Pemodelan Daya Pengadukan Selama Proses Dehidrasi Osmotik Irisan Mangga dalam Larutan Gula

This study discusses mathematical model of agitation power due to the change of sugar solution concentration during the process of mango slices osmotic dehydration. The sugar solution agitation was performed in several levels of rotational speed to correlate the power number with the Reynolds number. Then, the obtained model was used to calculate the power consumption for various temperature and initial rotational speed of shaft. The results showed that the correlation can be used for various conditions of shaft rotational speed and solution concentration. Osmotic dehydration for 8 hours at conditions of 30-50OC with rotational speed of 143-525 rpm results in solution dilution from 61OBx to 50.5-52.5OBx. Temperature of 30OC with initial shaft rotational speed of 500 rpm results in power consumption ten times higher than that of 50OC and 148 rpm. Moreover, power consumption reduction up to 80% of initial energy consumption due to the dilution of the sugar solution during the osmotic dehydration process was obtained

Pengembangan Tungku Gasifikasi Arang Biomassa Tipe Natural Draft Gasification Berdasarkan Analisis Computational Fluid Dynamics (CFD)

A biomass stove based on natural draft gasification (NDG) has been developed in a previous study (Nelwa, et al. 2013) by using simulation based on heat transfer and equilibrium modeling. In this study, a CFD simulation was performed in order to analyze the effect of chimney height, and inlet hole diameter of the stove to the performance of the stove. The results of simulation showed that power produced by stove was between 1863.9 J/s until 2585.7 J/s, and its gasification efficiency was 67.11%. The results of simulation also showed that charcoal gasification produces combustible gases (CO, CH4, and H2) at the bottom and the center of stove, and then they were oxidized by secondary air at the top of stove. This oxidation reaction produces sufficient heat energy which can be used for cooking process

Pemodelan Daya Pengadukan selama Proses Dehidrasi Osmotik Irisan Mangga dalam Larutan Gula

This study discusses mathematical model of agitation power due to the change of sugar solution concentration during the process of mango slices osmotic dehydration. The sugar solution agitation was performed in several levels of rotational speed to correlate the power number with the Reynolds number. Then, the obtained model was used to calculate the power consumption for various temperature and initial rotational speed of shaft. The results showed that the correlation can be used for various conditions of shaft rotational speed and solution concentration. Osmotic dehydration for 8 hours at conditions of 30-50OC with rotational speed of 143-525 rpm results in solution dilution from 61OBx to 50.5-52.5OBx. Temperature of 30OC with initial shaft rotational speed of 500 rpm results in power consumption ten times higher than that of 50OC and 148 rpm. Moreover, power consumption reduction up to 80% of initial energy consumption due to the dilution of the sugar solution during the osmotic dehydration process was obtained.

Analisis Computational Fluid Dynamics untuk Perancangan Reaktor Gasifikasi Sekam Padi Tipe Downdraft

AbstractRice husk is one of biomass type which can be utilized as gasification’s feedstock for producing combustible gas which can be used as fuel in internal combustion engine. The objective of this research was to obtain the best design of small scale rice husk gasifier from among geometry scenarios by applying computational fluid dynamics method. The geometry scenarios used in this study were angle of throat 70O, 80O, and 90O, and also angle of nozzel 10O and 20O. The softwares used in this study were Gambit 2.4.6 (meshing 3D model) and Ansys Fluent 13.0 (simulation). The reactions involved in gasification (3 heterogeneous reactions and 6 homogeneous reactions) were solved by finite rate/Eddy dissipation model.Results of simulation showed that gasifier with angle of throat 90O and angle of nozzel 10O produced the highest heating value of gas with volume fraction of CO, H2, and CH4 is 14.49%, 9.65%, and 2.39% respectively. This result showed reasonable agreement with experimental data from other researchers on rice husk gasification.Keywords: rice husk, gasification, computational fluid dynamics, combustible gasAbstrakSekam padi merupakan salah satu biomassa yang dapat dimanfaatkan sebagai bahan gasifikasi untuk menghasilkan gas mampu bakar yang dapat digunakan sebagai bahan bakar pada motor bakar. Tujuan penelitian ini adalah mendapatkan desain reaktor gasifikasi sekam padi skala kecil yang terbaik dari beberapa skenario bentuk reaktor melalui metode computational fluid dynamics. Skenario bentuk geometri reaktor adalah sudut throat 70O, 80O, dan 90O, serta sudut nozel 10O dan 20O. Perangkat lunak yang digunakan adalah Gambit 2.4.6 (pembuatan mesh model 3D) dan Ansys Fluent 13.0 (simulasi). Reaksi yang terlibat dalam proses gasifikasi (3 reaksi heterogen dan 6 reaksi homogen) diselesaikan dengan model finite rate/Eddy dissipation. Hasil simulasi menunjukkan bahwa reaktor dengan sudut throat 90O dan sudut nozel 10O menghasilkan nilai kalor gas paling tinggi dengan fraksi volume gas CO, H2, dan CH4 secara berturut – turut adalah 14.49%, 9.65%, dan 2.39%. Hasil simulasi cukup sesuai dengan data peneliti lain mengenai gasifikasi sekam padi.Kata kunci: sekam padi, gasifikasi, computational fluid dynamics, gas mampu bakarDiterima: 26 Mei 2014 ;Disetujui: 05 September 201

