Effect of Air Velocity and Thickness to Drying Rate and Quality

Temulawak (Curcum Xanthorrhiza Roxb) using Combination Solar

Moleculer Sieve Dryer

R. Hasibuan

, Yunal Maudi Pane

and Said Hanief

Department of Chemical Engineering,Universitas Sumatera Utara, Medan, Indonesia

Keywords: Curcuminoid, Combination solar moleculer sieve dryer.

Abstract: Temulawak (Curcuma xanthorrhiza Roxb) contains an active ingredient called curcuminoid which is a

substance that has many benefits in the health field. The active ingredient of high heat sensitive curcuminoids

for the dryer temperature uses relatively moderate temperatures and with low RH. This research using

combination solar molecular sieve, where the air from environment is first passed through a molecular sieve

box and then passed to the collector and then to the drying chamber in contact with the dried material. The

operating air speed conditions to the dried material varied 1,2, and 3m/s and thickness of varied 25, 50 and

75mm. Reserch aims to study and obtain the best drying process and effect operating conditions on dry

temuawak quality. Drying is done at 8:00 am to 4:00 pm. with an initial moisture content of 85%. Dry

Temulawak was analyzed according to parameters of SNI 8171: 2015. The results showed that the best air

velocity at 3 m/s with a thickness of 25mm obtained the highest drying rate of 0.226gr/cm

hour. The best

quality of dry ginger is in the condition of drying 2 m/s with a thickness of 25mm produced dry ginger with

moisture content below 10% and curcuminoid value of 1,46%.

1 INTRODUCTION

Temulawak (Temulawak xanthorrhiza) is one of

herbal medicinal plants that have chemical content of

curcuminoid which is efficacious in the health as anti-

cholesterol, anti-oxidant, overcoming of liver disease,

overcoming of kidney disorder, smooth digestion,

nourish the heart and others.

The active ingredient of curcuminoid that is

contained in temulawak can be lost during post-

harvest processing, if farmers do not understand how

to overcome them. One important factor in

maintaining the active ingredient in temulawak is the

drying process. The drying technique that has been

carried out by farmers, especially in developing

countries, is by conventional drying which is directly

under the sun. In this technique, drying cannot

guarantee quality of uniformity due to changing

weather, temperature too high at midday, and

materials that are dried in the open are not guaranteed

cleanliness (Hasibuan, 2009) (Dina l, 2015).

Solar energy that is abundant on the face of the

earth especially in tropical countries is an infinite

wealth if managed properly. Indonesia is one of the

tropical countries with sunshine throughout the year.

This sunlight can be used as a source of energy which

is very potential to dry agricultural products. But

tropical countries have high air humidity (RH) so the

drying time is longer than 1 week. Long drying times

can damage materials and remove the active

ingredients in the materials. Therefore a drying

system is needed that can dry the material at moderate

and low RH conditions. Using a drying system

combination of solar energy and molecular sieve can

reduce the RH content of the environment air with a

moderate drying temperature so it will not damage the

active material in the dried material..

2 EXPERIMENTAL

2.1 Material and Equipment

This study used fresh temulawak obtained from the

town markets. Silica gel was selected as the

molecular sieve for the drying process due to

economic reason. The equipments used for the

drying process of temulawak included a metal fan (Φ

Hasibuan, R., Pane, Y. and Hanief, S.

Effect of Air Velocity and Thickness to Drying Rate and Quality Temulawak (Curcum Xanthorrhiza Roxb) using Combination Solar Moleculer Sieve Dryer.

DOI: 10.5220/0010103503890394

In Proceedings of the International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches (ICOSTEERR 2018) - Research in Industry 4.0, pages

389-394

ISBN: 978-989-758-449-7

389

30 cm) to conduct air to the molecular sieve, solar

collector and drying chamber. A humidity sensor or

hygrometer was used to measure sample humidity in

drying chamber, a thermocouple to measure

temperature, a stainless steel connector for

connecting the humidity sensor and temperature

sensor, a load cell for weighing temulawak and

coneccted to a controller and a data acquisition

system. The construct materials consisted of glass

plate to cover solar collector and desicator,

aluminum plates and iron frames for solar collector,

molecular sieve and drying chamber.

2.2 Design and Construction

The preliminary study consisted of 2 parts, i.e. (i) to

investigate reduce of moisture content and drying rate

and; (ii) to examine the quality of dried temulawak.

