UNIVERSITI PUTRA MALAYSIA

DESIGN AND DEVELOPMENT OF COMPUTERIZED PHOTOFLASH METHOD FOR

THERMAL DIFFUSIVITY MEASUREMENT

THAI MING YEOW

FS 2007 51

DESIGN AND DEVELOPMENT OF COMPUTERIZED PHOTOFLASH METHOD FOR

THERMAL DIFFUSIVITY MEASUREMENT

By

THAI MING YEOW

Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfilment of the Requirement for the Degree of Master of Science

October 2007

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DEDICATION

To my dearest parents Thai Qui Yoong and Wong Ah Mooi

for their supports and concern……

To my beloved Fong Mei Mei

who loves and support me all the times...

To my supervisors

Assoc. Prof. Dr. Zaidan Abdul Wahab, Prof. Wan Mahmood Mat Yunus and

Prof. Mohd. Maarof Moksin

for their guidance and advice…

To all my friends

for their assistance and supports…

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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment of the requirement for the degree of Master of Science

DESIGN AND DEVELOPMENT OF COMPUTERIZED PHOTOFLASH

METHOD FOR THERMAL DIFFUSIVITY MEASUREMENT

By

THAI MING YEOW

October 2007

Chairman: Associate Professor Zaidan Abdul Wahab, PhD Faculty: Science Thermal diffusivity, α is a parameter that characterizes the rate of heat diffusion in

the material due to heat flux in an unsteady-state process. Flash method was

introduced by Parker et al (1960) as a fast and economical method for determination

of thermal diffusivity. A computerized experimental system was constructed in this

project to simplify and expedite the experimental process for determination of

thermal diffusivity of solid samples at room temperature.

In conventional photoflash method, a high intensity photoflash was used as the

energy pulse source. A thermocouple wire was used to monitor the temperature of

the rear surface of the sample and captured by an oscilloscope. The calculation of

thermal diffusivity value could be done either manually or with the aid of several

software tools.

The present work replaces these lengthy processes by automating the firing of the

photoflash and the capturing of temperature-time data of the sample rear surface. A

Personal Computer equipped with a National Instrument DAQ (Data Acquisition)

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card plays its role as a control center to control and monitor the experiment process

from firing of flash to the completion of thermal diffusivity determination.

Various electronics circuits were studied and developed in order to facilitate the

firing of flash such as relay driver circuits, photodiode amplifier and Schmitt Trigger

circuit. The circuit interacts with the DAQ card to perform specific functions such as

triggering acquisition or switching on the flash.

An event-driven application called ThermDiff was written using Microsoft Visual

Basic 6 allowing the user to control the experimental operations interactively. The

application provides a complete set of functions to the user include hardware control,

data acquisition, data conditioning and computation of thermal diffusivity value.

Besides, other features such as file storage, graphical presentation, printing and help

system are included into the application.

The functionality and workability of the computerized experimental system were

successfully tested. The reliability and accuracy was verified by testing several

samples of known thermal diffusivity value: Aluminum, Silicon Carbide and Boron

Carbide. As results, the computed thermal diffusivity values showed close

agreements to the literature values with difference of less than ±5%.

It is recommended that future researches can be carried out to develop a

computerized experimental system that is capable to determine thermal diffusivity

value accurately at various temperatures.

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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Sains

REKABENTUK DAN PEMBANGUNAN KAEDAH LAMPU KILAT

BERKOMPUTER UNTUK PENGUKURAN DAYA RESAPAN THERMAL

Oleh

THAI MING YEOW

Oktober 2007 Pengerusi: Profesor Madya Zaidan Abdul Wahab, PhD Fakulti: Sains Daya resapan terma, α merupakan salah satu parameter yang menyifatkan kadar

penyebaran haba dalam suatu bahan disebabkan oleh aliran haba dalam proses

keadaan tidak mantap. Kaedah lampu kilat diperkenalkan oleh Parker et al. (1960)

sebagai suatu kaedah yang cepat dan ekonomi untuk penentuan daya resapan terma.

