Hasil Pencarian  ::  Simpan CSV :: Kembali

"Since the analytical result of the frictional resistance of a rotating disk has been reported by Kérrnén (l92l), many studies have been done experimentally or analytically on the characteristics of the three-dimensional boundary layer at the disk surface. Frictional resistance of an impeller of a turbo-machinery is calculated by applying that of a rotating disk flow. To improve the performance of a turbo-machinery, attempt was done by applying a drag reduction to the tlow. Thus, the drag reduction phenomena have been studied on a rotating disk in drag reducing additives (Watanabe, K., l978) or a disk with hydrophobic wall (Watanabe, K., and Ogata, S., 1997). However, the drag reducing method reported in the past remains a problem- that the degradation or the durability becomes the iitilure forthe practical application.In this study, the experiments were carried out the measurement on the frictional moment, velocity fluctuation and protlle and flow visualization of an enclosed rotating disk in order to obtain a new passive drag reduction wall that is excellent in the durability and is practically applicable. An approximation theoretical analysis base on the momentum integral equation -also has been accounted for axial clearance ratio effects for the case of separate boundary layers onthe disk. This theory has been checked against experimental results.lt is well known that fluid in the boundary layer ata rotating disk surface flow with keeping a flow angle (Gregory, N. et al., 1955); By considering this flow pattern, was made a disk with a new passive drag reduction wall by an etching method. The disk with many fine spiral grooves is made of aluminum. The number of the spiral grooves varying at 120, 144, 150, 155 and 160 with 0.l and 0.2 mm depth each. The clearance between the disk and the housing wall was varied at l, 3, IO, 20 and 30 mm thick. Experimental result showed that for the close clearance l mm the moment coefficient in the turbulent region in the Reynolds number range of 4x 10" S Re S 6x 10? for the disks of l50 and |55 grooves with 0.1 and 0.2 mm depth, the drag reduction ratio was obtained about 15 %. While for the large clearance 20 mm for the disk of 144,150 and 155 grooves with 0.1mm depth in the Reynolds number range of 3.3 x to? < Re <4.0x105 the drag reduction ratio was obtained about 11 % .The experimental results of the velocity fluctuation, velocity profile and the flow visualization also add other evidences: the fine spiral grooves control the secondary flow of the boundary layer and have the effect which delays the generation oft he local turbulence in the transition range, and reduce wall skin friction in the turbulent region."

