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Re: [EnergyPlus_Support] Design coil load is zero
Filipe,
What version of the program are you running?
Fred Buhl
Filipe madureira wrote:
> Hi all,
>
>
>
> I’m trying to simulate a Constant Volume Air Handling Unit to control
> temperature in a single zone. The AHU has a constant volume fan and a
> cooling coil. Heating is provided by a terminal reheat coil.
>
> To control the exit cooling coil air temperature I’ve defined a
> controller:simple and a Set - point manager: Warmest to reset the cooling
> coil air temperature.
>
> To control zone temperature, I’ve defined a dual set-point with deadband
> thermostat (heating set-point temperature 20ªC, cooling set-point
> temperature 24ºC).
>
>
>
> The total air system and outside air volumetric flow rates are known. For
> this reason, in the zone sizing object I’ve defined the cooling and heating
> design air flow method to “flow/zone” and input the desired flow rates. I’ve
> defined also the outside air flow rate.
>
>
>
> ZONE SIZING,
>
> P1 - Sala_Cirurgia, !- Name of a zone
>
> 16, !- Zone cooling design supply air temperature
> {C}
>
> 25, !- Zone heating design supply air temperature
> {C}
>
> 0.008, !- Zone cooling design supply air humidity
> ratio {kg-H2O/kg-air}
>
> 0.008, !- Zone heating design supply air humidity
> ratio {kg-H2O/kg-air}
>
> flow/zone, !- outside air method
>
> 0, !- outside air flow per person {m3/s}
>
> 1.167, !- outside air flow per zone {m3/s}
>
> 1, !- zone sizing factor
>
> flow/zone, !- cooling design air flow method
>
> 5.139, !- cooling design air flow rate {m3/s}
>
> flow/zone, !- heating design air flow method
>
> 5.139; !- heating design air flow rate {m3/s}
>
>
>
> As I’ve read in the mailing list and in the EnergyPlus documentation, the
> flow rates are sized on the sum of zone air flow rates. If I define
> flow/zone method, design calculated flow rates are override. For this
> reason, I didn’t change the flow rate fields in the System Sizing to let
> the program compute the flows I’ve entered in the zone sizing object.
>
>
>
> SYSTEM SIZING,
>
> UTA_BO 2, !- name of an AIR PRIMARY LOOP object
>
> sensible, !- type of load to size on
>
> autosize, !- Design (minimum) outside air volumetric flow
> rate {m3/s}
>
> 1, !- minimum system air flow ratio
>
> 7, !- Preheat design set temperature {C}
>
> 16, !- Central cooling design supply air
> temperature {C}
>
> 25, !- Central heating design supply air
> temperature {C}
>
> noncoincident, !- Sizing Option
>
> no, !- Cooling 100% Outside Air
>
> no, !- Heating 100% Outside Air
>
> 0.008, !- Central cooling design supply air humidity
> ratio {kg-H2O/kg-air}
>
> 0.008, !- Central heating design supply air humidity
> ratio {kg-H2O/kg-air}
>
> design day, !- cooling design air flow method
>
> , !- cooling design air flow rate {m3/s}
>
> design day, !- heating design air flow method
>
> ; !- heating design air flow rate {m3/s}
>
>
>
> In the components (coils, fan…) I left the fields with the autosize option.
>
>
>
> To simulate a worst case scenario, I defined the day type as WinterDesignDay
> and defined the internal gains schedule to off for this day.
>
>
>
> I ran the sizing objects and the design day simulation and I’ get the
> following warning:
>
>
>
>
>
> ** Warning ** The design coil load is zero for COIL:Water:SimpleHeating P1 -
> SALA_CIRURGIA REHEAT COIL
>
> ** ~~~ ** The autosize value for max water flow rate is zero
>
> ** ~~~ ** To change this, input a value for UA, change the heating
> design day, or lower
>
> ** ~~~ ** the system heating design supply air temperature
>
>
>
> To debug the problem I’ ve asked the following report variables:
>
> Zone/Sys Sensible Load Predicted
>
> Zone/Sys Thermostat Heating Setpoint
>
>
>
> I don’t understand why I get this warning because zone temperature is lower
> than the set-point, a heating load is predicted and the thermostat heating
> set point is 20ºC. I also checked the component connections, flow rates and
> availability schedules and everything seems to be alright.
>
>
>
> I’m missing something? Could anyone help me?
>
>
>
> Thanks in advance for your help
>
>
>
> Best regards
>
>
>
>
>
> Filipe Madureira
>
> Tel: +351 919 293 876 | E-mail: filipe.madureira@xxxxxxxxxxxxx
>
> __________________________________________________________________
>
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>
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>
>
>
> [Non-text portions of this message have been removed]
>
>
>
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>
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>
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