Hasil Pencarian  ::  Simpan CSV :: Kembali

"Hasil beberapa penelitian menunjukan bahwa nanofluida memiliki karakteristik termal yang lebih baik dibandingkan dengan fluida konvensional (air). Berkaitan dengan hal tersebut, saat ini sedang berkembang pemikiran untuk menggunakan nanofluida sebagai fluida perpindahan panas alternatif pada sistem pedingin reaktor. Sementara itu, konveksi alamiah di dalam pipa anulus vertikal merupakan salah satu mekanisme perpindahan panas yang penting dan banyak ditemukan pada reaktor riset TRIGA, reaktor daya generasi baru dan alat konversi energi lainnya. Namun disisi lain karakteristik perpindahan panas nanofluida di dalam pipa anulus vertikal belum banyak diketahui. Oleh karena itu penting dilakukan secara berkesinambungan penelitian-penelitian untuk menganalisis perpindahan panas nanofluida di dalam pipa anulus vertikal. Pada penelitian telah dilakukan analisis numerik menggunakan program computer CFD (computational of fluids dynamic) terhadap karakteristik perpindahan panas konveksi alamiah aliran nanofluida Al2O3-air konsentrasi 2% volume di dalam pipa anulus vertikal. Hasil kajian ini menunjukkan terjadi peningkatan kinerja perpindahan panas (bilangan Nuselt- NU) sebesar 20,5% - 35%. Pada moda konveksi alamiah dengan bilangan 2,4708e+09 £ Ra £ 1,9554e+13 diperoleh korelasi empirik untuk air adalah dan korelasi empirik untuk nanofluida Al2O3-air adalah"

"This information packed text and reference book introduces mathematical models for describing microstructural phenomena. The teaching method of the book is enhanced with solved problems. Each chapter has exercises complemented with notes, hints, and answers, and references important literature. This solid background in computational thermodynamics will allows the material scientist and material designer to use computational methods to develop new materials by modeling phase equilibia, molecular structure, and dynamics."

"It is widely use ofair-conditioning systems in Thailand due to its location. It is located in atropical zone with relatively high temperatures all year round, with highhumidity and high intensity of sunlight. In order to save electrical energy forair-conditioning systems, preventing heat transfer into the building isrequired. The objective of this study is to investigate the physical andthermal properties of concrete blocks. An attempt is made to increase heatresistance of concrete blocks. Foam beads (0-0.30% by weight) and kaolin (0-70% by weight) wereadded in concrete block mixture to increase discontinuous voids in concrete.Compressive strength and water absorption of concrete blocks were tested. Thetesting results indicated that compressive strength decreased when foam beadsand kaolin were added. Water absorption increased when foam beads were added.In contrast, the more kaolin added the less water absorption. The thermalconductivity coefficient of concrete blocks was also investigated. The resultsconfirmed that the higher the amount of foam beads or kaolin added, the higherthe thermal resistance of concrete blocks. Thermal time-lag behavior was alsoinvestigated. The results indicated that concrete block with kaolin took thelongest time in heating and took the shortest time in cooling. These propertiesare good for heat prevention in hot climate regions. These concrete blockswhich were developed and tested in this research conform to the Thai IndustrialStandard. Finally, it can be concluded that because of its thermal behavior,concrete block with kaolin is a suitable energy-saving concrete block for hotand humid climates."

"Peningkatan konsumsi energi pada aplikasi bangunan merupakn isu global dunia. Penelitian ini berkaitan dengan pemanfaatan Phase Change Material PCM untuk penyimpanan termal. Konsep ini mendapat perhatian besar sebagai solusi untuk mengurangi konsumsi energi pada aplikasi bangunan. PCM Lilin memiliki kapasitas termal yang tinggi dipelajari dalam penelitian ini. Tujuan dari penelitian in adalah untuk mengukur dan menganalisis sifat termal lilin lebah/graphene sebagai PCM. Titik leleh, kapasitas kalor dan kalor laten diukur menggunakan Differential Scanning Calorimetry DSC , dan konduktivitas termal diukur menggunakan alat ukur konduktivitas meter. Untuk mengetahui perubahan morphologi PCM akibat pengaruh nanopartikel dan viskositasnya juga diteliti. Berdasarkan hasil DSC, kalor laten lilin lebah/graphene meningkat sebesar 22,5 pada 0,3 wt . Konduktivitas termal lilin lebah/graphene adalah 2,8 W/m.K pada 0,3 wt . Dengan penambahan nanographene meningkatkan kalor laten dan konduktivitas termal nano PCM lilin lebah/graphene. Oleh karena itu, berdasarkan hasil penelitian ini, lilin lebah/graphene disimpulkan memiliki potensi untuk digunakan pada aplikasi bangunan dengan harapan dapat mengurangi konsumsi energi.

