Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
Today, the air-conditioning and refrigeration industry is still searching for environmentally friendly refrigerants that could replace hazardous, ozone-depleting coolants – refrigerants that behave similarly, if not better, than the present ones. The present study examines optimization of the frictional pressure drop of R22 and R290 using genetic algorithm. Outcomes are compared against the measured pressure drop obtained from a horizontal 7.6 mm channel with a length of 1.07 meters. Three equations have been used for calculating the Darcy friction factor and two-phase flow pressure drop for both laminar and turbulent flow regimes in smooth and rough tubes. The effects of the different correlations for the friction factor and pressure drop utilized are demonstrated. The results illustrate that the differences between values of the Darcy friction factor are very small for the two refrigerants examined, with the frictional pressure of R-290 higher than R-22. Use of a smaller channel induced a much higher frictional pressure drop, as well.

Abstrak :
Maraknya isu tentang hemat energi dan ramah lingkungan menjadi topik hangat yang selalu diperbincangkan dan terus dikaji untuk dikembangkan. Isu energi begitu penting karena energi menjadi salah satu penopang ekonomi suatu bangsa. Di Indonesia, sumber energi baru dan terbarukan sangat melimpah untuk dikelola menjadi energi yang ramah lingkungan. Inovasi demi inovasi terus dikembangkan untuk menemukan metode yang tepat, berkualitas dan murah serta banyak tersedia di alam. Partikel nano calcium carbonate yang terbuat dari cangkang kerang adalah material ramah lingkungan yang tersedia melimpah di alam. Larutan yang bermuatan patikel nano calcium carbonate dapat digunakan sebagai solusi bagi upaya pengurangan hambatan DR pada aliran dalam pipa yang ramah lingkungan. Dalam penelitian ini, penggunaan partikel nano pada larutan fluida kerja air-etilen glikol dengan perbandingan 40:60. Konsentrasi partikel yang digunakan ialah 100 ppm, 300 ppm dan 500 ppm pada fluida kerja. Pengujian dilakukan pada alat uji yang dirancang horizontal dengan komponen sisem perpipaan yang menggunaan pipa spiral dengan P/Di 10.8 dan pipa bulat dengan diameter dalam 4 mm. Melalui pengujian yang dilakukan, perubahan nilai friction factor menjadi parameter terjadinya DR. Pada aliran laminar DR tertinggi pada pipa spiral sebesar 79.9 untuk konsentrasi 500 ppm dengan Re rsquo; 1500 dan DR pada aliran turbulen tertinggi pada pipa bulat yaitu 47 untuk konsentrasi 300 ppm serta pada Re rsquo; 2500. ...... The rise of energy saving issue and environmentally friendly become a trend topic that is always discussed and continue to be reviewed to be developed. The issue of energy is so important because energy becomes one of the economic support foundation of a nation. In Indonesia, new renewable energy sources are abundant to be managed into environmentally friendly energy. Innovations continues to be developed to find the right method, quality and cheap, widely available in nature. Calcium carbonate nano particles made of shellfish are environmentally friendly materials available in abundance in nature. The nano calcium carbonate nanoparticle solution can be used as a solution for reducing the drag DR in an environmentally friendly pipeline flow. In this study, the use of nanoparticles in aqueous solution of water ethylene glycol fluid with a ratio of 40 60. The particle concentration used is 100 ppm, 300 ppm and 500 ppm on the working fluid. The test is performed on a horizontally designed test with component of the piping system which uses a spiral pipe with P Di 10.8 and a circular pipe 4 mm of inner diameter. Through this test, the change of friction factor value becomes the parameter of the indicator of DR. In the highest DR laminar flow in the spiral pipe 79.9 for the 500 ppm concentration with Re 39 1500 and DR at the highest turbulent flow on the circular pipe are 47 for the 300 ppm concentration and at the Re 39 2500.

