미네랄 파울링 저감에 티타늄 촉매특성을 이용한 새로운 파울링 억제 기술에 관한 연구 : A study of new anti-fouling technology using the catalytic properties of titanium inmineral fouling mitigation

다국어 초록 (Multilingual Abstract)

Fouling can be defined as the accumulation of deposits on heat transfer surfaces that lowers down the heat transfer rate across the heat exchanger due to the deposit’s low thermal conductivity. It also increases the pressure drop due to higher fluid flow resistance and reduced flow area. Crystallization fouling and particulate fouling are the two most common fouling mechanisms in water cooling systems. These two are termed as mineral fouling. Mineral fouling involves the precipitation of inverse solubility salts and the transport of particles on heat transfer surfaces.
The present study investigated the performance of physical water treatment (PWT) device using titanium balls. It has been widely known that titanium has catalytic properties that could be useful in mineral fouling mitigation. A concentric tube heat exchanger in a counterflow set-up was used in the study. Concentrated hard water at 6,150+2% μS/cm electrical conductivity was utilized to hasten the fouling formation. Two different cold water velocities of 0.3 m/s and 0.5 m/s were in test while maintaining constant temperatures at both hot and cold sides.
The results showed that PWT-treated cases had 30% and 25% lower fouling resistances as compared to the untreated cases for 0.3 m/s and 0.5 m/s, respectively. The deposit also revealed a calcite form of scale that could easily be carried away by fluid flow shear forces. It was concluded that the mechanism of PWT may be in surface reaction via heterogeneous catalysis.

목차 (Table of Contents)

• Chapter 1. Introduction 1
• 1.1 General Background 1
• 1.2 Objectives of the Study 3
• 1.3 Scope of the Thesis 4
• Chapter 2. Review of Related Literature 5
• 2.1 Introduction 5
• 2.2 Fouling History 9
• 2.3 Fouling Mechanisms 11
• 2.3.1 Crystallization Fouling 12
• 2.3.1.1 Formation Process of Calcium Carbonate 14
• 2.3.1.2 Types of Calcium Carbonate 15
• 2.3.2 Particulate Fouling 17
• 2.3.3 Biological Fouling 18
• 2.3.4 Corrosion Fouling 20
• 2.3.5 Chemical Reaction Fouling 20
• 2.3.6 Solidification or Freezing Fouling 21
• 2.3.7 Interactive Fouling 21
• 2.4 Fouling Stages 22
• 2.5 Fouling Prevention and Mitigation Methods 23
• 2.5.1 Use of chemicals 24
• 2.5.2 Non-chemical Methods 25
• 2.6 Physical Water Treatment 26
• 2.6.1 PWT Devices 30
• 2.6.1.1 Solenoid-Coil Induction Technology 30
• 2.6.1.2 Permanent Magnets 32
• 2.6.1.3 Catalytic Materials 34
• 2.7 Titanium 36
• 2.7.1 Properties 36
• 2.7.2 Titanium Dioxide 37
• Chapter 3. Experimental Study 38
• 3.1 Facilities and Procedure 38
• 3.1.1 Experimental Set-up 38
• 3.1.2 Heat Exchanger 41
• 3.1.2.1 Heat Exchanger Efficiency 41
• 3.1.3 Cooling Tower Recirculation System 44
• 3.2 Bacterial Count 46
• 3.3 Heat Treatment of Titanium 48
• 3.4 PWT Catalytic Device 50
• 3.5 Experimental Procedure 52
• 3.6 Experimental Results and Discussion 55
• 3.6.1 Fouling Resistance 55
• 3.6.2 SEM Photographs 62
• Chapter 4. Conclusions 65
• References 67
• Appendix A. Water Analysis 70
• Appendix B. Details of Equipment and Facilities 77