Browsing by Author "Mutlu, Mustafa"
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Item Effects of piston speed, compression ratio and cylinder geometry on system performance of a liquid piston(Vinca Inst Nuclear, 2016) Mutlu, Mustafa; Kılıç, Muhsin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0001-6816-8377; 0000-0003-2113-4510; AAA-2005-2022; O-2253-2015; 56998409300; 57202677637Energy storage systems are being more important to compensate irregularities of renewable energy sources and yields more profitable to invest. Compressed air energy storage systems provide sufficient of system usability, and large scale plants are found around the world. The compression process is the most critical part of these systems and different designs must be developed to improve efficiency such as liquid piston. In this study, a liquid piston is analyzed with CFD tools to look into the effect of piston speed, compression ratio, and cylinder geometry on compression efficiency and required work. It is found that, increasing piston speeds do not affect the piston work but efficiency decreases. Piston work remains constant at higher than 0.05 m/s piston speeds but the efficiency decreases from 90.9 % to 74.6 %. Using variable piston speeds has not a significant improvement on the system performance. It is seen that, the effect of compression ratio is increasing with high piston speeds. The required power, when the compression ratio is 80, is 2.39 times greater than the power when the compression ratio is 5 at 0.01 m/s piston speed and 2.87 times greater at 0.15 m/s. Cylinder geometry is also very important because, efficiency, power and work alter by L/D, D, and cylinder volume, respectively.Item Evaluation of windshield defogging process in an automobile(Inderscience Enterprises, 2016) Mutlu, Mustafa; Sevilgen, Gökhan; Kılıç, Muhsin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; Uludağ Üniversitesi/Mühendislik Fakültesi/Otomotiv Mühendisliği Bölümü.; 0000-0003-2113-4510; 0000-0001-6816-8377; 0000-0002-7746-2014; O-2253-2015; AAA-2005-2022; ABG-3444-2020; 56998409300; 24722267300; 57202677637The defogging process on a windshield is one of the important concerns in the automotive industry for driver safety and certification. Therefore, the simulation of the windshield defogging process provides a very effective and useful tool for the designers to obtain a more efficient and rapid defogging process. In this paper, an experimental and numerical study is presented for the windshield defogging process of an automobile. A computational fluid dynamics (CFDs) tool was used to perform the relevant three dimensional (3-D) transient simulations. Both droplet and wall film models are employed for comparison of the demisted area on a windshield in the numerical calculations. The 3-D fluid flow, temperature distribution and heat transfer characteristics of the interior surfaces of the automobile cabin are also considered. It is shown that the results of the simulations are in a good agreement with the experimental data presented in this study.Item Experimental and theoretical analysis of headlight surface temperature in an infrared heated stress relieving oven(Uludağ Üniversitesi, 2015-03-11) Mutlu, Mustafa; Kılıç, Muhsin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.In this study, the IR heated stress relieve oven, was experimentally and theoretically examined. In experimental measurements, temperature was measured on headlight surface, placed in IR oven, at various conveyor speeds and various distances between IR lamps and headlight surface. In theoretical study, a mathematical model was developed for the headlights surface temperature by using heat transfer theory. The results obtained by the mathematical model and the measurement showed very good agreement with 6.5% average error. It is shown that mathematical model can be used to estimate the surface temperatures in case of different conditions were run in oven.Item İnfrared lambalı gerilim giderme fırını tasarım ve uygulaması(Uludağ Üniversitesi, 2009-08-06) Mutlu, Mustafa; Kılıç, Muhsin; Uludağ Üniversitesi/Fen Bilimleri Enstitüsü/Makine Mühendisliği Anabilim Dalı.Bu çalışmada Bursa'da kurulu olan bir sanayi şirketinde bulunan IR ısıtmalı gerilim giderme fırını deneysel ve teorik olarak incelenmiştir. Deneysel ölçümlerde fırının içerisine konulan farın yüzeyinden değişik konveyör hızları ve değişik IR lamba mesafeleri için sıcaklıklar ölçülerek zamana göre değişimleri belirlenmiştir. Teorik çalışmada, ısı transferi formülleri kullanılarak farın yüzey sıcaklığı için matematiksel model geliştirilmiştir. Matematiksel modelden alınan veriler, deneysel ölçümlerle %6.5 ortalama hata ile uyum göstermiştir. Fırının farklı şartlarda çalıştırılması durumunda yada yeni fırın tasarımlarında geliştirilen model rahatlıkla kullanılabilir.Item A novel design of a compressed air storage system with liquid pistons(Bulgarian Acad Science, 2016) Mutlu, Mustafa; Kılıç, Muhsin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0003-2113-4510; O-2253-2015; 57202677637Renewable energy systems (RES) require more efficient, reliable and cost effective energy storage systems to benefit more from these kind of environmentally friendly energy sources and reduce CO2 emissions. Compressed air energy storage (CAES) is one