I am trying to determine the effect of increasing the chilled water
delta T on the energy consumption in an office building. I set up 2
models,
one with 10 deg delta T, and the other increased to 15 deg on the
chilled water loop (elec. centrifugal chiller was used). All other
parameters are same in both models.
The results show a drop of ~14% in pump energy, but they also show a
reduction on both the cooling (~6%) and heat rejection (~3%).
Why does the increase in chilled water delta T show savings on these 2
other end-uses?
Thanks for any help
Since you didn't change the CHW supply temperature, the drop in chiller load
is a result of warmer return water returning to the chiller and improving
the rate of heat transfer to the evaporator. The drop in heat rejection is a
direct result of the reduced chiller load.
Depending on your HVAC system parameters, you may have seen an increase in
fan energy to account for the less efficient heat transfer taking place at
the cooling coils.
Rohini/Bob/Lance,
Thanks for your help,
Much appreciated.