[EnergyPlus_Support] Re: About exterior surface convection coefficient algorithms in EP

["hvacgeshen516" <geshen516@xxxxxxxxx>]

Thanks for your reply =) 
I get your idea, maybe.

In TAS, exterior surface convection coefficient is calculated :
hc=5.8+4.1Vm   CIBSE
In IES, 
hc=5.6+4V V<4.88; hc=7.2V^0.78 V>4.88
they are both stating these formulas are used for calculating surface convection. However,when calculating exterior surface long wave radiation, they do not involve the radiation between surface and air.. 
this means this radiation part has been added to convection.

In EnergyPlus, 
if "simple" is chosen for exterior surface convection, long wave radiation is added to convection and calculated together;
if other algorithms except "simple" are chosen, the long wave radiation between surface and air will be calculated separately.  

Correct? 

Thanks again =)
xiangjing 


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Ben Polly <pollyben@...> wrote:
>
> The simple model calculates combined convective and radiative heat transfer coefficients.  Are you subracting off the contstant radiative portion when you compare to other algorithms?  I'd also look into how the wind speed conversion (from weather station to surface centroid) affects your convection coefficients.  
> 
> Ben
> 
> 
> 
> ________________________________
> From: hvacgeshen516 <geshen516@...>
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Sent: Tuesday, June 2, 2009 12:56:38 AM
> Subject: [EnergyPlus_Support] About exterior surface convection coefficient algorithms in EP
> 
> 
> 
> 
> 
> If the algorithms except simple are chosen, the wind-driven convection coefficient will be much smaller than algorithms implemented by other software like TAS or IES. 
> 
> Is there any comments on this? 
> 
> Thanks and Regards
> Xiangjing =)
>




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