---

Increased energy consumption in buildings is a worldwide issue. This research is concerned with the implementation of a phase change material for thermal storage. This concept has gained great attention as a solution to reduce energy consumption in buildings. Beeswax, which is a phase change material with a high thermal capacity, is investigated in this research. This paper is intended to measure and analyze the thermal properties of beeswax graphene as a phase change material. The melting temperature, thermal capacity and latent heat were determined using differential scanning calorimetry DSC , and the thermal conductivity was investigated using a thermal conductivity measurement apparatus. To discover the change in the physical properties due to the effect of nanoparticles, the viscosity of the material was investigated as well. Based on the result from the DSC, the latent heat of 0.3 wt beeswax graphene increased by 22.5 . The thermal conductivity of 0.3 wt beeswax graphene was 2.8 W m.K. The existence of graphene nanoplatelets enhanced both the latent heat and thermal conductivity of the beeswax. Therefore, based on this result, beeswax graphene is concluded to have the potential to reduce energy consumption in buildings."

"It is widely use of air-conditioning systems in Thailand due to its location. It is located in a tropical zone with relatively high temperatures all year round, with high humidity and high intensity of sunlight. In order to save electrical energy for air-conditioning systems, preventing heat transfer into the building is required. The objective of this study is to investigate the physical and thermal properties of concrete blocks. An attempt is made to increase heat resistance of concrete blocks. Foam beads (0−0.30% by weight) and kaolin (0−70% by weight) were added in concrete block mixture to increase discontinuous voids in concrete. Compressive strength and water absorption of concrete blocks were tested. The testing results indicated that compressive strength decreased when foam beads and kaolin were added. Water absorption increased when foam beads were added. In contrast, the more kaolin added the less water absorption. The thermal conductivity coefficient of concrete blocks was also investigated. The results confirmed that the higher the amount of foam beads or kaolin added, the higher the thermal resistance of concrete blocks. Thermal time-lag behavior was also investigated. The results indicated that concrete block with kaolin took the longest time in heating and took the shortest time in cooling. These properties are good for heat prevention in hot climate regions. These concrete blocks which were developed and tested in this research conform to the Thai Industrial Standard. Finally, it can be concluded that because of its thermal behavior, concrete block with kaolin is a suitable energy-saving concrete block for hot and humid climates."

"This book presents the work done by the RILEM Technical Committee 227-HPB (Physical properties and behaviour of High-Performance Concrete at high temperature). It contains the latest research results on the behaviour of high-performance concretes at high temperature.The book presents the state of the art of experimental data on High-Performance concretes and it collects and synthesizes useful data about concrete behaviour at high temperatures. The book is divided into independent chapters dealing with degradation reactions in concrete exposed to high temperatures; mass transport properties; thermal properties; and mechanical properties.The results presented especially target a group of users composed by universities and testing laboratories, building material companies and industries, material scientists and experts, building and infrastructure authorities, designers and civil engineers."

