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8/6/2019 Project Navitha
1/21
Petrogasoline Purity Tester
CONTENTS
Page No.
1. INTRODUCTION... 2
2. BLOCK DIAGRAM 4
3.BLOCK DESCRIPTION....5
4. THEORY & PRINCIPLE OF OPERATION. .6
5. CIRCUIT DIAGRAM... 8
6. CIRCUIT DESCRIPTION... 9
7. HARDWARE DETAILS..11
8. MICROCONTROLLER PROGRAM..19
9. CONCLUSION..
10.REFERENCES.
Dept. of Electronics & Communication Engg.(Stream:- M&TV Engg.) COLLEGE OF ENGINEERING
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Petrogasoline Purity Tester
I. INTRODUCTION.
Recent years have witnessed dramatic progress in the design
and development of fiber optic sensors as detection of chemical species is
important in many industrial and chemical processes in addition to
environmental control. Fiber optic sensors offer several advantages over
conventional chemical sensing systems, specifically immunity to
electromagnetic interference, possibility of distributed sensing over long
lengths of fiber and their capability for safe operation in hazardous
environments. Fiber optic chemical sensors include refractometric` sensors
and evanescent wave absorption sensors, more recently indicator mediated,
in which the evanescent field of guided light is absorbed by the chemical of
interest.
Adulteration of petroleum products especially petrol and diesel
has become a serious problem. Kerosene is the most important domestic fuel
for economically weaker sections of society and hence is heavily subsidized.
The large differences in the prices of petrol, diesel and kerosene, the easy
availability of kerosene and the fact that it is miscible in petrol and diesel,
make the unhealthy and unethical practice of adulteration of petrol and
diesel. This not only results in less availability of kerosene to the poor, but
results in severely damaging automotive engines and increased motor
vehicle emissions which are a cause of major concern to environmental
pollution.
There have been a number of methods proposed for checking
adulteration of petrol and diesel by kerosene such as the filter test, American
Standards for Testing Materials (ASTM) distillation, checking properties
like density, flash point and viscosity, microprocessor based electronic
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method using principle of cooling on evaporation, odor based method,
ultrasonic techniques, titration techniques, optical techniques, dyeing
kerosene and adding chemical markers for kerosene etc. All the above
methods suffer from limitations in terms of accuracy and sensitivity in
determining adulteration levels.
In this project, we propose an intrinsic intensity modulated fiber
optic sensor based on the principle of change in refractive index and
evanescent wave absorption for detecting adulteration in petrol by kerosene,
and trying to demonstrate its suitability. The proposed configuration is
simple, safe and versatile and can be employed for on-site roadmeasurements.
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SOURCE
(LED)
PHOTODETECTO
R
AMPLIFIER ADC
MICROCONTROLLE
R
DISPLAY(LCD)
Optical Fiber
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II. BLOCK DIAGRAM.
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III. BLOCK DESCRIPTION.
Source: LED is used as the fiber optic source since it requires less complexdrive circuitry than laser diodes.
Optical fiber: Optical fiber consists of core & cladding in which refractive
index of core is greater than that of cladding. Here we used a fiber in which
the cladding is removed. This forms the sensor head. As the length of thefiber increases the sensitivity of the instrument also increases.
Photo detector: Converts the optical power from the channel into electrical
form. Here phototransistor is used for this purpose.
Amplifier: Amplifies the photo detector output in order to drive the ADC.
ADC: Analog to digital converters are the most widely used devices for data
acquisition. We need an analog to digital converter to translate the analog
signals into digital data so that the microcontroller can read them. A widely
used ADC chip is ADC0804.
Microcontroller: A single chip microcomputer is called a microcontroller. It
contains the CPU, ROM/EPROM, RAM, I/O Ports, timer, counters, decoder,
interrupts etc. Examples of single chip microcomputers are Intel 8048, 8051
and 8096 series, Motorolas M6801 series, Texas instrument TMS 1000,
Atmel 89C51, 89C52 and Zilog Z-80.
LCD Display: LCD module is used for displaying the percentage of
adulterant in petrol. The liquid crystals are one of the most fascinatingmaterials in nature, having properties of liquid as well as solid crystal.
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LCDs do not emit or generate light, but rather alter externally generated
illumination.
IV. THEORY & PRINCIPLE OF OPERATION.
Light is guided inside an optical fiber through the principle of
total internal reflection. If the cladding of an optical fiber is removed over a
small length of the fiber and is surrounded by a medium whose refractive
index changes with some physical or chemical parameter, it results in
variation of the output power. The output power varies due to variation inthe numerical aperture (NA) of the sensing region. Thus, one can measure
the refractive index of the surrounding medium and hence, the physical or
chemical parameter affecting it, by monitoring the output power. This
principle forms the basis of fiber optic refractometry.
