# Modelling Air Colled Chiller: Curve of Performance and Coefficients

Hello all,

Good Evening!

I found it here that to model a Chiller I would first need to get the coefficients of the curve of performance and then input these data on Open Studio. I also found here how to find the CurveFirTool, but I am not being able to get the coefficients.

1) I have tried to model an Air Colled Chiller to obtain its curve of performance and the corresponding coefficients using CurveFitTool but it is not working. As far as I am concerned I should input:

1.1) Other as DX Coil Type;

1.2) Temperature as the Independent Variable;

1.3) Biquadratic as Curve Type

1.4) SI as Units

And then, for Rated data: independent variable 1 a value of 19,4 °C, for independent variable 2 a value of 35,0 °C, for Capacity i should enter the Nominal Capacity (KW) and for Power I should enter the Power consumption (KW) related to the Nominal Capacity.

Last, for Performance Data I am entering: Independent Variable 1 as the Chilled water supply temperatura (which is fixed at 10 °C; Independent Variable 2 as the Entering Condenser Air Temperatura (which is also fixed) at 35 °C, a Part Load Capacity and its respective power consumption to complete the Performance Data.

I read that as both Independet variable 1 and 2 are fixed, I will get and error. Can someone help me with the Performance Curve and Coefficients?

The data I have includes A set of condenser inlet air temperatures - ECT (°C) and for each temperature I have the Nominal Capacity - CAP NON (KW), the Part Load Capacity - CAP (KW), and the Coefficient of Performance - COP (KW/KW). For this Chiller, the Evaporator Chilled Water Outlet is fixed at 10 (°C) and the Evaporator Water Inlet is fixed at 17 (°C).

2) Is it possible to generate the Performance Curve and get the respective coefficients from these data using CurveFitTool? If not, is there any other alternative to get these Coefficients?

3) Am I on the right path or should I use any other spreadsheet to get these results?

Thanks a lot