Kondenserli çamaşır kurutma makinesinin enerji ve kurutma performansının sayısal ve deneysel incelenmesi
Numerical and experimental investigation of energy and drying performance of condenser tumble dryer
Yazar: VASIF CAN YILDIRAN
Danışman: PROF. DR. HASAN GÜNEŞ
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Makine Mühendisliği Ana Bilim Dalı / Isı-Akışkan Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
Teknolojinin gelişimiyle beraber insan ihtiyaçlarını karşılamak için tasarlanan makinelerin gelişimi de artmaktadır. Günümüzde ıslak çamaşırların kurutulması için çamaşır kurutma makineleri kullanılmaktadır. Evinde çamaşır kurutma işlemi için yeterli alanı olmayan ya da doğrudan hızlı bir kurutma süreci tercih edenler için çamaşır kurutma makineleri gün geçtikçe kullanım talebinin arttığı cihazlar olmaktadırlar.
Müşterilerin çamaşır kurutma makinelerine olan talebi fiyat, kurutma performansı ve enerji tüketimi çıktılarına göre değişim göstermektedir. Tamburlu çamaşır kurutma makineleri piyasada genellikle; ısı pompalı kurutma makineleri, kondenserli kurutma makineleri ve bacalı kurutma makineleri olarak ayrılmaktadırlar. Her üç yapıdaki çamaşır kurutma makinelerinin de kendilerine özgü enerji tüketimleri ve kurutma performansları vardır. Beyaz eşya sektöründeki rekabetçi gelişim ve enerji tüketiminin yarattığı çevresel problemler göz önüne alındığında çamaşır kurutma makinelerinde de enerji tüketimi için iyileştirme çalışmaları yapmak elzem olmuştur. 
Literatür incelediğinde kurutma makineleriyle ilgili çok fazla çalışma olmadığı ve özellikle çalışmaların ısı pompalı ya da bacalı modelde yapıldığı gözlenmiştir. Tüm çamaşır kurutma modelleri içerisinde kondenserli kurutma makinesinin gelişmeye açık olduğu anlaşılmış ve tez çalışması için kondenserli çamaşır kurutma makinesi seçilmiştir. Kondenserli çamaşır kurutma makinesi incelenmiş ve geliştirmeye açık noktaları tespit edilmiştir. Tez çalışması kapsamında kurutma ve enerji performansını incelemek ve iyileştirmek için hem sayısal hem de deneysel yöntemler kullanılmıştır. 
Bu tez çalışması toplam dokuz bölümden oluşmaktadır. Birinci bölüm; girişle birlikte tez çalışmasının amacını ve tez çalışmasının yöntemini içermektedir.
İkinci bölümde iklimlendirme sistemlerinin teorisi aktarılmıştır. Sırasıyla, kuru ve atmosferik hava, mutlak ve bağıl nem, çiğ noktası sıcaklığı, adyabatik termometre sıcaklıkları, psikrometrik diyagram, hava iklimlendirme sistemleri, basit ısıtma ve soğutma ve soğutmayla yoğuşturma konularına değinilmiştir.
Üçüncü bölümde tamburlu çamaşır kurutma makineleri hakkında temel bilgiler verilmiştir. Piyasada bulunan ısı pompalı, kondenserli ve bacalı çamaşır kurutma makinelerinin temel kurutma prensipleri aktarılmıştır. Tez kapsamında çalışılan kondenserli çamaşır kurutma makinesinin fonksiyonel komponentleri incelenmiştir.
Dördüncü bölüm yapılan literatür çalışmasıyla ilgilidir. Kapalı çevrim ve açık çevrim olarak literatürde yerini alan çamaşır kurutma makinelerinde yapılan çalışmalar aktarılmıştır. 
Beşinci bölümde, tez kapsamında kullanılan laboratuvar ve ölçüm ekipmanları tanıtılmıştır. Rakip ürünlerle yapılan laboratuvar testlerinin karşılaştırmalı sonuçları da bu bölümde aktarılmıştır.
Altıncı bölüm bir boyutlu model çalışmasıyla ilgilidir. Bu bölümde test verilerinin bir boyutlu modelde kullanımı ve bir boyutlu sistem modellemesi ile yapılan çalışma aktarılmıştır.
