The performance of Photovoltaic/Thermal (PV/T) systems is critically dependent on effective heat removal, a challenge exacerbated in high-ambient temperature regions such as Baghdad, Iraq. Conventional PV/T cooling methods often struggle to maintain low PV operating temperatures while simultaneously recovering thermal energy efficiently. This study introduces and validates a novel dual-stage hybrid cooling architecture for PV/T collectors. The innovative core of this system is a primary internal cooling mechanism: an embedded, pumpless Enhanced Heat Pipe (EHP) closed loop. Utilizing a highly conductive nanoparticle-enhanced working fluid, the EHP system is positioned directly beneath the PV cells to facilitate rapid waste heat absorption. This heat is then passively transferred to a secondary external water-cooling circuit for thermal recovery. Experimental validation in the arid climate of Baghdad demonstrated that the EHP dual-stage system significantly mitigated thermal degradation, achieving a peak relative electrical power enhancement of 35.7% compared to a conventional uncooled PV module. This enhancement corresponds to a maximum net power gain (Delta P) of 67.2 W, restoring the absolute electrical efficiency of the panel to 16.9% under peak irradiance. Crucially, by recovering waste heat, the system reached a peak overall energy efficiency (thermal and electrical combined) of 92.1%. Furthermore, a transient Simscape model was validated with high accuracy (RMSEPmax = 2.84 W; RMSETpv = 1.29 degrees C), confirming the system's performance predictability. The results confirm that the EHP-integrated dual-stage design provides a highly responsive, scalable, and effective strategy for maximizing cogeneration performance in demanding environments.

well known the widespread use of nonrenewable energy sources such as fossil fuels cause environmental problems. Ground source heat pumps (GSHP) are highly efficient renewable energy system used for heating and cooling where cool deep ground source is used for higher efficiency. In this study, a new simulation model has been developed and used for heat pumps for low global warming potential (GWP) refrigerants such as R134a and validated by the experimental data. Also, the system parameters of a GSHP are obtained theoretically for heating and cooling modes of a building, located in Bolu City, Turkey. For this purpose, non-linear equations are determined by considering GSHP models in relevant literatures for heating and cooling capacity of 1.4 and 2.2 kW respectively for a building having dimensions as 4.4 m x 2.2 m x 3.6 m. In this respect, COPs for heating and cooling are calculated and obtained results are depicted. An algorithm is generated to design the R134a refrigerant heat exchanger to maximize the efficiency.

In this study, exergy and cost balance of a submerged arc furnace (SAF) producing high carbon ferro chrome (HC FeCr) is evaluated. Exergoeconomic analysis of the HC FeCr was carried out using real operating data. The exergy cost of HC FeCr is found as $9,929.32/h, and the cost per unit exergy is $125.74/GJ. The unit cost and hourly levelised cost of exergy loss are $69.32/GJ and $2,401.13/h, respectively. The resource reuse rate is 84.26%. The amount of CO2 is 958.12 kg-CO2/HC FeCr-ton. The capital cost flow is very high, due to hourly levelised operating and maintenance costs.

Demir-Çelik sektörünün Dünyadaki toplam enerji üretiminin, yaklaşık olarak %12'sini kullanması, sektörde enerji tasarrufu yöntemlerinin ne anlama geldiğini çok iyi ortaya koymaktadır. Bu noktada enerji tasarruflarında oldukça yaygın olarak kullanılan termodinamiğin birinci yasasına göre tanımlanmış enerji verimi ile birlikte, süreç boyunca enerji kalitesindeki farklılaşmaya bağlı olarak daha niteliksel sonuçlar veren, termodinamiğin ikinci yasası uygulamaları, oldukça fazla önem ifade etmektedir. Bu çalışmada alaşımlı çelik üretimi yapan bir firmada kullanılan, elektrik ark fırınında(EAF), bir cins çelik üretim için termodinamik analiz gerçekleştirilmiştir. Bu bağlamda, termodinamiğin birinci yasasına göre sistemde enerji analizi ile termodinamiğin ikinci yasasına göre tespit edilen iş potansiyellerinin hesabı ve tersinir iş elde edilmiştir. Çalışmanın sonunda da her iki analizden yararlanarak da hurda ön ısıtma sistemi, baca gazları, fırından çıkan tozlar ve soğutma suyu ile ilgili sonuçlara yer verilmiştir

