Design, Fabrication, and Evaluation of Polyglycolic Acid Modules with Canals as Tissue Elements in Cellular-Assembly Technology

The aim of the present study was to design and fabricate polyglycolic acid (PGA) modules on the basis of the Raschig ring as a tissue element for bottom–top tissue engineering to increase the feasibility of cellular-assembly technology. Three types of modules, namely, cylindrical, Raschig ring, and transverse-pore modules, with different numbers and orientations of canals, were designed and fabricated by modified selective-laser-sintering (SLS) technology. These modules maintained their structure in a flowing culture environment, and degradation did not create an acidic environment, hence promoting their ability to scale up to highly functional tissue. The modules were seeded with human hepatoma Hep G2 cells and cultured for 10 days. The transverse-pore modules were found to have the highest glucose consumption, albumin production, and cell viability among the three tested modules. Our study showed that the proposed module design provided better mass transfer and possessed the required mechanical strength to enable use in the construction of large tissue.

Effects of Raschig Ring Packing Patterns on Pressure Drop, Heat Transfer, Methane Conversion, and Coke Deposition on a Semi-pilot-scale Packed Bed Reformer

The effects of Raschig ring packing patterns on the efficiency of dry methane reforming reactions were investigated using computational fluid dynamics (CFD). The present study aims to understand the behavior of fluid flow in packed bed reactors, especially under low reactor-to-ring ratios between 4 and 8. Three packing patterns were studied: vertical staggered (VS), chessboard staggered (CS), and reciprocal staggered (RS). It was determined that packing pattern notably affected pressure drop across the reactor length. The VS pattern produced the lowest pressure drop of 223 mPa, while the CS and RS patterns produced pressure drops of 228 mPa and 308 mPa, respectively. The values of methane conversion can be increased by ca. 2 % by selecting a more suitable packing pattern (i.e., 76 % for the VS pattern and 74 % for the CS and RS patterns).

Comparison of Raschig Ring Packing Pattern via Mean Resident Time using CFD Particle Tracing Technique: Dry Methane Reforming for Case Study

This paper aims to study the effect of raschig ring packing patterns using Computational Fluid Dynamics (CFD). CFD module of particle tracing was established to measure particles diffusing through the packed bed. The support raschigs catalyst was modeled in three patterns within a tubular reactor – namely, vertical staggered, chessboard staggered and reciprocal staggered pattern. A case study of Dry Methane Reforming (DMR) was investigated at 600°C, 1 atm. The study of Mean Resident Time (MRT) and E(t) function were investigated to identify the packing pattern performance. The results showed that the minimum value of the E(t), which means the flow behavior, was close to ideal plug flow behavior. MRT can be used to systematically identify the deviation from the ideal plug flow reactor of the three different packing patterns.

Dinamika tetes ekstraksi cair-cair sistem air-metil etil keton (mek)-heksan dalam kolom isian

Mass transfer process occurs as effect of contact between continuous phase from above and dispersed phase from underside column. With existence of size and type of packing in column, that caused interfacial area to become bigger and residence time more and older so that improvement of mass transfer process. The aim of this research is to observe drop dynamics or movement behavior of drop in which the drop diameter size grouped based on current regime deputizing with Reynolds Number (Re) and to study mass transfer liquid-liquid extraction in packed column based on drop diameter size influenced by flow rate and packing type. Observation of drop behavior is done by using length square column transparent so that visually drop dynamics can be observed and recorded at every segment of column height using digital camera. This research will be done by varying packing type and flow rate of the dispersed phase and continuous phase to know behavior of drop. The research will be done by using water–MEK (methyl ethyl ketone)–n-hexane system. The result of this research for packing type of sphere and raschig ring show that more and more big dispersed phase flow rate and height from under side column (distributor), hence drop is more and more small with number of which more and more many. This caused significant increase on overall mass transfer coefficient.Keywords: drop distribution, sphere, raschig ring, drop diameter Abstrak Proses perpindahan massa ekstraksi cair-cair dalam kolom isian terjadi akibat adanya kontak antara fase kontinu dan fase dispersi yang dialirkan secara berlawanan. Berbagai macam ukuran dan jenis isian yang digunakan dalam kolom, menyebabkan luas permukaan kontak menjadi lebih besar dan waktu kontak makin lama sehingga terjadi peningkatan proses perpindahan massa. Penelitian ini bertujuan mengamati dinamika pergerakan tetesan dengan cara mengelompokkan ukuran diameter tetesan berdasarkan pada rezim aliran yang diwakilkan dengan Bilangan Reynold (Re) dan mempelajari perpindahan massa pada ekstrasi cair-cair dalam kolom isian yang didasarkan ukuran diameter tetesan yang dipengaruhi laju alir dan jenis isian. Pengamatan perilaku tetesan dilakukan dengan menggunakan kolom persegi panjang yang transparan sehingga secara visual dinamikanya dapat diamati dan direkam pada tiap segmen ketinggian kolom menggunakan kamera digital. Percobaan dilakukan dengan menggunakan sistem air-MEK (metil etil keton)-n-heksan. Hasil penelitian untuk jenis isian bola padat dan raschig ring menunjukkan bahwa makin besar laju alir fase dispersi dan ketinggian dari bagian bawah (distributor), maka tetesannya makin kecil dengan jumlah yang makin banyak. Hal ini menyebabkan kenaikan yang signifikan terhadap koefisien perpindahan massa keseluruhan.Kata kunci: distribusi tetesan, bola, raschig ring, diameter tetesan.