When light is reflected at the boundary of a denser and a rarer
optical medium, the field associated with the wave extends beyond theinterface in the cladding region. This field has an amplitude which decreases
exponentially with increasing distance from the boundary and is referred to
as an evanescent field. When this field interacts with an absorbing cladding,
it results in attenuation of the power of the propagating wave. If Po is the
power transmitted by the fiber in the absence of an absorbing species, then
the power transmitted in the presence of an absorbing medium is given by
P(z) = Po exp(-z) (1)
where z is the distance along the unclad length and is the evanescent
absorption coefficient of the medium. The evanescent absorbance A of an
unclad fiber of length L surrounded by a fluid of evanescent absorption
coefficient is given by
A = log10 [Po/P(z)] = L / 2.303 (2)
For a fluid obeying the LambertBeer law of absorption
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(where the bulk absorption coefficient is directly proportional to
concentration), Eq. (2) predicts that evanescent absorbance depends linearly
on both exposed fiber length L and fluid concentration.
Hence, the sensitivity of a sensor based on the above principle
can be increased by increasing the length of the exposed region of the core
which forms the sensor head and by increasing the depth of penetration of
the evanescent field inside the absorbing medium.
Variation of refractive index of petrol with percentage
concentration of kerosene.
The variation in the refractive index of petrol with
The variation in refractive index of petrol with the
increase in the percentage of adulteration by kerosene is as shown. From the
figure it is evident that the refractive index increases with increase in
adulteration by kerosene. The refractive index of the solution with 50%
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concentration of kerosene was measured to be 1.433, which is less than that
of the core of the fiber.
The refractive index of petrol at different levels of
adulteration will make a drastic decrease in output power as the condition of
total internal reflection gets violated.
V. CIRCUIT DIAGRAM.
VI. CIRCUIT DESCRIPTION.
The system consists of an input section, phototransistor,
amplifier section, ADC, microcontroller, LCD module and a power supply
unit.
Input section: This section comprises of an LED source and an optical fiber
in which the cladding is removed. This acts as the sensor head. When thePetrol which contains kerosene as the adulterant is in contact with the clad
less fiber, the adulterated fuel acts as the cladding and the intensity of light
which propagates through the fiber varies with the percentage of kerosene
concentration.
Phototransistor: An NPN phototransistor together with a 220K resistor is
used for photo detection. The variation of light intensity is converted into
electrical current by the phototransistor. The phototransistor is shunted with
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a 220K resistor and the output current through the resistor develops a
voltage which is proportional to the phototransistor output and thus to the
light intensity variation.
Amplifier: The voltage developed across the resistor is amplified in order to
drive the ADC section. For this an LM358 op-amp is used. It works in the
non-inverting mode and works with +5 V.
ADC: The amplified voltage is given as the ADC input. ADC converts the
analog variation into digital data so that the microcontroller can read them.
Here ADC 0804 chip is used. The ADC 0804 IC is an analog to digital
converter in the family of ADC 800 series from National Semiconductor. Itworks with +5 V and has a resolution of 8 bits.
Microcontroller: The digital output from ADC is given to the input ports of
the microcontroller. The digital output is converted to its corresponding
ASCII by using the program in the flash programmable memory of the
microcontroller and the LCD display module connected to the output ports
of the controller displays the corresponding output. Atmel 89C51microcontroller is used here.
Power Supply unit: All components in the circuit require a +5 V dc. For that
a 12-0-12V/1 Amp transformer is connected to the main supply. The
secondary side of the transformer is connected to a centre tap full wave
rectifier section to convert the 12 V ac into 12 V dc. A capacitor of 1000
mF/25 V is used for filtering purpose and is fed to the input of the 7805regulator IC for getting a constant output voltage of +5 V dc. A capacitor of
470 mF/25 V.
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VII. HARDWARE DETAILS.
7.1.Microcontroller : - IC ATMEL 89C51
The microcontroller used here is Atmels 89C51. The AT89C51
is a low power, high-performance CMOS 8-bit microcomputer with 4
Kbytes of Flash Electrically Programmable and Erasable Read Only
Memory (EEPROM). The device is manufactured using Atmels high-
density nonvolatile memory technology and is compatible with the industry
standard MCS-51 instruction set and pin out. The on-chip flash allows the
program memory to be reprogrammed in-system or by a conventional
nonvolatile memory programmer. The Atmel AT89C51 is a powerful
microcomputer which provides a highly flexible and cost effective solution
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to many embedded control applications. (The AT89C51 provides the
following standard features: 4 Kbytes of Flash, 128 bytes of RAM, 32 I/O
lines, two 16-bit timer/counters, five vector two-level interrupt architecture,
a full duplex serial port, ON-chip oscillator and clock circuitry.
