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Changing Discharge Curves for Ice Storage in Open Studio

asked 6 years ago

chris.h's avatar

updated 6 years ago

Hi,

I am attempting to generate ice storage discharge curves using the information given in OpenStudio's description of the quadratic curves. I am having trouble interpreting what general form the curve takes based on the given info in OpenStudio. My goal is to be able to see if I can generate my own curves and see how changing the coefficients affects the shape of the curve and ultimately how it affects my building model.

Does anyone know what variables x and y physically mean for the charge/discharge curves? Does anyone know if x**2 means x^2?

Generally, the curves are functions of how much ice is left in the storage tank (plotted on the x-axis) and effectiveness or cooling capacity is plotted on the y-axis. I am confused why there is x and y indicated for the curve fit.

(I tried uploading a screenshot of the ice storage parameters window but I do not have enough "points to do so")

Thanks

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answered 6 years ago

This is really a question about EnergyPlus rather than OpenStudio. Usually you'd find such information in the I/O reference guide (see I/O: ThermalStorage:Ice:Detailed) but in this case it's not terribly clear. Thankfully, the Engineering reference can be used, see here.

The Charging and Discharging Equation section will make you learn that x is either the Fraction charged or Fraction decharged. And yes, x**2 = x²

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Thank you Julien!

Also, the EnergyPlus manual states that "charging and discharging is a function of the fraction charged/discharged as well as the log mean temperature difference across the storage unit." Do you know if the dependent variable "charging or discharging" refers to the effectiveness or the cooling capacity?

Thanks

chris.h's avatar chris.h  ( 6 years ago )

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Asked: 6 years ago

Seen: 159 times

Last updated: Nov 05 '18