How to increase the CHW cooling Energy

asked 2016-09-21 10:05:03 -0500

NasimMirian

293 ●1 ●5

updated 2016-09-21 10:17:47 -0500

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

I have an E+ model with District Cooling and Heating, AHU With reheat coils which are off during summer. I am running the simulation for july and August.

I believe that I did the right hard sizing for coils and everything based on the mechanical drawings. The Chilled water flow rate are reasonable, matches with real building data, However, the cooling energy which considers the delta T (inlet-outlet CHW supply temperature), and CH Water mass flow rate are considerably low. which may be mean that cooling design capacity is not correct. I tried to increase that or change the coil settings but still I have this problem.

I have checked the ChW inlet and Outlet temperature and delta T is low.

How can I fix this? any idea would be helpful! :)

answered 2016-09-21 13:30:04 -0500

Aaron Boranian

13830 ●76 ●24 http://bigladdersoftware.com/

I would start by checking the flow rate of the chilled water pump and capacity of the district cooling system to see if they are higher than what the drawings specify. If both seem OK, and you're sure that the coils are defined correctly, then I would look at your sizing inputs for the cooling design day, which includes:

Design Day Schedules (look for the phrase "SummerDesignDay" in your various schedules)
Sizing:Zone objects for each zone connected to the AHU
Sizing:Plant object for the plant loop connecting the district cooling to the cooling coil(s)
Sizing:System object for the air loop connecting the central AHU to the zone terminal units

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I have all the sizing objects and they look fine to me. in Sizing:System I have chosen the CoolingDesignCapacity and is higher than drawings. Then I used the same number for the district cooling and cooling load range. is it correct to do that?

I used drawings data for the coil design but it seems that it does not work fine. real building CHW flow is quite more than the simulation result during weekends (only weekends). also I have the night cycle On. and there is some zones that are more that setback during night and evenings, the fans are getting On but the chilled water flow is zero orlow