YEDITEPE UNIVERSITY, ISTANBUL

Air Conditioning Measurement Device

ME 403 Instrumentation and Experiment Design

Term Project Report

Fall 2014

Group 3B

Berk KÖTEŞLİ

Göksenin ÖZKAN

Salih GÜVEN

Department: Mechanical Engineering

ME 403

Instructor: Asst. Prof. A. Bahadır OLCAY

Asst. Prof. Nezih TOPALOĞLU

Asst. Prof. Koray K. ŞAFAK

02.01.2015

Letter of Authorization

ME 403 Term Project Report

APPROVED BY:

Asst. Prof. A. Bahadır OLCAY :…………………………………………

Asst. Prof. Nezih TOPALOĞLU :………………………………………..

Asst. Prof. Koray K. ŞAFAK : ……………………………………...……

STUDENT NAME:

Berk KÖTEŞLİ: ...........................................................................................

Göksenin ÖZKAN: ………………………………………………………..

Salih GÜVEN: ............................................................................................

DEPARTMENT:

Mechanical Engineering

DATE OF APPROVAL: 02.01.2015

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Table of Contents

1. Objectives ………………………………………….……………………………..…….…1

2. Introduction......................……………………………………………………….………...2

3. Mechanical Design……………………………………………………...……………...…3

4. Procedure …………………………………………………...………………………...….7

5. Instruments and Wiring ………..……………………………...……..……………..……8

6. Calibration ………..…………………...…………………………..…………………....18

7. Codes of the System…………………………………………………………………...…20

8. Uncertainty Analysis….…………………………………………………………...……..24

9. Conclusion………………………………………………………………………………....27

10. References ………………………………………………………………………………28

III

1. Objectives

Air conditioning systems are one of the most crucial, indispensable and commonly used systems in large buildings and structures such as shopping malls, business centers, hospitals etc. Therefore, delivering the right amount of air at desired temperature and flow rate and efficiency of the air conditioning system plays very important role to provide comfortable and required environment conditions to people who make various activities in the buildings. For that reasons, several sensor are used in the system to check the air conditions in each part of the system and control the air conditioning system to provide desired air when heating and cooling coils of the system works properly. Aim of this project, a compact device will be designed and built to check and measure the temperature, pressure, velocity and mass flow rate of the air across the heating coil and cooling coil of an air handling unit. Also, instantaneous data of the temperature, pressure, velocity and mass flow rate will be read and after the analyzing process, each data which come from the sensors will be transferred to the Arduino microcontroller which is located into the device and average, maximum and minimum values of the data will be calculated and shown. Thus, according to data of the measurements, air handling unit can be controlled or calibrated. Also, uncertainty analysis will be completed to observe the reliability interval of the measurements.

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2. Introduction

For the selecting right equipment and sensor to measure the system conditions correctly and in a portable way according to adequate and expected accuracy interval, a comprehensive research have been completed to select sensors and part of the devices. Three useful and easily purchasable sensors and equipment have been purchased to build our device. Firstly, to measure the temperature, pressure, velocity and mass flow rate, commonly used and cheap equipment was purchased by considering accuracy interval. However, because of measuring the mass flow rate by using sensor or device in our air conditioning system would be too expensive or inefficient, mass flow rate will be calculated theoretically by using velocity of the air and geometry of the system. Also Arduino microcontroller was purchased to control all sensors which are connected to Arduino and data will be processed and calculations will be completed by using Arduino microcontroller. Data will be shown on the monitor which is located on the device. All details about the sensor and parts of the devices are shown in the next part of the report

3. Mechanical Design

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In this part of the report mechanical design criteria of the device is explained. Firstly, when the project details were announced, design criteria of the device were started to create. Measurement device should have been portable, compact, economical and device should have been controlled easily and used in various working areas. Also, it should have been built by using factory made products. It means that, all components must be purchasable and economical. There must be no handmade component in device because of the fact that, repairing and replacement of the parts of the device must be done easily. First 3D design of the device which is also shown in survey report is shown below.

Figure 3.1: First 3D model of device

First 3D model was drawn in Solidworks software and it can be produced as handmade. However, according to design motto, there must be no handmade component in the device. So, a new design of the device was created by using purchasable equipment. Final Mechanical design of the device is shown in figures.

