Energy Recovery Wheel

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I am modeling a project located in Chicago, IL with Trane Trace. I am unable to figure out as the following two situation.

1.       Put energy recovery wheel into energy model on proposed design while the other components remain the same, however,  I got negative result. The energy saving is reduced from 14.26% to 12.84%.  Does anyone has the same situation before? The input is as following:

 

 

2.      Three AHUs configured as “Bypass VAV with reheat (30% Min Flow Default)” help the energy model with 14.26% saving , after I changed them as” VAV reheat (30% Min Flow Default)” , the energy saving is from 14.26% to -2.6%, while the other components remain the same.

 

James

Trace Selection
Effectiveness
Anonymous's picture
Anonymous

Sometimes ERV's are not as effective as you would like them to be, or as expected. In this case, it's hard to test with the limited information, but a common factor is the supply fan's units. Does the supply fan have units of kw/cfm-in wg (or something pressure sensitive). The default for most energy wheels is to automatically add the static to the fan, which can often double fan energy.

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Bob
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Joined: 2010-06-30
Reputation: 275

I have same problem and I am not done either.  You have not finished modeling the wheel performance and have not input a proper wheel shedule.  The wheel should not spin when certain conditions occur such as the outside air enthalphy is perfect for exact room loads (free cooling).

I need help on modeling this wheel too.  The wheel is not saving as much energy as the energy wheel manufacturer represents, which he says that there are greater savings to be made over other energy recovery systems when using a wheel.  I have tried to duplicate Trane's wheel savings to the other company's savings.

Anonymous's picture
Anonymous

FYI guys-

To date, I have never seen one of these things perform as well as they mfg says they do. Not once. I'm not saying that they use false data, but they use, "ideal conditions".

For instance, if you add demand control ventilation (DCV) plus an enthalply wheel, your net savings is likely to increase as opposed to DCV alone or an enthalpy wheel alone.  However, the savings won't be additive. This is because they both save from the same piece of pie.

That said, in chicago, the wheel should perform better than you are seeing!. Sometimes the problem is that there isn't as much of a heating demand in your model as there should be. If the model doesn't need substantial heating in the winter, the wheel will cost more due to increased fan power. The first thing to check is your winter heating without the wheel.

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Bob
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Reputation: 275