Ultrasonik yöntemle oluşturulan nemlendirme işleminin kumaş kırışıklığı üzerine etkisi
The effect of ultrasonic humidification process on the fabric crease
Yazar: BURCU ÜNAT
Danışman: PROF. DR. SEYHAN UYGUR ONBAŞIOĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Makine Mühendisliği Ana Bilim Dalı / Isı-Akışkan Bilim Dalı
Derece: Yüksek Lisans, 2016
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
Nemlendirme işlemi, günümüzde birçok mühendislik probleminde rastlanabilir. Özellikle tekstil, gıda ve kağıt sektörlerinde nemlendirme prosesi içerisinde karşılaşmak mümkündür. Nemlendirme işlemi doymamış havanın sıvı su ile hava akışındaki suyun evapore olması ile havanın su içeriğini attırma işlemidir. Havanın ıslak yüzeyden geçirilerek nemlendirilmesinin sağlanması yanı sıra diğer bir yöntem suyun küçük damlacıklar halinde atomize olması ile geçen havanın spreylenmesi ile nemlendirme işleminin gerçekleştirilmesidir.
Tez kapsamında, ultrasonik ses dalgalarını kullanarak suyun sıvı halden buhar haline geçmesini sağlayan ultrasonik nemlendirme yöntemi üzerine çalışılmıştır. Su, 1.65 MHz ultrasonik titreşimle aerosol şeklindeki tanecikler haline getirilmektedir. Su haznesinin içinde ''piezo-elektrik'' denilen özel seramik parçalar vardır.
Su, 1.65 MHz'lik titreşimlerde parçacıklara ayrılır ve bu parçacıklar cihazın fanının yarattığı hava akımı yardımıyla ortama dağıtılır. 
Ultrasonik nemlendirme methodu günümüzde birçok alanda kullanılmaktadır. Medikal cihazlarda (sıvı ilaçların aerosol şeklinde alınması), oda nemlendiricilerinde, sprey sistemlerinde kullanılan bir yöntemdir. Üniform damlacık boyutlarına sahip olduğu ve homojen spreyleme sağladığı için bu yöntem tercih edilmektedir. Özellikle yüksek basınç gerektirmeyen yanma proseslerinde sıkça karşılaşılmaktadır. 
Çok küçük sıvı taneciklerin tireşimle sıvı yüzeyinden çıktığı olgusu ilk olarak Wood ve Loomis tarafından rapor edilmiştir. Bunu takip eden çalışmalarda, damla mekanizmasının sıvı yüzeyinde kapileri dalgaların parçalanması şeklinde oluştuğunu ve kavitasyon etkisinin olduğunu iddia edilmiştir. Damlacık çapı, titreşim frekansına, sıvının viskozitesine bağlı olarak değişmekte ve sıvı derinliği damlacık sayısını etkilemektedir. Bunun yanı sıra, su damlacıklarının taşınması ve havanın nemlendirilmesini sağlayan hava akımı da soğuk buhar debisini etkilemektedir. 
Tez çalışmasında, kapalı bir hacimde oluşturulmuş soğuk buhar, ultrasonik transdüserlerle hava içerisindeki su damlacıklarının buhar fazına geçişini ve çok küçük damlacıklar halinde ortama yayılmasını sağlamaktır. Nemlendirilen hava kumaş liflerinin şekillendirilmesi için kullanılmıştır. Tekstil kırışıklıklarının açılması için gereken nemin soğuk buhar ile maksimum seviyede sağlanması için parametrik çalışma yapılmıştır.
