Temperature distribution during conventional and microwave wood heating

Zielonka, Piotr; Gierlik, É.

doi:10.1007/s001070050051

Cited by 33 publications

(19 citation statements)

References 3 publications

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“…This agrees with information presented by Van Remmen et al, (1996) and Zielonka and Gierlik (1999). When the thickness of the material is small, the maximum temperature occurs in the center of the heated slab because the "subsurface" temperature peaks coincide with the center of the slab.…”

Section: Microwave Heating In Rectangular Coordinatessupporting

confidence: 92%

“…1 (a) shows the predicted temperature distribution in a rectangular block of agar gel heated in a multi-mode microwave oven. This distribution agrees with thermal images and other data found in the literature (Van Remmen et al, 1996;Zielonka & Gierlik, 1999). Agar gel is a useful medium for identifying hot spots during microwave heating because it melts at the hot spots, but remains solid where the temperature of the object is lower than its melting temperature.…”

Section: Multi-dimensional Solutionssupporting

confidence: 91%

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Microwave Heating in Moist Materials

Brodie¹

2011

Advances in Induction and Microwave Heating of Mineral and Organic Materials

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Section: Microwave Heating In Rectangular Coordinatessupporting

confidence: 92%

Section: Multi-dimensional Solutionssupporting

confidence: 91%

Microwave Heating in Moist Materials

Brodie¹

2011

Advances in Induction and Microwave Heating of Mineral and Organic Materials

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“…[1,2] During the past 50 years, research has been conducted to investigate microwave drying of solid wood products and veneer. [1][2][3][4][5][6][7][8][9][10] Microwave heating involves placing wood products in a microwave 35 field, which is oscillating at hyper-frequency (300 MHz-300 GHz). The wood products could be quickly heated to the boiling point of water throughout their whole volumes.…”

Section: Introductionmentioning

confidence: 99%

“…Harris and Taras [8] compared moisture content distribution, stress distribution, and shrinkage of red 45 oak lumbers dried in a radio-frequency=vacuum drying process with these in the conventional kiln process. Zielonka [9,10] provided the mathe matical equations of the moisture content and temperature versus heating time for drying of spruce lumbers. No reports have been found in the literature that investigates the temperature and moisture distributions 50 in wood strands or flakes during microwave drying.…”

Section: Introductionmentioning

confidence: 99%

Microwave Drying of Wood Strands

Wang

Cai

2005

Drying Technology

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Characteristics of microwave drying of wood strands with different initial moisture contents and geometries were investigated using a commercial 10 small microwave oven under different power inputs. Temperature and moisture changes along with the drying efficiency were examined at different drying scenar ios. Extractives were analyzed using gas chromatography=mass spectrometry (GC=MS). The results showed that the microwave drying process consisted of three distinct periods (warm-up period, evaporation period, and heating-up per-15 iod) during which the temperature, moisture change, and drying efficiency could vary. Most of the extractives were remnant during microwave drying. It was observed that with proper selections of power input, weight of drying material, and drying time, microwave drying could increase the drying rate, save up to 50% of energy consumption, and decrease volatile organic compound (VOC) 20 emissions when compared with the conventional drying method.

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“…Microwave heating is one of the fastest and most effective physical methods for subsequent treatment of attacked woodwork. Its advantage lies in the fact that, unlike the conventional methods, wood is heated from the inside out (Zielonka and Gierlik, 1999). However, due to possible adverse effects, treatment of wood with microwaves is still of limited use.…”

Section: Introduction Uvodmentioning

confidence: 99%

Effect of temperature on the eradication of house longhorn beetle larvae in wood by microwave treatment

Klinc¹,

Pohleven²

2017

Acta Silvae et Ligni

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In repressive protection of cultural/historical woodwork, microwaves have many advantages over conventional heating. The research's objective was to examine conditions for eradication of house longhorn beetle larvae (Hylotrupes bajulus) in spruce wood (Picea abies) using microwaves. Larvae, inserted at different depths of spruce blocks containing 12% and 42% of moisture, were exposed to microwaves. Two apparatuses were used; a 750W commercial microwave chamber and a newly developed horn antenna microwave device with the power of 800W and a frequency of 2.45GHz, for targeted radiation. We discovered that the inner part of wood warmed up quicker than the surface heated to 65°C. For successful suppression larvae in the wood need to be heated to 54.5°C, for 10 seconds. The necessary exposure time increases with increasing thickness of wood. The surface of wood containing more moisture is heated quicker, but increased moisture slows down the penetration of microwaves into the wood specimen. Therefore, larvae in wood of lower moisture (12%) died faster, both those 20mm under surface (1.5min) and those at 130 mm of depth (10.5min).Key words: wooden objects, repressive wood protection, microwaves, heating, wood moisture content, house longhorn beetle -Hylotrupes bajulus IZVLEČEKMikrovalovi imajo pri represivni zaščiti kulturnozgodovinskih lesenih predmetov veliko prednosti pred konvencionalnim gretjem. Namen raziskave je preučiti pogoje uničenja larv hišnega kozlička (Hylotrupes bajulus) v smrekovem lesu (Picea abies) z uporabo mikrovalov. Mikrovalovom smo izpostavili larve, vstavljene različno globoko v smrekove blokce z 12 % in 42 % vlažnostjo lesa. Uporabili smo komercialno mikrovalovno komoro z močjo 750 W in razvito mikrovalovno napravo z rogasto anteno moči 800 W s frekvenco 2,45 GHz, za usmerjeno obsevanje. Ugotovili smo, da se notranjost lesa bolj segreva kot površina, ki smo jo segrevali do 65 °C. Za uspešno zatiranje je treba larvo v lesu segreti na temperaturo 54,5 °C za 10 sekund. Z debelino lesa se podaljšuje čas izpostavitve. Vlažnejši les se hitreje segreva, vendar mikrovalovi počasneje prodirajo skozi volumen. Zato so larve v lesu z nižjo vlažnostjo (12 %) hitreje poginile, tako 20 mm pod površino lesa (1,5 minute) kot v tudi globini 130 mm (10,5 minute).Ključne besede: leseni predmeti, represivna zaščita lesa, mikrovalovi, segrevanje, vlažnost lesa, hišni kozliček -Hylotrupes bajulus GDK 413.3+453(045)=111 Prispelo / Received:

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Temperature distribution during conventional and microwave wood heating

Cited by 33 publications

References 3 publications

Microwave Heating in Moist Materials

Microwave Heating in Moist Materials

Microwave Drying of Wood Strands

Effect of temperature on the eradication of house longhorn beetle larvae in wood by microwave treatment

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