CHAPTER *

INTRODUCTION

*.* Carbon Dioxide Monitor

Global warming and climate change concerns have triggered global efforts to reduce the concentration of atmospheric carbon dioxide (CO2). Carbon dioxide capture and storage (CCS) is considered a crucial strategy for meeting CO2 emission reduction targets. In this paper, various aspects of CCS are reviewed and discussed including the state of the art technologies for CO2 capture, separation, transport, storage, leakage, monitoring, and life cycle analysis. The selection of specific CO2 capture technology heavily depends on the type of CO2 generating plant and fuel used. Among those CO2 separation processes, absorption is the most mature and commonly adopted due to its higher efficiency and lower cost. Pipeline is considered to be the most viable solution for large volume of CO2transport. Among those geological formations for CO2 storage, enhanced oil recovery is mature and has been practiced for many years but its economical viability for anthropogenic sources needs to be demonstrated. There are growing interests in CO2storage in saline aquifers due to their enormous potential storage capacity and several projects are in the pipeline for demonstration of its viability. There are multiple hurdles to CCS deployment including the absence of a clear business case for CCS investment and the absence of robust economic incentives to support the additional high capital and operating costs of the whole CCS process. Rapid economic growth has contributed to today s ever increasing demand for energy. An obvious consequence of this is an increase in the use of fuels, particularly conventional fossil fuels (i.e. coal, oil and natural gas) that

have become key energy sources since the industrial revolution. However, the abundant use of fossil fuels has become a cause of concern due to their adverse effects on the environment, particularly related to the emission of carbon dioxide (CO2), a major anthropogenic greenhouse gas (GHG). According to the Emission Database for Global Atmospheric Research, global emission of CO2 was 33.4 billion tonnes in 2011, which is 48% more than that of two decades ago. Over the past century, atmospheric CO2 level has increased more than 39%, from 280 ppm during pre-industrial time to the record high level of 400 ppm in May 2013 with a corresponding increase in global surface temperature of about 0.8 C . Without climate change mitigation policies it is estimated that global GHG emission in 2030 will increase by 25–90% over the year 2000 level, with CO2-equivalent concentrations in the atmosphere growing to as much as 600–1550 ppm

1.1.2 Purpose

To monitor the co2 level in industry to avoid the effect of air pollution, human,global warming and earth.

1.1.3 scope

Measuring carbon dioxide is important in monitoring indoor air quality and many industrialprocess.co2 level in industry in 5000 PPM. The above 5000 PPM reach the co2 level to monitor using lab view and also using this project in fire detection using the fire sensor .the fire accident in industry information passed through the address line detect the fire using fire sensor.

CHAPTER-2

LITERATURE SURVEY

2.1 Seismic monitoring of a co2 flood in a carbonate reservoir

A carbon dioxide (CO2) injection pilot project is underway in Section 205 of the McElroy field, West Texas. High resolution crosswell seismic imaging surveys were conducted before and after CO2 flooding to monitor the CO2 flood process and map the flooded zones. The velocity changes observed by these time lapse surveys are typically on the order of 6%, with maximum values on the order of 10% in the vicinity of the injection well. These values generally agree with laboratory measurements if the effects of changing pore pressure are included. The observed dramatic compressional and shear velocity changes are considerably greater than we had initially predicted using the Gassmann (1951) fluid substitution analysis (Nolen Hoeksema et al., 1995) because we had assumed reservoir pressure would not change from survey to survey. However, the post CO2 reservoir pore fluid pressure was substantially higher than the original pore pressure. In addition, our original petrophysical data for dry and brine saturated reservoir rocks did not cover the range of pressures actually seen in the field. Therefore, we undertook a rock physics study of CO2 flooding in the laboratory, under the simulated McElroy pressures and temperature. Our results show that the combined effects of pore pressure buildup and fluid substitution caused by CO2 flooding make it petrophysically feasible to monitor the CO2 flood process and to map the flooded zones seismically.