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Figure 3.2: 3D model of the device (Solidworks)

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Figure 3.3: Front view

Figure 3.4: Top view

Figure 3.6: Final design of device (real)

Figure 3.5: Left view

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Figure 3.7: Top view of the device

Figure

In final design of the measurement device, all criteria and mottos were reached. Device was built and became ready to measurement as compact, portable, efficient, economical, able to work all sensors together in various working areas. It can be work by using 9V battery or USB cable with energy supplier.

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4. Procedure

In this part of the report, procedure is shown below as step by step.

After informing about project details and objectives, sensors and equipment were investigated widely.

According to objectives, temperature, pressure and air velocity measurements would be accomplished. Then, air flow rate of the system would be determined by using air velocity measurements and geometry of the air handling unit.

Most efficient, compatible and economical sensors, microprocessor and screen which were the fundamental instruments of the device were selected by considering accuracy interval that is suitable for our requirement of the device.

According to our criteria and mottos, for building a compact device, all sensors worked together in only one run.

Codes of each sensor were written in Ardunio Software.

Device became ready to measure temperature, pressure and air velocity.

After that part sensors were calibrated by using different methods. For LM35 temperature sensors calibration, ice-water mixture was used. For BMP180 pressure sensor which has already been calibrated, sensor was checked at the sea level. For TCRT5000 sensor which was used for measuring air velocity and air flow rate, wind tunnel at the laboratory was used.

After the calibration, device was tested and confirmed the measurements results.

According to design criteria, device should have been compact. Therefore, all instruments have been gathered in box.

Device was built as working with 9V battery or USB cable. Also all measurements can be controlled and started using on-off button. Then measurements can be checked on screen.

For velocity measurements, a wooden stick was built whose size is compatible with air handling unit.TCRT5000 and weathervane fixed on it. Also measurements can be done each part of the unit by changing the position of the weathervane and sensor.

Finally, device and all other instruments were connected and device was set into operation as a whole and measurements were started. After the final testing, device ready to measuring successfully.

For each sensor and conditions, uncertainty calculations were completed.

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5. Instruments and Wiring

At the beginning of this project, detailed market search, internet search was done and this search was indicated in the survey report. After this search, three different options were determined for each sensor type, board type and these options were compared in the survey report. The most important parameters to choose sensors are economy and accuracy. After that, coherence between sensors and microcontroller board was also checked. Ultimately, the most suitable ones were chosen. All instruments were shown below.

Experimental Setup and Equipment;

LM35 : Temperature Sensor

BMP180 : Pressure Sensor

TCRT5000: Proximity Sensor, Weathervane

Arduino Uno: Single-board microcontroller

Jumper Wires

Bread board

16 x 4 LCD Screen

9 V Battery

15 Watt Standard Adapter Box

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5.1 LM35

LM35 (Figure 5.1) was used as the temperature sensor of our project. Although LM35 is the most economical sensor, this sensor provides all desired features including working perfectly with Arduino Uno. Additionally, there are several accessible sources on the measurement is determining the temperature difference between heat resistors in the air handling unit. One of the temperature sensors was placed in front of the heat resistors and other one was placed at the internet about LM35. These sources help very much especially at connection part.

Figure 5.1: LM35 Temp. Sensor

The main features of LM35 related with our project are like that;

Able to work in −55˚ to +150˚C range

Able to operate in 4 – 30 V interval ( Suitable for Arduino Uno)

0.5˚C accuracy

Low-self heating (Due to low-self heating there is no concern about at working high temperatures.)

Economical (3 TL)

Two LM35 temperature sensors were used for this project since the aim of the measurement is determining the temperature difference between heat resistors in the air handling unit. One of the temperature sensors was placed in front of the heat resistors and other one was placed at the back of these heat resistors. Thus, measuring two different temperatures from two different parts of the air-handling unit were completed.

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5.2 BMP 180

The market of the cheap pressure sensors is very narrow in Turkey. Despite this narrowness, BMP series barometric pressure sensors satisfy us and all sensors of BMP series provide all desired features. Therefore, the main parameter among the BMP series pressure sensors is the cost. Because of this, BMP 180(Figure 5.2) was selected as the pressure sensor. It is 10 TL that is significantly cheaper than the other pressure sensors such as BMP 085.

.

