The TES tank connects to the CHWS and CHWR headers similar to above; however, the water must always be pumped from the atmospheric pressure of the TES tank into higher-pressure chilled water headers.
* Maintain positive differential pressure between the CHWS and CHWR headers.
The electric savings from precooling the CHWR with a water economizer are shown in Figure 3.
load were developed from a typical fan-coil unit cooling coil to determine CHWR based on CHWS and load.
Therefore, for this installation, as result of the height of the chilled water tank, the connection of the tank into the system and the resulting chilled water system pressures the pumps are required to operate simultaneously (at least in some operating conditions) on both the CHWS and CHWR.
Using simultaneous dual pumping of CHWS and CHWR on a TES tank had been tried previously on other TES systems, but in each instance we studied, it was not successful.
The system in Figure 2 shows the TES tank, the CHWS and CHWR pumps as well as the chilled water production facilities at the existing central plant and the future east chiller plant.
In warmer months, when the cooling load dominates, the side-stream arrangement is used (valve V1 allows the chilled water from the heat pump to flow into the CHWR
pipe) and the heat pump runs in heating priority, since it is able to meet the entire heating requirement.
3C [T.sub.wb]<=80[degrees]F 100% 100% 100% 100% [T.sub.wb]<=70[degrees]F 89% 100% 62% 100% [T.sub.wb]<=60[degrees]F 66% 87% 36% 87% [T.sub.wb]<=50[degrees]F 50% 32% 20% 32% [T.sub.wb]<=40[degrees]F 33% 5% 7% 5% [T.sub.wb]<=30[degrees]F 15% 0% 1% 0% Table 5: Coil analysis for impact on CHWR
from change in supply air temperature.
= Chilled water return temperature, [degrees]F