Satu sistem eksperimen berkomputer telah dibangunkan dalam projek ini untuk

memudahkan dan mempercepatkan proses eksperimen bagi penentuan nilai daya

resapan terma bahan pepejal pada suhu bilik.

Dalam kaedah lampu kilat konvensyenal, suatu lampu kilat yang berkeamatan tinggi

digunakan sebaga sumber tenaga denyut. Dawai termogandingan digunakan untuk

memantau suhu pada permukaan belakang sampel dan direkodkan oleh sebuah

osiloskop. Pengiraan nilai daya resapan terma boleh dilakukan secara manual atau

dengan bantuan beberapa perisian komputer.

Dalam kajian ini, proses yang memakan masa ini digantikan dengan pengautomatik

pemancaran lampu kilat dan pencatatan data suhu-masa pada permukaan belakang

sampel. Sebuah komputer peribadi dilengkapi Kad DAQ dari “National Instruments”

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memainkan peranan sebagai pusat kawalan untuk mengawal dan memantau proses

eksperimen dari pemancaran lampu kilat hingga penyelesaian penentuan nilai daya

resapan terma.

Beberapa litar elektronik telah dikaji dan dibina untuk memudahkan pemancaran

lampu kilat seperti litar pemandu geganti, litar penguat diod peka cahaya dan litar

picuan Schmitt. Litar ini berinteraksi dengan Kad DAQ untuk menjalankan kerja-

kerja yang tertentu seperti picuan proses pemerolehan atau pengsuisan lampu kilat.

Suatu aplikasi berpandukan peristiwa dipanggil ThermDiff dibangunkan dengan

menggunakan Microsoft Visual Basic 6 membolehkan pengguna mengawal operasi

eksperimen secara interaktif. Aplikasi ini dilengkapkan dengan set fungsi yang

sempurna kepada pengguna termasuk pengawalan perkakas, pemerolehan data,

pelaziman data dan mengira nilai daya resapan terma. Di samping itu, fungsi-fungsi

lain seperti penyimpanan fail, pemaparan grafik, pencetakan dan sistem bantuan turut

dirangkumi aplikasi ini.

Fungsi dan kebolehan sistem eksperimen berpandukan komputer ini telah berjaya

diuji. Kebolehpercayaan dan kejituan sistem telah disahkan dengan pengujian

beberapa sampel yang nilai daya resapan termanya diketahui: Aluminium, Silikon

Karbida dan Boron Karbida. Sebagai keputusan, nilai daya resapan terma yang dikira

menunjukkan persetujuan yang hampir sama dengan nilai rujukan dengan perbezaan

kurang daripada ±5%. Adalah dicadangkan kajian ini dapat diteruskan dengan

pembangunan sistem berpandukan komputer yang dapat menentukan nilai daya

resapan terma pada sebarang suhu.

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ACKNOWLEDGEMENTS First of all, I would like to express my deepest gratitude to my parents for giving me

supports in material and spiritual form all the time and the immeasurable love given

to me keeping me living in comfortable and peaceful conditions.

My sincere thanks and highest respect to my supervisor, Assoc. Prof. Dr. Zaidan

Abdul Wahab who has been giving me advises and guidance throughout the whole

project. His willingness and helpfulness are always the strongest support for me to

keep going with the development process. Besides, I would like to express my

sincere gratitude to my co-supervisors, Prof. Dr. Wan Mahmood Mat Yunus and

Prof. Dr. Mohd. Maarof Moksin. Thanks for their guidance, advices and helpfulness.

Special thanks to my course mates and friend are also great supporters for me, I

appreciated all the helps and supports given to me.

Finally, may all of them who have helped and supported me living in peace,

happiness and prosperous.