"Cardiovasculer Diseases (CVD) adalah penyakit jantung yang meliputi empat hal yaitu (1) coronary arterial diseases (CAD) atau penyakit jantung koroner (PJK); (2) cerebrovaskular diseases termasuk stroke dan ischemic transient attack (TIA); (3) penyakit arteri yaitu perifer arterial diseases (PAD) dan (4) aterosklerosis aorta. CVD menjadi salah satu pembunuh nomor satu di dunia, karena banyak faktor risiko yang mempengaruhi baik yang dapat dimodifikasi dan yang tidak bisa dimodifikasi sehingga sulit ditangani. Tujuan penelitian ini adalah menganalisis berbagai faktor yang berhubungan dengan kejadian CVD di PT. X. Untuk saat ini di PT. X faktor risiko yang bepotensi menyumbang kejadian CVD 10 tahun mendatang sudah mulai muncul berdasarkan data kesehatan pemeriksaan kesehatan rutin tahunan pekerja tahun 2021. Berdasarkan hasil pemeriksaan kesehatan tahunan 2021 terdapat peningkatan faktor risiko CVD meliputi angka obesitas 65,5%; kolesterol total tinggi 50,13%; diabetes mellitus 4,3 % dan hipertensi 5,79%. Studi ini merupakan studi cross sectional dengan pendekatan kuantitatif dengan menganalisis data primer dan sekunder untuk menggambarkan faktor risiko CVD termasuk prediksi 10 tahun mendatang bagi para responden menggunakan metode Framingham Risk Score (FRS), Skor Kardiovasar Jakarta (SKJ) dan WHO Chart serta menganalisis risiko CVD di PT X tahun 2022. Penelitian ini menemukan bahwa dengan metode Framingham Risk Score (FRS); Skor Kardiovaskuler Jakarta (SKJ) dan WHO Chart diperoleh persentase responden dengan risiko tinggi terjadinya CVD masing-masing adalah (10,2%); (18,7%) dan (1,7 %) dengan (n=235). Hasil penelitian juga menunjukan dari beberapa faktor risiko didapatkan bahwa (46,0%) responden berusia dibawah 40 tahun dan (77,0%) responden berjenis kelamin laki-laki., sedang untuk faktor risiko CVD merokok didapatkan (26,8%); BMI dengan obesitas (26%); HDL poor (34,5%); kolesterol total tinggi (37,9%); diabetes militus (10,6 %); tekanan darah tinggi (11,9%) dan mempunyai aktivitas rendah (93,2%). Faktor risiko dominan berupa merokok dari hasil analisis diperoleh pula nilai (OR=13,7), artinya seseorang yang merokok mempunyai peluang 13,7 kali berisiko lebih tinggi mengalami CVD dibandingkan dengan seseorang yang tidak merokok. Selain merokok adalah diabetes mellitus, dengan nilai (OR=7,6) artinya seseorang yang mengalami diabetes mempunyai peluang 7,6 kali berisiko lebih tinggi mengalami CVD dibandingkan dengan seseorang yang tidak diabetes mellitus. Juga HDL, dari hasil analisis diperoleh nilai (OR=7,7), artinya seseorang yang memiliki HDL rendah mempunyai peluang 7,7 kali berisiko lebih tinggi mengalami CVD dibandingkan dengan seseorang yang HDL tinggi. Secara garis besar masukan terhadap perusahaan adalah program pencegahan CVD agar dibuat continues dan serentak di berbagai Region atau Unit, serta meningkatkan pengetahuan dan kesadaran pekerja akan pentingnya menjaga kesehatan dan menerapkan reward dan konsekuensi secara lebih konsisten.

---

Cardiovascular Diseases (CVD) is heart disease which includes four major diseases, namely (1) coronary arterial diseases (CAD) or coronary heart disease (CHD); (2) cerebrovascular diseases including stroke and ischemic transient attack (TIA); (3) arterial disease, namely peripheral arterial diseases (PAD) and (4) aortic atherosclerosis. CVD is one of the number one killer diseases in the world, because there are many modifiable and non-modifiable risk factors that affect it and making it difficult to treat. The purpose of this study was to analyse various factors related to be CVD at PT. X. Currently at PT. X risk factors that have the potential to contribute to be CVD in the next 10 years have started to appear based on the health data for the 2021 annual routine medical examination of workers. Based on the results of the 2021 annual health examination, there is an increase in CVD risk factors including an obesity rate of 65.5%; high total cholesterol 50.13%; diabetes mellitus 4.3% and hypertension 5.79%. This study is a cross-sectional study with a quantitative approach by analysing primary and secondary data to describe CVD risk factors including predictions for the next 10 years for respondents using the Framingham Risk Score (FRS) method, Jakarta Cardiovascular Score (SKJ) and WHO Chart as well as analysing CVD risk at PT X in 2022. This study found that using the Framingham Risk Score (FRS) method; The Jakarta Cardiovascular Score (SKJ) and the WHO Chart obtained the percentage of respondents with a high risk of developing CVD, respectively (10.2%); (18.7%) and (1.7%) with (n=235). The results of the study also showed that from several risk factors it was found that (46.0%) of respondents were under 40 years old and (77.0%) of respondents were male, while for CVD risk factors smoking was obtained (26.8%); BMI with obesity (26%); poor HDL (34.5%); high total cholesterol (37.9%); diabetes mellitus (10.6%); high blood pressure (11.9%) and have low activity (93.2%). The dominant risk factor in this study is smoking. From the results of the smoking analysis also obtained a value (OR = 13.7, meaning that someone who smokes has a 13.7 times higher risk of getting CVD compared to someone who does not smoke. Other dominant risk factor is diabetes mellitus, with a value (OR = 7.6) meaning that someone who has diabetes has a 7.6 times higher risk of getting CVD compared to someone who does not have diabetes mellitus. Also, HDL with the results of the analysis obtained a value (OR = 7.7), meaning that someone who has low HDL has a 7.7 times higher risk of getting CVD compared to someone with high HDL. Main input to the company is a CVD prevention program to be made continuously and simultaneously in various Regions or Units, as well as increasing employee knowledge and awareness of the importance of maintaining health and implementing rewards and consequences more consistently."