of the mechanical energy storage technologies that uses pressurized air to store and generate power when needed. Small scale CAES systems has been developed for RES application due to its advantages like easy installation, low maintaining costs, modular structure and running up time. In this study, a new small scale CAES system, which is running with liquid pistons to obtain isothermal compression and expansion, and a pressure regulator to compensate pressures between liquid pistons and air, is suggested. A detailed description of the novel CAES system design is given and effect of the components' specifications of the system are explained. Experimental results showed that, designed CAES system is a promising technology for RES, standalone and mobile applications. Specific components compatible with operating conditions of the system need to be designed in order to improve effectiveness and reliability.Publication Numerical investigation of an air cleaning device performance(Gazi Üniversitesi, 2022-01-01) Kılıç, Muhsin; Mutlu, Mustafa; Saldamlı, İsmail Hakkı; KILIÇ, MUHSİN; MUTLU, MUSTAFA; Saldamlı, İsmail Hakkı; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü; Bursa Uludağ Üniversitesi/Yenişehir Meslek Yüksekokulu; 0000-0003-2113-4510; 0000-0001-6816-8377; O-2253-2015; AAA-2005-2022; DRD-6981-2022In this study, the performance of a portable air cleaner, which is used to clean the air of a room with a person sitting in it, was investigated. The effects of different blowing angles and flow rates from the air supply vent on the device cleaning performance were investigated. In this context, air age and clean air delivery rate (CADR) parameters were calculated numerically. Randomly distributed particles in the room were tracked using the discrete phase model (DPM) and the relationship of pollutant concentrations with CADR and air age was examined. It has been seen that the blowing angle is an important parameter along with the flow rate. Moreover, it was concluded that the air age approach can be used to determine the performance of air cleaning devices. It has been found that the air cleaning device capture more than half of the particles in the environment, while the remaining particles are captured by other room surfaces.Item Numerical investigation of indoor air quality in a floor heated room with different air change rates(Tsinghua University Press, 2020-10) Mutlu, Mustafa; Bursa Uludağ Üniversitesi/Yenişehir İbrahim Orhan Meslek Yüksekokulu/İklimlendirme Soğutma Teknolojisi.; 0000-0001-6816-8377; AAA-2005-2022; 56998409300Nowadays, indoor air quality is no longer considered as providing thermal comfort. The pollutant concentration in the ambient air (CO2, O3, particulate matter, etc.) is an essential factor affecting both indoor air quality and human health negatively. Particle motion in a room is affected by air movements caused by heating systems and infiltration and needs to be examined. Therefore, this study aims to explain how infiltration rates in a room with floor heating affect both thermal conditions and particularly the particle concentration and distribution. In this study, the discrete phase model (DPM) was used for particle tracking using commercial software ANSYS FLUENT. It was assumed that drag, lift, thermophoretic and Brownian forces were affecting particle motions. It was seen that air change rates influence both thermal comfort and energy consumption as well as particle distribution significantly. It was found that increasing air change rates causes a rise in particle concentration in all sizes of particles, specifically for the lower parts of the room (below 0.75 m from the floor). It is recommended to place air purifying devices where the outdoor sourced air infiltrates the room. Additionally, an index that contains thermal comfort and particle concentration together was defined and its distribution in the room was examined. It is found that the air change rate is a critical factor in obtaining desired indoor air quality, but outdoor air conditions may worsen the indoor quality due to air pollution. As the air change rate significantly alters the airflow in the room, both thermal comfort perception and particle concentrations vary considerably.Publication Numerical simulation and analytical evaluation of the collection efficiency of the particles in a gas by the wire-plate electrostatic precipitators(MDPI, 2022-07-01) Kılıç, Muhsin; Mutlu, Mustafa; Altun, Ayşe Fidan; KILIÇ, MUHSİN; MUTLU, MUSTAFA; ALTUN, AYŞE FİDAN; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü; Bursa Uludağ Üniversitesi/Yenişehir İbrahim Orhan Meslek Yüksekokulu; Bursa Uludağ Üniversitesi/Orhangazi Yeniköy Asil Çelik Meslek Yüksekokulu; 0000-0003-2113-4510; 0000-0001-7236-8398; 0000-0001-6816-8377; O-2253-2015; ABB-9566-2020; AAA-2005-2022In this study, a numerical simulation model and an analytical method are introduced to evaluate the particle collection efficiency and transport phenomena in an electrostatic precipitator (ESP). Several complicated physical processes are involved in an ESP, including the turbulent flow, the ionization of gas by corona discharge, particles' movement, and the displacement of electric charge. The attachment of ions charges suspended particles in the gas media. Then, charged particles in the fluid move towards