# Dwsim Simulator

### References

The field of chemical engineering is in constant change, so are available calculation tools and software packages. In fast everyday life, it is a considerable challenge for a chemical engineer to know which tool can serve best for solving a certain problem.

The different packages can be applied to solve typical problems in mass and energy balance, fluid mechanics, heat and mass transfer, unit operations, reactor engineering, and process and equipment design and control. In this article, we highlight the most important tools and packages with their capabilities, based on the available professional experience of an author, available literature and discussions.

The Figure below summarizes the most useful software packages in chemical engineering:. So, let's start from the beginning.. Despite starting out as a hobby project named after Monty Python, Python is now one of the most popular and widely used programming languages in the world.

Besides web and software development, Python is used for data analytics, machine learning, and even design. Python is an object-oriented (based around data), high-level (easier for humans to understand) programming language. First launched in 1992, it’s built in a way that it’s relatively intuitive to write and understand. As such, it’s an ideal coding language for those who want rapid development.

### Modelling

Python is a popular and in-demand skill to learn. It is a known fact that Microsoft Office Excel is a spreadsheet application that features calculation, graphing tools, tables, and a macro programming language - Visual Basic. The main advantage of Excel is that it is available and is widely used in industry and academia.

Thus, it is a perfect tool or interface not only to perform calculations but also to connect different software so that the end user can interact with Excel, and behind the scenes, other software such as CHEMCAD, MATLAB etc.

is running and reporting the results back to Excel. It is best used for:. Built-In functions & formulas – there are a large number of built-in functions defined, such as statistics (MEAN, AVERAGE, t-test), algebraic (SUM, ROUND, LOG, LOG10), logical (IF, FALSE, etc.), reference, database, and information.

Those are easy to use in different kinds of formulas. Operations with columns and rows – it is easy to find & sort data and use them in replicated formulas etc. Plotting – there is a large number of options depending on the needs.

Solver - It is the tool to use within Excel to solve numerically a set of equations, problem optimization including fitting a set of data to a given linear and nonlinear equation and more.

Solver is an add-in that needs to be activated to be used. Building functions in Visual Basic for Applications - Excel has built-in capability to generate customized functions using Visual Basic for Applications (VBA). This is a powerful tool that can save time for you without becoming an expert in programming as it opens the possibilities to run loops and conditionals on the background.

This capability also allows the user to build relatively large equations that are used in several areas of the worksheet (e.g., polynomials for the esti¬mation of specific heat of components) and allows the user to read the calculations easily when looking at the formulas in the cells.

Link Excel with other software - Excel has become a standard package so that a number of other specialized software use it as a source of information to report data since it is more user-friendly.

Therefore, we can use the information in Excel to be loaded in MATLAB, Hysys or CHEMCAD or transferred back to Excel.

## History

MATLAB is one of the most used software packages in engineering in general and also in chemical engineering.

### DWSIM - an open source process simulator

Much has been written about this popular software, more than 1500 books serving more than 1 million users. MATLAB is a programming language. Its operation is based on the use of .m files that can be divided in two classes, scripts and functions. A script is basically a number of operations that we want to perform in a certain sequence. Functions are a particular type of scripts that must begin with the word “function” at the top of them.

Functions can be user-defined or typical operations such as equation solving or differential equations.

• Within MATLAB, we have all the algebraic, statistical functions predefined along with plotting capabilities. MATLAB has a number of functions that allow solving linear and nonlinear equations (fzero: for one variable alone, fsolve), optimizing a function (fmincon: constrained optimization, linprog: linear programming; fminin or fminsearch: unconstrained optimization; bintprog: binary and integer optimization), and solving differential equations (ode__) or partial differential equations (pdepe).
• Some examples of how MATLAB can be used in chemical engineering include: . Momentum, Mass, and Energy Transfer - There are a number of examples in the transport phenomena field that, even though represent different phenomena, they can be mathematically described using a partial differential equation, the “pdepe” toolbox.
• Distillation Column Operation - McCabeMethod - typical shortcut approach for the initial conceptual estimation of the operation of binary distillation columns. Modeling of different kinds of process equipment – heat exchangers, pumps, valves, evaporators, columns, reactors etc.
• Reactor design - The models are based on explicit algebraic equations and differential equations. Thus, we use ODEXX function in MATLAB to solve the concentration, temperature, and/or pressure profiles along the operation of such equipment.
• Control loops analysis, control design and tuning. Simulink® (Simulation and Link ) is a software add-on to MATLAB based on the concept of block diagrams that are common in the control engineering areas.
• It is an environment for dynamic simulation and process control. Each of the blocks can contain a subsystem inside, which is helpful for big problems.
• We only need to select a number of blocks and with the right button of the mouse, click and select create subsystem.

## Main principle

Simulink is easier to used for engineers because it does not require any programming skills, therefore models can be build using blocks instead of defining functions.

### Steady state and dynamic process simulation

Process Simulators. The simulation, design, and optimization of a chemical process plant, which comprises several processing units interconnected by process streams, are the core activities in process engineering.

These tasks require performing material and energy balancing, equipment sizing, and costing calculation.
A computer package that can accomplish these duties is known as a computer-aided process design package or simply a process simulator.
The process simulation market underwent severe transformations in the 1985–1995 decade. Relatively few systems have survived and they inclide: CHEMCAD, Aspen Plus, Aspen HYSYS, PRO/II, ProSimPlus, SuperPro Designer, and gPROMS.
Chemstations CHEMCAD. CHEMCAD is Chemstations’ software suite for process simulation. Features include process development, equipment design, equipment sizing, thermophysical property calculations, dynamic simulations, process intensification studies, energy efficiency/optimization, data reconciliation, process economics, troubleshooting/process improvement, Microsoft Visual Basic etc.
The CHEMCAD suite includes six products that can be purchased individually or bundled as needed for specific industries, projects, and processes. CC - steady state simulations of continuous chemical processes, features libraries of chemical components, thermodynamic methods, and unit operations, enabling you to simulate processes from lab scale to full scale.
Ideal for Users who want to design processes, or rate existing processes, in steady state. CC – dynamics is used to conduct dynamic flowsheet analysis, operability check-out, PID loop tuning, operator training, online process control and soft sensor functionality.

### Computational Fluid Dynamics

Ideal for users who want to design or rate dynamic processes. CC-THERM is used for sizing heat exchangers, covers shell-and-tube, plate-and-frame, air-cooled, and double-pipe exchangers.

Rigorous designs are based on physical property and phase equilibria data.

CC-BATCH allows you to design or rate a batch distillation column.

CC-SAFETY NET - used for analysis of any pipe network with the piping and safety relief network simulation software.