Abstrak :
Internal piping erosion adalah fenomena ketika partikel tanah dari bendungan tererosi secara terus-menerus dan menciptakan ruang berongga dalam bentuk pipa. Interaksi antara aliran fluida dan partikel solid dievaluasi menggunakan metode numerik Smoothed Particle Hydrodynamics (SPH) dan platform DualSPHysics. Aliran diasumsikan sebagai aliran laminar. Skenario pertama yang diamati dalam penelitian ini adalah aliran melalui pipa dinding halus dengan bilangan Reynolds yang berbeda yaitu 25, 50 dan 100. Ditemukan bahwa peningkatan bilangan Reynolds menyebabkan penurunan friction factor. Aliran melalui dinding pipa dengan geometri kekasaran yang berbeda yaitu semi-circular ribs, triangular ribs, dan rectangular ribs juga disimulasikan pada skenario kedua. Melalui penelitian ini ditemukan bahwa tinggi dan bentuk kekasaran berbanding lurus mempengaruhi friction factor. Distribusi kecepatan aliran menunjukkan nilai yang berbeda dibandingkan dengan skenario aliran melalui dinding halus. Dalam rangka mengevaluasi pengaruh kekasaran terhadap koefisien beban hidrodinamik dan vortex shedding, partikel padat antara dinding dengan geometri dan jari - jari kekasaran yang berbeda diamati pada skenario ketiga. Jari - jari kekasaran berbanding lurus dengan drag coefficient. Ditemukan juga bahwa semakin besar tinggi kekasaran, semakin kecil jarak antara vortisitas yang terbentuk. ......Internal piping erosion is a phenomenon when soil particles of the earth dam eroded continuously and it creates a hollow space in a form of a pipe. Interaction between fluid flow and the solid particles is evaluated using numerical approach of Smoothed Particle Hydrodynamics (SPH) and DualSPHysics platform. The flow assumed as a laminar flow. The first scenario observed in this study is flow through smooth wall pipe with different reynolds number of 25, 50 and 100. It is found that increase of Reynolds number causes the decrease of friction factor. Flow through pipe wall with different geometry of roughness which are semi – circular ribs, triangular ribs, and rectangular ribs pipe wall are also simulated in the second scenario. Through this study, it is found that the height and shape of roughness directly proporsional affected the friction factor. Velocity contour of the flow show a different value compared to the smooth wall pipe scenario. In order to evaluate the effect of roughness to hydrodynamic force coefficient and vortex shedding, a solid particle between wall with different geometry and height of roughness are observed in the third scenario. The height of roughness are directly proporsional to the drag coefficient. It is also found that the larger the height of roughness, the smaller the distance between the vortices formed.

Abstrak :
Aliran fluida untuk permukaan pipa mulus dan kasar telah diteliti. Eksperimen ini menggunakan pipa baja berdiameter 35,5 mm, pipa dikasarkan dengan dibuat ulir dalam dengan pitch 4 (nilai kekasaran (k) 2,0 mm) k/D 0,05 dan pitch 5 (nilai kekasaran (k) 2,75 mm) k/D 0,08. Setiap pipa diuji dengan air murni pada temperatur 30°C. Dengan mengatur bukaan katup maka kecepatan aliran fluida (air) dapat diketahui. Hasil pengolahan data ditampilkan hubungan koefisien gesek dengan bilangan Reynolds dalam bentuk grafik. Dari hasil data dan grafik menunjukkan bahwa dengan pengujian pada pipa pitch 5 (nilai kekasaran (k) 2,75 mm) k/D 0,08 menghasilkan koefisien gesek yang lebih besar dibandingkan dengan koefisien gesek pada pitch 4 (nilai kekasaran (k) 2,0 mm) k/D 0,05 Perbedaan nilai koefisien gesek rata-rata dari kedua pipa uji tersebut adalah sebesar 112%. Koefisien gesek pada aliran turbulen terlihat meningkat sebanding dengan kekasaran pipa. Rasio kekasaran yang besar mendapatkan koefisien gesek yang besar juga dan sebaliknya. Kenaikan rasio k/D diikuti dengan kenaikan nilai koefisien gesek. Pada aliran turbulen fluida Newtonian (air murni) pada pipa kasar, nilai koefisien gesek turbulen merupakan fungsi dari Re dan nilai k/D atau. Fluid flow on smooth and rough pipe surface has been researched. This experiment is using Steel Pipe with diameter 35,5 mm, which pipe is roughened by making inner thread with pitch 4 (roughness value (k) 2,0 mm) k/D 0,05 and pitch 5 (roughness value (k) 2,75 mm) k/D 0,08. Each pipe is tested using water in with temperature 30°C. By setting the valve opening, the fluid (water) flow speed can be discovered. Data processing result, which describes the connection between Friction Factor and Reynolds value, is showed in graphic. Data processing result and graphic show that the test on pitch 5 pipe (roughness value (k) 2,75 mm) k/D 0,08 has bigger Friction Factor compared to the test on pitch 4 pipe (roughness value (k) 2,0 mm) k/D 0,05. Difference of average Friction Factor on both tested pipes is 112%. Friction Factor on turbulence flow is increasing proportional to the pipe surface roughness. The bigger value of roughness ratio comes to the bigger Friction Factor and also in reverse. In the Newtonian (water) turbulence flow on rough surface pipe, the turbulence friction factor is the function of Re and value k/D or .

Abstrak :
Since B A Tom 's found out the drag reduction phenomena, which occurs in polymer solutions in 1948 many studies, have been done for it because we can apply to the economizing energy system the phenomena. The drag reduction is the application of the turbulent modification of the flow and we can apply it for the turbulent flow region. We measured the turbulent pressure loss in the square ducts and circular pipe flow of a guar gum solution by manometer, and found that the friction factor in the ducts flow ware expressed by Re. Pressure loss in ducts ware measured for various concentrations of guar gum and various diameters of pipes in water to study the effect of the additive on drag reduction, It is found that guar gum acts like other drag reduction polymer additives because it constant the friction factor in laminar regime, modify the transition to turbulent flow, and reduces the friction factor the fully turbulent regime.