Parametrik çalışma kapsamında;  hazne girişindeki hava hızının, damlacık sayısını arttıran transdüser sayısının ve transdüser üzerindeki su yüksekliğinin, oluşturulan 3 farklı seviye için soğuk buhar debisine etkisi incelenmiştir. Minitab 17 programı yardımıyla analiz edilen çalışma sonucunda en önemli parametrenin transdüser sayısı olduğu gözlemlenmiştir. Transdüserin belirli su seviyelerinde (10-60 mm) damlacık oluşturabildiği gözlemlenmiş ve bu aralıkta 3 farklı su seviyesi seçilmiştir. Seçilen su seviyelerinin soğuk buhar debisi üzerine etkisi görülmemiştir. Soğuk buhar debisinin maksimum olduğu durum olan 2,2 l/s hava debisi, 3 piezo elektrik transdüser ve 45 mm su yüksekliğinde kırışıklık ve enerji tüketimi testleri yapılmıştır. Mevcutta var olan ve tekstil kırışıklıklarının açılmasını sağlayan yüksek sıcaklık ve buharlı cihaz ile, hazırlanan prototip için enerji ve su tüketimi ve kırışıklık açma seviyeleri karşılaştırılmıştır.

Abstract:
New product line that facilitate our daily lives has created with the rapid development of technology. Moreover; it is emerged new products that is adapted to the new technologies. The necessity of a more economical use of limited energy resources and energy in the world, has revealed the idea to make the development of existing systems and efficient.
Iron is one of the small appliances commonly used in daily life. The increasing consumption of iron graph of market research have brought about the development of new technologies in this field. Iron used for maintanance of textile products has been investigated to be used more efficiently.
Ironing can be described as the process of removing wrinkles from a fabric. During ironing, the fabric is heated to relax the intermolecular bonds between the long-chain polymer molecules in the fibers of the fabric. Moreover, the weight of the iron provides removal of wrinkles between the fibers. Therefore, a higher moisture content enhance the degree of stress relaxation. When the factors influencing the ironing process is analyzed, steaming is seen that the most important factor with 32%. For many natural fabrics, such as cotton, wool and linen, the glass transition temperature is dependent on the moisture content. The conclusion is improved that an increase in the moisture content or humidity lowers the glass transition temperature. In subsequent work it has dealt with humidification process.
Humidification is a common process in engineering problems. In particular this process is typical in textile, food and paper industry. Humidification refers to evaporating water in the air flow to eliminate water content of the air. It could be realized by passing air through a wet surface. Besides atomizing water in the form of small droplets could cause humidification by spraying passing/passed air. 
This thesis deals with the ultrasonic humidification process which uses ultrasonic waves to convert water from the liquid phase to the vapor phase. This process transforms water into aerosol particles by using 1.65 MHz ultrasonic vibration. In the water reservoir there are ceramic particles known as piezoelectric. Water is separated into particles which diffuse in the environment thanks to the airflow produced by device fan.
Ultrasonic humidification method is currently being applied to many areas including medical devices (taking liquid medicines in the form of aerosol), room humidifiers or spray systems. This method is preferred as it provides uniform particle dimensions and homogenous spraying. It is really common especially in burning processes where high pressure is not necessary.
Wood and Loomis reported for the first time the fact of small rising particles from the liquid surface with vibration. In the following studies, it is asserted that droplet mechanism causes  fragmentation of capillary waves and has a cavitation effect.
Ultrasonic radiation on the liquid bring about the capillary waves in the liquid air interface. If the intensity of the ultrasound wave is large enough to break the hills and is composed of tiny droplets. Kelvin has developed equations to determine the capillary wavelength. Lang also has developed in his equation for the average droplet diameter with the ultrasonic application in the liquid surface depending on the wavelength a thin liquid film. The particle diameter depends on vibration frequency and liquid viscosity whereas the particle quantity depends on liquid depth. In addition to this, airflow transferring water particles and humidifying air affects the cold vapor flow rate. 
Cavitation process involves the vaporization and the condensation of liquid. The formation of vapor or gas-filled bubbles are realized in the form of growth and explosion. These bubbles consists when static pressure of the liquid at a certain temperature drops below the vapor pressure. The bubbles are burst vigorously with the shift to area at a higher pressure and they comprises high pressures.
Ultrasonic  vibration, was observed in several experimental studies to cause effects such as vibration, acoustic flow, and flow cavitation. As a result of these effects, the experimental and numerical modeling studies were conducted on issues such as the visualization of the discomfort associated with the flow, the determination of droplet size and droplet evaporation. Moreover, some experimental studies about ultrasonic humidification process, such as atomization ratio and the relative humidity of air, were examined according to driving the ultrasonic transducer at different frequencies and voltages.