2.2 NDIR Gas Sensor for Spatial Monitoring of Carbon Dioxide Concentrations in Naturally Ventilated Livestock Buildings

Nowadays, no reference method exists for measuring air ventilation rates in naturally ventilated (NV) animal houses. However, a number of different candidate approaches have been suggested, such as the tracer gas technique using either natural or artificial tracers . The application of carbon dioxide (CO2) as a tracer gas for measuring ventilation and emission rates in livestock buildings involves CO2 metabolically produced by the animals and manure, which presents good mixing with most of the target pollutant gases found in livestock houses . Representative sampling of the pollutant-tracer ratio is the most robust approach for quantifying emissions, and in case of inappropriate mixing spatial variability of this ratio should be included in the sampling strategy. The CO2 mass balance relies: (a) on accurate measurements of CO2 concentration in- and outside the animal barn; (b) on accurate prediction of the metabolic heat production; and (c) accurate registration of the parameters used in the heat and CO2 production model . Measuring gaseous concentration distribution in NV livestock structures represents a real challenge in research . For instance, Lefcourt, showed that incorrect selection of sampling positions for ammonia (NH3) in NV animal barns may lead to errors in calculated NH3 emission rates from 50% to over 200% of the actual values.

2.3 MONITORING EXHALED CARBON DIOXIDE

The measurement of CO2 in air was first developed around 1918 and performed to analyze gas concentrations in mines.1 This process of analysis was painstakingly tedious, using an intricate apparatus that involved measuring quantities of CO2 and other gases that were chemically absorbed from a known gas volume. The volume of absorbed CO2 was then compared with the total gas volume, which yielded the fraction or percentage of CO2 present. A decade later, a technique was developed to analyze exhaled CO2 from a single breath during vigorous exercise.2 This process entailed capturing exhaled gas using a system the size of a telephone booth consisting of a series of electro-mechanically controlled valves, which directed sequential portions of expired air into 6 small rubber bags. The collected CO2 in each bag was then analyzed multiple times to yield the average CO2, which was plotted over time, thus resulting in the first exhaled capnogram. By the 1970s, exhaled CO2 was monitored in ICUs using mass spectrometry systems that aspirated exhaled gas through long lengths of capillary tubing to a central monitoring location.3,4 Periodic measurements of the partial pressure of end-tidal CO2 (PETCO2 ) occurred on a timed schedule or in a sequential loop as the sampling cycle rotated between a number of monitored beds.4 With the introduction of the smaller infrared sensor, portable exhaled CO2 monitors came to the bedside in the 1980s.5 Miniature CO2 monitors that can fit into the palm of the hand and are capable of displaying an exhaled CO2 capnogram are currently available. The technological adv

2.4 Real-Time Indoor Carbon Dioxide Monitoring Through Cognitive Wireless Sensor Networks

Indoor Air Quality (IAQ) refers to the quality of the air within and around buildings and structures. It is an issue of great importance since it relates directly to the health and comfort of building occupants. Common issues associated with IAQ include improper or inadequately maintained heating and ventilation systems as well as contamination by construction materials (glues, fibreglass, particle boards, paints, etc.) and other chemicals.

CHAPTER 3

PROPOSED METHODOLOGY

3.1 BLOCK DIAGRAM

Fig:3.1.Block Diagram of Proposed Topology

3.2 PROJECT EXPLANATION

Now-a-days, co2 gas are occurring very frequently in many industry which causes the loss of most valuable human,animals and planet .Increase the tempature of the earth’s atmosphere it cases the global warming effect that has bad effects on the earth. To overcome this, we had proposed the system, when the gas percentage is increase the monitoring the co2 level in industry and also monitor the fire detection in same industry using lab view .

3.3 APPLICATION

Cold storage

Refrigeration

Hvac for all environment

Oem’s

CHAPTER 4

PROJECT DESCRIPTION

4.1 Hardware Components Requirement

The components used in this system are

Arduino UNO

Amplifier

LCD

Power supply

Co2 Sensor

Fire Sensor

Tempeture Sensor

PIR Sensor

Relay

SCU

Interface circuit

Driver circuit .

4.1.1.ARDUINO UNO

4.1.1.1.Introduction

Arduino/Genuino Uno is a microcontroller board based on the ATmega328P . It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz quartz crystal, a USB connection, a power jack, an ICSP header and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started..