"Benzene bersifat toksik dan karsinogenik yang ditemukan dalam proses operasional Kilang Paraxylene di PT. X. Dalam proses kerjanya, pekerja terpajan benzene sehingga dilakukan analisa pajanan benzene terhadap pekerja. Desain penelitian adalah analisa kuantitatif dengan metode potong lintang dari data sekunder perusahaan. Variabel penelitian meliputi konsentrasi personal benzene, kadar SpMA, usia, masa kerja, status gizi, kebiasaan merokok, konsumsi alkohol, shift kerja, durasi pajanan per hari dan penggunaan APP dari 64 pekerja. Konsentrasi personal benzene diukur pada breathing zone pekerja berkisar antara 0,02 sd 0,44 ppm. Sebanyak 28 pekerja (43,75%) memiliki kadar SpMA melebihi IPB ACGIH 2021 (25 µg/g kreatinin), UCL 1,95% di semua SEG melebihi IPB, berarti ada ketidakyakinan sebesar 95% bahwa kadar SpMA pekerja Kilang Paraxylene tidak melebihi IPB. Uji korelasi pearson menunjukkan tidak terdapat hubungan yang signifikan antara konsentrasi personal benzene dengan kadar SpMA, p=0,195. Hasil uji statistic menemukan adanya hubungan signifikan antara kadar SpMA dengan masa kerja, p=0,04. Kadar SpMA hanya menggambarkan metabolit di tubuh namun tidak dapat memberikan rute pajanan. Penelitian lanjutan diperlukan untuk menganalisa dampak pajanan benzene pada pekerja yang melebihi durasi aman pajanan benzene pada PT. X.

---

Benzene is presence in routine operational activities of Paraxylene Refinery Unit in PT. X. The process exposed the worker to benzene. Hence, the need to analyze its exposure to the workers. The study design was quantitative analysis with cross sectional design by analyzing secondary data. The variables studied were personal benzene, SpMA level, age, length of work, BMI, smoking habit, alcohol consumption, shift/non shift, length of exposure per day, and use of PPE from the sampel of 64 workers. The result showed personal benzene concentrations measured in the breathing zone are below the recommended exposure limit (NAB Permenaker No 5/2018: 0,5 ppm), 28 respondents (43,75%) had SpMA level above the value of BEI ACGIH 2021 (25 µg/g kreatinin ), UCL 1,95% of all SEG is higher than BEI meaning there is 95% inconfident that benzene concentrations in the breathing zones are below the standard. There is no correlation between personal benzene concentrations and SpMA p=0,195. There is a significant correlation between length of work with SpMA level, p=0,04. SpMA is useful in determining benzene exposure even in low level exposure however it does not recognize where benzene is coming from. Implementation of work rotation and benzene awareness need to be improved. Further study should be conducted to analyze risk of cancer to worker who has been exposed to benzene longer than the safe duration of exposure in PT. X."