Figure. Pin diagram of AT 89C51
Pin Descriptions :-
VCC: Supply voltage.
GND: Ground.
Port 0: Port 0 is an 8-bit open drain bi-directional I/O port. As an output
port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins,the pins can be used this mode P0 has internal pull-ups. Port 0 also receives
the code bytes during Flash as high-impedance inputs. Port 0 may also be
configured to be the multiplexed low order address/data bus during accesses
to external program and data memory. In programming, and outputs the code
bytes during program verification. External pull-ups are required during
program verification.
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Port 1: Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The
Port 1 output buffers can sink/source four TTL inputs. When 1s are written
to Port 1 pins they are pulled high by the internal pull-ups and can be used as
inputs. As inputs, Port 1 pins that are externally being pulled low will source
current (IIL) because of the internal pull-ups. Port 1 also receives the low-
order address bytes during Flash programming and program verification.
Port 2: Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The
Port 2 output buffers can sink/source four TTL inputs. When 1s are written
to Port 2 pins they are pulled high by the internal pull-ups and can be used as
inputs. As inputs, Port 2 pins that are externally being pulled low will sourcecurrent (IIL) because of the internal pull-ups. Port 2 emits the high-order
address byte during fetches from external program memory and during
accesses to external data, memory that uses 16-bit addresses (MOVX@
DPTR). In this application, it uses strong internal pull-ups when emitting
1s. During accesses to external data, memory that uses 8-bit addresses
(MOVX @ RI); Port 2 emits the contents of the P2 Special FunctionRegister. Port 2 also receives the high-order address bits and some control
signals during Flash programming and verification.
Port 3: Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The
Port 3 output buffers can sink/source four TTL inputs. When 1s are written
to Port 3 pins they are pulled high by the internal pull-ups and can be used as
inputs. As inputs, Port 3 pins that are externally being pulled low will sourcecurrent (IIL) because of the pull-ups. Port 3 also serves the functions of
various special features of the AT89C51 as listed below:
Port
Pin
Alternate Functions
P3.0 RXD (serial input port)
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P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
TXD (serial output port)
INT0 (external interrupt 0)
INT1 (external interrupt 1)
T0 (timer 0 external input)
T1 (timer 1 external input)
WR (external data memory write
strobe)
RD (external data memory read
strobe)Table. Port description
Port 3 also receives some control signals for Flash programming and
programming verification.
RST: Reset input. A high on this pin for two machine cycles while the
oscillator is running resets the device.
ALE/PROG: Address Latch Enable output pulse for latching the low byte
of the address during accesses to external memory. This pin is also the
program pulse Input (PROG) during flash programming. In normal
operation ALE is emitted at a constant rate of 1/6 the oscillator frequency,
and may be used for external timing or clocking purposes. Note, however,
that one ALE pulse is skipped during each access to external Data Memory.
If desired, ALE operation can be disabled by setting bit 0 of SFR location
8EH. With the bit set, ALE is active only during a MOVX or MOVC
instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-
disable bit has no effect if the microcontroller is in external execution mode.
PSEN: Program Store Enable is the read strobe to external program
memory. When the AT89C51 is executing code from external program
memory, PSEN is activated twice each machine cycle, except that two PSEN
activations are skipped during each access to external data memory.
EA/VPP: External Access Enable. EA must be strapped to GND in order toenable the device to fetch code from external program memory locations
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starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is
programmed, EA will be internally latched on reset. EA should be strapped
to VCC for internal program executions. This pin also receives the 12-volt
programming enable voltage (VPP) during Flash programming, for parts that
require 12-volt VPP.
XTAL1: Input to the inverting oscillator amplifier and input to the internal
clock operating circuit.
XTAL2: Output from the inverting oscillator amplifier.
CRYSTAL: The crystal l (XTL1) used here is of 11.059MHz. Here the
crystal is used for internal clock timing. The two terminals of the crystals areconnected across pin 19(X1) and pin 18(X2) Crystal oscillator must be
designed to provide a load Capacitance on the crystal as specified by the
manufacturer. This requirement is necessary to obtain oscillation at the
specified frequency. It is also important that the power fed to the crystal be
held to the specified maximum. Typical maximum drive levels for plated
crystals range from 2mW to10mW.