"ABSTRAK

Asap cair (pyrolysis  oil) merupakan produk yang dihasilkan dari proses pirolisis dari bahan baku biomassa dapat digunakan sebagai bahan bakar, bahan pengawet dan bahan kimia dasar. Produk cair yang dihasilkan dari proses pirolisis dipengaruhi oleh banyak parameter operasi dan jenis bahan baku. Proses optimum dari bahan baku lokal Indonesia dan sesuai dengan kondisi masyarakat menjadi dasar utama dalam penelitian ini. Parameter operasional  seperti temperatur optimum reaksi, laju pemanasan, temperatur uap pada zona reaksi, penyerapan kalor uap pada liquid collection system (LCS) dan jenis bahan baku menjadi kajian utama pada penelitian ini karena parameter-parameter ini menjadi penentu efisiensi proses dan produk pirolisis. Identifikasi jenis biomassa sesuai dengan karakteristiknya diperlukan pada penerapan proses yang sesuai untuk mendapatkan cairan yang maksimum.  Tujuan  penelitian untuk mendapatkan proses yang optimum dan fenomena transfer kalor pada proses pirolisis dengan menggunakan non-sweep gas fixed-bed reactor dengan bahan baku lokal Indonesia. Karakterisasi biomassa berdasarkan sifat difusivitas termalnya. Variasi temperatur reaksi dilakukan untuk mendapatkan temperatur optimum dan laju pemanasan bahan baku. Variasi temperatur pada zona reaksi untuk mendapatkan temperatur uap yang tepat berdasarkan jenis bahan baku. Beberapa jenis LCS digunakan, termasuk LCS yang menggunakan pipa kalor. Penggunaan LCS yang tepat meningkatkan efisiensi sistem secara keseluruhan.  Prediksi jumlah cairan dilakukan berdasarkan difusivitas termal bahan baku dengan menggunakan metode matrik, komposisi cairan yang dihasilkan diuji menggunakan GC/MS.  Temperatur optimum reaksi biomassa adalah 500 °C dan terjadi proses eksotermik pada bahan baku di dalam reaktor karena terjadinya self-ignition. Temperatur yang lebih tinggi cenderung menghasilkan produk gas sedangkan temperatur  yang lebih rendah menghasilkan lebih banyak zat arang.  Laju pemanasan tidak berpengaruh secara signifikan terhadap produk cair.  Temperatur uap pada zona reaksi mempengaruhi proses pirolisis dengan menggunakan Fixed-bed reactor non-sweeping gas. Temperatur optimum pada zona reaksi antara 150 °C sampai dengan 250 °C tergantung dari jenis bahan baku. Temperatur uap yang terlalu tinggi akan menghasilkan lebih banyak gas dan cairan dengan titik didih yang lebih tinggi, cairan ini mempunyai nilai bakar yang relatif lebih tinggi juga. Difusivitas termal  bahan baku yang lebih tinggi akan mengakibatkan penurunan laju pemanasan. Bahan baku dengan kondisi laju pemanasan yang rendah cenderung menghasilkan produk cair yang lebih tinggi. Bahan baku dengan tingkat gradien TGA rendah akan menghasilkan cairan yang lebih sedikit. Pipa kalor sebagai kondenser pada liquid collection system mampu menurunkan temperatur uap hingga mendekati temperatur ruangan dengan jumlah produk cair maksimum 42,5 wt% dengan bahan baku kayu merbau. Jumlah produk cair pada proses pirolisis dapat diprediksi dengan menggunakan variabel difusivitas termal bahan baku, laju pemanasan dan temperatur uap pada zona reaksi.  

---

ABSTRACT

---

Liquid smokes is a product originated from the pyrolysis process using biomass as a raw material. This product can be applied as fuel oil, preservation as the chemical base material. The liquid product from the pyrolysis process influenced by many operation parameters and feedstock materials. The optimum operation parameter and easy to apply as a base consider obtaining the maximum liquid yield.   The operational parameter such as optimum reaction temperature, heating rate, vapor temperature in the reaction zone, heat absorption in the liquid collection system and the variety of raw material as the main concern in this research. Raw material identified by its thermal characterization. This research aims to obtain optimum process and heat transfer phenomena by using a non-sweep gas fixed bed reactor with local Indonesian biomass in pyrolysis. The thermal characterization base on thermal diffusivity of raw material. The variation of the reaction temperature in the reactor and vapor temperature at the reaction zone was conducted to obtain an optimum temperature base on the type of feedstock and liquid collection system.  The use of proper LCS affects the amount of liquid yield.   The liquid yield prediction base on thermal diffusivity of biomass. The composition of liquid was analyzed using GC/MS. The optimum reaction temperature for biomass was 500 °C. The higher temperature tends to produce more gases, and the lower temperature will produce more char. The heating rate does not affect the liquid yield significantly, and vapor temperature at the reaction zone affect the liquid yield in pyrolysis using a non-sweeping gas Fixed-bed reactor. The optimum temperature at reaction zone between 150 °C - 250°C depends on the raw material. The higher vapor temperature at the reaction zone produce more gases and the liquid with the higher boiling point and has higher heating value. The higher thermal diffusivity of raw material decreases the heating rate.  The lower heating rate of raw material tends to increase liquid yield. The lowest TGA gradient tends to produce less liquid. Heat pipe was applied as a liquid collection system and able to condense pyrolysis vapor up to 42.5 wt%. The liquid yield can be predicted using thermal diffusivity of raw material, heating rate, and vapor temperature at the reaction zone.

