Ultrasonik emülsiyon sistmeleri için sürücü tasarımı ve ürün çıktılarının çeşitli parametrelere göre incelenmesi
Driver design for ultrasonic emulsion systems and investigation of product output  according to various parameters
Yazar: ERTUĞRUL YAMAN
Danışman: DR. ÖĞR. ÜYESİ METİN HÜNER
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Elektronik ve Haberleşme Mühendisliği Ana Bilim Dalı / Elektronik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2023
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering

Özet:
Emülsiyonlar, iki farklı sıvının, genellikle su ve yağın, mikroskobik olarak karıştırılmasıyla oluşan kararlı sistemlerdir. Önemli bir nokta, bu iki sıvının normalde birbirleriyle karışmayacak kadar farklı olmasıdır. İki farklı sıvı fazın istikrarlı bir şekilde bir arada kalabildiği emülsiyonlar birçok uygulamada kullanılabilirler.
Gıda endüstrisinde emülsiyonlar büyük bir öneme sahiptir. Mayonez, salata sosları, krema ve dondurma gibi birçok gıda ürününde emülsiyonlar kullanılmaktadır. Emülsiyonlar, gıdalarda istenen kıvamı ve tekstürü sağlamak için kullanılırken aynı zamanda lezzet ve tat açısından da önemli bir rol oynar. Emülsiyonlar, gıdalarda yağın dağılımını stabilize ederek, ürünlerin raf ömrünü uzatır ve duyusal kalitesini artırır.
Emülsiyonların özelliklerinin analizinde ve işlenmesinde ultrasonik teknikler, önemli bir araç haline gelmiştir. Ultrasonik dalgalar, emülsiyonların içerisinden geçerken damlacıklarla etkileşime girer ve geri dönen sinyallerin analiziyle emülsiyonların fiziksel özelliklerini belirlemede kullanılabilirler. Ultrasonik sürücüler, emülsiyonlarda mekanik titreşimler üretmek için kullanılan cihazlardır ve emülsiyonların karakterizasyonu ve işlenmesi için önemli bir rol oynarlar. Ultrasonik emülsiyon sistemleri, ultrasonik enerjinin kullanıldığı bir yöntemle emülsiyon oluşturmayı sağlar. Ultrasonik sürücü, yüksek frekanslı mekanik titreşimler üreterek emülsiyonu oluşturur ve stabilize eder. Bu sistemlerde, sürücü tasarımı ve ürün çıktılarının incelenmesi için çeşitli parametreler dikkate alınır.
Bu çalışmada, ultrasonik emülsiyon sistemleri için 220VAC-50 Hz çalışan, 2 kW gücüne sahip, 10 kHz ile 50 kHz frekans aralığında çalışma frekansına sahip sürücü tasarımı, simülasyonu ve gerçeklenmesi yapılmıştır. Geleneksel ultrasonik sürücülerin yanı sıra dönüştürücü yapıya ait rezonans frekansını saptama, ayarlanabilen 2 farklı frekans aralığında salınım yapma, zaman modlu çalışma, \%1 hassasiyette çıkış güç kademesini ayarlayabilme yeteneğine sahip ultrasonik sürücü tasarımı geliştirilmiştir. 
Geliştirilen sürücü ile farklı frekans değerlerinde ve farklı çalışma durumlarında, kararlı su içinde farklı (\%10, \%20, \%30, \%40, \%50) yağ oranlarına sahip emülsiyonların oluşturulması sağlanmıştır. Rezonans frekansında yapılan çalışmaların, güç çıkışı olarak maksimum enerji sarf ettiği, emülsiyon süresi olarak diğer frekans değerlerine göre daha hızlı sonuç oluşturduğu gözlemlenmiştir.  Rezonans frekansı ile anti-rezonans frekans değer aralığında yapılan uygulamaların oluşturduğu emülsiyonlara dair farklı görünür bölge dalga spektrumu oluşturduğu görülmüştür. Uygulama esnasında bu spektrum değerleri ile emülsiyonun özellikleri hakkında geri besleme bilgisi alınabileceği saptanmıştır.