In order to design the drying system, it should be

noted that the integrated system of solar

Energy and molecular sieve applying dried air

for the drying process. The very low humid dried air

was produced by conducting the air from

atmosphere through a silica gel molecular sieve.

The solar energy will be converted to heat energy in

the solar collector. The heat will be applied to

remove water vapor from the humid air.

In the context of designing the drying system, the

drying unit consisted of three main parts, i.e. the

solar collector, the molecular sieve (desiccant) and

the drying chamber as shown in Fig.1 shows the

picture of the overall integrated solar drying –

molecular sieve system applied for drying

temulawak. The integrated solar drying – molecular

sieve system was installed on a roof of a 4

floor

building to receive direct sunlight across from

north to south to obtain

2.3 Maximum Sunlight Exposure

The solar collector is in line with the desiccant, while

the position of solar collector and desiccant is in a

slope of 20 – 30

with the horizontal line. As shown

in (Fig 2.1), there are drying plates on the upper part

of the drying chamber to place the harvested

temulawak to be dried.

In the morning, evening and night or in grey/rain

weather the drying medium only applies dried air

yielded by conducting the atmospheric air to the

silica gel molecular sieve (desiccant). The fan

conducted the air from the atmosphere through the

drying chamber. On the other hand, on a strong hot

day the accumulated heat energy in the solar collector

is used to heat the air from the atmosphere. At the

same time, the drying process was carried out because

the temperature in the drying chamber was elevated

due to incident light entered the drying chamber

passing through the upper part of the chamber. The

drying process of emulawak was escalated by the

dried air conducted from the silica gel molecular

sieve. The drying unit is provided by two exhausters

to conduct the air circulation. A PVC (poly vinyl

chloride) connector (Φ 1.5 in) is installed between

the solar connector and the molecular sieve, and the

other one between the molecular sieve and the drying

chamber.

In order to investigate r ed u c e moistur e

content and the drying rate, a series of

experiments was conducted by varying the speed of

fan rotation and the size of samples temulawak in

the drying chamber in two terms, i.e. (i) the

normalized moisture content vs. time and (ii) the

drying rate vs. time in dry basis.

Regarding the product quality, this study

examined the product of dried temulawak

encountered with the physical appearance and

chemical composition before and after the drying

process applying the designed integrated solar drying

– silica gel molecular sieve system.

2.4 Solar Collector

The solar collector (Fig 2.1) is a wood rectangular

box (200 cm x 60 cm x 30 cm) covered by an

aluminum plate. In the middle part of the solar

collector (a distance of 15 cm from bottom part), a

black aluminum plate (200 cm x 60 cm x 1 cm) was

placed to absorb light and converted it to heat. The

hot aluminum plate heated the air stream both in the

upper and lower parts. The upper part of the solar

collector is covered by a transparent glass plate (200

cm x 60 cm x 0.8 cm).

2.5 Molecular Sieve

The molecular sieve or desiccant (Fig 2.1) is a wood

rectangular box (25 cm x 20 cm) with aluminum

plates covered the outside and inside parts. The

inside aluminum plate was black painted and the

upper part covered by a transparent glass plate.

The desiccant (molecular sieve) consists of two

chambers where each chamber filled by kg silica gel

and alternating operated. The function of the

desiccant is to produce dried air.

ICOSTEERR 2018 - International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches

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2.6 Drying Chamber

The drying chamber (Fig 2.1) is made of an

aluminum plate (80 cm x 80 cm x 120 cm) in black

painted. There are 1 hole-trays placed inside the

drying chamber to put the temulawak samples. The

dried air was conducted from the bottom part aided

by a fan passing through the temulawak samples and

gone out via the upper part.

Figure 1: Scematic of Research Using Moleculer Sieve

Solar Dryer Combination with Desicator Position Before

Collector

Information figure: 1. Transparant glass 2. Solar

Collector 3. Drying Chamber 4. Load Cell 5.

Desicator 6. Panel Load Cell, RH & T 7. Fan 8.