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I certify that an Examination Committee has met on 4th October 2007 to conduct the final examination of Thai Ming Yeow on his Master of Science thesis entitled “Design and Development of Computerized Photoflash Method for Thermal Diffusivity Measurement” in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulations 1981. The Committee recommends that the student be awarded the degree of Master of Science. Members of the Examination Committee were as follows: Sidek Hj. Abd. Aziz, PhD Associate Professor Faculty of Science Universiti Putra Malaysia (Chairman) Zainal Abidin Sulaiman, PhD Associate Professor Faculty of Science Universiti Putra Malaysia (Internal Examiner) Azmi Zakaria, PhD Associate Professor Faculty of Science Universiti Putra Malaysia (Internal Examiner) Sinin Hamdan, PhD Associate Professor Faculty of Engineering Universiti Malaysia Sarawak (External Examiner) ________________________________

HASANAH MOHD GHAZALI, PhD Professor and Deputy Dean School of Graduate Studies Universiti Putra Malaysia

Date: 17 December 2007

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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfilment of the requirement for the degree of Master of Science. The members of the Supervisory Committee were as follows: Zaidan Abdul Wahab, PhD Associate Professor Faculty of Science Universiti Putra Malaysia (Chairman) W. Mahmood Mat Yunus, PhD Professor Faculty of Science Universiti Putra Malaysia (Member) Mohd Maarof Moksin, PhD Professor Faculty of Science Universiti Putra Malaysia (Member)

____________________ AINI IDERIS, PhD Professor and Dean School of Graduate Studies Universiti Putra Malaysia Date: 22 January 2008

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DECLARATION

I hereby declare that the thesis is based on my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UPM or other institutions.

__________________ THAI MING YEOW Date: 3 December 2007

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TABLE OF CONTENTS Page DEDICATION ii ABSTRACT iii ABSTRAK v ACKNOWLEDGEMENTS vii APPROVAL viii DECLARATION x LIST OF TABLES xiii LIST OF FIGURES xiv LIST OF ABBREVIATIONS xvi CHAPTER

1 INTRODUCTION 1.1 1.1 Research Problems 1.1 1.2 Importance of the Study 1.1 1.3 Objectives of the Study 1.2 1.4 Scope of Study 1.3 2 LITERATURE REVIEW AND THEORY 2.1 2.1 Various Techniques for Determination of Thermal

Diffusivity 2.1

2.2 Reviews on Flash Methods 2.2 2.3 Reviews on Software Process Models 2.9 2.4 Reviews on Previous Computerized Projects 2.12 2.5 Theory of Flash Method 2.18 2.6 Estimation of Errors and Correction 2.24 2.6.1 Measurement Errors 2.24 2.6.2 Non-measurement Errors 2.25 3 EXPERIMENTAL SETUP AND HARDWARE

DESIGN 3.1

3.1 The Computerized Experimental System 3.1 3.2 Samples 3.4 3.3 Energy Source 3.6 3.4 The Electronic Switch 3.6 3.5 Temperature Sensor 3.9 3.6 The Photodiode 3.10 3.7 Instruments and Circuits for Signal Conditioning 3.12 3.7.1 Low-noise Preamplifier 3.12 3.7.2 Photodiode Amplifier 3.12 3.7.3 Analog-to-Digital Converter 3.15 3.8 Data Acquisition System 3.16 3.8.1 Data Acquisition Cards 3.17 3.8.2 The Oscilloscope

3.19

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3.9 The Experimental Setup 3.19 3.9.1 Experimental Setup with DAQ card 3.19 3.9.2 Experimental Setup with Oscilloscope 3.22 4 SOFTWARE DESIGN 4.1 4.1 The Programming Language – Visual Basic 6 4.1 4.2 NI-DAQ 4.2 4.3 The Graphical User Interfaces (GUI) Design of