"Indonesia khususnya Jawa Timur mengalami bencana luapan lumpur yang disebabkan oleh eksplorasi minyak dan gas. Bencana ini dikenal dengan sebutan lumpur Sidoarjo (lusi) atau lumpur Lapindo. Lumpur pada dasarnya adalah campuran antara partikel padat dan air yang membentuk suatu suspensi. Pada saat lumpur diangkut dengan menggunakan pipa, dan jika kecepatan alir tidak cukup tinggi maka lumpur tidak akan bertahan membentuk suspensi sehingga terjadi pengendapan. Dalam pipa spiral dengan rasio pitch perdiameter tertentu, terjadi aliran puntir sehingga mampu mempertahankan kecepatan aliran.Tujuan penelitian ini adalah untuk mengetahui karakteristik aliran lumpur dalam pipa spiral. Tegangan geser dan regangan geser dihitung dengan mengukur perbedaan tekanan (pressure drop) dan laju aliran volumetrik dalam pipa. Nilai indeks power law sekitar 0,93-1,0 untuk konsentrasi berat (Cw) lumpur sebesar 45%, 30% dan 20%. Diameter partikel adalah 0,95 mm dan massa jenis adalah 2,19 x 103 (kg/m3). Hubungan viskositas sesaat dengan regangan geser menunjukkan hubungan yang tidak konstan. Koefisien gesek di dalam pipa spiral dengan rasio pitch per diameter (P/Di) = 6,7 lebih rendah dari pipa bulat dan pipa spiral dengan P/Di = 3,9 ; 4,3 dan 7,0. Hal ini menunjukkan bahwa pipa spiral menyebabkan penurunan hambatan (drag reduction) aliran lumpur. Nilai drag reduction sekitar 28% untuk Cw = 30% pada Reynolds generalis, Re? = 3,2 x 104 . Analisis model matematika dari nilai koefisien gesek aliran lumpur pada pipa spiral sebagai fungsi dari kepadatan lumpur, rasio pitch/diameter, dan bilangan Reynolds generalis dapat ditunjukkan.

---

Indonesia particularly East Java has been suffering from eruption of gas and mud slurry, caused by oil and gas exploration. Everyone calls this disaster as Sidoarjo mud or Lapindo mud. Mud slurry is essentially a mixture of a carrying fluid and solid particles held in suspension. When the mud slurry flow speed is not sufficiently high the particles will not be maintained in suspension. In spiral pipe twisted with a constant pitch in relation to the diameter a swirling flow occurs when fluids flow in the pipe.The aim of this study is to examine characteristics of the hydraulic transport of mud slurry flowing in the spiral pipe with three-shaps groove pipe walls. Measurements of pressure drop was carried out for tap water and mud slurry solution in circular pipes and spiral pipes by means of a manometer. The shear stress and the shear strain are calculated by measuring the pressure drop and the volumetric flow rate in circular pipe, respectively. The power law index were about 0.93 ? 1.0 for mud slurry solution of 45%, 30% and 20% of weight concentrations. The diameter of particles was ± 0.95 mm and the density was 2.19 x 103 (kg/m3). The apparent viscosity of mud slurry solution is not constant to the shear rate but the relationship is approximated by model of power law. The friction factor of mud slurries in a spiral pipe with ratio pitch per diameter 6.7 is lower than circular pipe and spiral pipe with P/Di= 3.9, 4.3 and 7.0. It was shown that the spiral pipe caused drag reduction in flowing of mud slurries. The drag reduction ratio of spiral pipe was about 28% for Cw=30% at Reynolods generalis, Re?=3,2 x 104. Analysis of mathematical models of the value of the coefficient of friction on the mud flow as a function of weight concentration, the ratio of pitch per diameter, and generalist Reynolds number can be shown."