Blower 9. Valve

3 RESULT AND DISCUSSION

Combination solar drying + molecular sieve with air

velocity of 1m/s, obtained environment air

temperature data ranges from 25.8C - 36C, relative

humidity (RH) ranges from 62.7% - 96.6%, and solar

radiation range from 51.9 watt/m

- 691.9 watt/m

. At

the air velocity of 2 m/s, obtained air environment

temperature ranges from 28.3C - 36.4C, relative

humidity (RH) ranges from 57% - 93.4%, and solar

radiation range from 81.9 watt/m

- 713,1 watt/m

. At

the air velocity of 3m/s, obtained environment air

temperature data ranges from 25.4C - 38.1C,

relative humidity (RH) ranges from 46.9% - 93%, and

solar radiation range from 106.9 watt/m

- 744.4

watt/m

. During solar drying + molecular sieve look

at the air temperature in the optimum drying chamber

reaching 55.0°C - 56.7°C at (11:00 - 13:00) am.

3.1 Drying Rate, Moisture Ratio and

Time

Moisture ratio and draying rate is projected as rate of

decline weight ingredient every 5 minutes or rate of

decline moisture content during the drying process.

In the drying processs is obtained by plot data

of moisture ratio and drying

ratee with time that can be seen on picture below :

(a)

(b)

(c)

(d)

Figure 2: (a) Moisture ratio vs Time with Air Velocity 3

m/s (b) Drying Rate vs Time with Air Velocity 3 m/s (c)

Effect of Air Velocity and Thickness to Drying Rate and Quality Temulawak (Curcum Xanthorrhiza Roxb) using Combination Solar

Moleculer Sieve Dryer

391

Moisture ratio vs Time with Thickness 25 mm (d) Drying

Rate vs Time Time with Thickness 25 mm.

On that picture can be seen that chart of Drying

rate and time is fluctuate. But overall can be seen that

on early drying rate is up and then decreases along

increasingly moisture content. Decreasing water

content explaines that water content in wet ingredient

is still potentially to evaporate at the end of drying. It

happens because during the drying processs , there is

a free water which more easy to evaporate at early

drying , and there is a water bound that is difficult to

move up to surface of ingredients, so rate evaporation

of water is getting more and more decrease

(Supriyono, 2003). When air velocity is 3 m / s and

the thickness is 25 mm, drying of water content and

drying rate decline very significant. This is affected

by steam that evaporates from ingredient is free water

but at air velocity is 1 m / s and thickness is 75 mm,

drying rate tends to be slower. This is caused by free

water that collides with other material components

thus making the rate of drying is slow. Drying in the

afternoon declines drying rate to be constant.

Declining weight in the afternoon not too significant

because in the afternoon tends to release bound water

. Drying is continue decrease until the drying processs

is done or curcuma has reached the equilibrium

moisture content.

Decreasing the value of MR (Moisture Ratio) is

affected by decline value moisture content of the

material during the drying processs . And decreasing

water content is affected by increase temperature air

dryer . Increasing temperature air drying reduces time

that required for reach every level ratio humidity

since the heat transfer processs in room drying

increases . Whereas , on high temperature ,

displacement of hot and mass will increase and

moisture content of the material will increasingly

reduced (Amanto l, 2015).

Based on the figure, the drying process shows

an increase of drying rate of materials where most of

the dryer air is used completely to evaporate water on

the surface of the material and begin to decrease as

the air temperature decreases but in the afternoon it

begins to decrease. This is because drying in the

afternoon tends to evaporate bound water.

From the average experiments that is done on

each variation, the drying rate fluctuates constantly.

This shows drying rate at high air velocity variations

and thinner material thickness is faster than variations

at low air velocity and large material thickness. This

is because the high air velocity makes the free water

content in the material is forced out and Nothing is

entangled in the material, if low air velocity makes

the water content in the material is difficult to get out

due to lack of encouragement and water tends to be

difficult to get out. The thickness of the material also

affects the drying rate if the material is thick then the

water is difficult to get out of the material because the

free water collide with other material components and

also the thin material makes the water will more

easily come out due to fewer material components.

The greater the air velocity used, the higher the drying

rate, and vice versa, and if the thickness of the

material is greater then the drying rate will be less and

vice versa, the use of desiccation and the role of

radiation intensity have a higher impact.

Drying rate will decrease along decline water

content during drying . The amount of water bound

will more reduce . Changing from the constant drying

rate to be decrease drying rate for different materials

will happen on different water content . The highest

drying rate happens on early drying with air velocity

is 3 m/s and thickness is of 25 with value 0,226

gr/cm

.jam.

3.2 Characteristic of Drying

Characteristics of drying is projected as drying rate to

moisture ratio during drying processs . In the drying

processs is obtained by plot of data drying rate with

moisture ratio that can be seen on picture below.