Yedinci bölümde HAD analizi çalışmaları yer almaktadır. HAD analizi çalışmaları soğutma sisteminde yapılan çalışmalar ve tüm sistemin birleşik ısı transferinin incelendiği çalışmalar olmak üzere ikiye ayrılmaktadır. HAD analizlerinin hazırlık ve analiz sonrası incelemelerine dair bilgiler de bu bölümde verilmiştir.
Sekizinci bölüm ise sayısal çalışmalardan sonra tamamlanan deneysel çalışmaları içermektedir. Deneysel çalışmalarda literatürden ve sayısal çalışmalardan alınan veriler doğrultusunda tasarım çalışmaları yapılmıştır. Üç boyutlu yazıcılarda üretilen parçalar tez makinesine montaj edilmiş ve enerji performans laboratuvarında testlere alınmıştır. Test sonuçları Minitab yazılımı aracılığıyla analiz edilmiştir.
Dokuzuncu bölüm çalışmanın sonuçlarını ve sonraki potansiyel çalışmaları içermektedir. Çalışma sonunda eldeki çıktıların incelenmesi ve bir sonraki adımlarda neler yapılması gerektiği bu aşamada verilmiştir.

Abstract:
With the advancement of technology, the development of machines designed to meet human needs is also increasing. In today's world, drying machines are used for drying wet laundry. Drying machines have become increasingly popular devices as the demand for their use grows, especially for those who do not have enough space for laundry drying at home or prefer a fast-drying process.
The demand for clothes drying machines from customers varies depending on factors such as price, drying performance, drying time and energy consumption outputs. Drying machines are generally classified in the market as heat pump dryers, condenser dryers, and vented dryers. Each of these types has its own unique energy consumption and drying performance. Given the competitive development in the household appliance sector and the environmental issues caused by energy consumption, it has become essential to make improvements in energy consumption for drying machines.
Different systems are used in drying machines, where essentially heating for moisture removal and cooling for condensation processes take place. These systems determine the drying performance, drying time, and energy consumption value of the machine. Drying machines are available in the market as vented, condenser, and heat pump models. Vented drying machines operate in an open-loop system. Air drawn from the room is heated in an electric heater to increase its moisture absorption capacity and is then sent to the laundry. The drying air, which absorbs moisture from the laundry, is expelled to the outside through a vent. Condenser machines, on the other hand, have a closed drying cycle and an open cooling cycle. The place where the cooling air absorbs heat from the room and where the drying air condenses water vapor is the condenser. While the cooling air, which absorbs heat, is returned to the room, the drying air is directed back to the electric heater. Heat pump drying machines operate on a refrigerant cycle assisted by a compressor. The refrigerant absorbs heat in the evaporator and releases heat in the condenser. As the drying air passes through the evaporator, it releases heat to leave moisture, and then it absorbs heat in the condenser before being directed back to the laundry.
After reviewing the literature, it is observed that there are not many studies on drying machines, and especially studies are often conducted on heat pump or vented models. Among all drying machine models, condenser dryers are identified as having potential for improvement, and for the thesis study, a condenser clothes drying machine is chosen. Competing products with different load capacities have also been investigated to energy performance tests in the laboratory environment, and their results have been examined. The reviews not only concern energy performance tests but also involve determining the airflows and thermal maps of the machines. Both literature studies and tests on competing products have been informative in identifying improvement points.
The thesis study involves examining and improving both numerical and experimental methods for the drying and energy performance of the thesis machine. The thesis is divided into nine sections. The first section is related to the development of drying machines, the purpose of the thesis study, and the methodology.
The second section presents the theory of air conditioning systems. It covers topics such as dry and atmospheric air, absolute and relative humidity, dew point temperature, adiabatic thermometer temperatures, psychrometric chart, air conditioning systems, simple heating and cooling, and cooling by evaporation.
The third section provides basic information about drum-type clothes drying machines. It explains the fundamental drying principles of heat pump, condenser, and vented clothes drying machines available in the market. The functional components of the condenser clothes drying machine studied in the thesis are also examined.
The fourth section is related to the literature review. Studies conducted on clothes drying machines in the literature, categorized as closed-cycle and open-cycle, are discussed.
