This model performs a trial and error process to draw hot water when needed if tank temperature is sufficient or to postpone the drawing.
Hypothesis and equations
For each drawing, the model compares the needed drawing temperature and the available tank temperature.
If the needed temperature is available in the tank, the drawing is processed, else the drawing is delayed, waiting the needed temperature to be available.
The parameter MaxDelay allows to define a maximum delay time in the DHW queue. For a delayed drawing, if the maximum delay time is reached, the drawing is processed, even if the needed temperature is not available in the tank.
The parameter QueueSize allows to define a size for the DHW queue. If the queue is full, all the drawings will be processed instantly even if the needed temperature is not available in the tank.
Pseudo code of the algorithm
If a change is detected in the input drawing rate scenario then
If there is already an expected drawing being processed then
If this expected drawing being processed is a delayed drawing waiting to be completed (i.e. total duration is still not known) then
Complete this drawing (i.e. store its total duration), so that it is ready to be processed when the needed temperature is available
Else
Close this undelayed expected drawing
If a new expected drawing is beginning then
If this new expected drawing can be processed instantlty (i.e. needed temperature is available) then
Start processing this drawing
Update key performance indicators
Else
Delay this drawing and wait to know its total duration
For each complete delayed drawing in the queue then
If the needed temperature is available or if the maximum delay time is reached for this delayed drawing then
Start processing the delayed drawing
Else if the delayed drawing is being processed and the needed time duration of the drawing is reached then
Stop processing the delayed drawing
Delete the drawing from the queue
Update key performance indicators
Key performance indicators calculation
For each drawing, a time comparison between expected drawing time and effective drawing time is made to increment one of these counters:
Then percentage indicators PercNoDelay, PercWithin30Min, PercWithin60Min, PercMoreThan60Min are calculated from the counters above.
Bibliography
none
Instructions for use
none
Known limits / Use precautions
The model is not able to deal with multiple drawings at the same time. When a new drawing is detected, the previous one is considered as closing.
Validations
Validated model - Benoît Charrier 09/16
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Licensed by EDF under a 3-clause BSD-license
Copyright © EDF 2009 - 2023
BuildSysPro version 3.6.0
Author : Benoît CHARRIER, EDF (2016)
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