modelDHWQueue

Information

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:

• Number of drawings delivered instantly
• Number of drawings processed within 30 minutes
• Number of drawings processed within 60 minutes
• Number of drawings processed within more than 60 minutes

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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