development of industrial prototype of microwave ...thep-center.org/upload02/pptmod1.pdf ·...

Development of industrial prototype

of microwave technology for drying

of agricultural products

M. Nisoa and Pr. Kerdtongmee

Plasma technology for agricultural applications

research laboratory

School of Science, Walailak University

Topics

• Microwave interaction with bio-materials

• Applications of microwave heating

• Advantages of microwave drying

• Laboratory prototype system

• Small industrial prototypes

Microwave and its interaction with bio-materials

Maxwell’s equations𝜵 × 𝑬 = −

𝜕𝑩

𝜕𝑡

𝜵 × 𝑯 = 𝑱 +𝜕(𝜀𝑬)

𝜕𝑡

Microwave and its interaction with bio-materials

Dielectric heating

materials

Dipole molecules

j

Selective heating

Applications of microwave heating

Microwave

Heating

T < 100o C

T < 180o C

T < 60o C

T > 300o C

Cooking

Processing of materials

Extraction

Drying

Advantages of microwave drying

• Alternative use during rainy season

• Fast and energy efficiency

• Preserve good qualities

• Bulk heating


Fast and energy efficiency

Dried materials Methods SEC(MJ/kg)

Okara (Product from

soymilk) Jet spouted bed with hot air 1.6 – 4.1

vegetable starch solutions

Jet spouted bed with hot air 3 - 5

Rice grain Fluidized-bed drying with hot air 4.7-7.0

Barley FIR – convection 12.1 – 20.3

Oion Osmo – convective drying 7.2 – 12.6

Carrot Microwave 0.4 – 1.4

Pumpkin Microwave – air drying 0.1 – 0.6

Specific energy consumption SEC =Total energy supplied in drying process

Amount of water removed during dryingkJ/kg


Preserve good qualities (Leaves of Coccinia grandis)

Fresh

1 h microwave drying

8 h solar drying

Laboratory prototype system


Control of microwave power


Control of microwave power

Power efficiency is about 67%


Door’s choke configuration for leakage suppression


Typical drying curve


Nonlinear drying effect

Run away heating


Food chemistry

e

a

b

c

d

0.0

0.5

1.0

1.5

2.0

C 10 W 15 W 20 W 25 W

Fre

e fa

tty

aci

d c

on

ten

t (g

/100 g

lip

id)


Sensory test

123456789

Colour

Appear

ance

Odor

Hardnes

sTas

teTex

ture

Overall

liking

Attributes

Scale

(1-9

)

Microwave

Sun dry

Small industrial prototype

Multi-magnetron

And power controlMulti-modes cavity

Leakage’s shielding


1

2

3

4

5

6

Uniformity of the microwave field


Uniformity of the microwave field

Capacity 60×70×160 cm3

Microwave power 4.8 kW, 6 magnetrons


Drying of graviola leaf


Drying of cardamom


Drying of coix seed


Drying of surimi


Drying of salmon fish’s skin


Drying of fish


Thawing frozen fishes


Conveyor microwave food processing


Weevill control in rubber wood for children’s toys

ขนาด: ไม ้1000 kg/10นาทีก าลงั: 72 kW (50 magnetrons)



Power 72 kWCapacity: 200 cm x 200 cm x 200 cm

Treatment 1 ton within 20 minutes



Science - Manager Online - ฆ่ามอดในของเล่นไม้ยางพาราด้วยไมโครเวฟ.pdf

Science - Manager Online - ฆ่ามอดในของเล่นไม้ยางพาราด้วยไมโครเวฟ.pdf


Drying of rubber block STR20

Petty patent

1.ไดรั้บการคุม้ครองอนุสิทธิบตัรเร่ือง เคร่ืองใหค้วามร้อนเมลามีนก่อนข้ึนรูป (Preheat)ดว้ยคล่ืนไมโครเวฟ