In this study, for increasing the flow of cold steam including to water droplets formed by ultrasonic atomization method. Thesis study consists of four chapters.
Firstly, a literature search was performed and represented in the second chapter. As a result of this research it has been understood how the ultrasonic vibrations effect liquid surface and which parameters effect liquids droplet production.
Secondly, the experimental system used in the study is described with details in the third chapter. Therefore, sensors and equipments were used in this setup are explained. At the end of the chapter, cold steam rate correlation were detailed using Minitab 17.0 according to the selected parameters. Furthermore, the uncertainty analysis of the system and the experiments that includes air flow measurements and regression equations take part in this chapter.
Finally in the fourth chapter; results are discussed in detail. In the final chapter results of this study have been evaluated and suggestions have proposed  in this study for increasing the flow of cold steam including to water droplets formed by ultrasonic atomization method. 
In this thesis it is showed that the cold vapor formed in an enclosed volume enables water droplets in the air to be converted into vapor phase with ultrasonic transducers and to disperse in the environment in the form of too small droplets. The humidified air was used to form fabric fibers. Moreover, a parametric study was conducted in order to obtain the humidity required to eliminate textile creases with cold vapor at the maximum level.
Experimental studies were done in order to eliminate the wrinkles of fabric. Fabrics are moistened with ultrasonically instead of steam to moisten the cloth as the traditional  steam with heating water. Ultrasonic chamber is designed in accordance with the size of steam boiler iron available for humidification. Fan is located to ultrasonic chamber's inlet for transporting the droplets produced by ultrasonic vibration. To examine the effect of air flow driven radial fans with different voltages, flow measurements are made by connecting the wind tunnel. Made in flow measurement, it was found in the point which coincides with the operating point of the fan curve and system curve in three different voltages including 8, 10 and 12 V, respectly. Air humidity and temperature sensor values are recorded in real time where placing the inlet and outlet of ultrasonic humidification chamber.
In subsequent studies, wrinkles tests were performed for cotton woven fabrics due to the fact that it is the most ironed fabric type in daily life. It was compared the existing steam boiler irons and iron has features ultrasonic humidification in terms of wrinkle recovery, water and energy consumption.
The parametric study was performed to analyze the effects of the air speed in the entry of water reservoir, the number of transducers that increases the droplet quantity and the water level at the transducer on the cold vapor flow at 3 different levels formed. This analysis made by using Minitab 17.0 program showed that the most important parameter is the number of transducer. Furthermore, it was observed that transducer could produce droplets at certain water levels (10-60 mm) and three different water levels were selected in this range accordingly. However, the selected water levels didn't have any effect on cold vapor flow. The crease and energy consumption tests were performed at the air flow of 2,2 l/s (where the cold vapor flow rate is maximum) and the water level of 45 mm with 3 piezoelectric transducer. The existing device used to eliminate textile creases with high temperature and vapor was compared with the prototype formed in terms of energy/water consumption and the ability to eliminate creases as well.
The prototype formed with this thesis is able to eliminate creases at 3,8 level. Furthermore the energy consumption was reduced by 41,3%. A crease level of 2,4 was achieved with 76 g/min vapor with the device used to eliminate fabric creases while a crease level of 3,8 was obtained through the iron prototype with cold vapor using 4,41 g/min cold vapor flow rate formed by water droplet and humid air. As a result, water consumption was reduced by 94,2% and the ironing performance was improved. 
In future studies, it can be analyzed wrinkle recovery performance obtained the cold vapor flow for different fabric types. Moreover, it can be investigated the effect of different parameters on cold vapor rate except water level, number of transduser and air flow rate. It is recommended that surfaces can coat with a hydrophobic material to prevent condensation of the carrying cables surface. The prototype providing humidification with ultrasonic method, 26% of the water droplets produced in the reservoir may be thrown out. Steam outlet diameter (due to the product's limitations) is small, the water droplets are produced out of failing to be sufficiently effective.