AN ANALYSIS OF HEATING UNIFORMITY IN WOOD HIGH-FREQUENCY DRYING
Keywords:High frequency heating, wood drying, temperature field simulation model, heating uniformity
The high-frequency heating temperature field simulation model was built using finite element method and validated by experiments. Under the premise of ensuring model accuracy, the model parameters (plate spacing and area, wood dielectric constant, stack length and width, and heating time) were individually varied to assess the impact of these parameters on wood heating uniformity. The results showed the following: 1) The model has good accuracy as verified by experiments. 2) In the thickness direction, the middle layer temperature was higher than the upper and lower surface temperatures; in the length and width directions, the center temperature was lower than those of both ends and both sides, and the temperature at the corners was the highest. 3) The smaller the distance between the plates, the better the heating uniformity; with the plate area increasing, the heating uniformity first increased and then decreased; the smaller the wood dielectric constant, the better the heating uniformity; as the continuous heating time increased, the heating uniformity first decreased, then increased, and then again decreased; as the length and width of the stack increased, the heating uniformity decreased first, then increased, and then again decreased; when they were the same size as the plate, the heating uniformity was the best.
Ai MY (2016) Practice and application of wood drying.
Chemical Industry Press, Beijing, China. 311 pp.
Alfaifi B, Tang J, Jiao Y, Wang S, Rasco B, Jiao S, Sablani S
(2014) Radio frequency disinfestation treatments for
dried fruit: Model development and validation. J Food Eng
Cai Y, Hayashi K, Sugimori M(2001) Three-dimensional
measurement of temperature distribution in wood during
radio-frequency/vacuum drying. Mokuzai Gakkaishi
Choi CTM, Konrad A (1991) Finite element modeling of the
RF heating process. IEEE Trans Magn 27(5):4227-4230.
Guo W, Fei BH, Chen EL (2009) Wood structural construction
industry in China. China Wood Ind 23:19-22.
Huang R, Wu Y, Zhao Y, Lu J, Jiang J, Chen Z (2013) Factors
affecting the temperature increasing rate in wood during radiofrequency heating. Dry Technol 31(2):246-252.
Huang Z, Zhu H, Yan R, Wang S (2015) Simulation and
prediction of radio frequency heating in dry soybeans.
Biosyst Eng 129:34-47.
Jia XR (2015) Radio frequency vacuum drying of squareedged
timber with pith: Mathematical model and numerical
analysis. PhD thesis, Northeast Forestry University,
Harbin, IN. 33 pp.
Jiao Y, Tang J, Wang S (2014) A new strategy to improve
heating uniformity of low moisture foods in radio
frequency treatment for pathogen control. J Food Eng
Lee NH, Li C, Zhao XF, Park MJ (2010) Effect of pretreatment
with high temperature and low humidity on drying time and prevention of checking during radiofrequency/vacuum drying of Japanese cedar pillar. J Wood Sci 56(1):19-24.
Li XJ (2009) Characteristics of microwave vacuum drying of
wood and mechanism of thermal and mass transfer. China
Environmental Science Press, Beijing, China. 65 pp.
Li XJ, Sun WS, Zhou T (2012) Mathematical modeling of
temperature profiles in wood during microwave heating.
Sci Sil Sin 48:117-121.
Li XJ, Zhang BG, Li WJ (2008) Mathematical modeling
of wood microwave-vacuum drying. J Beijing For Univ
Liu HH, Yang L, Cai Y, Hayashi K, Li K (2014) Distribution
and variation of pressure and temperature in wood cross
section during radio-frequency vacuum (RF/V) drying.
Liu HH, Yang L, Wu ZH (2017) Effect of vacuum drying set
and radio-frequency/vacuum drying on wood quality.
Dongbei Linye Daxue Xuebao 45(2):61-64.
Lu J, Xu J, Wu Y (2015) Climatic signals in wood property
variables of Picea crassifolia. Wood Fiber Sci 47(2):
Lv YY, Fu ZY, Song TY (2015) The effect of radio-frequent
heating on water migration for boxed-heart larch lumber.
J Anhui Agric Sci 2:148-151.
Rabidin ZA, Seng GK, Wahab MJA (2017) Characteristics of
Timbers Dried Using Kiln Drying and Radio Frequency-
Vacuum Drying Systems. MATEC Web of Conferences.
EDP Sciences 108: 10001.
Simpson WT (2004) Two-dimensional heat flow analysis
applied to heat sterilization of ponderosa pine and douglasfir
square timbers. Wood Fiber Sci 36(3):459-464.
Wang Y (2013) Study on control method of high-frequency
vacuum combined wood drying. MS thesis, Northeast
Forestry University, Harbin, IN. 10 pp.
Xiao H (2009) Characteristics of heat and mass transfer in
wood during radio-frequency vacuum drying. MS thesis,
Northeast Forestry University, Harbin, IN. 31 pp.
Zhao JY, Fu ZY, Jia XR, Cai YC (2015a) Mathematical
model to predict preheating time and temperature profile in
boxed-heart square timber during preheating. Wood Fiber
Zhao JY, Fu ZY, Jia XR, Cai YC (2015b) Modeling conventional
drying of wood: Inclusion of a moving evaporation
interface. Dry Technol 34(5):530-538.
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.