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Re: [EnergyPlus_Support] DX COP Rating


The DXSystem:AirLoop object has an input for cooling coil type and name:

   A6,  \field Cooling coil type
        \type choice
        \key COIL:DX:CoolingBypassFactorEmpirical
        \key COIL:DX:CoolingHeatExchangerAssisted
        \key COIL:DX:MultiSpeed:CoolingEmpirical
        \key COIL:DX:MultiMode:CoolingEmpirical
   A7,  \field Cooling coil name
        \type object-list
        \object-list CoolingCoilsDX

Each of these coil types requests performance curves for that DX Coil.  
For example, COIL:DX:CoolingBypassFactorEmpirical has the following inputs:

  A5 , \field Total Cooling Capacity Modifier Curve (function of 
       \type object-list
       \object-list BiquadraticCurves
       \note curve = a + b*wb + c*wb**2 + d*edb + e*edb**2 + f*wb*edb
       \note wb = entering wetbulb temperature (C)
       \note edb = drybulb temperature seen by the condenser (C)
  A7 , \field Energy Input Ratio Modifier Curve (function of temperature)
       \type object-list
       \object-list BiquadraticCurves
       \note curve = a + b*wb + c*wb**2 + d*edb + e*edb**2 + f*wb*edb
       \note wb = entering wetbulb temperature (C)
       \note edb = drybulb temperature seen by the condenser (C)

This DX cooling coil object requires the names of curve objects that 
specify total capacity and energy input ratio (1/COP) as a function of 
the air temperature entering the condenser and the wetbulb temperature 
of the air entering the cooling coil.  An example curve object for the 
EIR modifier curve might be:

    WindACEIRFT,             !- Name
    0.342414409,             !- Coeff1 Constant
    0.034885008,             !- Coeff2 x
    -0.000623700,            !- Coeff3 x**2
    0.004977216,             !- Coeff4 y
    0.000437951,             !- Coeff5 y**2
    -0.000728028,            !- Coeff6 x*y
    12.77778,                !- minimum value of x
    23.88889,                !- maximum value of x
    23.88889,                !- minimum value of y
    46.11111;                !- maximum value of y

So the Curve:Biquadratic object above is evaluated every simulation time 
step that the DX coil is requested to operate to determine the energy 
input ratio (1/COP) of the DX cooling coil at the entering air 
temperatures during that simulation time step (i.e., based on the 
weather conditions specified for the simulation for the condenser 
entering air temperature and the calculated cooling coil entering air 

See the IO Reference for DXSystem for more details.  Also, the example 
input file TermRHDXSystem.idf should be reviewed.


Ali_Ajmi wrote:

> Hi Linda,
> Do you mean that the COP of the DX system will be calculated based on 
> the weather condition associated with IDF file. For example if my 
> weather file is representing a very hot climate where temperature may 
> reach 50 C, will the performance of the cooling coil adopted to match 
> that outdoor condition? Because as far as I know the COP curve 
> coefficients of the DX system are generated at New York, Syracuse 
> climate condition. Consequently, the energy consumption of the DX will 
> be performed on that climate condition.
> Ali
> Linda Lawrie <linda@xxxxxxxxxx> wrote:
> At 08:53 AM 7/17/2005, Ali_Ajmi wrote:
> >Could any one advice of which objects in E+ need to be change if I
> >use a different than USA weather file. For instance I am using DX
> >cooling coil so I think the COP rated for the DX system need to be
> >change, but how? and what else require changing?
> >
> It wouldn't be due to the non-USA weather file location -- it would
> be a change needed due to climate. At least I think that's what
> you're reasoning for changing the DX cooling coil parameters
> are? You could, perhaps, autosize your system so that the objects
> are more in line with your design climatic conditions.
> Linda
> EnergyPlus WebSite: http://www.energyplus.gov
> Owner: EnergyPlus_Support list
> Member: EnergyPlus Development Team

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