Simulation of the Thermal Budget of Biosphere 2
Using Bond Graphs
Introduction
Biosphere 2 is a closed ecological system that had been constructed as a
research unit in the vicinity of Tucson. In its early phase, the aim of
this project was to investigate whether a team of human astronauts could
be supplied on long space flights with air and food that are produced
locally by use of solar energy.
Our project, which was partially supported by Biosphere 2, dealt with
the development of a thermal model of Biosphere 2 with consideration of
the levels of humidity.
Thus, our model had to consider also the latent heat, not only the sensible
heat, in contrast with the earlier
building models. For this
reason, the model also contains modules for the description of the processes
of evaporation and condensation.
Historical Development
- In 1995,
Àngela Nebot, during a postdoctoral research visit to
the University of Arizona, developed a first version of the thermal
model of Biosphere 2. Àngela's research visit with the University of
Arizona was financed by the Generalitat de Catalunya under its CIRIT
program. The model was based on an earlier model that had been developed
by Francisco Luttmann as part of his PhD dissertation. The earlier model
had been coded in TRNSYS with extensive programming in Fortran. The code
was totally monolithic and highly unreadable. In contrast, Àngela's code
was built in an object-oriented fashion from bond graph models.
- In 1996,
Julia Miersch developed additional modules describing the
water storage in the plants of Biosphere 2 during a student exchange year
spent at the University of Arizona. Julia's visit with the University of
Arizona was financed partly by the deutscher akademischer Austauschdienst
and partly by Biosphere 2.
- In 2001, I ported Àngela's model over from its original non-graphical
version of Dymola to Dymola/Modelica Version 4 employing a graphical
user interface.
- In 2005, an improved and fully documented version of the model was
included with the
bond graph library as a standard sample
program.
Most Important Publications
- Miersch, J. (1996),
Bond Graphs in Modeling Plant Water Dynamics,
MS Thesis, Dept. of Electr. & Comp. Engr., University of Arizona, Tucson, AZ.
- Nebot, A., F.E. Cellier, and F. Mugica (1999),
Simulation of Heat and Humidity Budget of Biosphere 2
without Air Conditioning,
Ecological Engineering, 13, pp. 333-356.
Sponsors
- Biosphere 2
- Deutscher Akademischer Austauschdienst (DAAD)
- Generalitat de Catalunya
Deutsche Version
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Last modified: July 12, 2005 -- © François Cellier