Figure 3: Moisture ratio vs Time (a) with Air Velocity

3 m/s (b) with Thickness 25 mm

There are 3 period drying , such as period of

drying rate increases, constant drying rateand period

of drying rate decreases .where on firts period

ICOSTEERR 2018 - International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches

392

happens a very important event , because on this

period, half of the drying processs, happens

(Fortienawati, and Melly Agustia, 2015)

Based on theory , characteristics curve on drying

curcuma uses combination solar dryer + molecular

sieve with variation air velocity and material

thickness already corresponding with theory Where

there are three period drying that is period of drying

rate increases, period of drying rate decreases, and

constant drying ratethat can be seen on curve at air

velocity is 3 m/s and thickness is 25 mm.

On picture can be seen that period of drying rate

increases up suddenly towards top curve ( rate drying

maximum ). On maximum drying rate, period of

constant drying rate should be seen because on this

stage , the surface of ingredient will always be wet ,

so drying rate will be constant . But period of constant

drying rate couldn’t be seen on all variation air

velocity. The highest points from curve characteristic

drying is maximum drying rate , which depends on

condition operation drying (at this point is air

velocity and material thickness).

Analysis Quality of Curcuma Zanthorrhiza is

done according to national standard in National

Research and Standardization Agency (BARISTAN).

Table 1:

Test quality result dry curcuma with thickness

25 mm

Air

Velocity,

m/s

Moist

ure

Content,

%, Max

Curcumin

oid Content,

%, Min

Ash

Content,

%, Min

1 11,7 0,71 5,46

2 8,0 1,46 5,32

3 3,4 0,6 5,32

Table 2:

Test quality result dry curcuma with

thickness 50 mm

Air

Velocity,

m/s

Moist

ure

Content,

%, Max

Curcumin

oid Content,

%, Min

Ash

Content,

%, Min

8,4 1,13 5,325

5,6 0,81 5,64

6,3 0,72 5,31

Table 3:

Test quality result dry curcuma with thickness

75 mm

Air

Velocity,

m/s

Moistur

e Content,

%, Max

Curcumin

oid Content,

%, Min

Ash

Content,

%, Min

15,9 1,48 5,47

16,8 1,64 5,38

12,5 0,99 5,67

From the table above, the result of dry

temulawak’s test using a dryer solar combination–

molecular sieve with variation in air velocity and

thickness of the material can be seen that the quality

of dried temulawak has a distinctive color, odor, and

taste according to fresh ginger. It means that there is

almost no significant change in physical properties

between fresh ginger and dried ginger (figure 3.4).

According to SNI temulawak is divided into 3

qualities, quality 1 curcuminoid content> 2%, quality

2 levels of curcuminoid 1-2%, quality 3 levels of

curcuminoid <1%. Curcuminoid level in this study is

consisted at two qualities, there are quality 2 and 3,

while quality 1 was not available because in this study

did not pay attention to temulawak varieties that is

used. Ginger was obtained from traditional markets

with any variety. Curcuminoid which is obtained at

high drying conditions at 3 m/s and a thickness at 25

mm produces smaller curcuminoid because air that

moving faster will increase the rate of evaporation of

water to the surface of the material more quickly and

the possibility of curcuminoid that follow vapor will

move rapidly to the material surface. However in

general, the dry temulawak in this study contains

curcuminoid in accordance with SNI. The best drying

conditions is with a drying air velocity at 2 m / s, a

thickness at 25 mm . It produces dry temulawak with

moisture content less than 10% and a curcuminoid

value 1.46%.

Figure 4: Wet and Dry Temulawak

4 CONCLUSIONS

This study showed that the designed integrated solar

drying – molecular sieve system has successfully

conducted the drying process of temulawak. Air

velocity and thickness of materials that affect drying

Effect of Air Velocity and Thickness to Drying Rate and Quality Temulawak (Curcum Xanthorrhiza Roxb) using Combination Solar

Moleculer Sieve Dryer

393

rate and quality of drying temulawak.The best air

velocity at 2 m/s with thickness 25 mm, produces dry

temulawak which has almost no significant change in

physical, color, smell and tasteDry temulawak with

the best drying conditions is air velocity 2 m/s and

thickness 25 mm produces temulawak with moisture

content < 10 % and curcuminoid value of 1,46 %.

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