Pemodelan Matematik Kinerja Pengering Surya Efek Rumah Kaca (ERK)-Hibrid Menggunakan Rak Berputar secara Vertikal

Makalah ini menyajikan uji unjuk kerja dan pemodelan matematik pengering energi surya (ERK)-Hibrid menggunakan rak berputar secara vertikal. Pengering terdiri dari bangunan rumah kaca berukuran (1100 × 860 × 1300) mm dengan delapan buah rak dan sistim pemanas tambahan yang terdiri dari kolektor plat datar (1,04 m2), tangki penyimpan air panas (197 liter) dan penukar panas. Untuk mengetahuikinerja pengering energi surya, dilakukan lima kali percobaan variasi kecepatan putar rak (1, 4, 7, 10 ) rpm dan tanpa pemutaran rak. Bahan yang dipergunakan pada pengujian adalah kapulaga lokal (Amomum cardamomum Wild). Masing-masing percobaan seberat 9 sampai dengan 10 kg. Rata-rata suhu air tangki penyimpan panas bervariasi dari 50,0 sampai dengan 55,0 °C suhu ruang pengering antara 38,9 sampai dengan 45,9 °C, sedangkan kelembaban relatif (RH) ruang pengering berkisar antara 32,1 sampai dengan 47,4 %. Perlakuan pemutaran rak berpengaruh terhadap keseragaman suhu bahan maupun kadar air pada masing rak pengering. Pada perlakuan pemutaran 1 rpm (percobaan II), didapatkan kondisi terbaik (suhu bahan maupun kadar air yang paling seragam). Dengan kecepatan putar rak yang semakin meningkat menyebabkan nilai ragam suhu bahan maupun kadar air semakin meningkat. Untuk melakukan simulasi unjuk kerja dilakukan pemodelan matematik berdasarkan pindah panas dan massa serta pendekatan pengeringan lapisan tipis. Persamaan diselesaikan secara numerik menggunakan finite difference Euler dengan bantuan bahasa pemrograman Visual Basic Aplication (VBA) Excell. Validasi dilakukan dengan membandingkan antara perhitungan hasil pemodelan (data prediksi) dengan data hasil pengukuran (data observasi). Kriteria kevalidan ditentukan dengan melihat nilai koefisien determinasi (R2), nilai RMSD maupun nilai MAPD. Pemodelan matematik yang telah dibangun dapat menggambarkan dengan tepat Perubahan suhu air tangki penyimpan panas, suhu ruang pengering, suhu bahan maupun penurunan kadar air

Penyebaran Pencemar Udara Di Kawasan Industri Cilegon(the Dispersion Air Polutant at Cilegon Insdustry Area)

The dispersion of the air polution, especially from the industry is much decided by the height of the stack, the higher the stack the farthest pollutant being emitted. To analyze the pollutant dispersion in the industrial area, Screen3 model US-EPA from Environmental Protection Agency, USA is used. This model is used to analyze the pollutant dispersion emiitted by factories. After implementing the model to various atmosphere stability, it is found that the fastest the wind velocity, the bigger the maximum pollutant concentration emitted and the smaller the distance dispersion. After implementing the model with the wind velocity of 2.45 m/s , it is found that the air pollution (SO2) in Pulomerak area, the maximum concentration of pollutan is 252.20 μg/m3 with the dispersion distance of 4664 m. Meanwhile, based on the measurement, with the same wind velocity at the same area, the maximum concentration of the pollutant is of 29.57 μg/m3. Within the atmosphere C to E, the two pollutants spread out at the range of 9921 m to 18800 m from the source

Penentuan kondisi proses pengeringan temu lawak untuk menghasilkan simplisia standar

