Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
Seiring dengan cepatnya kemajuan teknologi dalam industri elektronik, muncul banyak produk baru yang semakin kecil. Kondisi ini menimbulkan tantangan baru, yaitu kebutuhan akan sistem pendinginan berdimensi kecil dan hemat energi namun memiliki efisiensi termal yang tinggi, dimana jet sintetik dengan input massa nol dan output momentum tidak nol hadir sebagai sistem pendingin yang menjanjikan. Penelitian ini membahas karakteristik perpindahan panas oleh jet sintetik bertipe aliran silang dan dilakukan dalam dua tahap, yaitu tahap komputasi dan eksperimental. Tahap eksperimental dilakukan menggunakan function generator untuk menggerakkan membran dua buah membran dengan mengirimkan variasi fungsi sinusoidal dan segiempat dengan frekuensi osilasi sin 80 Hz - square 80 Hz, sin 80 Hz - square 120 Hz, sin 80 Hz - square 160 Hz, sin 120 Hz - square 80 Hz, sin 120 Hz - square 120 Hz, sin 120 Hz - square 160 Hz, sin 160 Hz - square 80 Hz, sin 160 Hz - square 120 Hz, sin 160 Hz - square 160 Hz untuk melihat karakteristik perpindahan panas konvektif pada heat sink. Tahap komputasi dilakukan menggunakan software CFD Fluent dengan model turbulensi k-ω SST dengan tipe meshing Tet/Hybrid Tgrid untuk melihat distribusi aliran dari jet sintetik aliran silang. Hasil penelitian menunjukkan pengaruh gelombang dan frekuensi getaran membran terhadap laju perpindahan panas yang didapat pada jet sinjetik bertipe aliran silang, dengan penurunan terbesar dicapai variasi gelombang sin 120 Hz - square 80 Hz. ......Along with rapid technological advances in the electronics industry, there are many new emerging advanced products which getting smaller in dimension with high space efficiency and work relying on components such as transistors and integrated circuit (IC). However, these conditions also cause new challenges to overcome, one of which is how to cope with the heat generated by the operation of the electronic components in the product with sophisticated cooling system. The cooling system, hence, needs less space and energy consumption but has high thermal efficiency. This is why the synthetic jet with zero net mass flux and non-zero net momentum flux sounds practicable as the new cooling system. This research will discuss the characteristics of flow and convective heat transfer in the cross-flow synthetic jet that was conducted in two stages, computational and experimental stage.The experimental stage was executed using the function generators to drive the upper and lower membranes by sending functions of sinusoidal and square frequency variations with multiple oscillation frequency of sin 80 Hz - square 80 Hz, sin 80 Hz - square 120 Hz, sin 80 Hz - square 160 Hz, sin 120 Hz - square 80 Hz, sin 120 Hz - square 120 Hz, sin 120 Hz - square 160 Hz, sin 160 Hz - square 80 Hz, sin 160 Hz - square 120 Hz, sin 160 Hz - square 160 Hzto see the characteristics of convective heat transfer on the heat sink at each trial. Computational stage was conducted by Fluent CFD software with k-ω SST turbulence model with Tet / Hybrid Tgrid meshing elements type to see the flow distribution of creoss-flow synthetic jet. The results showed the significant influence of waves mode and frequencies to the heat transfer rate of cross-flow synthetic jet, with the best result is on sin 120 Hz- square 80 Hz waves.

Abstrak :
Indonesia adalah penghasil utama kelapa sawit di dunia. Dari proses pengelolaan tandan buah segar di dapatkan limbah tandan kosong sawit yang berlimpah, sehingga bisa dimanfaatkan menjadi bahan bakar alternatif yang tak akan habis. Dimulai dengan mengeringkan tandan kosong tersebut di dalam drying yang membutuhkan udara dengan temperatur tinggi. Oleh karena itu peran heat exchanger sangat diperlukan dengan memanfaatkan flue gas boiler sehingga tidak memerlukan listrik atau sejenisnya untuk memanaskan udara. Dengan diketahui desain tube yang diinginkan dan parameter kecepatan, massa laju perpindahan, panjang diameter pipa serta banyaknya pipa yang diperlukan adalah 192 ,255 dan 384 buah pipa. Sehingga didapatkan dimensi heat exchanger adalah 2m x 1,1m x 1,6m, 1,5m x 1,1m x 1,9m dan 1m x 1,1m x 3m dengan penyusunan 16 x 12 pipa, 17 x 15 pipa dan 16 x 24 pipa. Dari ketiga dimensi heat exchanger tersebut didapatkan hasil simulasi menggunakan software SolidWorks Flow Simulation 2012 yang memenuhi kebutuhan untuk dryer yaitu pada pipa dengan panjang 1m, dengan didapatkan data outlet udara sebesar 76.7°C dan volume flow rate udara sebesar 3.17 m3/s.

---

Indonesia is the most largest palm oil producer in the world. From palm fruit processing, producing abundant empty fruit bunch, thus, have must be developed to be endless alternative fuel. Starts from drying empty fruit bunch require high temperature airflow. For this reason, heat exchanger needed by employing flue gas boiler in order to avoid electric consumption or equal to increase heat airflow. By knowing desired tube design and velocity parameter, flow rate, pipe dimension and quantity of pipe, we need 192, 255 and 384 pipes. Thus, we acquire heat exchanger dimension as follows: 2 m x 1.1 m x 1.6m; 1.5 m x 1.1 m x 1.9m and 1m x 1.1m x 3 m with pipe arrangement 16 by 12 pipes, 17 by 15 pipes and 16 by 24 pipes. Solidworks Flow Simulation 2012 were employed to acquire these three heat exchanger dimesion which fulfil dryer requirement which is 1 meter pipe length and outlet air temperature 76.7°C and airflow volume rate 3.17m3/sec.

Abstrak :
This book presents the theory of periodic conjugate heat transfer in a detailed way. The effects of thermophysical properties and geometry of a solid body on the commonly used and experimentally determined heat transfer coefficient are analytically presented from a general point of view. The main objective of the book is a simplified description of the interaction between a solid body and a fluid as a boundary value problem of the heat conduction equation for the solid body. At the body surface, the true heat transfer coefficient is composed of two parts, the true mean value resulting from the solution of the steady state heat transfer problem and a periodically variable part, the periodic time and length to describe the oscillatory hydrodynamic effects. The second edition is extended by (i) the analysis of stability boundaries in helium flow at supercritical conditions in a heated channel with respect to the interaction between a solid body and a fluid, (ii) a periodic model and a method of heat transfer simulation in a fluid at supercritical pressure and (iii) a periodic quantum-mechanical model for homogeneous vapor nucleation in a fluid with respect to nanoscale effects.

Abstrak :
The revised edition of this systematic investigation of convection in systems comprised of liquid layers with deformatable interfaces offers new material on flows in ultra thin films. The text also reflects progress into dynamics of complex fluids.