ThermDiff 4.3

4.4 Process Flows of ThermDiff 4.8 4.5 Algorithm Designs 4.11 4.5.1 The GUI Management Routine 4.11 4.5.2 Data Acquisition Routines 4.12 4.5.3 Memory Management Routines 4.13 4.5.4 Data Manipulation Routines 4.14 4.5.5 File Handling Procedures 4.23 4.5.6 Graphical Representation 4.23 4.5.7 Printing 4.23 4.6 The Help System 4.24 4.7 Deployment of ThermDiff 4.24 5 RESULTS AND DISCUSSIONS 5.1 5.1 The User Interfaces of ThermDiff 5.1 5.2 Functionalities and Features of ThermDiff 5.6 5.2.1 ThermDiff Settings 5.6 5.2.2 Data Acquisition 5.7 5.2.4 Features of ThermDiff 5.13 5.2.3 Data Processing and Manipulation 5.8 5.3 Reliability and Accuracy of the Computerized

System 5.14

6 CONCLUSION AND RECOMMENDATIONS 6.1 6.1 Conclusion 6.1 6.2 Suggestions For Framework 6.3 6.2.1 Hardware Improvement 6.3 6.2.2 Software Improvements 6.4 6.2.3 Further Studies 6.4

REFERENCES R.1 APPENDICES A.1 BIODATA OF THE AUTHOR B.1

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LIST OF TABLES

Table Page 2.1 Value of Kx for Various Percent Rise 2.23 2.2 Finite-Pulse Time Factors 2.28 2.3 Coefficients for Cowan Corrections 2.30 3.1 Properties of K-type thermocouple 3.11 3.2 Description of some I/O connector signal 3.18 4.1 Descriptions of Forms and Doalogboxes in ThermDiff 4.3 5.1 τ/tc Ratio 5.18 5.2 Corrected Values of Thermal Diffusivity 5.18 5.3 Comparisons of Thermal Diffusivity Values of Samples with

Reference Value 5.18

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LIST OF FIGURES

Figure Page 2.1 Schematic of Boris Kirdric Institusion laser flash apparatus 2.17 2.2 An example screen of program developed by Teh, 2001 2.17 2.3 Dimensionless Plot of the Rear Surface Temperature History 2.23 2.4 Sawtooth pulse shape 2.27 3.1 The signal flow diagram for a computer-controlled instrument 3.5 3.2 Pulse Shape for Minolta 5400HS Photoflash 3.7 3.3 The socket and the custom-made adaptor 3.7 3.4 The relay driver circuit 3.8 3.5 Rise time of K-type Thermocouple 3.11 3.6 Schematic diagram for electronic circuits used for switching,

amplification and A/D conversion 3.13

3.7 Schematic diagram for photodiode amplifier 3.14 3.8 Schematic diagram for Schmitt Trigger 3.14 3.9 Schematic diagram for experimental setup with DAQ card 3.21 3.10 Schematic diagram for experimental setup with oscilloscope 3.21 3.11 Experimental setup with DAQ card 3.22 4.1 Organization of GUIs in ThermDiff 4.7 4.2 General Processes of Thermdiff 4.9 4.3 A Screenshot of macromedia Dreamweaver MX 4.25 4.4 A Screenshot of Package and Deployment Wizard 4.25 5.1 The GUI of the Main Window at Startup 5.2 5.2 A screenshot of ThermDiff with an Experiment Project 5.3 5.3 Acquisition setup

5.10

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5.4 The Satisfy? Messagebox Allows User to Accept of Discard the Acquired Data

5.10

5.5 The Outcome of Spike Removal (a) Before Spike Removal (b)

After Spike Removal 5.11

5.6 The Temperature History Curve of Boron Carbide Before

Adjacent Average Smoothing (RAW), After smoothing with 25 points (AV25 ), After smoothing with 50 points (AV50), After smoothing with 75 points (AV75) and After smoothing with 100 points (AV100)

5.12

5.7 The Temperature History Curve of Boron Carbide Before FFT

Smoothing (RAW), After FFT smoothing with 25 points (FFT25), After FFT smoothing with 50 points (FFT50), After FFT smoothing with 75 points (FFT75) and After FFT smoothing with 100 points (FFT100)

5.12

5.8 A Screenshot of Temperature History after Performing

Normalization Function 5.13

5.9 Computed Thermal Diffusivity for Aluminum Sample 5.15 5.10 Computed Thermal Diffusivity for Silicon Carbide Sample 5.16 5.11 Computed Thermal Diffusivity for Boron Carbide Sample 5.17

