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Re: [EnergyPlus_Support] Rated SHR for DX coil
I'm not sure what to suggest. As explained in the engineering
documentation for this object, the model calculates the bypass factor of
the coil at the rated conditions of 26.7C drybulb / 19.4C wetbulb air
entering the DX cooling coil and 35C drybulb / 23.9C wetbulb air
entering the outdoor condenser coil. If the rated SHR of the DX coil is
0.5 at these inlet air conditions, then the performance line of the coil
does not intersect the saturation curve and a bypass factor can not be
calculated. Without this information, the model can not estimate
performance at off-rated conditions.
Does your customized air handler include some type of air-reheat
downstream of the cooling coil? And are you including this reheat when
specifying the rated SHR of the DX cooling coil (you shouldn't be)?
A rated SHR of 0.5 at the rated inlet air conditions defined above
doesn't sound reasonable for a DX cooling coil alone. Is there any
chance that the SHR of 0.5 for your customized air handling unit
corresponds to a different set of inlet air conditions to the DX cooling
coil?
zhaicq98 wrote:
> I have a customized air handling unit, where the rated SHR for the DX
> coil is 0.5. I tried to simulate this in EnergyPlus, however I got a
> severe error saying:
>
> coil bypass factor calculation did not converge after max
> iterations.The line defined by the coil rated inlet air conditions
> ** ~~~ ** (26.7C drybulb and 19.4C wetbulb) and the RatedSHR
> (i.e., slope of the line) must intersect
> ** ~~~ ** the saturation curve of the psychrometric chart. If
> the RatedSHR is too low, then this
> ** ~~~ ** intersection may not occur and the coil bypass factor
> calculation will not converge.
>
>
> How should I handle this?
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