.Buildings.DHC.Plants.Combined.Controls.BaseClasses.DirectHeatRecovery

Information

In direct heat recovery mode, the HRC is internally controlled in heating mode and tracks a HW supply temperature setpoint. The CHW supply temperature setpoint is maintained by means of supervisory controls that act on the evaporator flow rate and condenser entering water temperature as described below.

A direct acting control loop runs for each HRC operating in direct heat recovery mode. Each loop is enabled with a bias of 50 % whenever the HRC is commanded On and in direct heat recovery mode. The loop is disabled with output set to 50 % otherwise. The loop output is mapped as follows. From 0 % to 33 % the evaporator flow setpoint of cooling-only chillers is reset from 1.2 times its minimum value to 1.2 times its design value. From 33 % to 67 % the evaporator flow setpoint of the HRC is reset from 1.2 times its minimum value to 1.2 times its design value. From 67 % to 100 % the HRC condenser entering temperature setpoint is reset from THeaWatRet + 0.5 °C to THeaWatRet - 15 °C.

Revisions

• February 24, 2023, by Antoine Gautier:
  First implementation.