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LIST OF ABBREVIATIONS ADC Analog to Digital Converter ANSI American National Standard Institution API Application Programming Interface BJT Bipolar Junction Transistor CAD Computer Aided Design CAM Computer Aided Modeling CPU Central Processing Unit CRT Cathode Ray Tube DAC Digital to Analog Converter DAQ Data Acquisition DC Direct Current DLL Dynamic Link Library DSP Digital Signal Processing DUT Device under Test FFT Fast Fourier Transform GB Gigabyte GPIB General Purposes Interface Bus GUI Graphical User Interface HTML Hypertext Markup Language IC Integrated Circuit I/O Input/Output ISA Industrial Standard Architecture LSI Large Scale Integration

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MAX Measurement & Automation Explorer MB Megabyte MS-DOS Microsoft Disk Operating System NI National Instruments PC Personal Computer PCI Peripheral Component Interconnect PFI Programmable Function Input RAD Rapid Application Development SDI Single Document Interface SPDT Single Pole Double Throw STC System Timing Control T.D. Thermal Diffusivity TTL Transistor-transistor Logic USB Universal Serial Bus VLSI Very Large Scale Integration Win32 32-bit Windows

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LIST OF SYMBOLS

α thermal diffusivity

αcorrected corrected value of thermal diffusivity αx thermal diffusivity calculated at x percent rise β adjustable parameter of the energy pulse Δ sampling rate λ thermal conductivity ρ density ω dimensionless parameter τ pulse time ak raw data point with index k bi new data point derived from averaging of neighboring points c specific heat / number of adjacent points involved in averaging Cp heat capacity d sum of specified element values f frequency fn frequency estimated at the discrete value Fk parameter Fn parameter g small depth at the front surface i index of element in an array Ip current generated by photodiode KC correction factor for Cowan cooling curve data KR correction factor for Taylor rising curve data Kx constant corresponding to x% of maximum temperature rise

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L thickness of the sample N total number of data points / points of input Q energy of the light pulse Rf resistance S seeback coeffcient T temperature TM, TMax maximum temperature rise at the sample rear surface t time t1/2 time required for the back surface of the sample to reach half

the maximum temperature rise tc characteristic rise time tk time when k-th points is sampled tx time required to reach x% of TMax

t0.5 time required to reach half maximum temperature rise t0.25 time required to reach 25% maximum temperature rise t0.75 time required to reach 75% maximum temperature rise V voltage / dimensionless parameter Vb base voltage Vin input voltage Vout output voltage

CHAPTER 1

INTRODUCTION

Thermal diffusivity α is a parameter that characterizes the rate of heat diffusion in

the material due to a heat flux in an unsteady-state heat transfer process. It measures

how quickly a material can absorb heat from its surroundings and change

temperature. Higher value of thermal diffusivity implies higher rate of heat

propagation. Photoflash method is a simple and inexpensive method for

determination of thermal diffusivity, α.

1.1 Research Problems

Experiments that required routine data collection can be done more easily with the

help of computers. In photoflash experiment, data points were collected repeatedly in

very short intervals, and would be more effectively done in a computer-controlled

environment. Development of computerized system would help to enhance and

expedite the experiment.

1.2 Importance of the Study

Researches about thermal diffusivity are not something new. For instance, in

Universiti Putra Malaysia, many researches pertaining to thermal diffusivity were

carried out. (Teh, 2001), (Josephine, 2003). Regardless what methods are used, what

types of samples are tested or how the apparatuses are set up, computer is one of the

1.2

essential instruments in an experimental setup. Computers play important roles many

experimental processes such as data capturing, data manipulation and analysis,

equipments control, signal generation, simulation etc.

Computer interfacing and automation are common terms to many people yet projects

that computerize thermal diffusivity measurement are still rarely conducted.

Although computers have been used for the above-mentioned purposes, complete

and specialized solutions for the entire experimental procedure are still needed.