Abstract:
Emulsions are stable systems formed by microscopic mixing of two different liquids, usually water and oil. An important point is that these two liquids are so different that they normally do not mix with each other. The importance of emulsions is related to the stable coexistence of two different liquid phases and their use in many applications.
In the cosmetics industry, it is used in many products such as emulsions, skin care products, shampoos, lotions and make-up products. Since emulsions are obtained by mixing different oils with water, they have moisturizing, softening and protective effects on the skin. Therefore, emulsions in cosmetic products not only provide the desired consistency, but also ensure that the products are easily absorbed by the skin and are effective.
Emulsions are also used in many other sectors such as the pharmaceutical industry, agriculture, paint and coating industry. In the pharmaceutical industry, emulsions are used to increase the effectiveness of drugs and to ensure the delivery of drugs to targeted areas. In the agricultural sector, emulsions are used to increase the adhesion and effectiveness of pesticides to plants. In the paint and coating industry, emulsions are used by providing color distribution and stabilizing paint films.
Emulsions are also of great importance in the food industry. Emulsions are used in many food products such as mayonnaise, salad dressings, cream and ice cream. While emulsions are used to provide the desired consistency and texture in foods, they also play an important role in terms of flavor and taste. By stabilizing the distribution of fat in foods, emulsions extend the shelf life of products and increase their sensory quality.
Besides these uses, emulsions are also a fundamental part of research and development. Studies on emulsions in the formulation of new products, optimizing rheological properties and ensuring product stability contribute to the progress of the industry.
Ultrasonic techniques have become an important tool in the analysis and processing of the properties of emulsions. Ultrasonic waves interact as they pass through emulsions and can be used to determine the physical properties of emulsions. Ultrasonic drivers are devices used to generate mechanical vibrations in emulsions and thus play an important role in the characterization and processing of emulsions.
Classical sonochemistry is a field of research aimed at controlling, accelerating and improving chemical reactions using conventional power ultrasound. Work in this area includes developing specialized reactors, methods and protocols designed to understand and optimize the impact of ultrasound on chemical processes.
Ultrasonic emulsion system consists of 5 units: ultrasonic driver, ultrasonic transducer structure, immersion horn, mixing bowl and cooling system. The ultrasonic driver creates sinusoidal signals in the range of 10 kHz-50 kHz, at 300V-800V high amplitude level, and provides the drive of the transducer structure. The ultrasonic transducer structure used in the system creates mechanical vibrations using these electrical signals and these vibrations are transmitted into the liquid mixture in the mixing bowl as ultrasonic waves. The high-frequency vibrations of ultrasonic waves make liquids move at the molecular level.
Ultrasonic waves cause high-frequency vibrations in the liquid, creating local pressure changes. These pressure changes lead to a phenomenon called cavitation in the liquid. Cavitation refers to the formation and growth of microbubbles in liquid.
The cavitation process occurs when gas bubbles in the liquid expand and collapse due to pressure changes of ultrasonic waves. Under the influence of ultrasonic waves, the pressure in the liquid decreases rapidly, while the gas bubbles expand. Then, when the pressure suddenly rises, the bubbles quickly collapse, creating violent shock waves. These shock waves break the bonds between the particles in the liquid or the liquid phases, causing them to separate. In this way, the particles or liquid phases are mixed together to form a homogeneous emulsion.
In this thesis, ultrasonic driver design for emulsion applications and visible region spectrum analysis of the obtained emulsion outputs are discussed. The main aim of the study is to present a design process for optimizing the use of ultrasonic drivers in emulsions. This design process includes the steps necessary to improve the physical properties, performance and control of ultrasonic drivers. It is thought that the innovative advantages of the developing electronics industry will be beneficial in the development of the electronic circuit structure in the driver design in ultrasonic emulsion systems. In this context, necessary circuit designs have been developed. The developed ultrasonic emulsion driver can generate emulsion outputs in the operating frequency range of 10khz-50khz. The operating frequency resolution is 2 Hz. The operating power of the drive is determined as 2kw. There are 3 different operating modes: fixed frequency operation, resonance frequency detection and multi-frequency operation. In fixed frequency mode operation, the inverter can be operated at the desired power value and frequency value. In the resonance frequency detection operating mode, the resonance frequency of the transducer structure to be used in applications can be determined. At the time of application, the parameters of the ultrasonic structure may change due to environmental factors. During operation, current and voltage information of the ultrasonic driver structure can be monitored instantly on the touch control panel. Thanks to the limits set for these current and voltage values of the transducer structure included in the driver algorithm, the driver algorithm can terminate the output voltage of the transducer structure in order to avoid danger at the time of application. Power output control can be provided in the range of 0\%-100\% in the driver algorithm. Output power control is provided by changing the duty cycle value of the PWM signals in the microcontroller structure. A half-bridge switching circuit is designed to generate the sinusoidal signals required for driving the piezoelectric material in the ultrasonic structure. IGBTs, which can operate efficiently at high powers and frequencies, are used as switching elements. The necessary isolated gate driver circuit design for IGBTs has been made.

SCCP peripheral unit was used to detect the phase difference in the current and voltage signals of the transducer structure. In this context, current and voltage signals in sinusoidal form belonging to the transducer structure are converted into square waveforms by the comparator circuit and the phase difference value is calculated with the algorithm in the microcontroller structure. With this calculated value, the resonance frequency determination and application of the ultrasonic structure in the safe area were carried out.
Impedance matching circuit has been added to ensure maximum power transfer of the ultrasonic transducer structure. In this context, the equivalent circuit model of the Butterworth-Van Dyke transducer structure of the transducer structure was created. In order to create the impedance-frequency graph of the ultrasonic transducer structure, a test circuit was set up in the laboratory environment by using a signal generator and an oscilloscope. The resonance frequency and anti-resonance frequency of the transducer structure were found on the impedance-frequency graph created. The necessary impedance matching circuit in accordance with the equivalent circuit model of the transducer structure has been designed in LTspice application. Impedance circuit simulation was carried out with different coil values for the impedance matching circuit created. According to the simulation outputs obtained, it was given importance that the frequency value at which the gain of the ultrasonic transducer structure would be maximum should be close to the resonance frequency.
In the laboratory environment, emulsions with different (10\%, 20\%, 30\%, 40\%, 50\%) oil ratios were created in stable water at different frequency values and different operating conditions with the developed driver at 22 °C. It has been observed that the studies carried out at the resonance frequency consume maximum energy as power output and produce faster results in terms of emulsion time than other frequency values. Power dissipation tests were carried out with the ultrasonic driver at different duty cycle power stages with the same oil ratio. Emulsification processes with the same density of oil-water mixtures with different operating frequencies were carried out. The changes in the reflectance spectrum values of the obtained emulsion mixtures were determined by spectrometer. It has been observed that the applications made in the resonance frequency and anti-resonance frequency value range create different visible region wave spectrums for the emulsions formed. It has been determined that feedback information can be obtained about the properties of the emulsion with these spectrum values during the application. With this feedback, the ultrasonic driver can work with certain control algorithms and improve the efficiency and stability parameters of the applications.