For the issue of high pump power, the easiest thing to do would be to hardsize the power (design_power_consumption) that you're looking for at the pump. You could also adjust the pressure head (design_pump_head) to get to the desired power value as well if you're using the default Design Power Sizing Method. The issue with this is if you have a cooling tower or some other equipment on your condenser loop, it is also going to be using too much energy due to the higher than expected flow. Maybe that isn't a problem in your use case though.
Alternatively, a more robust way to go about it would be from the loads side. E+ is essentially telling you (via the autosizing results) that based on the loads and equipment/loop design parameters you've given, it needs to have a pump that can flow 80 kg/s, and therefore an appropriate power for that flow. So the first thing you should do is compare the autosized parameters (from the EIO file) to the real system you're trying to represent. If the chiller capacity and flow are too high then you might need to consider adjusting your zone loads and coil sizing. If everything is acceptable on the chw side, then you just need to review the condenser loop parameters. Check out design_loop_exit_temperature and loop_design_temperature_difference in Sizing:Plant. If temperature looks good there, you can use the dT parameter to directly adjust flow (as long as the chiller reference_chilled_water_flow_rate is autosized I think), where increasing dT should decrease flow and vice versa.
Good luck!
Hi Ahmad, are you autosizing the design condenser flow for the chiller? If so, you should take a look at your EIO file and see if it's autosizing to 80 kg/s. The chiller is going to request its full design condenser flow when it is on, regardless of pump type, so that may be what you're running into here.
Hi Cody, thanks for the reply. Yes, I am auto-sizing.
I took a look at the EIO file and here is what is inside:
"Design Size Design Condenser Water Flow Rate [m3/s], 7.75550E-002 CONDENSER WATER LOOP, Maximum Loop Flow Rate [m3/s], 7.75550E-002
CHILLED WATER LOOP, Maximum Loop Flow Rate [m3/s], 2.23400E-002 Design Size Design Chilled Water Flow Rate [m3/s], 2.23400E-002"
Seems I am running as you are suggesting. Please give me your thoughts on how to solve this issue.
Many thanks !
Got it! So is the main problem that the flow is much higher than you expect, or that you expect it to operate with variable flow? Or is the flow reasonable and your concern is that the pump power is sizing too high?
The basic idea started from results showing high pump power consumption throughout the summer period which should be from cooling. Then after plotting the flow, it showed higher than expected. I would be grateful to prioritize solving the issue of high power consumption since my end work is related to energy consumption.