The compressor is the heart of the refrigeration system, extension of its life and preservation of its moving parts such as pistons, rotors, valves, connecting rods and cranks lubrication require improvement. Recently the studies focus on the use nanoparticles with lubricants in refrigeration and air conditioning systems in view of their significant impact on improving the coefficient of performance of these systems as well as thermophysical properties of pure lubricating oils and thus reducing energy consumption. In this study, nanoparticles were synthesized in an easy and cheap way and from materials available in chemistry laboratories as following copper oxide, cerium oxide, mixture 1 consisted of 50% copper oxide with 50% cerium oxide, mixture 2 consisted of 60% copper oxide with 40% cerium oxide, mixture 3 consisted of 70% copper oxide with 30% cerium oxide, mixture 4 consisted of 40% copper oxide with 60% cerium oxide, and mixture 5 consisted of 30% copper oxide with 70% cerium oxide to study their effectiveness on enhancing the thermophysical properties of POE, PAG lubricating oil using mathematical equations available from earlier studies. The results obtained from the mathematical equations showed an increase in the viscosity of POE from 40 mm2/sec to 45 mm2/sec at 0.05 wt.% and reached 108.86 mm2/sec by increasing the concentration of nanoparticles to 0.33wt.%, as well as the improvement of viscosity of PAG from 46 mm2/sec to 52.9 mm2/sec at the concentration of nanoparticles 0.05 wt.%, recording a significant improvement when the concentration of nanoparticles reached 0.33 wt.%, as well as for the rest of the other physical properties. This is consistent with earlier studies that confirmed the improvement of the physical properties of lubricants through mixing them with nanoparticles.

In this study, it is aimed to establish one-day mass balance of the materials entering into and leaving from a submerged arc furnace (SAF) where high-carbon ferrochrome is produced in it. The SAF is used in a plant located in Elazig, Turkey. For this purpose, measurements were taken from the SAF during one month by obtaining the necessary permits from the plant. In addition to these measurements, chemical reactions in the SAF are defined based on the information obtained from the literature and the plant. Chrome ore and rich slag are raw materials for furnace; as auxiliary raw materials, coke, coal, electrode paste, quartzite, and bauxite are fed. The product and the waste coming out of the SAF are high-carbon ferrochrome, slag, flue gas, and fly ash. Samples were taken from each raw material and auxiliary raw materials fed into the SAF and the products, then the chemical composition analysis was carried out by using an X-ray fluorescence (XRF) device. The reactions that take place in the SAF are carbothermic reduction reactions. Metal oxides (Cr2O3, Fe2O3, Al2O3, etc.) react with carbon and are reduced as MO + C = M + CO (M = metal). As a result of this study, the mass amounts of the materials entering into and leaving from the SAF established a balance.

Designing and manufacturing of CubeSats have a rapidly growing interest lately as they can serve in a wide range of space missions. To ensure that they are safe, stable, and functional in harsh space environment, thermal studies are very important. New design approaches have been introduced to manufacture more efficient and long-lasting satellites, and deploying solar panels is one of them aiming to harness more solar energy. In the literature, however, the studies focusing on CubeSats with deployed solar panels at different angles are very limited. Due to this reason, we investigated the thermal influences of solar panel deployment angle for a 3U CubeSat at low Earth orbit in this study. With this aim, the solar panel deployment angles of 75, 60, 45, 30, 15, 0, -15, -30, -45, -60, and -75 deg were modeled and simulated thermally. Besides, various orbital positions corresponding to different Earth days were examined for the 3U CubeSat with fully deployed solar panels. In addition, the heat absorbed by CubeSat structural panels and its solar panels were analyzed in detail. The results showed that solar panel deployment angles are highly influential on the satellite heating, and hence, maximum heat input occurs at the deployment angle of 15 deg. It can be here noted that our results of this study may give rise to valuable contribution for optimizing the design and energy budget of CubeSats. Furthermore, the available energy harnessed by solar panels can be maximized accordingly.