The purpose of this research was to study the effect of drying conditions on the simplicia quality of java turmeric (Curcuma xanthorrhiza Roxb.) and determine the best conditions to make standardized simplicia. There are some criteria such as the conditions which can reach the standard moisture content of 10%, drying time is relatively fast, the result of dried simplicia still contains high level of curcumin, optimum shrinkage and good visual appearance. The results showed that the final moisture content can not reach 10% at the drying temperatures below 50 °C and RH above 40%. The average surface area shrinkage during the drying process crude ginger was 66.2%. There is a tendency of the lower temperatures and higher RH drying the higher levels of curcumin. Drying condition for Java turmeric recommended by this research is at a temperature of 50 °C and 30% RH.Keywords : Curcumin, drying, java turmeric, quality standardAbstrakTujuan penelitian ini adalah untuk mempelajari pengaruh kondisi proses pengeringan terhadap mutu simplisia temu lawak (Curcuma xanthorrhiza Roxb.) dan menentukan kondisi proses pengeringan terbaik untuk menghasilkan simplisia standar. Kriteria kondisi tersebut adalah yang dapat memenuhi kadar air standar 10%, waktu pengeringan yang relatif cepat, hasil pengeringannya masih mengandung kadar kurkumin yang tinggi dan penyusutan serta tampilan visual yang optimal. Hasil studi menunjukkan bahwa pada kondisi pengeringan di bawah suhu 50 oC dan RH diatas 40% kadar air akhir temu lawak tidak dapat mencapai kadar air standar. Rata-rata penyusutan luas permukaan simplisia temu lawak selama proses pengeringan adalah 66,2%. Terdapat kecenderungan semakin rendah suhu dan semakin tinggi RH pengeringan maka semakin tinggi kadar kurkumin simplisia temu lawak. Kondisi proses pengeringan simplisia temu lawak yang direkomendasikan adalah pada suhu 50 oC dan RH 30%.Kata kunci : Kurkumin, mutu, pengeringan, standar, temu lawa

PENYEBARAN PENCEMAR UDARA DI KAWASAN INDUSTRI CILEGON(THE DISPERSION AIR POLUTANT AT CILEGON INSDUSTRY AREA)

The dispersion of the air polution, especially from the industry is much decided by the height of the stack, the higher the stack the farthest pollutant being emitted. To analyze the pollutant dispersion in the industrial area, Screen3 model US-EPA from Environmental Protection Agency, USA is used. This model is used to analyze the pollutant dispersion emiitted by factories. After implementing the model to various atmosphere stability, it is found that the fastest the wind velocity, the bigger the maximum pollutant concentration emitted and the smaller the distance dispersion. After implementing the model with the wind velocity of 2.45 m/s , it is found that the air pollution (SO2) in Pulomerak area, the maximum concentration of pollutan is 252.20 μg/m3 with the dispersion distance of 4664 m. Meanwhile, based on the measurement, with the same wind velocity at the same area, the maximum concentration of the pollutant is of 29.57 μg/m3. Within the atmosphere C to E, the two pollutants spread out at the range of 9921 m to 18800 m from the source

REKONSENTRASI LARUTAN GULA PADA PROSES DEHIDRASI OSMOTIK IRISAN MANGGA (Mangifera indica L.) DENGAN TEKNIK DISTILASI MEMBRAN DCMD

ABSTRAKTeknik distilasi membran DCMD (direct contact membrane distillation) dengan jenis membran ultrafiltrasi PP (polypropylene) digunakan untuk merekonsentrasikan larutan gula pada proses dehidrasi osmotik buah mangga (varietas Indramayu). Variabel yang digunakan adalah konsentrasi larutan gula pada taraf 30, 35, 40 oBrix serta suhu sisi dingin permeat membran pada suhu 5, 10, 15oC. Dehidrasi osmotik dilakukan selama 8 jam dengan suhu umpan membran 50oC. Hasil pengamatan menunjukkan bahwa peningkatan konsentrasi larutan akan meningkatkan laju kehilangan air, laju perpindahan padatan terlarut, penyusutan massa dan volume. Perbedaan suhu umpan dan permeat membran juga menyebabkan meningkatnya fluks membran. Fluks permeat yang diperoleh dalam penelitian ini sebesar 0,051-0,135 L/m2h serta derajat konsentrasi rejeksi membran DCMD sebesar 96,5%, menunjukkan distilasi membran DCMD efektif dalam proses rekonsentrasi larutan gula.Kata kunci : dehidrasi osmotik, rekonsentrasi gula, distilasi membran DCM