1.

0 SUMMARY

The experimental study revolves around the drying process, a crucial aspect in
numerous manufacturing processes. The introduction emphasizes the diverse
requirements for drying in different industries, underscoring factors such as heat
sensitivity and material characteristics. The SOLTEQ Tray Drier serves as the
experimental platform, allowing exploration of fundamental drying principles and
associated challenges in Fluid Mechanics, Surface Chemistry, Solid Structure, and
Mass Heat Transfer. The drying process involves reaching a steady state, with
subsequent phases influencing the moisture content and temperature of the wet solid.
Detailed experimental procedures outline the startup, operation, and shutdown steps,
utilizing the SOLTEQ Tray Drier (Model: BP 772). Results and discussions prompt
researchers to delve into mass and energy balances, fostering a comprehensive
understanding of the drying dynamics.

2.0 OBJECTIVES

The objective of the experiments were to :

a) To conduct mass balance in the drying process.

b) To conduct energy balance in the drying process
c) To do a mass balance and energy balance in the drying process using :
- SOLTEQ Tray Drier (Model: BP 772)

3.0 INTRODUCTION AND THEORY

Drying is a critical process in numerous manufacturing operations, where the choice of
drying equipment is tailored to the specific material and process requirements. The SOLTEQ
Tray Drier (Model: BP772) serves as an experimental facility designed to investigate
fundamental principles of drying. The equipment facilitates the study of fluid mechanics,
surface chemistry, solid structure, and mass heat transfer, offering valuable insights into the
drying behaviours associated with diverse materials. The drying process involves the transfer
of liquid from a wet solid to an unsaturated gas phase, and the SOLTEQ Tray Drier provides
a platform for understanding the intricacies of this phenomenon. As drying significantly
influences the shape, colour, stability, and overall marketability of the final product, a
comprehensive exploration of drying behaviours becomes paramount.

Industrial dryer help remove moisture while keeping the material in good condition. In this
experiment, the SOLTEQ Tray Drier (Model: BP 772) is use to study drying under set
condition. The experiment look at how heat and moisture move, helping to understand air
flow, surface properties, and heat transfer.

When drying start, the wet material meets the drying air, which transfer heat and cause
moisture to evaporate. The system reach a steady state when the solid’s temperature stays the
same as the wet bulb temperature of the drying air. Drying happen in two stage: the constant
rate period, where moisture is removed quickly, and the falling rate period, where drying
slows as the material gets dry.

The SOLTEQ Tray Drier's operation involves air drawn through a mesh guard, passing over
electrically heated elements, and into the central section where trays of material are
suspended. The trays, mounted on a support frame with a digital balance, enable continuous
weight measurement. Wet and dry bulb temperatures are measured using an aspirated
psychrometer, providing critical data for understanding the drying process. The general
startup involves checks on switches, fan speed, heater operation, and balance functionality.
The experimental procedures encompass filling trays with dry sand, saturating it with water,
recording weights, and initiating the drying process by switching on the fan and heater. The
shutdown procedure involves removing the tray with dried material and switching off the fan,
heater, and power supply.

4.0 RESULT AND DATA

Weight of Empty Tray = 306.72 g

Weight of Dry Sand and Tray = 1199.65 g

Weight of Dry Sand = 892.93 g

Weight of Wet Sand and Tray = 1227.90 g

Weight of Wet Sand = 921.18 g

Air Velocity = 1.85 g

Weight of Water = 28.25g

Time Mass of Total Inlet Outlet

(min) Wet Sand Moisture
(g) Content,
XT
Dry Wet Dry Wet
Bulb Bulb Bulb Bulb
0 921.18 0.0316 41 35 42 34
5 915.88 0.0257 45 39 47 40
10 912.60 0.0220 48 42 48 45
15 909.88 0.0190 48 46 48 47
20 907.25 0.0160 49 48 49 48
25 904.80 0.0133 50 48 49 48
30 902.50 0.0107 50 49 49 48
35 900.70 0.0087 50 49 49 48
40 898.98 0.0068 50 49 49 48
45 897.28 0.0049 50 49 49 48
50 895.86 0.0033 50 49 49 49
55 894.50 0.0018 50 49 49 49
60 893.20 0.0003 50 49 49 49

Table 1 : Data Of Experiment

Time (min) Total Moisture Content, XT

0 0.0316
5 0.0257
10 0.0220
15 0.0190
20 0.0160
25 0.0133
30 0.0107
35 0.0087
 40 0.0068
45 0.0049
50 0.0033
55 0.0018
60 0.0003

Table 2 : Time Vs Moisture Content

Graph 1 : Time Vs Total Moisture Content, XT

5.0 DISCUSSION AND ANALYSIS

The aim of this experiment was to conduct mass balance and energy balance in drying
process and to compare the experimental results and the predicted results from software. The
process of drying plays an important role in industries, especially in the industry of food
processing. The application of the drying rate involves the large varieties of instant and
dehydrated foods that are available to the customer today. Drying may generally be described
as the process of reducing moisture on the product because of producing dry solids. In other
terms, it’s a process to remove water from the material as vapour by air by supplying heat to
wet feed. There are many types of drying method used in industries such as tray dryer, drum
dryer, spray dryer, freeze dryer and so on. Dryer that used in this experiment was tray dryer.
Tray dryer operates by passing hot air over the surface of a wet solid that is spread over trays
arranged in racks by circulation (Wiki Zero, n.d).