Termodinamik en temel enerji bilimidir. Termal (ısı) ve dinamik (devimsel) kelimelerinden türetilmiştir. Termodinamiğin yasaları; evrenin varoluşundan beri mevcut olmasına rağmen bilimin gelişiminin başlangıcı, İngiltere’deki buhar makinalarının icadından sonradır. Yasalar, sıfırdan başlayarak üçe kadar rakamlarla ifade edilmektedir. Sıfırıncı, Birinci, İkinci ve Üçüncü Yasa olarak tanımlanmaktadır. Tanımlar en temel yasadan başlayarak sıralanmıştır. Bunlar makro yasalardır ve mikro evrende de geçerlidir. Gözleme ve deneye dayalı olarak belirlenmiştir, kuramsal düşünce ürünü değildir. Sıfırıncı Yasa, sıcaklık ölçümünün temelini oluşturmaktadır. Yasa, iki farklı sistemin (veya cismin) diğer üçüncü bir sistemle (veya cisimle) ayrı ayrı ısıl dengede (aynı sıcaklıkta) olması hâlinde, kendi aralarında da ısıl dengenin kendiliğinden (doğal olarak) oluşması gerektiği gerçeğinden hareketle sıcaklık ölçümünün temel ilkesini ve geçerliliğini ortaya koymaktadır. Birinci ve İkinci Yasalar, enerji ile ilgili temel yasalardır. Enerjinin Sakınımı (veya Korunumu) Yasası olarak bilinen birinci yasa ile Entropi Yasası olarak bilinen ikinci yasa, kâinattaki (toplam) enerjinin davranışı ve değişimi ile enerji dönüşümünün hangi bedelle, hangi yönde gerçekleştiğinin temel prensiplerini açıklamaktadır. Bununla birlikte kâinatın ve buna bağlı olarak maddenin (dolayısıyla eşyanın) davranış mekanizmasının anlaşılmasına da ciddi manada katkı sağlamaktadır. Üçüncü Yasa ise kimyasal olarak saf kristal yapılardaki maddelerin, mutlak sıfır sıcaklığa (273 C, 0 K) doğru yaklaştığında, entropilerinin de sıfıra yaklaşacağını; bu sıcaklıktaki söz konusu maddelerde düzensizliğin ve hareketin oluşamayacağını aksine mutlak düzen ve durağanlığın oluşacağını belirtmektedir. Termodinamik biliminin teknik alanlardan felsefeye kadar geniş bir uygulamaya sahip olması, geniş kitleler tarafından tanınmasına neden olmuştur. Termodinamiğin yasaları, evrenin en temel yasalarındandır yani evrenseldir. Bunlar, mühendislik ve diğer pek çok sistemlerin kurulması, işletilmesi ve analizi açısından olduğu kadar evrenin düzeninin ve işleyiş mekanizmasının anlaşılması açısından da önemlidir. Bu bakımdan bazı evren bilimciler; evrenin düzenini ve işleyiş mekanizmasını, termodinamiğin yasalarından yararlanarak açıklamaya çalışmaktadır. Kaldı ki termodinamiğin yasaları, evrenin yaratılışı hakkında da önemli iddialar ortaya koymaktadır. Termodinamiğin ikinci yasasına göre tanımlanan entropi, aslında maddenin (eşyanın) ve enerjinin bir özelliğidir. Özellikler ise basınç, sıcaklık ve hacim gibi sistemi tanımlayan büyüklüklerdir. Entropi, bir sistemin düzensizliğini veya karmaşıklığını diğer ifadeyle kaotik durumunu gösteren nicel bir olgudur ve sayısal olarak hesapla belirlenebilmektedir. Bir sistemin düzensizliği veya karmaşıklığının derecesi ile sistemde oluşan tersinmezlikler, doğru orantılıdır. Tersinmezlikler arttıkça sistemin entropisi de benzer oranda artacaktır. Yasanın, evreni ve içindeki her sistemi etkileyen, bir yapısının olduğu da açıktır. Zamandan ve mekândan bağımsızdır. Zaman ve özellikle mekân adeta bu yasaya bağlıdır. Yasa, evrenin var oluşundan yani t=0 anından beri yürürlüktedir. Evren var olduğu sürece varlığını ve etkisini sürdürmesi beklenmektedir. Zira evren, içindeki madde ve canlılarla birlikte yasaların etkisi altında, belli bir mekanizmaya sahip, sistem veya yapı olarak tanımlanabilir. Yaşamın sürdürülmesi için enerjiye ihtiyaç vardır. Enerji yok olmasa da kaynakların kullanılması süreci, entropi yasasının sonucu olarak onların belli bir potansiyelden (değerden), ölü hâle (çevreye) doğru geçişi (transferi) anlamına gelmektedir. Söz konusu süreç, kâinattaki tüm sistem ve yapılar için benzerdir. Enerji dönüşümlerinin tamamı aynı süreçle gerçekleşirken doğadaki canlılar da yaşamdan ölüme doğru ilerleyen, benzer bir süreçten geçmektedir. En nihayetinde evrendeki tüm enerji kaynakları, çevreye veya üretilen eşyaya transfer olarak (veya edilerek) ölü forma geçecektir. Bu durum evrenin entropi kıyameti olarak tanımlanabilecektir. Kıyametin kopuşu ise gürültü, patırtı, çatırtı, çalkantı vb. kaotik koşulları yansıtmaktadır. Kaynaklarda kıyamet kopmadan önce kozmik olarak durgun bir durumun oluşacağı da bildirilmektedir. Söz konusu durum, kozmik ölü durumdur. Bu çalışmada termodinamiğin yasalarından yararlanılarak entropi ve kıyamet arasında bir ilişki kurulmaya çalışılmıştır. Bu bağlamda evrenin zaman olarak sonunda oluşacak entropi kıyametinin, tıpkı dinî kaynaklardaki (İslam dini de dâhil) kıyamet olgusunda ifade edilen hâle (noktaya) benzediği gerçeği, bilim ve din düzleminde ortaya konmaya çalışılmıştır.