"ABSTRAKKondisi pencemaran udara khususnya di kota-kota besar sudah sangat memprihatinkan. Salah satu penyebab pencemaran udara adalah polusi yang disebabkan oleh aerosol smoke. Aerosol smoke yang memiliki partikel berukuran submicron (0,01 ? 5 µm) banyak dijumpai pada asap rokok, asap kendaraan bermotor diesel, asap dari industri-industri, dan lain-lain. Tentunya kondisi ini akan bertambah parah dengan bertambahnya jumlah penduduk perokok, bertambahnya jumlah kendaraan bermotor dan industri. Oleh karena itu perlu diupayakan penangulangan pencemaran udara tersebut. Pada studi literatur didapatkan bahwa metode penyaringan udara dari partikel-partikel halus yang berukuran 0,01 ? 5 µm adalah dengan menggunakan thermal precipitator. Thermal precipitator adalah salah satu tipe penyaringan udara berbasis thermophoretic force. Thermophoresis adalah fenomena dimana aerosol partikel yang berada di antara dua buat plat akan bergerak ke arah yang memiliki temperatur yang lebih rendah. Jadi bila ada perbedaan temperatur antara dua buah plat, maka akan menimbulkan gaya dan partikel-partikel yang berada di antara kedua plat tersebut akan bergerak menuju ke daerah yang memiliki temperatur yang lebih rendah akibat gaya tersebut.Dalam rangka upaya membantu pengendalian dan mengurangi pencemaran udara, maka pada penelitian ini dibuat suatu alat uji thermal precipitator untuk mendepositkan partikel-partikel yang ada di dalam udara dengan memanfaatkan gaya thermophoretic. Gaya tersebut adalah gaya yang diberikan kepada partikel yang tersuspensi di suatu aliran udara. Langkah pertama yang dilakukan adalah membuat alat eksperimen baik untuk plat vertikal maupun plat horisontal. Simulasi thermophoresis juga dilakukan untuk mengklarifikasi hasil eksperimen. Setelah didapat data yang akurat dan tepat, dibuatlah thermal precipitator. Spesifikasi dari thermal precipitator adalah sebagai berikut : perbedaan temperatur antara kedua plat di set pada DT=5, 10, 15, dan 20 oC. Jarak antar plat panas dan dingin adalah 5 mm. Jenis aerosol smoke yang digunakan adalah dari tobacco smoke. Untuk melihat karakterisasi dari thermal precipitator digunakan gas sensor dan partikel counter. Dari hasil eksperimen alat uji thermal precipitator, terbukti bahwa thermal precipitator ini dapat digunakan sebagai smoke collector dengan fraksi deposit ratarata 0,56.

---

ABSTRACT

Air pollution in major cities in many countries has reaching a very concerning level one of the cause of air pollution is pollution cause by smoke aerosol. Smoke aerosols that has an average particle diameter of 0.1 µm ? 1 µm can be found in cigarette smoke, diesel vehicle fume, industrial fume and many else. This condition will be worsen by the increase in the number of smokers, motor vehicles and industry. Therefore we need to pursue the control method for that kind of air pollution. In the literature study, it?s found that the cleaning method of air filtration for fine particle with dimension of 0.01 ? 5 µm are by using thermal precipitator. Thermal precipitator is one method of air filtration based on thermophoretic force. Thermophoresis is a phenomenon in which aerosol particle migrate in the direction decreasing temperature. So, if there is a temperature difference between two plates, it will cause the force that will push the particles between the two plates toward the plate that have lower temperature.

In the effort to help control and reduce the air pollution, for this study we made a thermal precipitator test equipment to deposit the particles in the air with the use of thermophoretic force. That force is the force applied to the particles that suspended in the fluid flow. The first step is to be done is making an experimental apparatus for vertical plate and horizontal plate. The thermophoresis phenomenon simulation was carried out too. This simulation is to clarify the experimental result. After got the accuracy data and then making an aerosol thermal precipitator. The aerosol thermal precipitator specification is the temperature difference between two plates is set at DT=5, 10, 15, and 20 oC. The distance between hot and cold plat is 5 mm. For the aerosol smoke we use the tobacco smoke. This study utilized gas sensors to observe the characterization of thermal precipitator. From the experiment and analysis can be concluded that thermal precipitator can be applied as a smoke collector with 0.65 deposit fraction in average."