7.2. Analog to Digital Converter :- IC ADC 0804
Figure. Pin diagram of ADC0804
Pin Descriptions :-
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CS: Chip select is an active low input used to activate the ADC 0804 chip.
To access the ADC 0804, this pin must be low.
RD: Read is an active low input signal. It is used to get the converted data
out of the ADC 0804 chip. The RD pin is also referred to as output enable.
WR: Write is an active low input signal. It is used to inform the ADC to
start the conversion process. It is also referred to as SOC (Start of
Conversion).
CLK IN and CLK R: CLK IN is an input pin connected to an external clock
source when an external clock is used for timing. To use the internal clock
generator the CLK IN and CLK R pins are connected to a capacitor and aresistor. In that case the clock frequency is determined by the equation:
f = 1 / 1.1RC.
INTR: Interrupt is an active low output pin. It is normally a high pin and
when the conversion is finished, it goes low to signal the CPU that the
converted data is ready to be picked up. It is also referred to as EOC (End of
Conversion).Vin(+) and Vin(-): These are the differential analog inputs where Vin =
Vin(+)-Vin(-). Often the Vin (-) pin is connected to ground and the Vin (+)
pin is used to connect the analog input.
Vref/2: This is an input voltage used for the reference voltage. If this pin is
open, the analog input for ADC is in the range of 0-5 V. Vref/2 is used to
implement the analog input voltage other than 0-5 V.D0-D7: These are the digital data output pins, where D7 is the MSB and D0
is the LSB. These are tristate buffered and the converted data is accessed
only when CS = 0 and RD is forced low.
AGND and DGND: Analog ground and digital ground are the input pins
providing the ground for both the analog and digital signal. Analog ground is
connected to the ground of analog Vin while digital ground is connected to
the ground of Vcc pin. The two ground pins is used to isolate the analog Vin
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signal from transient voltages caused by digital switching of the output.
Such isolation increases the accuracy of the digital output.
7.3.Operational Amplifier :- IC LM 358
Figure. Pin diagram of LM358
General Description :-
These devices consist of two independent, high-gain, frequency-
compensated operational amplifiers designed to operate from a single supply
over a wide range of voltages. Operation from split supplies also is possible
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if the difference between the two supplies is 3 V to 32 V (3 V to 26 V for the
LM2904), and VCC is at least 1.5 V more positive than the input common-
mode voltage. The low supply-current drain is independent of the magnitude
of the supply voltage.
Applications include transducer amplifiers, dc amplification
blocks, and all the conventional operational amplifier circuits that now can
be implemented more easily in single-supply-voltage systems. For example,
these devices can be operated directly from the standard 5-V supply used in
digital systems and easily can provide the required interface electronics
without additional 5V supplies.
7.4. LCD Module
LCD module is used for displaying message that send from
remote location. The liquid crystals are one of the most fascinating materials
systems in nature, having properties of liquid as well as solid crystal. LCDs
do not emit or generate light, but rather alter externally generatedillumination. Their ability to modulate light when electrical signal is applied
has made them very useful in flat panel display technology. The crystal is
made up of organic molecules, which are rod like In shape with a length of ~
20 A 100 A., the different arrangements of this rod like molecules led to
three main categories of liquid crystals.
Smectic Nematic
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Cholestric
There are two types of LCDs according to the theory operation
Dynamic scattering
Field effect
Advantages
Less power consumption
Low cost
Uniform brightness with good contrast
Low operating voltage and current
Disadvantages
Poor reliability
Limited temperature range
Slow speed
LCD panel used here has 15 pins (8-data line, 3-control line and a
contrast line). Data line and control line are connected to microcontroller.Contrast line is connected to a voltage divider using preset (R9). Contrast
can vary by this preset.
VIII. MICROCONTROLLER PROGRAM.
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IX. CONCLUSION.
We proposed an intrinsic intensity modulated fibre optic sensor
based on the principle of evanescent wave absorption and change in
refractive index for detecting adulteration in petrol by kerosene. The
proposed sensor would be useful in automotive and petrochemical industries
due to its simple design, safety with inflammable fuels, sensitivity and the
fact that it can be made into a portable device for on-road measurements.
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X. REFERENCES.
1. www.sciencedirect.com
2. www.intertek-cb.com/petrotesting/gasolinetest.shtml
3. Optical Fiber Communications: Gerd Keiser
4. Kenneth J Ayala, 8051 Programming and application
5. www.microchip.com.
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