The approach adopted by THERPROP is based on the graphs normally employed in Thermodynamic, as  the graphs Temperature-Entropy (T,S) and Enthalpy-Pressure (H,P).

Once the fluid and the type of graph have been selected, the desidered graph appears on the screen; you may draw on the graph the isoproperty lines, i.e. the lines at constant pressure or enthalpy etc.

Clicking one point of the graph, THERPROP calculates the properties of that point, pressing the mouse button over one point and moving the mouse over a different point, THERPROP calculates the properties of both the points involved, as well as their variations.

When the process involves a pressure variation THERPROP interpretates the process as an expansion or compression: an isentropic efficiency may be specified to allow a correct process evaluation.

This feature makes quick and easy the evaluation of a simple process that actually requires much more time if carried out by handy interpolation through tables or by the use of more complex software products.

 

You may draw in one session as many graphs as you need of different fluids, you may keep them open or closed and switch from each other

 

Two systems of units are available: the international system referred as SI and the British system. The unit of bar is used in SI for pressure.

A system can be defined for each graph you generate; you may also monitor in the other system the results generated using one system.

 

Moist air is represented by the usual psychrometric diagram complete of adiabatic saturation lines.

The psychrometric diagram of moist air generated using the data file Moistair.tab. Clicking one point the properties of that point, including the wet bulb temperature, are calculated. You have the option to refer the properties to the unit of dry gas, as common practice, or to the unit of moist gas. You may also draw the adiabatic saturation line passing through the point of your interest. If you are interested in the low temperature field you may use the Zoom option to enlarge a selected area or you may change the scale limits.

Mixtures of ideal gas and steam, as well as pure ideal gas or mixtures of ideal gas, are represented by the Temperature-Entropy (T,S) diagram.

Two phase, single component real fluids are represented by diagrams Enthalpy-Pressure (H,P) and Temperature-Entropy (T,S). Isoproperty lines may be drawn on both the diagrams.

Mixtures of Water and Ammonia are represented by the phase diagram and by the graph Enthalpy vs Ammonia mass fraction at Vapour Liquid Equilibrium.

 

THERPROP operates also as the conventional programs aimed at thermodynamic properties calculation. You may avoid the use of graphs and specify through the keyboard the fluid state. This approach is useful for generating tables of properties to be used eventually later for generating graphs.

 

If you want analyze a process generate the T, S diagram. A process is normally accomplished by a number of steps: each step involves a transformation of the fluid physical state. You may easily calculate the fluid properties at the ends of each step. THERPROP records them and calculates the variations. If a step involves a fluid expansion or compression, you may specify the isentropic efficiency to allow THERPROP a correct process evaluation.

Let we consider  the expansion  process of steam between the pressures of 100 bar and 1 bar. The physical state of the steam before the expansion is labeled with the number 1 in the T,S diagram. To determine the final state after expansion  specify the isentropic efficiency of the transformation, place the mouse pointer over the initial state in the T,S diagram, click  and move the mouse towards the isobar of the final state with  the same entropy of the initial.

After having released the mouse button, over the T,S diagram is drawn the straight line that connects the final state of the transformation to the initial.

 

You may print and save your work. Diagrams are saved as bitmap and  you may manipulate and use them in your reports and presentations.

In all the cases you need a quick calculation of  the more common thermodynamic properties as for instance: enthalpy, entropy or density, you may use THERPROP. THERPROP replaces the  printed thermodynamic diagrams and can be also used to evaluate  the fluid properties variation during a real transformation like expansion or  compression.