Fig 4.1 TOP View of Arduino Uno kit

Fig 4.1.1.Side view of Arduino Uno kit

"Uno" means one in Italian and was chosen to mark the release of Arduino Software (IDE) 1.0. The Uno board and version 1.0 of Arduino Software (IDE) were the reference versions of Arduino, now evolved to newer releases.

4.1.1.2.Technical specification of Arduino

Microcontroller

ATmega328P

Operating Voltage

5V

Input Voltage (recommended)

7-12V

Input Voltage (limit)

6-20V

Digital I/O Pins

14 (of which 6 provide PWM output)

PWM Digital I/O Pins

6

Analog Input Pins

6

DC Current per I/O Pin

20 mA

DC Current for 3.3V Pin

50 Ma

Flash Memory

32 KB (ATmega328P)

of which 0.5 KB used by bootloader

SRAM

2 KB (ATmega328P)

EEPROM

1 KB (ATmega328P)

Clock Speed

16 MHz

Length

68.6 mm

Width

53.4 mm

Weight

25 g

Table 4.1 Technical Specification of Arduino Uno Kit

4.1.1.3 Pin Diagram of Arduino

Fig:4.1.2.Pin Diagram of Arduino

Fig :4.1.3.ATmega IC

4.1.1.4 Pin specification of Arduino

4.1.1.4.1 Power

The Arduino/Genuino Uno board can be powered via the USB connection or with an external power supply. The power source is selected automatically.External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery.

The adapter can be connected by plugging a 2.1mm center-positive plug into the board's power jack. The board can operate on an external supply from 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may become unstable. If using more than 12V, the voltage regulator may overheat and damage the board.

The power pins are as follows:

The input voltage to the Arduino/Genuino board when it's using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). supply voltage through this pin, or, if supplying voltage via the power jack, access it through this pin.

This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board.

A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 50 mA.

GND. Ground pins.

IOREF: This pin on the Arduino/Genuino board provides the voltage reference with which the microcontroller operates. A properly configured shield can read the IOREF pin voltage and select the appropriate power source or enable voltage translators on the outputs to work with the 5V or 3.3V.

4.1.1.4.2 Memory

The ATmega328 has 32 KB (with 0.5 KB occupied by the boot loader). It also has 2 KB of SRAM and 1 KB of EEPROM (which can be read and written with the EEPROM library).

4.1.1.4.3 Input and Output

See the mapping between Arduino pins and ATmega328P ports. The mapping for the Atmega8, 168, and 328 is identical.

Each of the 14 digital pins on the Uno can be used as an input or output, using pinMode,digitalWrite, and digitalRead functions. They operate at 5 volts. Each pin can provide or receive 20 mA as recommended operating condition and has an internal pull-up resistor (disconnected by default) of 20-50k ohm.

A maximum of 40mA is the value that must not be exceeded on any I/O pin to avoid permanent damage to the microcontroller.

In addition, some pins have specialized functions:

Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip.

External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a change in value. See the attachInterrupt function for details.

PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the analogWrite function.

SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI communication using the SPI library.

LED: 13. There is a built-in LED driven by digital pin 13. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off.

TWI: A4 or SDA pin and A5 or SCL pin. Support TWI communication using the Wire library.

The Uno has 6 analog inputs, labeled A0 through A5, each of which provide 10 bits of resolution By default they measure from ground to 5 volts, though is I t possible to change the upper end of their range. using the aref

There are a couple of other pins on the board:

AREF: Reference voltage for the analog inputs. Used with analogReference .

Reset: Bring this line LOW to reset the microcontroller. Typically used to add a reset button to shields which block the one on the board.

4.1.1.5 Software Communication

Arduino/Genuino Uno has a number of facilities for communicating with a computer, another Arduino/Genuino board, or other microcontrollers. The ATmega328 provides UART TTL (5V) serial communication, which is available on digital pins 0 (RX) and 1 (TX). An ATmega16U2 on the board channels this serial communication over USB and appears as a virtual com port to software on the computer. The 16U2 firmware uses the standard USB COM drivers, and no external driver is needed. However, on Windows, a .inf file is required. A SoftwareSerial library allows serial communication on any of the Uno's digital pins.

