Pemrograman Komputer Reza Diharja S Si MT Teknik

Pemrograman Komputer Reza Diharja S. Si, MT. Teknik Elektro FTI Universitas Jayabaya

Aturan Komponen Penilaian • Tugas • UTS • UAS • Kehadiran : Latihan (Bobot 20%) : Ujian praktek ( Bobot 35% ) : 10 %

Referensi • Utgikar, Vivek. , Fundamental Concepts And Computations In Chemical Engineering, Prentice Hall, 2017 • Kirk-Othmer, Encyclopedia of Chemical Technology, Wiley, 2001 • Musto, J. c. , Howard, W. E. , Wlliams, R. R. , Engineering Computations An Introduction Using Matlab and Excel. Mc Graw Hill. , 2009 • Larsen, Ronald. W. , Engineering with Excel, Pearson, 2013 • Billo, E. J. , Excel for Scientists and Engineers Numerical Method. Wiley 2007 • Law, Victor J, Numerical Methods for Chemical Engineers Using Excel, Vba, and Matlab, CRC Press (2013).

Pendahuluan • Perkembangan ilmu pengetahuan ikut membawa pengaruh yang besar kepada teknologi terkini. Penciptaan alat bantu berupa komputer, mesin-mesin hingga aplikasi digital dimaksudkan untuk membuat hidup manusia semakin mudah. • Seiring berjalannya waktu, permasalahan-permasalahan yang dihadapi oleh manusia semakin kompleks. Manusia terus berupaya agar dapat menciptakan tools yang bisa membantu manusia dengan keandalan tinggi, kuat, akurat, cepat dan tepat. • Pada bidang keilmuan Teknik Kimia yang sangat pesat, dibutuhkan suatu cara agar kinerja proses menjadi optimal, desain alat pemroses lebih efisien dan pengendalian yang terjadi di dalam proses lebih intensif dan mendalam.

• Permasalahan-permasalahan yang terdapat di bidang Teknik Kimia seperti proses kimia, perancangan proses, reaktor dan unit operasi membutuhkan penyelesaian yang bersifat iteratif. • Penyelesaian yang bersifat iteratif menggunakan teknik analisis numerik sebagai salah satu upaya untuk menyelesaikan masalah sistem analitik yang sulit dilakukan. • Teknik analisis numerik dilakukan dengan bantuan komputer beserta perangkat lunaknya dengan tujuan untuk melakukan perhitungan yang awalnya diangggap tidak mungkin menjadi mungkin.

• Peralatan instrumentasi yang terdapat di lingkup industri kimia selalu berubah dan semakin disempurnakan. Meskipun prinsip dan konsep dasarnya tidak banyak berubah. • Konsep-konsep dasar yang terdapat pada bidang ilmu Teknik Kimia antara lain adalah: 1. 2. 3. 4. Neraca massa Neraca energi Kesetimbangan (fisis: kesetimbangan fasa; dan kimiawi ) Proses-proses kecepatan (fisis: transfer momentum, panas, massa; dan kimiawi: kinetika kimia) 5. Ekonomi 6. Humanitas

Pengantar Komputasi Teknik Kimia • Teknologi komputer banyak membantu para Chemical Engineers untuk ‘melompat’ dari level keilmuan yang semi kuantitatif di ranah sistem teknik kimia dan aplikasinya kepada level yang sepenuhnya kuantitatif. • Contoh pengaplikasian: • Aliran partikel - Particulate flow • Micro-mixing pada Reaktor Kimia

Aliran Partikel – Particulate Flow

Aliran partikel dengan fase k memiliki persamaan: Dimana Fk adalah gaya yang dialami oleh partikel di dalam volume terkendali (control volume) pada fase yang kontinyu, yang mana merupakan penjumlahan dari semua gaya fisik. Fi pada partikel i dan gerakan partikel diskrit memiliki persamaan: Dua persamaan di atas dapat memberikan informasi mengenai gerakan partikel tunggal di dalam medium cairan tidak berbatas (unbound)

• Gaya Fi yang terjadi di partikel secara intuisi terbagi lagi menjadi beberapa komponen yang mana bisa atau tidak mengandung arti fisik sebenarnya. Fi = Fdrag + Fgravity + Fpressure + Fvirtual mass + FBasset + Flift + Fturb dispersion + … • Gambar 2 adalah contoh particulate flow non tunggal

Micro-mixing pada Reaktor Kimia

• Numerical simulation (scientific computation) has greatly helped chemical engineers to deepen their understanding of the hydrodynamics and fluid mixing in single phase and multiphase chemical reactors [30], but the study of micro-mixing seems to lag behind. • Mathematical modeling of micro-mixing did develop along with the discipline of chemical engineering. Mao and Toor [33] proposed a simple slab model in form of partial differential equations by perceiving that two reactant feed streams were represented as two stacking slabs containing respective reactant, and the reaction proceeded as the reactants diffuse towards one another. •

