Welcome
S-M4-V1: Discovery of Thermoptim
GlossaryDiscovery of Thermoptim
- Introduction
- Loading a model
- Discovery of processes
- Discovery of points
- Substances in Thermoptim
- Cycle plot in the (h, ln (P)) thermodynamic chart
- Overall cycle performance, efficiency determination
- Using the example catalog
- Change in model settings
Introduction
The objective of this exploration is to guide you in your first steps of using Thermoptim, by making you discover the main screens and functionalities associated with a simple refrigeration installation model.
You will discover the layout of the screens of the points and the processes, the way in which their parameters can be set and they are calculated, the concepts of useful and purchased energies making it possible to draw up the global energy balances and to determine the Coefficient of Performance COP.
You will plot the cycle in the (h, ln (P)) thermodynamic chart.
If you wish, you can also learn about Thermoptim using the available Diapason sessions, and in particular the Session S07En_init First steps with Thermoptim.
Brief presentation of the refrigerator model
In a vapor compression refrigeration installation, an attempt is made to maintain a cold enclosure at a temperature below ambient
The
principle consists in evaporating a refrigerant at low pressure (and
therefore low temperature), in an exchanger in contact with the cold
enclosure. For this, the evaporation temperature Tevap of the
refrigerant must be lower than that of the cold enclosure Tef.
The fluid is then compressed to a pressure such that its condensation temperature Tcond is greater than the ambient temperature Ta.
It is then possible to cool the fluid by heat exchange with the ambient air, until it becomes liquid. The liquid is then expanded without work (we speak of isenthalpic throttling) to low pressure, and directed into the evaporator. The cycle is thus closed.
This figure illustrates the enthalpy transfers that
take place in the facility. Small arrows pointing downwards represent
the heat exchange, which, as can be seen, do not infringe the second
law of thermodynamics, heat flowing from warmer areas to colder areas.
The long upwards arrow represents the enthalpy contribution of the
compressor, which can raise the temperature of the fluid (note: the
energies put into play are not proportional to the length of arrows).
Setting retained
The compression refrigeration cycle of R134a operates between an evaporation pressure of 1.78 bar and a condenser pressure of 12 bar.
At the outlet of the evaporator, a flow rate
of fluid is entirely vaporized, with an superheating of 5 ° C.
It is then compressed to 12 bar following an irreversible adiabatic compression. The actual compression is characterized by an isentropic efficiency, defined as the ratio of the work of the reversible compression to the real work. In this example, its value is assumed to be 0.75
The cooling of the fluid in the condenser by exchange with the outside air involves two stages: desuperheating in the vapor zone followed by condensation.
It is then expanded without work in a capillary, down to the pressure of 1.78 bar.
Main environments of Thermoptim
When you launch the Thermoptim browser, three windows are open:
- the one you are currently reading which contains the html file of the exploration to be carried out
- that of the Thermoptim diagram editor
- that of the Thermoptim simulator
The diagram editor allows one to graphically and qualitatively describe the system studied. It includes a palette presenting the existing components and a work panel where these components are placed and interconnected by vector links.
The simulator allows you to quantify and then calculate the model described in the diagram editor. It includes the lists of the points, processes, nodes and heat exchangers comprising the model.
This document provides more information on these two environments.