The experiment started by weighed the mass of the empty tray (306.72g), mass of the tray
with dry sand (892.93g) and the mass of the tray with sand which has been sprayed with 20g
of water (1227.90g). All the mass was recorded on the data above. The tray with wet sand
then inserted into the SOLTEQ Tray Drier (Model: BP 722) where the fan and heat were
switched on, the power was set to maximum, and the speed control was set to mid position.
The weight of tray was taken for every 5 minutes to calculate the weight loss of wet sand
after drying until it got the same amount as mass of dry sand. While the temperature of inlet
and outlet for dry bulb and wet bulb was taken for every 5 minutes by using psychrometer.

The mass of wet sand (excluding tray weight) was recorded every 5 minutes. Based on the
table 1, it shows that the mass of wet sand decreased as the time increased. This was due to
the heated of fresh air was directed to flow in a circulation form over the wet sand (Rajnikant,
2018). Thus, the water contained in the sand to undergo a process of evaporation. The process
stopped at the 60 minutes where the mass of wet same with the mass of dry sand, as shown in
table 1. This showed that the amount of water that contained in the wet sand had completely
removed.

This experiment also used psychrometer to measure the humidity of air and temperature
simultaneously by measurement of dry bulb temperature and wet bulb temperature from both
inlet and outlet for time interval of 10 minutes as shown at table 1. The psychrometer is an
instrument that counts the temperatures of both the wet-bulb and the dry-bulb. Two
thermometers are required to count these constraints. The relative humidity can be known
from the values obtained (Megadepot,2015). Dry bulb temperature is typically classified as
‘air temperature’ which is the air feature that most frequently used to refer the temperature of
the air. Meanwhile, wet Bulb temperature can be measured by using a thermometer with the
bulb wrapped in wet muslin. The wet bulb temperature is a temperature at which water
convert into air by the evaporation process adiabatically or also known as adiabatic saturation
temperature (CheggStudy, n.d). Based on the results, the temperature of wet bulb will always
be lower than the dry bulb due to the evaporating water which creates a cooling effect for
example, at 5 minutes the temperature of dry bulb was 45°C while temperature of wet bulb
was 39°C.

Based on the data obtained from the drying process experiment, the total moisture content
was calculated by using the formula of XT below

Thus, from table 1, graph of time against total moisture content, XT was constructed. From
the graph1, it shows total moisture content is indirectly proportional to time. In other terms,
the value of the total moisture content decreases when the time increases. The total moisture
content decreases due to the loss of water from the sand. In the process of drying in the
experiment, heat by air velocity at 1.85 m/s (heat travels through air) was applied to the sand
in the tray resulting inwater vapour produced and was carried away as humidity (Elert, 1998).

Mass Balance of drying process (non-reactive process):

Sand (SIO2)
Mass: 892.93
Mole = 892.93/60.09 g/mol

Dry Sand
water H20
Drying Mass : 921.18
mass : 28.25 g Mass Fraction :
892.93/892.93
mole = 28.25/18.01 g/mol
g/total
 Figure 1: Flowchart of Drying wetsand process

Based on figure above, the mass balance was conducted to describe the performance and
capacity of each unit process within the plant and how that performance affects other unit
processes. . The mass on the input stream that consists of wet sand and water was 892.93 g
and 28.25 g respectively. Meanwhile, the mass at output stream was 935.9g which was same
value as the initial mass of dry sand (before adding water). . Therefore, this showed that the
drying process takes place perfectly because the water has been completely removed from the
sand and causes the weight of the wet sand to be equal to the weight of the dry sand because
of the drying process. Thus, the mass fraction at output stream was 1.

6.0 RECOMMENDATIONS
To sum up, drying process experiment on wet sand was conducted to
observe how moisture content decreases over time and the results clearly
demonstrated a consistent reduction in total moisture content (Xt). It is
from an initial value of 0.0316 to 0.0003 along 60 minutes. This trend
represents a typical drying curve and proves the theoretical
understanding of drying mechanism.
The results clearly indicate that drying is a process that changes with time
and that moisture removal gradually loses importance over time, which
aligns well with mass and heat transfer theory in drying operations. From
the table of results, the weight of dry sand and tray is 1199.65 g, weight
of dry sand is 892.93g. After the sand is sprayed with water until it is
saturated, the weight of wet sand is 921.18g. The air velocity is equal to
1.85m/s. From table 1, the mass of wet sand was 902.50 at 30 minutes
until the value of mass is approaches to the origin mass of dry sand, which
is 893.20 at 60 minutes.
To improve the experimental reliability, use a more sensitive digital
balance for calibrating the instruments before collect the data. Also,
ensure constant airflow throughout the process would increase
measurement accuracy.
Overall, the experiment successfully achieves its objective, and the
recommended improvements can help enhance the accuracy for future
analysis.
7.0 REFERENCES/APPENDICIES
1. Keey, R. B. (2013). Drying: principles and practice (Vol. 13). Elsevier.
2. Parikh, D. M. (2014). Solids drying basics and applications. Chemical
Engineering, 121(4), 42-45.
3. Grau, R., Andres, A., & Barat, J. M. (2014). Principles of drying.
Handbook of fermented meat
and poultry, 31-38.
4. Van't Land, C. M. (2011). Drying in the process industry. John Wiley &
Sons.
5. Mujumdar, A. S., & Devahastin, S. (2000). Fundamental principles of
drying. Exergex, Brossard,
Canada, 1(1), 1-22.
6. Raghavan, G. V., Rennie, T. J., Sunjka, P. S., Orsat, V.,
Phaphuangwittayakul, W., & Terdtoon, P.
(2005). Overview of new techniques for drying biological materials with
emphasis on energy
aspects. Brazilian Journal of Chemical Engineering, 22, 195-201.
Appendices