"Kerusakan lingkungan hidup semakin menjadi issue penting dalam diskusi perubahan iklim di dunia. Penggunaan refrigeran natural pada saat ini menjadi alternatif pilihan sebagai pengganti refrigeran yang sering merusak lingkungan hidup, baik dampak akan pemanasan global maupun penipisan lapisan ozon. Koefisien perpindahan kalor mengindikasikan banyaknya kalor yang dapat dipindahkan oleh alat penukar kalor. Salah satu penggunaan refrigeran dalam bidang engineering adalah aplikasinya pada alat penukar kalor atau heat exchanger. Desain heat exchanger berkembang dengan penggunaan heat exchanger dengan dimensi pipa yang makin kecil atau dikenal dengan kanal mikro.Penelitian ini bertujuan untuk mengkaji perpindahan kalor dua fase didih nukleat dan pengembangan korelasi perpindahan kalor satu fase sebagai bagian kontribusi terjadinya perpindahan kalor aliran dua fase didih nukleat. Penelitian perpindahan kalor aliran didih dua fase pada kanal mikro bertujuan untuk mendapatkan karakteristik perpindahan kalor dua fase dengan menggunakan parameter fluks massa, bilangan Reynolds dua fase dan fluks kalor pada penelitian yang dilakukan.Metode penelitian menggunakan proses evaporasi pada pipa test section berdiameter 0.5 mm dan panjang 0.5 meter. Pengukuran temperatur pada dinding pipa serta pengukuran perbedaaan temperatur dengan menggunakan thermocouple type K. Parameter pengukuran divariasikan untuk mendapatkan data penelitian. Hasil dari penelitian antara lain adalah perpindahan kalor satu fase dipengaruhi oleh bilangan Reynolds. Semakin tinggi bilangan Reynolds maka perpindahan kalor satu fase akan semakin tinggi. Dari data penelitian perpindahan kalor satu fase dikembangkan korelasi baru untuk perpindahan kalor satu fase pada kanal mikro dengan basis perpindahan kalor dari Dittus-Boelter. Korelasi baru perpindahan kalor satu fase adalah 7.608 x 10-7 Re1.913 Pr0.4. Perbandingan data penelitian perpindahan kalor satu fase dengan persamaan baru perpindahan kalor satu fase mempunyai MRD = - 2.87 dan MAD = 30 . Perbandingan perpindahan kalor satu fase penelitian dengan korelasi peneliti yang sudah ada diperoleh MRD terendah dari peneliti Wang Peng 1994 sebesar ndash; 7 dan MRD tertinggi dari peneliti Dittus Boelther 1930 sebesar minus 70 . Karakterisasi aliran kalor dua fase didih nukleat pada kanal mikro dengan refrigeran natural R-290 sangat dipengaruhi oleh fluks kalor, bilangan Reynolds dua fase dan tegangan permukaan.

---

Environmental damage is increasingly becoming an important issue in climate change discussion in the world. The use of natural refrigerant at this time to be an alternative choice as a substitute for refrigerant that often damage the environment, both the impact of global warming and ozone layer depletion. The heat transfer coefficient indicates the amount of heat that can be transferred by a heat exchanger. One of the use of refrigerant in the field of engineering is the application on heat exchangers. The heat exchanger design develops with the use of heat exchangers with dimensions of smaller pipes known as microchannels.This study aims to examine the heat transfer of the two phases of boiling nucleate and the development of one phase heat transfer correlation as part of the contribution of the transfer of heat flow of the two phases of boiling nucleate. The research of two phase flow heat transfer on microchannel aims to obtain the characteristics of two-phase heat transfer by using mass flux parameters, two-phase phases of Reynolds and heat flux in the research conducted.The research method used the evaporation process in the test section pipe 0.5 mm in diameter and 0.5 meter of length. Measurement of temperature on pipe wall and measurement of temperature difference by using thermocouple type K. The measurement parameters are varied to obtain the research data. The results of the research include the one-phase heat transfer influenced by the Reynolds number. The higher the Reynolds number the single-phase heat transfer will be higher. From a single phase heat transfer research data was developed a new correlation for single-phase heat transfer on a microchannel based on heat transfer from Dittus-Boelter. The new correlation of one-phase heat transfer is 7.608 x 10-7 Re1.913 Pr0.4. Comparison of single phase heat transfer research data with new phase single phase heat transfer has MRD = - 2.87 and MAD = 30 . The comparison of single phase heat transfer of the research with the correlation of existing researchers was obtained by the lowest MRD of Wang Peng 1994 - 7 and the highest MRD from Dittus Boelther 1930 by minus 70 . Characterization of the heat transfer of nucleate boiling two-phase flow in the microchannel with natural refrigerant R-290 is strongly influenced by the heat flux, the two-phase Reynolds number and the surface tension."