Petty patent

2.ยืน่จดอนุสิทธิบตัรเร่ือง เคร่ืองใหค้วามร้อนวสัดุผสมยางดว้ยคล่ืนไมโครเวฟ

Petty patent

3. ยืน่จดอนุสิทธิบตัรเร่ือง เคร่ืองอบลูกเดือนก่อนการแปรรูปดว้ยคล่ืนไมโครเวฟ

Patent

4. ยืน่จดสิทธิบตัรเร่ือง เคร่ืองอบรังนกแอ่นความดนัต ่าดว้ยคล่ืนไมโครเวฟ

การถ่ายทอดเทคโนโลยใีหภ้าคเอกชนในเชิงพานิชย์

1. การถ่ายทอดเทคโนโลยกีารอบแหง้และควบคุมก าลงัไมโครเวฟ ใหก้บั ภาคเอกชน บ.ไซโนเทค จ าจดั วงเงิน 600,000 บาท ระยะเวลา 5 ปี

การถ่ายทอดเทคโนโลยใีหภ้าคเอกชนในเชิงพานิชย์

2. การถ่ายทอดเทคโนโลยีการควบคุมก าลังไมโครเวฟ ให้กับ ภาคเอกชน บ.ประดู่ เอ็นจเินียริ่ง จ าจัด วงเงิน 450,000 บาท++ ระยะเวลา 5 ปี

Thank you very much

Questions and Comments

The 20th International Drying Symposium (IDS 2016)

Gifu, JAPAN, 7-10 August 2016

DEVELOPMENT OF INDUSTRIAL PROTOTYPE OF MICROWAVE

TECHNOLOGY FOR DRYING OF AGRICULTURAL PRODUCTS

Mutorlep NISOA1* and Priwan KERDTONGMEE2

1Plasma agricultural application research laboratory, Walailak University

222 Taiburi, Tasala, Nakhon-si-thammarat,80160, Thailand

Tel.:+66-75-672-006, E-mail: [email protected]

2Center for scientific and technological equipment, Walailak University

222 Taiburi, Tasala, Nakhon-si-thammarat, Thailand, 80161

Tel.:+66-75-673-248, E-mail: [email protected]

Abstract: The conventional method for drying agricultural products, such as fish, chili,

fruits and herbs, is by hot air circulation. Normally, it will take long time and high energy

consumption for finishing products. An alternative drying method by using microwave

energy has been developed at Walailak university. Because of strong interaction between

dielectric dipoles of water molecules and microwave field, the drying time of the

agricultural products can be reduced drastically. We have developed a novel microwave

heating system for the efficient drying of the products. The system utilizes a phase control

high-voltage power supply so that the magnetron can generate a microwave field

continuously, and its output power can be adjusted for each magnetron. Door chokes have

been carefully investigated by simulation and experiment for safety of microwave

leakage. The experimental results reveal that heat produced by the microwave system

causes evaporation of moisture from the products at low temperature, making it possible

to produce high quality dried foods and herbs. The prototypes of various microwave

drying systems for different agricultural products have been developed and used by local

industries and communities. These prototypes have high-potential for foods and herbs

business in the future.

Keywords: agricultural products, microwave drying, dielectric dipole, industrial prototype,

Door choke

INTRODUCTION

The conventional drying process of agricultural

products around the world utilizes heat from the sun

in the dry season or heat from burning wood or gas

during the rainy season as energy sources. Such

natural energy sources unfortunately require long

period of time for drying, and may lead to

contamination from dust and pathogens.

Consequently, it is very difficult to control the

quality of the dried products. Microwave technology,

developed for RADAR application in the 2nd World

War: (ET Thostenson and TW Chou,1999), has long

been known as an effective energy source for the

drying of agricultural products: (JM Osepchuk,

2002). Microwaves are electromagnetic waves with a

frequency ranging from 300 MHz to 300 GHz.

Typically, microwaves at 2.45 GHz are used for

processing food products because these materials

contain a lot of water molecules which can absorb

energy from microwave field very effectively: (AK

Datta, E Sun and A Solis, 1995). The dried products

can preserve good qualities of nutrition, colour,

texture and aroma. Although microwave drying has

shown proven advantage, utilization of microwave

drying for businesses, industry or small and medium-

sized enterprises, are quite limited: (M. Zhang, J.

Tang, A.S. Mujumdar and S. Wang, 2006). To

promote microwave drying technology, scaling up of

the microwave oven, as shown in Fig. 1, is necessary.