In this study submerged arc furnace (SAF) of an important ferrochrome production facility in Elazig-Turkey is discussed. The 1st and 2nd laws of thermodynamics are applied to the SAF in which smelting processes of chrome ore are carried out. It has been concluded that, the energy efficiency of the SAF in the facility is 50.69% and the exergy efficiency is 46.49%. The energy losses are nearly 5.85% of the total energy entering into the control volume, and the exergy losses is 20.39% of the total exergy input. The results show that there are some areas to improve the energy and exergy efficiencies. The energy efficiency is 50.69%. The exergy efficiency is 46.49%. Lost energy is 182.85 GJ. Lost exergy is 831.16 GJ.

This study was built on the basis of experimental results from a simple refrigeration system using R134a as a refrigerant. Based on the real dimensions of the system and the experimental results, Ansys fluent software was used to simulate the system to prepare the system to introduce the nanoparticles theoretically. Since the nanoparticle preparation process is expensive, this research presents a simple, easy, and inexpensive method for the preparation process based on, distilled water, ammonia, copper nitrate, and cerium nitrate to synthesize seven types of nanoparticles as a single oxide and as a mixture from two different oxides The results of preparing using X-ray diffraction and scanning electron microscopy confirmed that the particles were spherical in shape, with suitable average diameters ranging between 78.95 nm, 79.9 nm, 44.15 nm and 63.3 nm for copper oxide, cerium oxide, the first mixture, and the second mixture respectively. The theoretical study confirmed that both copper oxide, cerium oxide, and the mixture consisting of both improved the performance of the refrigeration system and reduced energy consumption. Moreover using the numerical equations available in the literature to calculate the thermophysical properties proved an improvement in these properties with an increase in the nanoparticle concentration when mixed with R134a.