In the fifth section, the laboratory and measurement equipment used in the thesis are introduced. Comparative results of laboratory tests conducted with competing products are also presented in this section. The results of energy performance tests completed according to standards have been examined. Both the drying and cooling airflow rates of both the thesis machine and competing products were measured using an anemometer. Thermocouples were placed in areas where temperature changes occur during the energy performance tests of the machines. Thermal mapping was conducted using temperature data obtained from thermocouples. Humidity measurement devices were placed at the inlet and outlet of the condenser for the analysis of relative humidity changes in the drying air of the thesis machine. All data collected were utilized in various stages of the thesis study.
The sixth section is dedicated to one-dimensional modeling studies. The utilization of test data in a one-dimensional model and the work conducted with one-dimensional system modeling are discussed. Amesim software was used to create a one-dimensional model. Components such as heater, moisture supplier, heat exchanger, and fan were used to build the digital twin of the drying machine. These components were obtained from the software library, and their setup utilized test data. For the heater, on-off time and power values were inputted. Modeling of wet laundry was facilitated by a component providing continuous water vapor to the system. A heat exchanger of condenser dimensions was created for the heat exchanger, and a fan model was developed for the circulation of drying air. The study initially focused on running the existing model. In the subsequent step, the water collection rate at different temperatures and flow rates for the cooling side was examined. A total of 171 different analyses were conducted for various flow rates and temperatures of the cooling air, and the results were analyzed. The outcomes were examined using Minitab software. The results indicate that an increase in the flow rate and a decrease in the temperature of the cooling air have a positive effect on the water collection rate. The water collection rates were analyzed through Minitab, revealing that the cooling air flow rate is more effective than its temperature in influencing the water collection rate.
The seventh section comprises CFD (Computational Fluid Dynamics) analysis studies completed with Ansys Fluent. CFD analysis studies are divided into those conducted on the cooling system and those examining the unified heat transfer of the entire system. Initially, the fluid volumes of the cooling system were established. Since the thickness of the condenser fins was less than 1 mm, the condenser fins were modeled using the porous media method. A solution mesh was generated for the fluid volumes, and the appropriate number of cells was determined through a mesh independence study. The cell count was determined using data from tests conducted in the laboratory. Energy equations were not utilized in the CFD studies of the cooling system. Pressure losses in grids and channels were analyzed. Improvements were made to the fan inlet geometry aiming at improving fan efficiency. The second CFD study is a comprehensive one where the entire system is modeled. Alongside the cooling air, the drying air was also modeled. A fan modeled with the MRF (Multiple Reference Frame) method provided the cycle for the cooling air, while a constant flow rate was assigned for the drying air. The flow rate of the cooling air was validated by comparison with laboratory results, and a directly measured flow rate used in laboratory measurements was defined for the drying air. Initial conditions for pressure inlet and outlet were set to 1 atm. Flow distribution and temperature distributions were examined in the analysis. Weak points in the system were identified. A pressure drop was observed in the grill of the fan channel, indicating a resistance created in the system. By increasing the gaps in the grill, the resistance against the cooling air was reduced. This allowed for an increase in the flow rate of the cooling air at the same fan speed. As a result of this increase, there was an improvement in heat transfer in the condenser. The exit temperature of the drying air from the condenser decreased compared to the current state.
The eighth section covers experimental studies completed after numerical studies. Design changes were made based on data obtained from the literature and numerical studies, and parts produced with three-dimensional printers were assembled into the thesis machine and tested in the energy performance laboratory. Design modifications were made to increase the airflow of the cooling air or reduce the inlet temperature to the condenser. The tests began with the existing machine, and each modification progressed to include the previous one. Tests were repeated three times, and average values were taken. At the end of the energy performance tests in the laboratory, data such as drying rate, energy consumption, temperature changes, and operating time of the heater were tabulated. Test results were analyzed using Minitab software. Following the analysis, it was determined that an increase in the airflow of the cooling air and a decrease in the inlet temperature to the condenser positively affected the drying performance. As the effectiveness of the cooling air increased, the exit temperatures of the drying air from the condenser began to decrease, leading to increased energy consumption. As the exit temperature of the drying air from the condenser decreased, it was found that the heater operated more frequently, resulting in increased energy consumption. Optimization with Minitab determined the most optimal result for drying performance and energy consumption.
Chapter nine encompasses the conclusions of the study and outlines potential future research. At this stage, an examination of the obtained outputs and the necessary steps for the next phase are presented.