Figure 5.2 : BMP 180 Pressure Sensor

The major feature that provides all requirements is like that;

Able to work in wide pressure range 300 - 1100hPa (1 hPa = 100 Pa)

Able to operate in 1.8 – 3.6 V interval (Suitable for Arduino Uno)

Factory-calibrated

Including a temperature sensor

The first goal of the project is measuring the pressure in the air- handling unit, although instant pressure difference was tried to measure as the second - goal, when the deadline was come closer. Because of the late informing about second-goal, this goal was cancelled by the instructor. In addition, our group was able to accomplish this goal, but a switch that is not economical for connecting to the Arduino Uno must be bought and the remaining time to deadline was not enough for doing demo about that.

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Figure 5.3 : Red circle shows the location of the BMP 180 in the air-handling unit

As shown in Figure 5.3 , BMP 180 was placed after the heating resistors and before the fan.

5.3 TCRT5000 and Weathervane

Actually, TCRT5000 (Figure 5.4) is a proximity sensor that measures distance. In this project, this proximity sensor was used with different working principle. The eyesight of this sensor is between 0.2 mm and 1.5 mm. According to this information, new working principle for TCRT5000 was formed like that if the propeller of the weathervane (Figure 5.5) is in TCRT5000’s eyesight, it must be counted, so RPM of the weathervane can be found .In other words, TCRT5000 was sticked at the back of the weathervane (Figure 5.6) and it counts all passes of the propellers to measure the RPM of the weathervane. Figure 5.4 : TCRT 5000

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Figure 5.5 : Weathervane Figure 5.6 : TCRT5000 and Weathervane

RPM can be converted to velocity and mass flow rate of air can be found.Converting RPM to velocity is done with a equation that was found in the calibration part.This part was explained detailly in the calibration part of this report.

The price of TCRT5000 is 7 TL and the price of the weathervane is just 2 TL. This is the one of the cheapest measurement type.

TCRT5000 and weathervane combination was located in front of the fan in the air-handling unit.(Figure 5.7)

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Figure 5.7 : Weathervane was placed in front of the fan/compressor.

5.4 Arduino Uno

Arduino Uno (Figure 5.8) was selected as the microcontroller – board for this project. It is an economical solution (35 TL) and compatible with all sensors that were chosen. Also, Arduino Uno is the most common microcontroller board and mini/portable device that was wanted.

Figure 5.8: Arduino Uno

The significant properties of Arduino Uno were shown in Table 1.

Table 1

Arduino Uno was connected to computer via USB connection.Therefore, Arduino Uno was controlled from computer via Arduino Software and codes were uploaded to board.Arduino Software is an application that provides writing a code and uploading it to the

Microcontroller ATmega328Input Voltage (recommended) 7 - 12 VInput Voltage (limit) 6 - 20 VOperating Voltage 5 VDigitan I/O Pins 14Analog Input Pins 6DC Current per I/O Pin 40 mADC Current for 3.3V Pin 50 mAFlash Memory 32 KBClock Speed 16 MHz

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board.Wiring diagram of sensors and Arduino Uno was shown in experimental setup part of this report.Also, codes were indicated in codes part of this report.5.5 Jumper Wires

Jumper wires (Figure 5.9) were used to make connection between sensors and the microcontroller board.These wires are easy-to-connect type cables.

Figure 5.9: Jumper Wires

5.6 Bread Board

Bread boards (Figure 5.10) that are used to make electronic prototypes are quite expensive plastic rectangular tool.Working principle of bread board is that the vertical columns on the bread board are connected to the same conductor , so electricity circuit can be prepared easily with increased hole numbers.

Figure 5.10 : Bread Board

5.7 LCD Screen

16 x 4 Lcd screen (Figure 5.11) was used to show the measurements.

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Figure 5.12 : Device with Connected Sensors

At the end of this project, air conditioning measurement device was set on to air-handling unit in thermodynamics lab.Temperature difference, pressure , velocity , mass flow in the air-handling unit can be measured at the same time via our device as shown in Figure 5.13.

Figure 5.11 : LCD Screen

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Figure 5.13 : Air Conditioning Measurement Device on the Air-Handling Unit

5.8 Adapter Box

This equipment was used as outer case of the device.Except for sensors, all other instruments are placed into this box which is shown below.

