Description

This is the first in a series of papers presenting the fundamentals of a new simulation toolkit developed by ASHRAE TC 4.7. The modelling approach used in this toolkit is oriented toward simple solutions with a minimum number of parameters and is accurate enough for annual energy calculations of whole building systems. The boiler model is developed and documented on the basis of the following elements – an information flow diagram in which a selection of input-out variables and parameters is proposed, two conceptual schemas in which the main physical assumptions are stated, and a set of equations derived from the conceptual schemas. After the modelling of the combustion chamber and the heat exchangers, describes the simulation of a boiler submitted to a certain heat demand. Three types of combustion control systems are considered – on-off, low-high/low-off, and modulating. For the first two control systems, it is assumed that the cyclic operation can be represented by a simple linear combination of two steady-state regimes (“quasi-static” model). Particular attention is paid to parameter identification – the toolkit must allow the user to “translate” the (sometimes incomplete) information found in catalogues into fundamental characteristics of the component being considered. Boiler parameters consist of a set of heat transfer coefficients (two or three, according to the burner control mode). Special identification procedures are provided to the user in order to identify these heat transfer coefficients on the basis of the available experimental tests and/or default values. The proposed model is well validated on the basis of available experimental results.

KEYWORDS: calculating, accuracy, energy consumption, building services, boilers, combustion chambers, counterflow heat exchangers, heat exchangers, models, heat load, properties, heat transfer coefficient, heat loss, validating

Citation: Symposium, ASHRAE Trans. 1994, Vol.100, Part 2

Product Details

Published:

1994

File Size:

1 file , 1.1 MB

Product Code(s):

D-17548