The ATmega328 also supports I2C (TWI) and SPI communication. The Arduino Software (IDE) includes a Wire library to simplify use of the I2C bus; see the documentation for details. For SPI communication, use the SPI library.

4.1.1.5.1 Automatic (Software) Reset

Rather than requiring a physical press of the reset button before an upload, the Arduino/Genuino Uno board is designed in a way that allows it to be reset by software running on a connected computer. One of the hardware flow control lines (DTR) of the ATmega8U2/16U2 is connected to the reset line of the ATmega328 via a 100 nanofarad capacitor. When this line is asserted (taken low), the reset line drops long enough to reset the chip. The Arduino Software (IDE) uses this capability to allow you to upload code by simply pressing the upload button in the interface toolbar. This means that the bootloader can have a shorter timeout, as the lowering of DTR can be well-coordinated with the start of the upload.

This setup has other implications. When the Uno is connected to either a computer running Mac OS X or Linux, it resets each time a connection is made to it from software (via USB). For the following half-second or so, the bootloader is running on the Uno. While it is programmed to ignore malformed data (i.e. anything besides an upload of new code), it will intercept the first few bytes of data sent to the board after a connection is opened.

4.1.2. LCD DISPLAY

4.1.2.1. Introduction

Liquid crystal displays (LCDs) have materials which combine the properties of both liquids and crystals. Rather than having a melting point, they have a temperature range within which the molecules are almost as mobile as they would be in a liquid, but are grouped together in an ordered form similar to a crystal.

An LCD consists of two glass panels, with the liquid crystal material sand witched in between them. The inner surface of the glass plates are coated with transparent electrodes which define the character, symbols or patterns to be displayed polymeric layers are present in between the electrodes and the liquid crystal, which makes the liquid crystal molecules to maintain a defined orientation angle.

One each polarisers are pasted outside the two glass panels. These polarisers would rotate the light rays passing through them to a definite angle, in a particular direction

When the LCD is in the off state, light rays are rotated by the two polarisers and the liquid crystal, such that the light rays come out of the LCD without any orientation, and hence the LCD appears transparent.When sufficient voltage is applied to the electrodes, the liquid crystal molecules would be aligned in a specific direction. The light rays passing through the LCD would be rotated by the polarisers, which would result in activating / highlighting the desired characters.

The LCD’s are lightweight with only a few millimeters thickness. Since the LCD’s consume less power, they are compatible with low power electronic circuits, and can be powered for long durations.The LCD’s don’t generate light and so light is needed to read the display. By using backlighting, reading is possible in the dark.

4.1.2.2POWER SUPPLY

The power supply should be of +5V, with maximum allowable transients of 10mv. To achieve a better / suitable contrast for the display, the voltage (VL) at pin 3 should be adjusted properly.

A module should not be inserted or removed from a live circuit. The ground terminal of the power supply must be isolated properly so that no voltage is induced in it. The module should be isolated from the other circuits, so that stray voltages are not induced, which could cause a flickering display.

4.1.2.3 HARDWARE

Develop a uniquely decoded ‘E’ strobe pulse, active high, to accompany each module transaction. Address or control lines can be assigned to drive the RS and R/W inputs.

If a parallel port is used to drive the RS, R/W and ‘E’ control lines, setting the ‘E’ bit simultaneously with RS and R/W would violate the module’s set up time. A separate instruction should be used to achieve proper interfacing timing requirements.

4.1.2.4 MOUNTING

Cover the display surface with a transparent protective plate, to protect the polarizer.Don’t touch the display surface with bare hands or any hard materials. This will stain the display area and degrade the insulation between terminals.Do not use organic solvents to clean the display panel as these may adversely affect tape or with absorbant cotton and petroleum benzene.The processing or even a slight deformation of the claws of the metal frame will have effect on the connection of the output signal and cause an abnormal display.Do not damage or modify the pattern wiring, or drill attachment holes in the PCB. When assembling the module into another equipment, the space between the module and the fitting plate should have enough height, to avoid causing stress to the module surface.Make sure that there is enough space behind the module, to dissipate the heat generated by the ICs while functioning for longer durations.

