Re: underground structures

[Jeff Thornton <thornton@xxxxxxxxxxxx>]

At 12:01 PM 3/9/2004 +0000, you wrote:

> certainly
> the modeling assumption that
> you have described is more detailed of
> mine. However I'm using type501ground temperature model;
> it works satisfactoryly if I
> assume an amplitude of the surface temperature function throughout the
> year (parameter 3) of 8,8°C (disequal to the amplitude of the annual
> air temperature for the given location (16,2°C in Palermo); I accept this
> assumpion only for the mean surface temperature (parameter 1), in which
> case TRNSYS reference manual suggests to use the average annual air
> temperature (18,4°C)).

The type 501 model uses the mean surface temperature, amplitude and phase
delay parameters to calculate the temperature of undisturbed soil at any
depth below the surface.  The key term here is undisturbed - meaning
in this case the soil is not subject to heat flows from structures or
other nearby items.  In your case you have a buried structure which
will be thermally communicating with the soil.  By using only the
Type 501 model you will be grossly over-predicting the heat losses from
the structure after a few years as the soil around the structure heats up
over time (and hence your losses decrease).  The new ground models
account for the this heat build up and would provide a much better
estimate for your simulations.

Jeff Thornton
TESS