This study was built on the basis of an experimental study that was carried out on a simple refrigeration system that works with R134a as a refrigerant, and based on the real dimensions of the system and the experimental results, the Ansys fluent software was used to simulate the system to prepare the system to introduce the nanoparticles theoretically. Since the nanoparticles preparation process is expensive, this research presents a simple, easy, and inexpensive method for the preparation process based on the following materials, distilled water, ammonia, copper nitrate, and cerium nitrate to synthesize seven types of nanoparticles as a single oxide and as a mixture from two different oxides The results of preparing using X-Ray Diffraction and Scanning Electron Microscopy proved that particles of samples were spherical in shape, with suitable average diameter ranging between 78.95, 79.9, 44.15 and 63.3 nm for both copper oxide, cerium oxide, first mixture, and second mixture, respectively, the theoretical study confirmed that both copper oxide, cerium oxide, and the mixture consisting of both improved the performance of the refrigeration system and reduced energy consumption.

energy is one of the most popular field for high potential countries such as Turkey where the cooling is a serious need for ventilating purposes in many residences. Using the solar energy in cooling systems reduces the cost of energy and greenhouse gases emission. So, solar assisted absorption cooling systems have become considerably charming in nowadays due to its sustainability. In this study, energy and exergy analysis on a solar assisted single effect absorption cooling system is carried out. Heat transfer rates at each component and the coefficient of performance (COP) of the system are calculated. Additionally, exergy analysis of the system is performed. The energy and exergy analysis of the system components is undertaken by using the EES program. COP of the system is computed as 74.43%. COP difference results between this study and the reference studies are compared. Fuel exergy, product exergy, exergy loss, exergy destruction is calculated at each components of the system by using related equations. The exergy analysis results show that the highest exergy destruction and exergy loss occurs at evaporator assembly. So, evaporator assembly has the minimum exergetic efficiency as 23.88%. The maximum exergetic efficiency exists in the generator as 74.39%. Exergetic efficiency of the overall system is obtained as 16.75%. The exergy destruction ratio, exergy loss ratio and exergetic efficiency difference of the system results between this study and the reference studies are compared.

Most studies report that dispersing nanoparticles into refrigerants and lubricating oils leads to performance improvements in refrigeration systems, due to improvements in the thermal physics properties of a pure refrigerant, which leads to reduced energy consumption. Using nanoparticles in a refrigeration system is associated with many difficulties, such as the cost of preparing and obtaining a stable and homogeneous mixture with less agglomeration and sedimentation. Most current studies focus on the use of metals, metal oxides, and a hybrid of oxides as nanoparticles in refrigeration systems. In this research, nanoparticles were prepared in an inexpensive and easy way as a single oxide and as a mixture consisting of copper and cerium oxides. The results of nanoparticle preparation using X-ray diffraction and scanning electron microscopy prove that the particles of the samples were spherical in shape, with suitable average diameters ranging from 78.95 nm, 79.9 nm, 44.15 nm and 63.3 nm for copper oxide, cerium oxide, the first mixture, and the second mixture, respectively. Cerium oxide has not been used in a refrigeration system; this study preferred the implementation of a theoretical study using Ansys Fluent software to verify the possibility of improving the performance of the refrigeration system. The results confirmed that copper oxide enhanced the coefficient of performance of the refrigeration system by 25 %, and cerium oxide succeeded in improving the performance of the. system by a lesser value. The mixture containing a higher percentage of copper oxide yielded better results.

