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Title: Rapid determination of wood fuel moisture content using a microwave oven for drying

Abstract

A method of determining moisture content (MC) of wood fuel using a microwave oven for drying the wood was evaluated by drying paired samples of five different wood fuel types in a microwave oven and a conventional oven. When compared to the conventional oven drying method, the microwave technique produces consistently lower MC determinations, although the differences are less than 1 percent. The advantage of the microwave technique is the speed at which MC determinations can be determined (less than 15 minutes). Schedules for drying five wood fuel types are presented. (Refs. 7).

Authors:
Publication Date:
Research Org.:
Forestry Dept, Clemson Univ., Clemson, SC 29631
OSTI Identifier:
5917903
Resource Type:
Journal Article
Resource Relation:
Journal Name: For. Prod. J.; (United States); Journal Volume: 32:10
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; WOOD; DRYING; MEASURING METHODS; MICROWAVE OVENS; MOISTURE; APPLIANCES; OVENS 140504* -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989); 090400 -- Solid Waste & Wood Fuels-- (-1989)

Citation Formats

Harris, R.A. Rapid determination of wood fuel moisture content using a microwave oven for drying. United States: N. p., 1982. Web.
Harris, R.A. Rapid determination of wood fuel moisture content using a microwave oven for drying. United States.
Harris, R.A. 1982. "Rapid determination of wood fuel moisture content using a microwave oven for drying". United States. doi:.
@article{osti_5917903,
title = {Rapid determination of wood fuel moisture content using a microwave oven for drying},
author = {Harris, R.A.},
abstractNote = {A method of determining moisture content (MC) of wood fuel using a microwave oven for drying the wood was evaluated by drying paired samples of five different wood fuel types in a microwave oven and a conventional oven. When compared to the conventional oven drying method, the microwave technique produces consistently lower MC determinations, although the differences are less than 1 percent. The advantage of the microwave technique is the speed at which MC determinations can be determined (less than 15 minutes). Schedules for drying five wood fuel types are presented. (Refs. 7).},
doi = {},
journal = {For. Prod. J.; (United States)},
number = ,
volume = 32:10,
place = {United States},
year = 1982,
month =
}
  • This article presents a model to predict the surface moisture content distributions for wood products subjected to drying. The wood products are idealized in the modeling as either infinite plates or long cylinders. The analysis for transient moisture loss is carried out under two important conditions, namely, 0.1 < Bi < 100 and Bi > 100 where Bi = Biot number. The case where Bi < 0.1 is not considered, since the center and surface moisture contents may be almost the same because of negligible internal resistance to the moisture loss. The center moisture contents are estimated and compared withmore » experiments. Results show that the method presented here is capable of determining the surface moisture contents for such wood products. The model can be used for a variety of wood-drying applications.« less
  • The goal of this project was to develop a prototype moisture sensor system suitable for a hardwood dry kiln based on the microwave transmission measurements of the complex dielectric constant of the wood. In this project, prototypes of two designs of microwave-based moisture sensor probes (launchers) working in the frequency range from 4.5 GHz to 6 GHz were developed and tested. A prototype set of battery powered electronics that both provides the microwave excitation and records the amplitude and phase of the returned signal after passing through the wood was built and tested. The sensors and electronics built in thismore » project allow a swept frequency microwave transmission measurement through a small area of a board. Using the prototype electronics and launchers, measurements of moisture content (MC) over a range of 6 percent to 70 percent MC for red oak and 6 percent to 100 percent for yellow-poplar with standard deviations of less than 1.5 percent MC have been obtained.« less
  • A properly designed microwave oven can be a useful instrument for rapid determination of moisture in eight-mesh coal. Accuracy may be limited due to the wide variability of coals and their different behavior when subjected to microwave energy. However, as a technique for screening coal for total moisture content the small sacrifice in accuracy may be more than compensated for by the speed and ease of the test. Test data is recorded for comparison.
  • This study deals with the development of an analytical technique for determining the moisture diffusivities and moisture transfer coefficients for wood products subjected to drying. The wood products are idealized in the modeling as either infinite plates or long cylinders. The analysis of transient moisture diffusion is carried out on the basis of two important practical criteria: 0.1 < Bi < 100 and Bi> 100 where Bi = Biot number. The drying coefficients and lag factors were incorporated into the models. The developed analytical models are then verified by experimental measurements taken from the literature. Results show that the methodmore » presented here is capable of accurately determining the moisture diffusivities and moisture transfer coefficients for such objects. The models can be used for a variety of wood-drying applications.« less
  • An 8-electrode capacitance tomography (ECT) sensor was built and used to measure moisture content (MC) and mass flow of pine chip flows. The device was capable of directly measuring total water quantity in a sample but was sensitive to both dry matter and moisture, and therefore required a second measurement of mass flow to calculate MC. Two means of calculating the mass flow were used: the first being an impact sensor to measure total mass flow, and the second a volumetric approach based on measuring total area occupied by wood in images generated using the capacitance sensor’s tomographic mode. Testsmore » were made on 109 groups of wood chips ranging in moisture content from 14% to 120% (dry basis) and wet weight of 280 to 1100 g. Sixty groups were randomly selected as a calibration set, and the remaining were used for validation of the sensor’s performance. For the combined capacitance/force transducer system, root mean square errors of prediction (RMSEP) for wet mass flow and moisture content were 13.42% and 16.61%, respectively. RMSEP using the combined volumetric mass flow/capacitance sensor for dry mass flow and moisture content were 22.89% and 24.16%, respectively. Either of the approaches was concluded to be feasible for prediction of moisture content in pine chip flows, but combining the impact and capacitance sensors was easier to implement. As a result, in situations where flows could not be impeded, however, the tomographic approach would likely be more useful.« less