 

"

"This short book deals with the mathematical modeling of jets impinging porous media. It starts with a short introduction to models describing turbulences in porous media as well as turbulent heat transfer. In its main part, the book presents the heat transfer of impinging jets using a local and a non-local thermal equilibrium approach."

"Luasnya aplikasi dan rentang sifat yang dimiliki poliuretan, memicu berbagai modifikasi dari material poliuretan.Tidak menutup kemungkinan modifikasi menggunakan biomassa yang banyak tersedia di alam untuk menghemat biaya produksi sekaligus memperoleh sifat material yang berstabilitas tinggi. Penelitian berfokus pada pembuatan poliuretan rigid untuk aplikasi otomotif dengan metode pelapisan menggunakan biomassa kitosan yang diperkuat dengan kalsium karbonat. Metode pelapisan yang digunakan adalah dip coating dengan cara mencelupkan busa poliuretan fleksibel berdensitas 16 kg/m3 ke dalam larutan kitosan yang berisi 4 gram kitosan dalam 5% CH3COOH berpelarut air sampai 100 ml, ditambah kalsium karbonat dengan rasio bervariasi dari 0,1% s.d. 0,5% sebagai variabel bebas. Busa di-drying selama 30 menit pada temperatur 60oC dan dilakukan pemanasan (curing) selama 90 menit pada suhu 120oC. Sampel kemudian diuji Tarik, Densitas, ILD, FTIR, STA, dan SEM. Diperoleh hasil yang mendekati hipotesis pada Densitas dan Kekuatan Tarik Maksimum yang mengalami peningkatan dengan penambahan kalsium karbonat dibandingkan busa virgin dan busa perlakuan tanpa kalsium karbonat. Pada morfologi ditemukan pembentukan lapisan di permukaan busa fleksibel sesuai yang diperkirakan. Hasil optimum ditemukan pada sampel dengan kalsium karbonat 0,2% yang memiliki densitas 31 kg/m3 dan kekuatan tarik maksimum 4.05 kg/cm2. Penelitian masih dalam tahap pengembangan disarankan untuk dapat dilakukan peneletian dan analisis lanjutan.

---

The massive application and range of properties that polyurethane possess, triggered countless modification of polyurethane. It is not impossible to use biomass, which is happen to be abundant in nature, as a modification of polyurethane in order to save production cost while obtaining relatively high-stable material properties. This research focused on creating rigid polyurethane foam for automotive application with coating method using chitosan that reinforced by calcium carbonate. The coating method used in this research is dip coating by immersing 16 kg/m3 polyurethane flexible foam into chitosan solution containing 4 grams of chitosan that dissolved into 100 ml of 5% CH3COOH electrolyte with aquades solvent, with various ratio of calcium carbonate ranging from 0,1% until 0,5% weight/volume. The foam was dried for 30 minutes at 60oC and cured for 90 minutes at 120oC. The material samples then tested for tensile, density, ILD, FTIR, STA and SEM. The results obtained close to the hypothesis on Maximum Tensile Strength and Density which increased with the addition ratio of calcium carbonate compared to virgin foam and treated foam without calcium carbonate. In the morphology the formation of layers on flexible foam surfaces is obtained as expected. The optimum results were found in samples with 0.2% ratio of calcium carbonate which had a density of 31 kg/m3 and a maximum tensile strength of 4.05 kg/cm2. This research is still under development and further research and analysis is expected."