4.1.2.5 ENVIRONMENTAL PRECAUTIONS

Operate the LCD module under the relative condition of 40 C and 50% relative humidity. Lower temperature can cause retardation of the blinking speed of the display, while higher temperature makes the overall display discolor.When the temperature gets to be within the normal limits, the display will be normal. Polarization degradation, bubble generation or polarizer peel-off may occur with high temperature and humidity.Contact with water or oil over a long period of time may cause deformation or colour fading of the display. Condensation on the terminals can cause electro-chemical reaction disrupting the terminal circuit.

4.1.2.6 Introduction of Trouble Shooting

When the power supply is given to the module, with the pin 3 (VL) connected to ground, all the pixels of a character gets activated in the following manner.All the characters of a single line display, as in CDM 16108.

The first eight characters of a single line display, operated in the two-line display mode, as in CDM 16116.The first line of characters of a two-line display as in CDM 16216 and 40216. The first and third line of characters of a four-line display operated in the two-line display mode, as in CDM 20416.If the above mentioned does not occur, the module should be initialized by software.Make sure that the control signals ‘E’, R/W and RS are according to the interface timing requirements.

4.1.2.7 IMPROPER CHARACTER DISPLAY

When the characters to be displayed are missing between, the data read/write is too fast. A slower interfacing frequency would rectify the problem.When uncertainty is there in the start of the first characters other than the specified ones are rewritten, check the initialization and the software routine.In a multi-line display, if the display of characters in the subsequent lines does’nt take place properly, check the DD RAM addresses set for the corresponding display lines.

When it is unable to display data, even though it is present in the DD RAM, either the display on/off flag is in the off state or the display shift function is not set properly. When the display shift is done simultaneous with the data writa operation, the data may not be visible on the display.

If a character not found in the font table is displayed, or a character is missing, the CG ROM is faulty and the controller IC have to be changed

4.1.2.8 CRYSTALONICS DISPLAY

4.1.2.8.1 Introduction

Crystalonics dot –matrix (alphanumeric) liquid crystal displays are available in TN, STN types, with or without backlight. The use of C-MOS LCD controller and driver ICs result in low power consumption. These modules can be interfaced with a 4-bit or 8-bit micro processor /Micro controller.

The built-in controller IC has the following features:

Correspond to high speed MPU interface (2MHz)

80 x 8 bit display RAM (80 Characters max)

9,920 bit character generator ROM for a total of 240 character fonts. 208 character fonts (5 x 8 dots) 32 character fonts (5 x 10 dots)

64 x 8 bit character generator RAM 8 character generator RAM 8 character fonts (5 x 8 dots) 4 characters fonts (5 x 10 dots)

Programmable duty cycles

1/8 – for one line of 5 x 8 dots with cursor

1/11 – for one line of 5 x 10 dots with cursor

1/16 – for one line of 5 x 8 dots with cursor

Wide range of instruction functions display clear, cursor home, display on/off, cursor on/off, display character blink, cursor shift, display shift.

BUSY FLAG

When the busy flag is1, the controller is in the internal operation mode, and the next instruction will not be accepted.

When RS = 0 and R/W = 1, the busy flag is output to DB7.

The next instruction must be written after ensuring that the busy flag is 0.

ADDRESS COUNTER

The address counter allocates the address for the DD RAM and CG RAM read/write operation when the instruction code for DD RAM address or CG RAM address setting, is input to IR, the address code is transferred from IR to the address counter. After writing/reading the display data to/from the DD RAM or CG RAM, the address counter increments/decrements by one the address, as an internal operation. The data of the address counter is output to DB0 to DB6 while R/W = 1 and RS = 0.

DISPLAY DATA RAM (DD RAM)

The characters to be displayed are written into the display data RAM (DD RAM), in the form of 8 bit character codes present in the character font table. The extended capacity of the DD RAM is 80 x 8 bits i.e. 80 characters.

CHARATCER GENERATOR ROM (CG ROM)

The character generator ROM generates 5 x 8 dot 5 x 10 dot character patterns from 8 bit character codes. It generates 208, 5 x 8 dot character patterns and 32, 5 x 10 dot character patterns.

