Chiller selection/modification for Ice storage

asked 2016-07-14 14:12:38 -0600

rkbest
1392 ●1 ●4 ●13

I am using the chillers provided by default for the CHILLER:ELECTRIC:REFORMULATEDEIR as

Bicubic:ReformEIRChiller Carrier 19XR 1259kW/6.26COP/Vanes EIRFPLR,

ReformEIRChiller Carrier 19XR 1259kW/6.26COP/Vanes EIRFPLR,  !- Name
4.602131E-02,            !- Coefficient1 Constant
2.433945E-02,            !- Coefficient2 x
6.394526E-05,            !- Coefficient3 x**2
-3.648563E-01,           !- Coefficient4 y
1.854759E+00,            !- Coefficient5 y**2
-2.809346E-02,           !- Coefficient6 x*y
0.000000E+00,            !- Coefficient7 x**3
-4.821515E-01,           !- Coefficient8 y**3
0.000000E+00,            !- Coefficient9 x**2*y
0.000000E+00,            !- Coefficient10 x*y**2
14.56,                   !- Minimum Value of x
34.97,                   !- Maximum Value of x
0.18,                    !- Minimum Value of y
1.03,                    !- Maximum Value of y
,                        !- Minimum Curve Output
,                        !- Maximum Curve Output
Temperature,             !- Input Unit Type for X
Dimensionless,           !- Input Unit Type for Y
Dimensionless;           !- Output Unit Type

Biquadratic:WC Screw Default 90.1-2004 Cap_fT

Curve:Biquadratic,
WC Screw Default 90.1-2004 Cap_fT,  !- Name
0.9061150,               !- Coefficient1 Constant
0.0292277,               !- Coefficient2 x
-0.0003647,              !- Coefficient3 x**2
-0.0009709,              !- Coefficient4 y
-0.0000905,              !- Coefficient5 y**2
0.0002527,               !- Coefficient6 x*y
0.0,                     !- Minimum Value of x
20.0,                    !- Maximum Value of x
0.0,                     !- Minimum Value of y
50.0;                    !- Maximum Value of y

Biquadratic:WC Screw Default 90.1-2004 EIR_fT

Curve:Biquadratic,
WC Screw Default 90.1-2004 EIR_fT,  !- Name
0.3617105,               !- Coefficient1 Constant
-0.0229833,              !- Coefficient2 x
-0.0009519,              !- Coefficient3 x**2
0.0131889,               !- Coefficient4 y
0.0003752,               !- Coefficient5 y**2
-0.0007059,              !- Coefficient6 x*y
0.0,                     !- Minimum Value of x
20.0,                    !- Maximum Value of x
0.0,                     !- Minimum Value of y
50.0;                    !- Maximum Value of y

Minimum temperature from the chiller outlet should be as low as (-)10 oC, The range of the leaving CW Temp is set 0 to 20. Is it safe to modify the range to meet the low temperature and get valid performance? The Included Chillers.idf have the curves with even narrower temperature range with the minimum around 4 oC.

I am getting some errors and I suspect they might be due to this limitation.

   ** Warning ** CHILLER:ELECTRIC:REFORMULATEDEIR "COOLSYS1 CHILLER 1": The evaporator outlet temperature (-0.51 C) is outside the range of evaporator outlet temperatures (X var) given in Cooling Capacity Function of Temperature biquadratic curve = WC SCREW DEFAULT 90.1-2004 CAP_FT

 **   ~~~   ** The range specified = 0.00 C to 20.00 C. Environment=TAMPA INTERNATIONAL AP ANN CLG .4% CONDNS WB=>MDB HVAC Sizing Pass 1, at Simulation time=08/21 00:30 - 00:40
** Warning ** CHILLER:ELECTRIC:REFORMULATEDEIR "COOLSYS1 CHILLER 1": The condenser outlet temperature (35.01 C) is outside the range of condenser outlet temperatures (X var) given in Electric Input to Cooling Output Ratio Function of Part-load Ratio bicubic curve = REFORMEIRCHILLER CARRIER 19XR 1259KW/6.26COP/VANES EIRFPLR
 **   ~~~   ** The range specified = 14.56 C to 34.97 C. Environment=TAMPA INTERNATIONAL AP ANN CLG .4% CONDNS WB=>MDB HVAC Sizing Pass 1, at Simulation time=08/21 09:50 - 10:00
*************  ** Warning ** CHILLER:ELECTRIC:REFORMULATEDEIR "COOLSYS1 CHILLER 1": The evap outlet ...

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answered 2016-07-15 11:48:45 -0600

Archmage

7185 ●3 ●11

Yes, that warning is saying that the curves do not cover a broad enough range of temperatures for the actual operating conditions. This is a common problem with energy modeling because the annual operating ranges are often wider than that available in catalog data for design. Often need to just ignore this warning because the data are not available. But here with ice storage charging you are intentionally running the chiller much colder than usual for chilled water, so I think it would be better to develop or find curves known to be appropriate ice production.

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Thanks @Archmage Developing these curves is tricky, for we need the measured data at different chiller part loads and desired temperatures. If anyone in the community has used or obtained these curves for a Chiller for Ice storage, please share on Unmethours.