Considering the problems above, an all-in-one solution for determination of thermal

diffusivity is needed. Photoflash method was chosen because it is one of the fastest

and most economical methods for determination of thermal diffusivity while

providing reasonable accuracy. Thus, specialized software to computerize photoflash

method was developed.

1.3 Objectives of the Study

As mentioned in previous section, all-in-one solutions for determination of thermal

diffusivity are hardly available in the market. The objectives of this project are:

(i) To develop a user friendly computerized experimental system for

determination of thermal diffusivity of solids at room temperature based

on photoflash method that runs under the most popular Win32 (Windows

95, Windows NT or later) platform.

(ii) To perform thermal diffusivity measurement in a fraction of time

compare to the manual calculation method.

1.3

(iii) To attempt the usability of general-purpose programming language as an

alternative to the commonly used LabVIEW graphical language as a

development tool for computer interfacing.

1.4 Scope of Study

The project involves the following aspects:-

(i) Selection of a suitable programming language and tools and familiarized

with it. Microsoft Visual Basic 6 was used as the programming language,

development environment and compiler while NI-DAQ API (Application

Programming Interface) was used to interface with the acquisition

hardware.

(ii) Study or design related algorithms for manipulation and processing of

captured data such as smoothing, normalization, interpolation,

determination of parameters etc.

(iii) Design and handle GUI (Graphical User Interface).

(iv) Design electronic circuits for switching, amplification and triggering.

(v) Design routines for data capturing, flash switching and data storage.

(vi) Software integration – integration of GUI, processing routines and

acquisition routines to create a complete software system.

(vii) Test various samples and compare with reference values to verify the

reliability and accuracy of the system.

(viii) Creation of documentation or help system.

CHAPTER 2

LITERATURE REVIEW AND THEORY

2.1 Various Techniques for Determination of Thermal Diffusivity

Methods used for measuring thermal diffusivity can be categorised into two main

classes: transient heat-flow methods and periodic heat-flow methods. The basic

principle for the former is that if one end of a sample is heated periodically, then the

temperature of the sample also varies with the same period with diminishing

amplitude. As temperature wave travels along the sample with finite velocity there is

a varying phase relationship. Measurement of the amplitude decrement and either

phase difference or velocity enables the diffusivity to be determined. For the latter, a

sample is initially in equilibrium with uniform surrounding temperature, and then the

part of it is subjected to a change in thermal flux. The thermal diffusivity is evaluated

from changes in temperature which occur in measured time intervals at one or more

points within the sample. The naming of these methods are given based on the

originator or to the nature of the technique used (Toloukian, 1970):

i. transient heat-flow methods

a) Forbes' bar method

b) Moving heat-source method

c) Thermoelectric effect method

d) High intensity arc method

e) Flash method

ii. periodic heat-flow methods

2.2

a) Modified Angstrom's method

b) Temperature wave velocity

c) Temperature wave amplitude-decrement method

d) Phase-Lag method

e) Radial-wave method

Amongst these methods, more attention is given to the flash method and the

modified Angstrom's method. The have the advantages of being high speed and

considerable freedom from the effect of heat losses. These methods are valuable for

usage under extreme conditions, for instance at very high temperature.

2.2 Reviews on Flash Methods

Flash technique is not a new method for determination of thermal physical properties

of materials. The method was firstly used for homogenous, isotropic and opaque

materials. However, it was proven to work well when applied on disperse non-

homogenous materials, materials with two-dimensional anisotropy, multi-directional

anisotropic, layered materials as well as translucent materials. (Maglic et al., 1992)

The prototype of flash method was developed and studied by Parker et al in 1961. In

their research, the model was used to measure thermal diffusivity, heat capacity and

thermal conductivity of solid materials. A high intensity short duration heat pulse is

absorbed in the front surface of a thermally insulated specimen with a few millimeter

thickness and coated with camphor black to enhance heat absorption. An

oscilloscope was used to record the resulting temperature rise at the rear surface of

the specimen. The output of the oscilloscope was captured by oscilloscope camera.