Carlos Salinas

Energy Consumption in Industrial Drying of Radiata Pine

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-m3 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%.

SIMULACIÓN DEL SECADO CONVENCIONAL DE LA MADERA

El presente trabajo dice relacion con la modelacion numerica bidimensional de la cinetica del secado de madera basada en el concepto de potencial hidrico. El modelo matematico contempla ecuaciones de transporte del tipo diferencial parcial no lineal de segunda orden resuelto numericamente a traves del Metodo de Volumen Finitos en coordenadas generalizadas. Resultados de curvas de secado e isoconcentraciones son mostrados para madera de Populus sp. comparados con datos experimentales y/o publicados en la literatura especializada. Se concluye que el metodo numerico propuesto permite simular satisfactoriamente el secado de la madera obteniendo informacion transitoria detallada de las distribuciones de humedad al interior de esta Palabras clave : Secado; Potencial hidrico; Simulacion; Volumenes Finitos.

Drying Schedules for Canelo Wood

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.

Unidimensional Simulation of Drying Stress in Radiata Pine Wood

This article reports an experimental and numeric methodology for studying the development of internal stresses during drying of solid wood. For validation purposes, tests were performed for drying of radiata pine at the equivalent of constant air-drying conditions at 44°C dry-bulb and 36°C wet-bulb temperatures. The methodology involves the simulation of drying stresses caused by the development of internal moisture content gradients during drying, where the moisture content gradients are also simulated numerically based on the theory of effective diffusion coefficient. The resulting mathematical model is a second-order nonlinear set of partial differential equations with variable coefficients, which are integrated numerically through the Control Volume Finite Element Method (CVFEM). The results showed consistency between simulated values and the experimental strain and moisture content data, both in the radial and tangential directions. It was concluded that the proposed method could be a valuable tool for studying general trends in the development of stress during drying, trends which are difficult to evaluate by measuring only due to the limited amount of data points and high experimental error associated with destructive strain tests.

Testing New In-Kiln Meter for Monitoring Lumber Moisture Content during Drying

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.

MODELACIÓN DEL SECADO CONVENCIONAL DE COIGÜE: PARTE 2: RESULTADOS EXPERIMENTALES

Un modelo fenomenologico unidimensional basado en el coeficiente global de transferencia de materia (K x ) es utilizado para representar la cinetica del secado convencional del coigue ( Nothofagus dombeyi ) . Este modelo consiste en un conjunto de cuatro ecuaciones diferenciales parciales no lineales de primer orden el cual es discretizado de acuerdo al metodo de diferencias finitas y resuelto como un problema de valor inicial. Para determinar K x se realizaron cuatro experimentos de secado variando el espesor y la velocidad del aire. El valor de este coeficiente oscilo entre 1,87 · 10 -5 y 3,37 · 10 -5 kg/m 2 ·s. El modelo predijo adecuadamente el comportamiento transiente de la humedad durante el secado de la madera de coigue. K x vario con el espesor de la madera pero no con la velocidad del aire Palabras clave : Cinetica de secado; coeficiente de transferencia de masa; coigue; Nothofagus dombeyi .

Modelación fenomenológica de las curvas de secado por alta temperatura de pino radiata

Experiments at industrial scale to show the high temperature wood drying of radiate pine were performed. After that, physical parameters of transport phenomena (global heat and mass transfer coeffi cients), required by the phenomenological mathematical models for the simulation of the drying process, were determined. Results of global heat transfer coeffi cients, experimental drying curves and simulated process were shown. It was concluded that the simulation of the drying process at high temperature of radiata pine can be satisfactorily carried out by phenomenological model based on the global mass transfer coeffi cient. The values of these coeffi cients were between 1 x 10 -4 and 4.2 x 10 -4 kg/m 2 s.

MODELACIÓN DEL SECADO CONVENCIONAL DE COIGÜE: Parte 1: Fundamentación teórica

Se presenta la modelacion fenomenologica del secado a temperatura convencional (T ≤80 °C) y se describe su ecuacionamiento unidimensional sobre la base de un coeficiente global de secado. Resultados numericos transitorios de humedad y temperatura en la madera y en el aire ambiente, para el caso del secado de coigue Nothofagus dombeyi, son concordantes con aquellos obtenidos por otros autores. Se concluye que el modelo predice satisfactoriamente el proceso de secado a baja temperatura de una madera refractaria. La validacion experimental de la simulacion se abordara en la parte 2 de este estudio