Reference conditions of equipments

asked 2015-06-23 15:29:08 -0500

hugopft
723 ●1 ●11

updated 2015-07-26 18:49:23 -0500

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

I Have Been working with simulation of models and I have some concerns about the REFERENCE INPUT of the equipaments . To explain my concerns I will take a chiller as an example: So , I have imported a chiller from the e+ library to my model and some of the inputs of my chiller are already set.

For instance : REFERENCE COP : 3:05 REFERENCE LEAVING CHILLED WATER TEMPERATURE : 6.67 ° C ENTERING refrence CONDESER FLUID TEMPERATURE : 35 ° C

For the real project I already have the Chilled selected and the datasheet of this equipments selected for my project conditions . REFERENCE LEAVING CHILLED WATER TEMPERATURE : 7 ° C Refrence ENTERING CONDESER FLUID TEMPERATURE : 34 ° C

My question is : Do I have to change this for the inputs the ones I have in the data sheet , or should I leave then and the program will take the chiller coefficients, that define the perfomance curves of this equipament, and do the calculations with the plant input que I had set?

I read the INPUTOUTPUTREFERENCE, but there they say that inputs are reference inputs and do not say if I should change it.

Thank you very much guys.

answered 2015-07-26 01:44:31 -0500

rraustad

13599 ●72 ●12 http://www.fsec.ucf.edu/

updated 2015-07-26 13:33:12 -0500

The reference conditions identify the rating point used to normalized the performance curves. If you enter the reference conditions into the performance curve equation, the result should be equal to or very near 1.

The chiller reference conditions for Chiller:Electric:EIR are only used to test the performance curves to see if they result in a value of 1 +/-10%. For this specific chiller, changing the reference conditions will not change the model, except that you may see warnings stating that the performance curve does not evaluate to 1 at the reference conditions (if you change the reference conditions sufficiently).

The chiller reference conditions for Chiller:Electric:ReformulatedEIR are also used to test the performance curves but more importantly are used within the model to calculate lift when Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Type = Lift. Changing the reference conditions in this case will change the results.

What you should keep in mind is that the reference conditions define the performance curve normalization point and should only be changed if the performance curves are also re-normalized to this point. The chiller rated nominal capacity is based on these reference points or on the Sizing:Plant inputs if different from the reference point.