As the efficiency of the CCWP was being evaluated, a need existed to determine if the site was experiencing low [DELTA]T syndrome.
How does the presence of low [DELTA]T syndrome impact the operation of the CCWP? Figure 3 is a simplified schematic of the site's chilled water system showing the hydraulics of what is happening around the system with a 7[degrees]F (3.9[degrees]C) example secondary [DELTA]T.
This is not what really happens at the CCWP, but it is what would happen if another chiller were not started.
Thus, starting the next chiller is how the CCWP deals with the effect of low [DELTA]T syndrome at this primary/secondary chiller plant.
Is there a controls logic change that could be implemented at the CCWP that would enable the chillers to control the secondary temperature setpoint and load to 100% despite the impact of low [DELTA]T syndrome?
How did this new control logic alter the operation of the CCWP? From the data collected around the time of the implementation of this logic change, it was apparent the change was activated between 10 a.m.
The same random starting of chillers existed in relation to the clock hour for both cases so the difference between the 57.7% and 86.4% is a true improvement in the starting sequence for the chillers at this CCWP. Evaluating the change in operation in this way removes the impact of the weather and load.
As previously stated, the site added a Loop B to the CCWP in the summer of 2005, which means that even with an increased load, the new code operated with fewer chillers.
Starting a chiller at the CCWP requires a 75 hp (56 kW) primary pump and 100 hp (74.6 kW) condenser pump to be started.
Using the example figures, which are not the real system but represent generally what is happening for this CCWP, the following simplified, single-point, winter season evaluation is presented:
Four electrical meters log the kWh consumption for the CCWP. Comparing the one year preceding this code change (Dec.
This article describes the results of this code change for this specific CCWP that is hydraulically designed as a primary/secondary system.