# Software

Software for calculations of gas, district heating, pressurized sewage- and water networks with the application of GIS technology.

Commercial software – for sale
Non-commercial software – software which is used for consultancy activities

The basic element of the software used for calculating the network are computer programs that use mathematical models of network elements. The mathematical model is an equation or a system of equations, which in a certain way and accuracy represents the actual system. The mathematical model is obviously a simplification of the real system because it includes only those aspects of the system that correspond to the requirements for the model.

Developing a mathematical model is to identify the relevant variables and then formulate equations that meet these variables. This goal is achieved using well-known laws of physics, such as conservation of mass, momentum and energy equations. For example, the gas flow through the pipe commonly uses an empirical factor to express the effect of the flow resistance caused by the inner wall of the pipe.

Models can be classified according to the assumptions. If the system has a variable that changes continuously over time, generally, the use of dynamic models is described by differential equations. If the variables are not a function of time, then a static model featured algebraic equations should be used. The choice of model depends on the situation. For example, in low pressure gas network, changes in pressure and flow are very fast. They are ignored in the majority of cases involved, hence, the steady state - algebraic equations are used. In the case of the high-pressure gas flow dynamics, it is much slower due to the huge amount of gas stored in pipelines. Omission leads to large errors in the description of the phenomenon. Hence, it is necessary to use the mathematical models in the form of differential equations.

Developed on the basis of mathematical models, the software can be divided into two groups:

• simulation programs
• optimization programs

The main purpose of the use of simulation programs is to study the behavior of the gas network under certain conditions. A solution to the algebraic or differential equations that describes the network for assumed loads and supply network will give us answers to questions about the pressure or flow at selected points or parts of the network.

Optimization programs, in turn, make it possible to find such system conditions or such structures in which the value of the indicator determining the economic aspect or the technical process or the structure will have externalization, while parameters of the system shall not exceed the limitations imposed on them. For example, optimization of the mill depends on choosing such parameters of its work (the number of machines involved and the performance of each of them) to minimize the aggregate operating costs, while meeting the constraints e-g. On speeds. Depending on the model used in both simulation and optimization, it can be further divided into steady state and dynamic.