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Figure 5.14 : Adapter box – Outer case of the device

Wiring:

In this part, wiring of the device is shown below.All connectoions between sensors, LCD, battery, Arduino and breadboard are monitored in Figure 5.15. Device can be used by using 9V battery or USB cable. It means that, in terms of portability, device can be used 9V battery, but in terms of efficiency and economical reasons, device can be used by using USB connection.

Figure 5.15 : Wiring diagram of the measurement device

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Figure 5.15 : Wiring schema of the device

LM35 (1) LM35 (2) BMP180 TCRT5000 SDA SCL GND VIN D0 VCC GND

5V A0 GND 5V A1 GND A4 A5 GND 3.3V 2 3 4

Figure 5.16 : Wiring orientation of sensor extension socket

6. Calibration

6.1 LM35 Calibration

The safest calibration method for LM35 is done with ice-water mixture.If it is done with kettle some safety problems may be occured.Therefore, this way was chosen.

LM35 was dropped in the cup that was filled with ice-water mixture.When the balance between water and ice was observed, LM35 was indicated as 0 ˚C which is the melting point of ice.Although LM35 was come fully-calibrated , calibration was checked with this way.(Figure 6.1)

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Figure 6.1 : LM35 Calibration

6.2 BMP 180 Calibration

BMP 180 was come fully-calibrated, it gives reliable results.In spite of coming fully-calibrated,calibration of BMP 180 was checked at the sea level.It indicated 101326 Pa at the sea level at the Uskudar Coast.

6.3 TCRT5000 Calibration

TCRT5000 is used to calculate/measure RPM of the weathervane, but the requirement of this project is not calculating RPM.That’s why,weathervane with TCRT5000 needs a calibration to find each velocity value for each RPM. After this, mass flow can be calculated easily.

Figure 6.2: Weathervane in the Wind Tunnel

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TCRT5000 was calibrated in the wind tunnel (Figure 6.2). Instant Hz. value in the wind tunnel was measured by pitot tube in the wind tunnel and sent to excel on the computer.These Hz. values was converted to velocity on excel.At the same time RPM of weathervane was measuring.This procedure was done for various Hz. Values.At the end of the calibration, RPM values and velocity values were gathered in one excel document and Graph 1 was plotted as Velocity vs. RPM . Third order equation that was shown in Graph 1 was occured after third order polynomial trendline was plotted.Founded equation was put in our code. Instant RPM values are put in this equation, so velocity can be calculated through this equation. Mass flow can be found with this procedure.Q = V.A equation where “A = 0.29 m x 0.29 m” is used to calculate mass flow. Some Velocity-RPM values was shown in Table 2.

0 500 1000 1500 2000 2500 30000

1

2

3

4

5

6

7

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f(x) = − 1.94375E-10 x³ + 0.00000158042 x² − 0.000472912 x − 0.03917762R² = 0.978837955130078

Velocity vs. RPM

RPM

Velo

city

(m/s

)

Graph 1:Velocity vs. RPM

7. Codes of the System

In this part of the report, codes which were used in Arduino Microprocessor for measurements are shown below.

RPM velocity(m/s)0 0

962,17 0,671238,90 1,121291,53 1,601435,09 2,081584,67 2,611766,30 3,091871,59 3,622075,90 4,122305,38 4,602496,19 5,162639,45 5,672733,49 6,252731,27 6,762701,28 7,18

Table 2

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21

22

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8. Uncertainty Analysis

In this part uncertainty analysis was done for Reynolds number because the velocity sensor is hand made. Reynolds Number contains three different parameters. These parameters are velocity, diameter and kinematic viscosity.

First of all, velocity sensor is hand made so there is not any data about uncertainty of this sensor. Thus, 80 data were taken in air handling unit at 10 Hz fan speed for calculating uncertainty for velocity.

Secondly, the uncertainty of diameter must be calculated. Our air handling unit has square profile thereby according to knowledge of Fluid Mechanics; the Hydraulic Diameter

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calculation is needed. After the Hydraulic Diameter calculation, the uncertainty analysis for diameter is finished.

Lastly, Kinematic Viscosity was found from dry air properties table for 20oC. The uncertainty about Kinematic Viscosity is coming from temperature measurement. However, when the values of Kinematic Viscosity checked for 19.5o C and 20.5oC there was no necessary change (9x10-8). Thus, the Kinematic Viscosity value at 20oC can be used directly at calculations.

