Does anyone know a way to do waterside economization other than through the airside tabs. The building I'm currently modeling has older multizone systems with a water to water heat exchanger for waterside economization. Equest does not give the option for waterside economization for multizone units. I thought there may be a way to create a heat exchanger and accomplish this through a water side route but have so far been unsuccessful.
Charles,
I haven't done this myself, but have an idea that you might try.. Set
up your chilled water loops so that the chiller and heat exchangers are
in parallel. Then, set up equipment control with a schedule so that the
chiller is disabled and the heat exchanger enabled when the outside air
conditions are suitable. You may have to put the hourly ourside air dry
bulb/ wet bulbs temps in Excel to crunch and figure out the schedule.
Again, I haven't had to do this before so there may very well be a
simpler approach to modeling a waterside economizer, but I think this
would work. Let me know how you make out.
Greg Collins
Yes -- there is a new chiller type in eQUEST that is a water side
economizer and represents your heat exchanger between the chilled and
condenser water loops. Note that you do not need equipment control for
this heat exchanger but it will only run when it can carry all of the
cooling load.
It was introduced I believe in version 3.62 or 3.61 or so.
You can create a water economizer in your plant. Create a new chiller of type "water economizer".
Jeremy McClanathan, LEED(r) AP
Hi Charles,
You can model this using a chiller of the type called 'water economizer chiller' this has some limitations however.
Note however that the waterside economizer chiller will be used only as a 'all or nothing' where it is used only when it can meet all of the load, not partial loads hence possibly under estimating the energy savings. Also it is important to have only one cooling tower assigned when using water side economizer chiller.
I have pasted the help section below that describes this -
Chiller Water-Economizer
The program assumes a water-side economizer is used in an "all or nothing" mode. If the water-side economizer can handle the entire cooling load, then it will be used. Otherwise, the loop will use its other chillers. A water-side economizer cannot precool the return flow prior to entering the chillers.
The "all or nothing" mode precludes the use of an EQUIP-CTRL sequence to coordinate the operation of an economizer chiller with other chillers. If you list a water-side economizer chiller in an EQUIP-CTRL sequence, it will be ignored.
There must be a one-to-one correspondence between a CHW loop, a water-side economizer, and a CW loop. A CHW loop may be supplied by only one water-side economizer, and a CW loop may supply only one water-side economizer. In other words, a plant may have any number of chilled water loops having water-side economizers, but those economizers cannot draw from the same CW loop. The program will generate an error if this condition is not met.
If a CW loop supplies a water-side economizer, it may also supply chillers serving the same CHW loop as the economizer. However, it cannot supply chillers serving other CHW loops. The program will generate an error if this condition is not met.
A CW loop supplying a water-side economizer should have only one cooling tower. More than one cooling tower is allowed, however only the first tower defined will be checked to see if sufficient free cooling capacity is available. Once free cooling is allocated to a CW loop, the program may use any combination of towers to satisfy it. The program may underpredict the water-side economizer savings if more than one cooling tower serves a given CW loop. To minimize the underprediction, define the largest tower first.
If there is any water-cooled packaged equipment in the SYSTEM command, this equipment will be ignored when determining whether the tower has sufficient free cooling capacity. This may cause the program to overpredict water-side economizer savings.
For maximum effectiveness, the CHW loop should have COOL-SETPT-CTRL = LOAD-RESET. This allows the CHW temperature setpoint to rise during periods of low loads, maximizing the effectiveness of the water-cooled economizer.
Enjoy!
Amarpreet Sethi MSc LEED AP
Is anyone willing to share an eQ example project input files with waterside economizer? The waterside economizer is for a centrifugal chiller plant with plate and frame heat exchangers and open cooling towers for a very large data center system in Chicago?
I cannot find the equivalent DOE2.1E keywords in the DOE22 Basics, Topics & Dictionary manuals:
DIRECT-COOL-MODE
STRAINER-CYCLE
THERMO-CYCLE
DC-MAX-OAT
DC-MAX-CHILL-WTR-T
DC-TWR-WTR-SETPT
DIRECT-COOL-SCH
DIRECT-COOL-KW
Is there DOE2.2 documentation that gives schematics and BDL examples of plant scenarios - Load Management, Thermal Storage, etc? Is there a ?DOE2.2 BDL Summary? manual (similar to DOE2.1E) showing default, minimum & maximum.
The best way to teach building energy modeling & simulation is with case studies.
Varkie
Dear E-Quest Modelers,
Does anyone know how to access the refrigeration library file of the above?
I would like to see the list of refrigeration components listed there.
Your cooperation on the above is highly appreciated.
Sincerely,
ECHC
Sounds like you?ve looked at the pertinent DOE2.2 Manuals. If you can?t find it, try editing the input file directly with the DOE2.1 commands. More than likely eQuest will error if they are no longer functional.
Jonathan R. Smith AIA LEED?AP
Thanks. I will try that and I will also try DOE2.1E.