CHARACTER GENERATOR RAM (CG RAM)

In the character generator RAM, the user can rewrite character patterns by program. For 5 x 8 dots, eight character patterns can be written, and for 5 x 10 dots, four character patterns can be written.

INTERFACING THE MICROPROCESSOR / CONTROLLER:

The module, interfaced to the system, can be treated as RAM input/output, expanded or parallel I/O.Since there is no conventional chip select signal, developing a strobe signal for the enable signal (E) and applying appropriate signals to the register select (RS) and read/write (R/W) signals are important.The module is selected by gating a decoded module – address with the host – processor’s read/write strobe. The resultant signal, applied to the LCDs enable (E) input, clocks in the data.

The ‘E’ signal must be a positive going digital strobe, which is active while data and control information are stable and true. The falling edge of the enable signal enables the data / instruction register of the controller. When the host processor is so fast that the strobes are too narrow to serve as the ‘E’ pulse

a.Prolong these pulses by using the hosts ‘Ready’ input

b.Prolong the host by adding wait states

c.Decrease the Hosts Crystal frequency.

Inspite of doing the above mentioned, if the problem continues, latch both the data and control information and then activate the ‘E’ signal

When the controller is performing an internal operation he busy flag (BF) will set and will not accept any instruction. The user should check the busy flag or should provide a delay of approximately 2ms after each instruction.

The module presents no difficulties while interfacing slower MPUs.

The liquid crystal display module can be interfaced, either to 4-bit or 8-bit MPUs.

4.1.3 FIRE SENSOR

4.1.3.1 Introduction

Disclosed herein is a fire alarm system for connecting a plurality of fire sensors to sensor lines, and giving an alarm in response to fire information output from the fire sensor in a line unit. The fire alarm system includes a current modulation section and an address specification section. The current modulation section is used for maintaining a current flowing in the sensor line at a predetermined value for a predetermined time at the time of a fire, and modulating the current in accordance with the inherent address information of the fire sensor. The address specification section is used for sensing fire information by judging whether or not the current has been maintained at the predetermined value for the predet that issued the fire information, from the modulated state of the current.A

A fire detector comprising:a gas sensor; and control circuitry coupled to the gas sensor, the control circuitry includes pattern recognition circuitry to evaluate pluralities of sampled output data from the sensor, as a function of gas sensor operating temperature, to determine the presence of a fire. . A detector as in claim 1 where the sensor comprises a heatable sensor of selected gasesEarly detection and control of unwanted fires is and has been a national priority for decades

4.1.4 TEMPERATURE SENSOR

4.1.4.1 Introduction

A thermistor is a type of resistor whose resistance varies with temperature. The word is a portmanteau of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self-resetting overcurrent protectors, and self-regulating heating elements.Thermistors differ from resistance temperature detectors (RTD) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. RTDs are useful over larger temperature ranges, while thermistors typically achieve a higher precision within a limited temperature range [usually 90 C to 130 C].

4.1.4.2 Basic operation

4.4 Thermistor symbol

Assuming, as a first-order approximation, that the relationship between resistance and temperature is linear, then:

Where,

ΔR = change in resistance

ΔT = change in temperature

k = first-order temperature coefficient of resistance

Thermistors can be classified into two types, the device is called a positive temperature coefficient (PTC) thermistor, or posistor. If k is negative, the resistance decreases with increasing temperature, and the device is called a negative temperature coefficient (NTC) thermistor. Instead of the temperature coefficient k, sometimes the temperature coefficient of resistance α (alpha) or αT is used. It is defined as

For example, for the common PT100 sensor, α = 0.00385 or 0.385 %/ C. This αT coefficient should not be confused with the α parameter below.

4.1.5 CO2 SENSOR

4.1.5.1 Introduction

A carbon dioxide sensor or CO2 sensor is an instrument for the measurement of carbon dioxide gas. The most common principles for CO2 sensors are infrared gas sensors (NDIR) and chemical gas sensors. Measuring carbon dioxide is important in monitoring indoor air quality and many industrial processes.

4.1.5.2 NDIR CO2 Sensors

NDIR sensors are spectroscopic sensors to detect CO2 in a gaseous environment by its characteristic absorption. The key

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