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Faz değiştiren maddeler (FDM’ler), ısıl enerjinin gizli ısı olarak depolanabilmesine olanak sağlayan, sıvıdan katıya ya da katıdan sıvıya faz değişimi esnasında büyük miktarda ısının depolanmasına veya salınmasına izin veren yeni nesil enerji depolama malzemeleridir. FDM’lerin faz değişimi esnasında belirli bir hacimde tutmak amacıyla makro veya mikro/nano ölçekte kapsüllenmeleri gerekmektedir. Kapsülleme işlemi sayesinde malzemenin dış çevrelerden etkilenme derecesi azaltıldığı gibi malzemenin katıdan sıvıya geçişi esnasında mevcut kabuk hacminde sabit tutulması mümkün olmakta ve ısı transfer yüzeyi de arttırılmaktadır. Bu çalışmada, organik FDM’ler sınıfında yer alan bir parafin olan ve binalarda iç ortamın ısıl konforunun sağlanması hususunda uygun faz değişim sıcaklık aralığı sayesinde ısı depolama malzemesi olarak kullanım potansiyeli bulunan n-hekzadekan (n-HD), faz inversiyon emülsifikasyonu yöntemiyle mikro boyutta kapsüllenmiştir. Faz dönüşümü esnasında sızdırma problemi nedeniyle doğrudan uygulamalarda kullanımı uygun olmayan n-hekzadekanın kapsülleme işleminde, kabuk olarak binalarda yalıtım amaçlı sıklıkla kullanılan stiren (St) ve çapraz bağlayıcı divinilbenzen (DVB) kullanılmıştır. Elde edilen mikrokapsüllerin ısıl özellikleri diferansiyel taramalı kalorimetre (DSC) ve Termogravimetrik Analiz (TGA) ile incelenirken, morfolojik özellikleri ve kimyasal yapısı ise sırasıyla Taramalı Elektron Mikroskobu (SEM) ve Fourier Dönüşümlü Kızılötesi (FT-IR) spektroskopisi ile belirlenmiştir. Elde edilen mikrokapsüllerin erime entalpisi 131,074 J/g olarak bulunurken, FDM içeriği %68,55 olarak hesaplanmıştır. Mikrokapsüllenmiş FDM’nin (MikroFDM) ve saf n-hekzadekanın ısı depolama özellikleri ısıtmalı-soğutmalı sirkülasyonlu bir banyo sisteminde karşılaştırmalı olarak test edilmiştir. T-Kayıt yöntemiyle gerçekleştirilen ölçümlerde elde edilen ısıl özellikler DSC analizinden elde edilen sonuçlarla karşılaştırmalı olarak sunulmuştur. N-hekzadekan faz değişim maddesini içeren mikrokapsüllerin sahip oldukları boyut aralığı, faz değişim sıcaklık aralığı, ısı depolama kapasitesi ve gösterdikleri ısıl performans açısından binalarda iç mekan uygulamalarında ısıl konforun sağlanması noktasında kullanımının uygun olduğu ve binalarda enerji tasarrufu açısından önemli kazanımlar sağlayabilecekleri öngörülmüştür., Phase change materials (PCMs) are new generation energy storage materials that allow the storage of thermal energy as latent heat, allowing the storage or release of large amounts of heat during the phase change from liquid to solid or solid to liquid. PCMs have to be encapsulated on a macro or micro / nano scale to maintain a certain volume during phase change. By means of the encapsulation process, the degree to which the material is affected from external environments is reduced and it is possible to keep the material constant volume during the phase change process of the material from solid to liquid and the heat transfer surface is increased. In this study, n-hexadecane (n-HD), which is a paraffin which is in the class of organic PCMs and which has the potential to be used as heat storage material with the appropriate phase change temperature range in order to provide the thermal comfort of the indoor environment in buildings, is encapsulated in micro-dimension by phase inversion emulsification method. Styrene (St) and cross-linker divinylbenzene (DVB), commonly used for insulation purposes in buildings, were used as the shell in the encapsulation process of n-hexadecane, which is not suitable for direct applications due to leakage problems during phase change process. The thermal properties of the obtained microcapsules were investigated by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) whereas morphological properties and chemical structure of them were determined by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR), respectively. The melting enthalpy of the obtained microcapsules was 131,074 J / g, while the PCM content was calculated as 68.55%. The heat storage properties of microencapsulated PCM (MicroPCM) and pure n-hexadecane were comparatively tested in a heated-cooled circulation bath system. The thermal properties obtained in the measurements performed by T-History method are presented in comparison with the results obtained from DSC analysis. It is envisaged that microcapsules containing n-hexadecane phase change material are suitable for use in indoor applications in buildings in terms of particle size range, phase change temperature range, heat storage capacity and thermal performance and they can provide significant gains in terms of energy savings in buildings.

A potential cathode material for lithium ion battery was synthesised by combustion reaction. The thermal behaviour of the as-synthesised precursor was measured using a thermogravimetric analyser and the range of calcination temperature from 500 $^{\circ}$C to 800 $^{\circ}$C was determined. X-ray diffraction analysis showed that all calcined powders crystallised in the cubic spinel structure of the $Fd\bar{3}m$ space group. The particle size distributions and morphologies of the powders were obtained using a particle size analyser and scanning electron microscope. The effect of calcination temperature on the electrochemical performance was investigated using galvanostatic charge/discharge measurements. The potential profiles of charge and discharge exhibited flat plateaus, emphasising that the synthesised batteries are not super capacitors. Results showed that the batteries prepared from powders calcined at 800 $^{\circ}$C exhibited higher coulombic efficiency and better cycling performance than powders calcined at 500 $^{\circ}$C.

Challenges to the effectiveness of specific activities and production technologies in agriculture become more pressing each day as worldwide demand for agricultural products increases. The mechanization of agriculture brings positive quantitative and qualitative effects; however, the modernization of production tools (tractors and agricultural machinery) needs to be directly linked to increasing economic efficiency of use. Period of use and life expectancy of agricultural tractors can be increased by reducing the friction and wear that occurs among moving mechanical parts. A special case in point is the cold start process in compression ignition engines. In a cold start great forces develop, and a lack of lubricating oil film can lead to the damage of engine components. This paper proposes use of an ultrasound emitter device that manages minimum energy consumption in order to modify the rheological properties of engine oil lubrication and reduce friction losses. The results of laboratory experiments were processed in a computer simulation of the diesel engine tractor cold start process. Losses due to internal friction among engine components were comparatively analyzed, and a lower percentage of friction loss was obtained through ultrasonic conditioning of lubricating oil. The proposed method offers benefits in terms of rational use and can prolong engine life with positive effects on the economic efficiency of agricultural processes.