Abstract- There are many industries which make
use of dryers. Such as chemical industry, clothes industry, food industry, etc.
Drying plays a vital role in these industries. Humidity has an important part
in drying process, as the relative humidity is inversely proportional to the
drying rate i.e. lower the humidity faster the drying process. Also high
humidity may result in spoiling of products. Main purpose of our project is to
keep humidity low, which will result in faster drying. Every dryer have flaps
basically made to control the humidity. They’re opened or closed manually. Our
project helps to open or close these flaps automatically depending on the
humidity inside the dryer.
Stepper Motor, Humidity Sensor, Humidity, Rotation, Dryer
Drying is defined as
the application of heat under controlled conditions, to remove the water
present in foods, chemicals, etc. by evaporation to yield dried solid products. In order to
achieve optimum performance of a food dryer, we need to keep in check the
humidity surrounding the dryer before and during the drying process. The main
purpose of drying is to extend the shelf-life of foods by reducing their
in-water activity. This is a
very crucial requirement in
certain industries. So, in order to achieve this, it is important that the
operating conditions are correctly specified and that the dryer is fitted with
an effective control system. The operating conditions will naturally influence
the quality of the dried product.
Adequate control of the humidity inside a
dryer is important for maintaining the production of consistent, high quality
product at least cost. Dryers have a life in service of 20 years and often
more. In consequence, it is common for them to be used to dry several different
products during their lifetimes.
II. LITERATURE REVIEW
Relative humidity is a
measure of the current amount of water vapor in the air relative to the total
amount of water vapor that can exist in the air at its current temperature, and
is expressed as a percentage. A relative humidity of 100% means the air cannot
contain any more water vapor at that temperature, whereas a relative humidity
of 50% means that the air only has only half as much water vapor as it can hold
at the current temperature.
Drying simply means removal
of liquid remaining on the part as a result of the cleaning and rinsing
process. This is accomplished in one of two ways. One is physical
removal. Physical removal of liquids may be as simple as placing the part
in an orientation that will allow liquid to drain due to gravity. Or, it
may involve using a blast of air or some other means such as centrifugal
force or vibration to cause removal of liquid from the part being
dried. The other (and probably more common) method of drying is
evaporation. Evaporation of liquid is usually enhanced through the use of
heat and the movement of air over the parts.
The rate of
evaporation is actually driven by the relative humidity to a greater degree
than by temperature. But, in fact, the two are inter-related.
As the temperature of air is increased, it can absorb more liquid and,
therefore, the relative humidity is decreased. Lower relative humidity
promotes faster drying. The following chart and graph which both
show essentially the same data are very interesting.
The next graph (Figure 3)
shows that as the temperature of air increases, the amount of water required to
saturate it increases exponentially. A few degrees of increase in temperature
has an increasingly large effect on the saturation point.
From the information we
gathered, we decided to conduct experiment. We visited food industry; there we observed
that air drying is widely used in the drying process. We set up a humidity
sensor inside a dryer and took readings overnight throughout the drying
process. From this we came to the conclusion that humidity is inversely proportional
to drying that means at low humidity drying is faster. Another important
observation came under our notice that humidity is not constant. Sometimes it
is high sometimes it is low. We have to maintain constant low humidity.
The objective of a
project is to control humidity and improve speed of drying.
The humidity can be
controlled by opening and closing of the flaps. So we decided to define sets of
ranges of humidity. Each range given an angle at which flaps should be opened.
microcontroller is the heart of the device. The input to the controller are the
humidity values which are provided through the humidity sensor. Humidity sensor
is placed inside the dryer in order to keep track of humidity inside.
Microcontroller processes the data and then gives appropriate command to the
motor driver circuit which drives the motor for the motion of flaps accordingly.
The rotation of the flaps depends on the range in which particular humidity
lies. Rotation flaps allow us to maintain the humidity inside the dryer and
thus prevent spoiling of the goods.
ATMEGA 328P microcontroller- Controls the
overall working of the device.
Humidity sensor, used to measure humidity and temperature.
Motor- Used for rotating motion of the flaps.
Motor driver circuit, used to drive the motor.
Module- Mobile communication services.
Step 1: Define input and output pins
for humidity sensor and stepper motor.
Step 2: Define stepper motor
sequence for clockwise and anticlockwise movement.
Step 3: Define a variable humidity
and temperature to store value of humidity and temperature respectively.
Step 4: Take reading from surrounding
(humidity) and store it in humidity.
Step 5: Define ranges of humidity
(No particular number of steps).
Step 6: Define an angle for an each
set of which we want the flaps to be open at.
Step 7: Check the value in humidity
lies in which range.
Step 8: According instruct stepper
motor to rotate at that angle and direction.
Step 9: Go
to step 4.
a swirl element at the entrance of the drying chamber to give rotation effect
to the air and fixing bended sheet strips inside the chamber to direct the
collector tilt angle length and breadth to a certain limit to raise the
temperature of the dryer.
dehumidifier before the drying chamber for removing moisture in the air to
improve the drying rate.
in the performance of the dryers could lead to the performance enhancement of
the dryer for use in small scale business enterprises.
network model can be used to predict the potential of the dryer for different
locations and can also be used in a predictive optimal control algorithm.
have so far seen that humidity play a very important role in the drying
industry which further decides the quality of the products. We have made a
device which controls the humidity level inside the dryer by automatic rotation
of flaps. This rotation depends on current humidity which is processed by the
We are deeply indebted to our respected co-guide
of S4S TECHNOLOGIES, Mr. Swapnil
Kokate, for giving us this valuable opportunity to do this project and we
express our hearty thanks to them for their assistance without which it would
have been difficult in finishing this project successfully.
Origins of Food Preservation.” University
of Georgia, National Centre for Home Food Preservation. Accessed June 2011.
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