The instructions I got were "the HX is piped between the CHW and CW loops. It should be active when the cooling tower can produce 42 degree water so the chilled water can be 44 degrees. Generally, for Chicago area it would be from December through March???? When it is on the chiller is off as it basically becomes a chiller"
I tried this with eQUEST "If you just simply place a chiller of type water economizer in parallel with your current chiller equest should take care of the rest for you and run the economizer when the conditions are correct for it."
I am still waiting for the actual project model. In the meantime I used 200,000 sf industrial building with cooling load of 750 tons and got the attached error message.
Varkie
Hi Gang:
I am trying an EEM (ECM) to a 200 ton Mammoth Rooftop unit. I want to take the evaporatively cooled condenser fans and make them variable speed. The only options?I see are CONTINUOUS or INTERMITTANT flow for the condenser fans.
Any ideas?
John R. Aulbach, PE, CEM
Hi There!
Does anyone know how to access the refrigeration library file of the above?
I would like to see the list of refrigeration components listed there.
For example:
Compressors:
Copeland Model: xxxxxxxxx
Carlyle Model: xxxxxxxxxxxxx
Bitzer:Model: xxxxxxx
Your cooperation on the above is highly appreciated.
Sincerely,
ECHC
I am having a hard time getting ?Chiller Type = Waterside Economizer? to work in eQ. I received 2 messages recommending this as the solution. I have 2 more saying that they have not been able to model WSE in eQ. Please let me know if it is not supposed to work.
Unlike DOE2.1E this is the only minimum input required in eQ. In this project during WSE operation we require a Clg-Twr leaving temp (Plate & Frame HX entering temp) of 42F so that the CHW temp leaving the HX is 44F or 46F. The eQ default is 85F. Even with this default and ?Chiller Type = Waterside Economizer? I get the error message ?Condenser Water Loop has Zero Design Flow?.
Unlike DOE2.1E there is no way of attaching a schedule for WSE operation. I have attached eQ input-output ?Without-WSE-1? and ?With-WSE-2?; DOE2.1E definitions of WSE commands and keywords; a sample DOE2.1E plant section input showing WSE; a schematic of Plate & Frame HX; and my eQ input for WSE and the resulting error message. The attached project is dummy to test eQ for WSE.
Has anyone modeled WSE with eQ? WSE works with DOE2.1E commands and keywords. Does Waterside Economizer work with EnergyPlus (this project is also going to be modeled with E+ using Design-Builder interface for building and systems), TRACE or HAP
Varkie
I have modeled water-side economizers successfully a number of times. But instead of putting it under the chiller, as you are showing in your attachment, I have always input it on the air side. To input the water-side economizer go under Air-Side HVAC and then under Cooling and then under Economizer. After you are in this input area then the program will allow you to select that you want a water-side economizer and then when selected yes, will allow you to put in the water-side economizer inputs. I have attached the helps that pull up in this area, when you right click and select item help.
David A. Bastow
Varkie,
Which version of eQUEST are you using? If it's a new version then you should be able to model it as a chiller. See attached documentation - pg 68 (73 of the PDF)
Vikram Sami, LEED AP
The only problem is this:
Timothy Howe, MS, LEED? AP
I do have a question about that - point # 1 - A water-side economizer cannot precool the return flow prior to entering the chillers.
I might be showing my ignorance here, but - isn't that what the cooling tower does? So if you have a CHW loop with two chillers attached - a normal (lets say centrifugal) chiller and a water side economizer. When the water side economizer cannot satisfy all the load, it would switch completely to the centrifugal. However - wouldn't the cooling tower still be used as a heat rejection to " precool the return flow prior to entering the chillers"? In which case is point 1 not really a shortcoming?
Vikram Sami, LEED AP
There are two loops as you know: the condenser water (CW) and the chilled water (CHW) loops. The economizer acts on the CHW side, and the cooling towers, on the CW sides. Basically, the water-side economizer may be seen as a chiller with no compressor.
In some cases, economizers are used to pre-cool the return chilled water (CHW loop) before it gets back to the chillers: that is what the rule 1 below precludes.
________________
Demba NDIAYE
Varkie,
You need the water economizer ?
"water economizer" = CHILLER
TYPE = WATER-ECONOMIZER
CHW-LOOP = "Chilled Water Loop"
CHW-PUMP = "WE pump"
CW-LOOP = "Condenser Water Loop" ..
And a pump attached to the water economizer ?
"WE pump" = PUMP
CAP-CTRL = VAR-SPEED-PUMP
..
Along with the chilled water loop and a condenser water loop.
I think the problem you are facing may be due to the 42deg temperature input.
Hope this helps.
Amarpreet
Varkie,
I took a look at your model. I think the reason you are getting zero flow in your condenser loop is that you only have one chiller (the water side economizer). When its not satisfying the whole load, it goes off, and there's no chiller to create loop demand (hence zero flow). If you add a chiller to the loop the error should go away.
Vikram Sami, LEED AP
Hi all,
I have a ?Differential temperature Economizers with maximum temperature of 70 deg. F?
Can anyone advise on where to input this 70 deg. F in eQUEST (which tab/box)?
Many thanks,
Omar Katanani