In the paper we will we will present the development

of industrial prototype of microwave technology for

drying of agricultural products.

C-4-3

Fig. 1. Scaling up of the microwave oven

DEVELOPMENT OF INDUSRTRIAL

PROTOTYPE

Fig. 2. Drawing of the industrial prototype

microwave drying system

The industrial prototype microwave drying system

shown in Fig. 2 has dimension of 60×70×160 cm3,

powered by six magnetrons, mounted vertically on

the same cavity surface. There are twenty rotatable

trays for placing agricultural products. The picture of

the prototype is shown in Fig. 3.

Fig. 3. Picture of the prototype

Phase control high-voltage power supply

Fig. 4. Diagram of phase controlled magnetron

circuit

Fig. 5. Dependence of microwave power on phase

angle

Microwave oven utilizes on-off power control

scheme for delivering microwave energy to the loads.

During the on duration whereas maximum

microwave power is radiated, serious damages, such

as burning, run away heating, arcing, may occur to

the materials. It is quite difficult to obtain high-

quality dried product by on-off microwave oven.

Phase control microwave power has advantage of

adjustable power for suitable drying of various kinds

of agricultural products. Therefore dried product will

preserve its original properties. The diagram of the

phase controlled circuit to power magnetron is shown

in Fig. 4. Triac is a power electronic device that will

function as switch to control the flow of electric

current. Therefore variable waveform, depending on

the phase angle, will supply to the high-voltage(HV)

transformer which resulted in different microwave

power as shown in Fig. 5. The microwave power is

generated by magnetron when biasing by high-

voltage and heating its filament. The threshold high-

voltage is about 3.5 kV for minimum microwave

power output, whereas maximum high-voltage is

about 7 kV, to generate highest microwave power

about 800 W. Each magnetron is separately

controlled to generate microwave power.

Cavity Cavity

Magnetrons

Trays

y

Multi-modes, multi-magnetron cavity

Fig. 6. Distribution of microwave power in the cavity

The uniformity of the microwave power in the cavity

is shown in Fig. 6. The microwave power density is

measured by using water load placed on the trays

along the vertical y axis.

Performance of the system

Fig. 7. Diagram of phase controlled magnetron

circuit

To evaluate the drying performance of the system,

fresh leaves of Coccinia grandis are placed on the

each tray as shown in Fig. 7 to heat by microwave

radiation. The experiments show that drying of 400

grams of Coccinia grandis take only about 1 hour as

shown in Fig. 8 and Fig. 9.

Fig. 8. Decreasing of mass of Coccinia grandis

leaves on time

Fig. 9. Drying rate of Coccinia grandis leaves at

different times.

Microwave power can be appropriately chosen to

preserve their original color. The color is better

preserved than color of those drying by sunlight and

by on-off power control household microwave oven

as shown in Fig. 10 and Fig. 11

Fig. 10. Dried leaves obtained by on-off control of

microwave power.

Fig. 11. Dried leaves obtained by phase control of

microwave power.

CONCLUSIONS

The experimental results reveal that heat produced by

the microwave system causes evaporation of

moisture from the products at low temperature,

making it possible to produce high quality dried

foods and herbs. The prototypes of various

microwave drying systems for different agricultural

products have been developed and used by local

industries and communities. These prototypes have

high-potential for foods and herbs business in the

future.

ACKNOWLEDGEMENTS

We would to Thailand Excellent center in

Physics(ThEP) and the institute of research and

development, Walailak University, for their funding

support.

REFERENCES

Datta, A.K.; Sun, E.; Solis, A. Food Dielectric

Property Data and Their Composition-Based

Prediction: Engineering Properties of Foods;

Marcel Dekker Inc.; New York, 1995, p. 457-494.

Osepchuk, J.M. Microwave power applications.

IEEE Transactions 2002, 50, 975-985 .

Thostenson, E.T.; Chou, T.W. Microwave

processing: fundamentals and applications.

Composites: Part A 1999. 30, 1055-1071.

Zhang, M.; Tang, J.; Mujumdar, A.S.; Wang, S.

Trends in microwave related drying of fruits and

vegetables. Trends in Food Science &

Technology 2006, 17, 524-534

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