drying conditions within the calibration range. The study demonstrated that the implementation of the Q-Sift strategy decreases the process drying time, and reduces shrinkage and kiln-drying degrade in comparison with a single conventional pass. An economic model was also developed in order to determined the industrial viability of the method, and for the studied industrial case it was demonstrated that the revenues of the new strategy allow an investment payback in less than 1.5 years.
|
|
| 46. |
- Elustondo, Diego
(författare)
-
The wrong assumption : revolutionary scientific theories that shape the elusive supernatural world
- 2012
-
Bok (refereegranskat)abstract
- The Wrong Assumption: Revolutionary Scientific Theories That Shape the Elusive Supernatural World provides a scientific approach to philosophical thinking and encourages readers to explore their spiritual beliefs. By using simple language and honest scientific rigor, this e-book illuminates fascinating and revolutionary scientific theories that provide physical shape to the otherwise elusive concept of the supernatural world. Readers are exposed to a large variety of scientific theories that justify the existence of spiritual beliefs. Unlike other similar books that explore the connection between science and religion, this e-book refrains from manipulating science to fit a particular dogma; rather, it highlights scientific concepts remarkably similar to those ideas traditionally associated with spiritual beliefs. This e-book condenses the scientific knowledge that is currently dispersed throughout many books into a reader friendly volume.
|
|
| 47. |
- Elustondo, Diego, et al.
(författare)
-
Visual Method to Assess Lumber Sorting Before Drying
- 2013
-
Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 31:1, s. 32-39
-
Tidskriftsartikel (refereegranskat)abstract
- This article explores the possibility of using a simplified but intuitive method to quickly assess the potential benefits of sorting lumber before industrial kiln drying. The method consists of using scatter plots to visualize the probability of obtaining a certain drying result, such as final moisture content, as a function of a property of the green lumber that can be measured in practice. The method was first validated with four drying runs of 116 mm × 52 mm hemlock lumber: one run contained unsorted lumber and the others contained the same type of lumber but sorted into low, medium, and high groups depending on the electrical capacitance of the green wood. After validation, the scatter plots were used to assess the benefits of two typical industrial sorting strategies, namely, sorting by electric capacitance and sorting by weight. It was found that both methods have the potential to increase lumber production and reduce over dried lumber in approximately the same magnitude. For a typical industrial schedule, sorting into three groups reduced the drying time by approximately 10% and over dried lumber to practically zero
|
|
| 48. |
- Grimm, Alejandro, et al.
(författare)
-
Drying recycled fiber rejects in a bench-scale cyclone : Influence of device geometry and operational parameters on drying mechanisms
- 2017
-
Ingår i: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 167, s. 631-640
-
Tidskriftsartikel (refereegranskat)abstract
- Significant amounts of waste sludge and rejects are generated by pulp and paper mills, and stricter environmental regulations have made waste handling a global challenge. Thermochemical conversion of mechanically dewatered by-products is expensive and inefficient due to their high moisture content; therefore drying is a vital unit operation in waste management. This paper reports results from drying of light coarse fiber reject in a bench-scale cyclone that allows changes in geometry. For the sake of comparison, convective fixed-bed drying tests were also performed. The results showed that the drying rate in the cyclone was hundreds of times higher than in the fixed-bed. For cyclone drying, the inlet air velocity was the most important factor in both determining the drying rate and residence time of the material. This led to the hypothesis that grinding of the reject particles due to particle-wall and particle-particle collisions play a crucial role in enhancing the efficiency of heat and mass transfer. In addition to inlet air velocity, cyclone geometry was the main factor that determined particle residence time, as drying air temperature mainly determined drying rate.
|
|
| 49. |
- Karlsson, Olov, et al.
(författare)
-
Thermally modified wood treated with methacrylate
- 2018
-
Ingår i: Proceedings IRG Annual Meeting IRG49 Scientific Conference on Wood Protection Sandton, Johannesburg, South Africa 29 April-3 May.
-
Konferensbidrag (refereegranskat)abstract
- Thermally modified timber (TMT)from Scots pine sapwood similar to Thermo-D quality was impregnated with methacrylate resin by the hot-and-cold method and subsequently cured at elevated temperatures. The results showedthat methacrylate resin could be used to reduce colouring of painted TMT wood during accelerated weathering probably by hindering the migration of extractives. The resin itself did not reduce greying of the unpainted wood. Hardness was only slightly improved by treatment with the resin probably due to a higher density of the material. Formation of blisters occurred but wasreduced by treatment with the resin. Resistance to mould growth by a mixture of Aureobasidium pullulans, Cladosporium cladosporioides, Aspergillus versicolor, Penicillium purpurogenumwas performed by applying EN-15457:2014. Treatment with methacrylic resin hindered the colonisation of the three last mouldfungi.
|
|
| 50. |
- Korkut, Süleyman, et al.
(författare)
-
Effect of thermal modification on the properties of narrow-leaved ash and chestnut
- 2012
-
Ingår i: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 35:1, s. 287-294
-
Tidskriftsartikel (refereegranskat)abstract
- The concept of thermal modification has evolved from a challenging research program to commercial reality in several European countries in recent years. The aim of this study is to determine the change of various physical properties (oven-dry density, air-dry density, weight loss, swelling and anti-swelling efficiency (ASE)), compression strength parallel to grain, colour difference (ΔE), glossiness and surface roughness of narrow-leaved ash (Fraxinus angustifolia Vahl.) and chestnut (Castanea sativa Mill.) woods after heat treatment under different temperatures and durations. For this study two different temperatures (160°C and 180°C) and two different durations (2h and 4h) were considered. A stylus method was employed to evaluate the surface characteristics of the samples. Roughness measurements by the stylus method were made in the direction perpendicular to the fiber. Four main roughness parameters which are mean arithmetic deviation of profile (Ra), mean peak-to-valley height (Rz), root mean square roughness (Rq), and maximum roughness (Ry) obtained from the surface of wood were used to evaluate the effect of heat treatment on the surface characteristics of the specimens. The properties studied were significantly different (p=0.05) at two temperatures and two durations of heat treatment. Based on the findings of this study, the results showed that oven-dry density, air-dry density, swelling, compression strength parallel to grain and surface roughness decreases with increasing heat treatment temperature and time.
|
|