the collection plate and stick on it. The numerical model comprises the gas flow, electrostatic field, and particle motions. The collection efficiency of the wire-plate type ESP is investigated for the particle diameter range of 0.02 to 10 mu m. It is observed that electric field strengths and current densities show considerable variation in the solution domain. Meanwhile, changing supply voltage and charging wire diameters significantly affect the acquired charges on the electrostatic field and particle collecting efficiencies. Simultaneously, the distance between the charging and collecting electrodes and the main fluid inlet velocity has an important effect on the particle collection efficiency. The influence of the different ESP working conditions and particle dimensions on the performance of ESP are investigated and discussed.Publication Particle concentration comparison of radiator and floor heating systems under zero air change rate condition(Taiwan Assoc Aerosol Res-taar, 2021-11-01) Mutlu, Mustafa; MUTLU, MUSTAFA; Bursa Uludağ Üniversitesi/Yenişehir İbrahim Meslek Yüksekokulu/İklimlendirme ve Soğutma Teknolojisi Programı; 0000-0001-6816-8377; AAA-2005-2022As a result of isolating doors and windows very well to reduce heating energy costs, some environments' air change rate becomes zero. Two different heating systems (radiator and floor heating systems) widely used in residential applications were compared for a room where the air change rate is zero, using numerical methods in terms of particle concentrations. 3D dimensional CFD simulations show that the floor heating system performs better in removing the pollutants dispersed homogeneously in the room, while the radiator system is more effective in removing the pollutants emitted from a source close to the floor. It was concluded that special care should be taken not to have a source of pollutants close to the ground surface in the environments where a floor heating system is used.Item Sıkıştırılmış hava ile enerji depolama(Uludağ Üniversitesi, 2015-09-07) Mutlu, Mustafa; Kılıç, Muhsin; Uludağ Üniversitesi/Fen Bilimleri Enstitüsü/Makine Mühendisliği Anabilim Dalı.Son yıllarda yenilenebilir enerji kaynaklarının enerji üretimindeki payının artması ile enerji depolama sistemlerinin de önemi artmıştır. Yenilenebilir enerji kaynaklarının tahmin edilemeyen karakteristiklerinden kaynaklı dezavantajlarını ortadan kaldırmanın yollarından biri enerji depolama sistemi kullanmaktır. Günümüzde çok çeşitli enerji depolama sistemleri bulunmakta ve bu sistemlerin daha da geliştirilmesine ihtiyaç duyulmaktadır. Bu çalışmada, mekanik depolama sistemlerinden biri olan sıkıştırılmış hava ile enerji depolama sistemleri ile ilgili bilgi verilmiş ve küçük ölçekli bir enerji depolama sisteminin tasarımı yapılmıştır. Bu tasarımda sıvı pistonlar kullanılarak havanın sıkıştırılması ve genişlemesi süreçlerinin izotermal koşullarda gerçekleşmesi amaçlanmıştır. Tasarımı yapılan sistemin matematiksel modeli oluşturularak sistemin çalışması hakkında bilgi edinilmiştir. Sıvı pistonlar içerisindeki havanın basıncı ve diğer özelliklerinin sıkıştırma sürecinde nasıl değiştiğini belirleyebilmek için sayısal çözüm yapılmıştır. Sayısal çözüm için sonlu hacimler metodunu kullanan paket yazılımlardan faydalanılmıştır. Tasarımı yapılan sistemin imalatı gerçekleştirilmiş ve laboratuvar koşullarında testler yapılmıştır. Elde edilen sonuçlar göstermiştir ki, bu tarz bir sistemde performansı etkileyen en önemli parametre sıkıştırma ve genişleme süreçlerindeki sıvı pistonun hızıdır. Değişken hızlar kullanılarak sistemin performansı iyileştirilebilmektedir. Sıkıştırma ve genişleme süreçlerinin veriminin, sıvı pistonların geometrisinin değiştirilmesi ile de geliştirilebileceği görülmüştür. Deney sistemi ile enerji depolama sisteminin farklı şartlarda sıkıştırma performansı incelenmiştir. Tasarımı ve imalatı yapılan sistemin, yenilenebilir enerji kaynakları ve diğer depolama uygulamalarında da kullanılabileceği görülmüştür.Item Three-dimensional conjugate numerical analysis of fin and tube heat exchangers with various fin thermal conductivity values and geometric parameters(Türk Isı Bilimleri ve Teknolojisi Derneği, 2016-01-06) Mutlu, Mustafa; Kılıç, Muhsin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0003-2113-4510; 0000-0001-6816-8377; O-2253-2015; AAA-2005-2022It is obvious that heat exchanger performance is highly related with fin material thermal conductivity. In this paper 3-D numerical simulations were performed for conjugate heat transfer and fluid flow characteristics of fin and tube heat exchanger. The effects of the fin materials interacting with five factors: Reynolds (Re) number, fin pitch (FP), fin thickness (FT), tube diameter (TD) and fin length (FL) were examined. However, high thermal conductivity materials may not be suitable under some operating conditions such as food processing. It is found that thermal conductivity of the material slightly increases the effect of the Re number on Nusselt (Nu) number and the thermal conductivity is becoming very important parameter while investigating the effect of tube diameter on Nu number. Similarly the effect of fin length and fin thickness is also affected by fin material. A new correlation is proposed to predict Nu number includes the effect of all these parameters.