Pemodelan perpindahan massa ekstraksi kolom isian dengan distribusi ukuran tetesan

Mass transfer modeling of extraction in a packed bed with droplet size distribution The evaluation of liquid extraction packed column is not able yet to give a satisfying result caused by constant spherical droplet size assumption. Droplet size from dispersion phase that is not homogeneous causes column calculation approach with assumption form of droplet haves the character of constant cannot be applied again. The goal of this research is to build droplet distribution model and mass transfer model at various heights of extraction column both in continuous phase and in dispersion phase. Droplet distribution model is more accurately applied to describe droplet breaks distribution for extraction in glass ball packed column with average of errors 4.53% compared to raschig ring packed column with average error of 11.52 %. At glass ball packing, the mass transfer modeling with total droplet has errors average to 57.67% while at raschig ring packing the model has errors average to 121.38%. Glass ball packing column model has smaller mean errors compared to raschig ring packing column because the glass ball packing form is more regular than the raschig ring packing. The amount of error between the mass transfer models and the experiment is caused by difference of the initial number of droplets that exit from the nozzle in the half circle column and in the full circle column. Keyword: extraction, packed column, droplet distribution model, mass transfer model AbstrakUkuran tetesan dari fasa dispersi yang tidak homogen menyebabkan pendekatan perhitungan kolom dengan asumsi bentuk tetesan bersifat konstan tidak dapat digunakan lagi. Tujuan dari penelitian ini adalah untuk membangun model distribusi tetesan dan model perpindahan massa pada berbagai ketinggian kolom ekstraksi baik di fasa kontinu maupun di fasa dispersi. Model distribusi tetesan lebih tepat digunakan untuk memodelkan fraksi tetesan pecah hasil penelitian pada ekstraksi kolom isian bola kaca dengan rata-rata error sebesar 4,53% dibandingkan dengan kolom isian raschig ring yang mempunyai error sebesar 11,52 Pada isian bola kaca pemodelan perpindahan massa dengan tetesan total mempunyai error rata-rata sebesar 57,67% sedangkan pada isian raschig ring mempunyai error rata-rata sebesar 121,38%. Model kolom isian bola kaca mempunyai error rata-rata yang lebih kecil dibandingkan dengan kolom kolom isian raschig ring, dikarenakan model isian bola kaca bentuknya lebih beraturan dibanding dengan kolom isian raschig ring yang bentuknya lebih tidak beraturan. Besarnya error perpindahan massa antara model dengan percobaan disebabkan oleh tidak samanya jumlah tetesan awal pada kolom setengah lingkaran dengan jumlah tetesan awal pada kolom lingkaran penuh.Kata kunci : ekstraksi,kolom isian, model distribusi tetesan, model perpindahan massa

PEMEKATAN ETANOL DENGAN METODE STRIPPING MENGGUNAKAN GAS NITROGEN DAN UDARA

<p>Abstract: Nowadays, the use of ethanol as an alternative fuel in Indonesia is less attractive than<br />fossil fuel because its price is relatively high due to the high cost of purification process. While<br />the fuel grade ethanol must have a very high purity. That’s why another low costed way to purify<br />ethanol is needed, in this research we used stripping method. The focus of this research are the<br />optimum conditions such as the type of stripping gas, stripping gas flow rate, and the type of<br />packing material. The research was conducted with a packed stripper. The variables used in this<br />research is the type of stripping gas (nitrogen and air), stripping gas flow rate (air : 67,5 ml/s; 90<br />ml/s; 112,5 ml/s and nitrogen: 61,16 ml/s; 70,02 ml/s; 92,87ml/s), the type of packing materials<br />(ball packing with average diameter of 1,5 cm and a 5/12 inch diameter raschig ring; average<br />length of 1,5 cm), while the ethanol flow rate of 29,14 ml/s and 48 cm packing height are not<br />changed during the process. The optimum result shown in the nitrogen gas flow rate of 77,02<br />ml/s with packing materials raschig ring, for 85,31%.<br />Keywords: ethanol, stripping, nitrogen, packed stripper</p>