• Most micro-mixing researchers used the averaged structure of fluid packets (fluid filament, slab, lamellae, swirling vortex etc. ) as the simplified physical models for further modeling steps. To remove these defects, the principles in transport phenomena, turbulence theory, modern mechanics etc. should be resorted to simultaneously with the support of modern applied mathematics and high performance supercomputer techniques. • When successful simulation of competitive reactions in a stirred tank reactor (Fig. 3(a)) is done with sufficient spatial and temporal resolution, we would know the true picture of turbulent flow and the macro-mixing between two feed streams of reactants A and B, how the mechanism of engulfment (Fig. 3(b)) or other mechanisms gear to accomplish the micro-mixing step and the reactions proceed according the intrinsic kinetics at each point inside the reactor, what the local selectivity of desired products is, and how it averages to a measurement we used to get at the reactor outlet (the segregation index in Fig. 3(c)).

Kerangka Berpikir di Bidang Teknik Kimia

• First two paradigms have laid solid foundations for chemical engineering, or more generally process engineering, to develop as the knowledge base and operation guideline for chemical industry and her sisters. • Experiment, theory, and numerical simulation are main essential tools for all engineering sciences. Computational Chemical Engineering, allows exploration of even wider scope and deeper understanding of chemical processes and systems. • Chemical engineers deal with a multitude of equations ranging in complexity from simple linear equations to highly involved partial differential equations. • The solution techniques accordingly range from simple calculations to very large computer programs. The classification of the problems based on the mathematical nature is presented in the following sections.

Permasalahan Komputasi di Teknik Kimia 1. Persamaan Aljabar Linear • Linear algebraic equations are often encountered in phase equilibrium problems associated with separation processes. • Figure 4. 1 is a representation of one such separation operation, wherein a high-pressure liquid stream is fed to a flash drum where the system pressure is reduced, resulting in the formation of a vapor and a liquid stream that exit the drum. The compositions of the liquid and the vapor stream depend on the process conditions, and a chemical engineer has to calculate these compositions.

• These two equations should be intuitively clear, as the mathematical statements of the concept that all fractions of any quantity must add up to the whole. Equation 4. 3 is actually a system of n equations relating the mole fraction of a component in the gas phase to the mole fraction of the same component in the liquid phase. Ki is a characteristic constant for component i and is dependent on pressure, temperature, and the nature of the component mixture. • Solution of this system of equations allows us to calculate the compositions of the two different phases, which is necessary for designing the separation scheme for the mixture. Each term in the system of equations is linear (variables having power of 1) in x or y.

2. Persamaan Transcendental • Many of the equations in chemical engineering involve functions of variables more complex than simple powers. An equation containing exponential, logarithmic, trigonometric, and other similar functions is not amenable to solution by algebraic means—that is, by simple addition, multiplication, or root extraction operations. • Such equations “transcend” algebra and are called transcendental equations [4]. Equation 4. 7, the Nikuradse equation, often used in fluid flow calculations, is an example of a transcendental equation [5]. Nikuradse equation allows us to calculate f, the friction factor, a quantity that further leads to the estimation of pressure drop for a flowing fluid and, ultimately, the power requirements for material transfer.

3. Persamaan Diferensial Ordinary (ODE) • All the processes and phenomena occurring in the larger system are represented in the differential element. The modeling approach involves writing conservation of mass and/or conservation of energy equations for the differential element. • These equations yield ordinary differential equations when all the quantities are functions of a single independent variable. • For example, equation 4. 10 is a first-order differential equation relating the rate of change of concentration to time in a chemical reaction [6]. The equation indicates that the rate at which the concentration of species A, CA, changes with time t is linearly dependent on the concentration of A itself—an example of a firstorder reaction. The parameter k is called the rate constant.

• Solution of this equation yields the concentration-time profile for the reactant A in the reaction, which provides the basis for the design of the reactor.

Penyelesaian Komputasi di Teknik Kimia • Masalah komputasi yang cenderung rumit dapat diselesaikan secara analitik maupun numerik. • Kekurangan yang terdapat pada penyelesaian analitik kemudian dibantu dengan menggunakan penyelesaian secara numerik yang mana saat ini menjadi sesuatu yang lumrah digunakan. • Perangkat lunak yang digunakan untuk penyelesaian masalah secara numerik antara lain adalah VBA Ms Excel, Matlab dan HYSYS. • Di perkuliahan ini kita akan berkenalan lebih jauh dengan VBA Ms Excel dan Matlab untuk nantinya diaplikasikan kepada masalah perhitungan yang terdapat di Teknik Kimia.

Ms Excel

Ms Excel

Matlab

Software sebagai Tools Penyelesaian Masalah • Microsoft Excel • MATLAB • HYSYS

Pertemuan 2

Ms Excel Pengenalan