.BondLib.Examples.SolarHouse

Information

The code is collected into individual models describing the walls, the windows, etc. The main model to be simulated is the last model of the set, called House.

The design of this model has been described in [1,2].

The model makes use of six data tables. Although these tables are not very large, they are used by many of the models. In order to avoid an unnecessary explosion of table lookup in the model, the six tables were collected into a single block, called TabularFunctions, that is being invoked by the top level model. The TabularFunctions block collects the outputs of the six tables into a single vector output signal, which gets connected down through various layers of the model hierarchy to the models that actually need the tabular data.

The data items themselves are stored on an external binary file (Solar_tables.mat), rather than in memory, for the purpose of speed-up.

I don't have pictures available from the time, when the research was done that is presented in this code (around 1991). By now, this research unit is no longer in use. The pictures below were taken in 2005.

This is a view from the front (South side). The solarium has meanwhile been taken out.

This is a view from the back (North side).

This is a view from the West side. The house is built as an adobe structure. In the background, there is another (more modern) research unit that is still being used for experimentation.

Experimentation:

This model uses hours as time units. If you wish to only experiment with this model, you can simulate it over 4 days by setting the final time to 96 hours. However, if you wish to reproduce the results obtained by Markus Weiner in his MS Thesis [1], you need to simulate the model for a full year, i.e., during 8600 hours.

The model uses SIunits throughout for its computations. The display units of hours instead of seconds for time are achieved by a time scaling procedure. To this end, the input of each integrator in the model needs to be multiplied explicitly by a factor of 3600. Since in a bondgraphic thermal model, all integrators are associated with capacitors, it suffices to divide each of the final capacitor values explicitly by the conversion factor of 3600. This is the approach that was taken in the model.

Also, the temperature values on the top-level output variables are displayed in Celsius degrees rather than in Kelvin. The conversion is accomplished by manually converting the temperature values at the top level for the output variables, whereas internally, the model uses absolute temperature values throughout.

Unfortunately, this model is rather large. It produces far too much I/O, when all variables are being stored. Dymola by default stores each and every variable. Thus, if you wish to simulate over an extended period of time, you should turn off the automatic storage of all variables, and selectively store only those variables that you wish to look at. This will speed up the simulation dramatically. At least, you should turn off the storage of the auxiliary variables.

References:

1. Weiner, M. (1992), Bond Graph Model of a Passive Solar Heating System, MS Thesis, Dept. of Electr. & Comp. Engr., University of Arizona, Tucson, Arizona.
2. Weiner, M., and F.E. Cellier (1993), "Modeling and Simulation of a Solar Energy System by Use of Bond Graphs," Proc. 1^st SCS Intl. Conf. on Bond Graph Modeling, San Diego, California, pp.301-306.

Contents

Name	Description
TabularFunctions	Tabular time-dependent functions
DayHour	Conversion of fractional days to hours
Temperature	Ambient temperature
Temperature2	Ground temperature
TFilter	Auxiliary block for air conditioning
AirConditioning	Air conditioning unit
SolarPosition	Solar position in the sky
SolarRadiation	Solar radiation
SolarGlass	Solar radiation through glass
DirectGlassAbsorption	Absorption coefficient of glass for direct solar radiation
DiffuseGlassAbsorption	Absorption coefficient of glass for diffuse solar radiation
DirectGlassTransmission	Transmission coefficient of glass for direct solar radiation
DiffuseGlassTransmission	Transmission coefficient of glass for diffuse solar radiation
C1D	Heat conduction through wall
C1V	Heat convection in boundary layer
ExWall	Exterior wall
IntWall	Interior wall
Roof	Roof
Window	Window
ExDoor	Exterior door
IntDoor	Interior door
Slab	Slab below the experimental house
LivingRoom	Living room
BedRoom1	Bed room #1
BedRoom2	Bed room #2
SunSpace	Solarium
House	Experimental house