Bu çalışmada ev tipi bir buzdolabının analitik olarak incelemesi yapılmıştır. Bu bağlamda buzdolabının soğutma yükü hesaplanmış, ana ve yardımcı parçaları seçilmiş ve tasarlanan buzdolabının enerji tüketim değeri hesaplanmıştır. Soğutma yükünün hesaplanmasında transmisyon, infiltrasyon, ürün ısı yükü ve diğer ısı yüklerinin soğutucu ve dondurucu bölümde oluşturduğu etkiler hesaplanmıştır. Ayrıca soğutma yüküne etki eden her bir ısı yükünün, toplam soğutma yüküne olan etkisi araştırılmıştır. İletim ısı yükünün toplam soğutma yükününün % 33,32’sini ve ürün ısısının toplam soğutma yükününün %31,10'unu oluşturduğu görülmüştür. Son olarak, TSE EN 62552 standardı ve literatürden alınan bilgilere dayanılarak buzdolabının enerji tüketimi göz önüne alındığında, enerji sınıfının A++ olduğu belirlenmiştir.

Most of studies reported that disperse nanoparticles into refrigerants and lubricating oils lead to improve a coefficient of performance, due to improvement of thermal physics properties of a pure fluid, which leads to reduced energy consumption. Using nanoparticles in a refrigeration system is associated with many difficulties such as the cost of preparing and obtaining a stable and homogeneous mixture for a longer time with less agglomeration and sedimentation. In this research, nanoparticles were prepared as a mixture in an inexpensive and easy way consisting of copper and cerium oxides for the first time, with suitable average diameter to verify the possibility of overcoming the problem of stability of nanoparticles for a longer time with refrigerant. As most studies focus on improving the thermal properties of a refrigerant by using high thermal conductivity nanoparticles, while this study focuses on improving both of thermal conductivity of refrigerant and stability of nanoparticles with a refrigerant. Some studies have reported on the use of copper oxide and its effect on improving the performance of refrigeration system, but cerium oxide has not been used in refrigeration systems and this research will open the door to cerium oxide as a single material and as a mixture with copper oxide to verify the possibility of this oxide to create greater stability of nanoparticles and improve thermal properties.

An electric arc furnace with a liquid steel capacity of 30 t was analyzed using the second law of thermodynamics. To carry out the exergy analysis, materials and energies entering and exiting the electric arc furnace were determined. The materials included several types of scrap, cokes, fluxes, oxygen, liquid steel, stack gases, and dust. Electrical and exothermic chemical energies of these materials were considered. Energies of the materials leaving the furnace, including liquid steel, slag, stack gases, and dust, were determined, as were the chemical reactions and exergies entering and leaving the electric arc furnace. Exergy efficiency and lost exergy were calculated. It was found that 42.6% of exergy is lost because of the chemical reactions, heat transfer, and other reasons. The overall exergy efficiency of the entire system was found to be 46%.

Solar hot water and space heating systems have been an important energy conservation technique in buildings, along with improving insulation efficiency of building envelopes and HVAC systems. According to statistical data from EU, installations of solar hot water heating systems are increasing progressively. The purpose of this study is to illustrate quantitatively the feasibility of optimal space and water heating system using solar energy. The house is assumed to be located in Cesme, Turkey, where 1304 kWh/m 2 -year of solar radiation for the period of 2734 h/year is measured. Considering the space heating and hot water demand in this geographic location, solar collector and storage capacity are optimized using f -Chart method. The results showed that a 92% of the total energy demand can be covered by solar energy.

Solar hot water and space heating systems have been an important energy conservation technique in buildings, along with improving insulation efficiency of building envelopes and HVAC systems. According to statistical data from EU, installations of solar hot water heating systems are increasing progressively. The purpose of this study is to illustrate quantitatively the feasibility of optimal space and water heating system using solar energy. The house is assumed to be located in Cesme, Turkey, where 1304 kWh/m 2 -year of solar radiation for the period of 2734 h/year is measured. Considering the space heating and hot water demand in this geographic location, solar collector and storage capacity are optimized using f -Chart method. The results showed that a 92% of the total energy demand can be covered by solar energy.