Detailed Fan (Pressure Dependent)
by M. Brandemuehl  Revised for TRNSYS by N. Blair and R. Schwarz

      	This model was adapted strictly for use with the TRNSYS Program by
the Solar Energy Laboratory.

	The algorithm calculates the power consumption and leaving fluid 
conditions for a given flow rate and entering fluid conditions.  The algorithm
determines the performance and outlet conditions based on a dimensionless
performance curve that relates pressure rise and efficiency to fluid flow rate.
The performance curves are represented by polynomials with empirical 
coefficients supplied by the user.  It is designed for use with system energy
calculations that include detailed pressure balancing to determine flow rates.
	The same model applies both to this fan model and the component 1211
Pump model.  The only fundamental difference is in the calculation of fluid
properties.  In particular, the fan model uses psychrometric routines to 
calculate fluid density and temperature rise, while the pump model uses a 
constant density and specific heat of fluid.  This algorithm will correctly 
calculate inlet air conditions given outlet air conditions by specifying a 
negative airflow rate, assuming there is a negligible change in air density 
across the fan.
	Sample input and output are included in the source code.

REF: A Toolkit for Secondary HVAC System Energy Calculations  May 25, 1992
     Joint Center for Energy Management   University of Colorado at Boulder