Velocity Uncertainty :

Figure 8.1 : The Velocity vs # of Data

Table 2 : Sample data for Velocity Uncertainity

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Diameter Uncertainty :

Area=a∗b=0.29 m∗0.29m(a=b=0.29 m± 0.0005 m)

Hydraulic Diameter :d= 4 ab2(a+b)

, d=0.29 m

d¿4 (ab)

2(a+b)

∂ d∂ a

=2 b2

¿¿

∂ d∂ b

=2 a2

¿¿

Wd=√( ∂ d∂ a

wa)2

+( ∂ d∂ b

wb)2

=0.000035355 m

Kinematic Viscosity :

γ=1.505 x 10−5 m2

s

Reynolds Number:

V=2.75± 0.24 m /s D=0.29± 3.5355 x10−5 m

γ=1.505 x 10−5 m2

s

ℜ=VDγ

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∂ℜ∂V

=Dγ

=0.29

1.505 x10−5 =19269.10299

∂ℜ∂ D

=Vγ

=2.75

1.505 x10−5 =182724.2525

W ℜ=√( ∂ℜ∂V

wV )2

+( ∂ ℜ∂ D

wD)2

=4635.433

ℜ=52990 ± 4635.433(± 8.7 %)

9. Conclusion

The major aim of this project is making a device that can measure temperature difference, pressure, velocity and mass flow in the air-handling unit. Fortunately, all of these aims were achieved. Firstly, temperature difference between the heating resistors in the air-handling unit can be measured with two LM35 temperature sensors which were located in front of and at the back of the heat resistors.

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Secondly, pressure can be measured easily through BMP 180 and if it is needed BMP 180 can be placed another place, so pressure difference can be observed like that. As it is said in Instruments/BMP 180 part, two BMP 180 sensors could not be used due to late informing about pressure difference goal. Additionally, Arduino Uno needs a switch that is not suitable to run two BMP 180. Despite these drawbacks; our group was able to run two BMP 180 at the same time if our group had more time to deadline. At least, pressure difference can be observed with one BMP 180, because our device is very compact and mobile, so it can carry easily.

Next, mass flow and velocity in the air-handling unit can be seen with the RPM of the calibrated weathervane. TCRT5000 and Weathervane combination was located in front of the compressor/fan to measure RPM of the air in the air-handling unit. These RPM values that are taken from TCRT5000 are used to find velocity and mass flow. Thus, RPM is converted to velocity and mass flow with the help of the velocity vs RPM graph which was plotted after calibration. Calibration is the most important part of this measurement type since this measurement type was created from scratch. Calibration was really needed to find each velocity, mass flow value for each measured RPM. Only counting RPM specifies nothing. After calibration, RPM values are meaningful now.

Finally, uncertainity analysis was done for system. In this system, uncertainity of all sensors were known. However, velocity measurement sensor was handmade thereby there is not any meaningful knowledge about uncertainity. For this reason, uncertainity analysis was done for Reynolds Number that contains velocity, diameter and kinematic viscosity. Here, the key point is velocity. The fluctuation of the velocity was found to determine the uncertainity of the velocity measurement. Then, uncertainity for diameter was found. In addition, there was no need to include uncertainity of kinematic viscosity because a 1oC difference in temperature made 9x10-8 change in viscosity there by it was really unnecessary for calculations. With all these knowledge uncertainity analysis was done successfully.

Actually, all of these goals were achieved in this project. Additionally, device was designed carefully and it is compact, easy-to-use; it has just one button and one screen on it, portable; it can be carried everywhere and sensors are removable. Also, our device can run all sensors at the same time, so all measurements can be taken simultaneously.

10. References

[1] Arduino http://www.arduino.cc/

[2] Fritzing Software http://fritzing.org/home/

[3] LM35 Data Sheet http://pdf.datasheetcatalog.com/datasheet/nationalsemiconductor/DS005516.PDF

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[4] TCRT 5000 Data Sheet http://www.vishay.com/docs/83760/tcrt5000.pdf

[5] BMP180 Data Sheet https://ae-bst.resource.bosch.com/media/products/dokumente/bmp180/BST-BMP180-

DS000-09.pdf

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