Type 97 --- BOILERCT 
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NUMERICAL SIMULAITON OF A BOILER SUBMITTED TO A CERTAIN HEAT DEMAND

Most modern boilers are equipped with combustion control systems that 
satisfy heat demands. Three types of combustion control systems are 
considered in this Toolkit1; ON-OFF, low-high-low-OFF and modulating 
control systems. Boilers with a single burner levels make use of the 
ON-OFF control system that simply starts and stops the fuel burner in 
order to satisfy the heat demand; a low-high-low-OFF ("low" applies 
to the minimium firing rate and "high" to the maximium one) control 
system is used for burners with two burner levels. These two control 
systems are referred to as "cyclic" operating modes because the burner 
is passsing from one firing rate to another. This regimes are described 
by reference as a "quasi-static" model : it is assumed that the cyclic  
operation can be represented by a simple linear combination of two 
steady state regimes. In the case of a burner with two boiler levels, 
a gas-water heat transfer coefficient associated with the lower level
is assumed to be the same as for the higher level. 

Ther exists a third combustion control system for boilers equipped 
with a modulating burner. The boiler regulates the fuel mass flow rate 
by means of a modulating burner in order to reach the given set point 
temperature. Thereofre within the range of the modulating operation, the 
boiler operates continuously with the same fuel flow rate. Once again, 
the water-environment heat transfer coefficient is assumed to remain 
constant whatever the regime may be.

The aim of routine BOILERCT is to determine the boiler operating mode 
in order to reach a given set point temperature. Once again, the water 
envorinment heat transfer coefficient is assumed to remain constant 
whatever the regime may be. 

The aim of routine BOILERCT is to determine the boiler operating mode in 
order to reach a given set point temperature (i.e. a mean exhaust 
temperature).
 

Input, Output and Parameter descriptions are in the *.for file. For More 
details, see the HVAC1KIT manual.

For a complete  description of the routine, reference the HVAC1KIT manual, 
prepared by;
Jean Pascal BOURDOUXHE and Marc GRODENT, Research Assistants.
Jean LEBRUN, Principle Investigator.