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Re: [EnergyPlus_Support] Re: temperature gradient

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Re: temperature gradient
From: neslihan turkmenoglu <neslihanturkmenoglu@xxxxxxxxx>
Date: Thu, 17 Apr 2008 06:50:44 -0700 (PDT)
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thank you very much Lixing.
--- Lixing Gu <gu@xxxxxxxxxxxx> wrote:

> Neslihan:
> 
> No, it is not as simple as you mentioned. The model
> calculates wind pressure 
> first based on wind speed and wind pressure
> coefficient. Engineering 
> Reference has a section to provide detailed
> information on page 386. If you 
> use a crack component, the airflow across the
> component is flow coefficient 
> * (Pressure difference)^(flow exponent). Therefore,
> you have to know indoor 
> and outdoor pressures also. If you the
> AirflowNetwork:Multizone:Component 
> Detailed Opening, the equations used in calculations
> are provided in the 
> Engineering Reference on page 383.
> 
> Lixing
> ----- Original Message ----- 
> From: "neslihan turkmenoglu"
> <neslihanturkmenoglu@xxxxxxxxx>
> To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
> Sent: Thursday, April 17, 2008 4:35 AM
> Subject: Re: [EnergyPlus_Support] Re: temperature
> gradient
> 
> 
> > hi Lixing
> > I wanted to make a simple calculation  to see if
> get
> > the same results in Energyplus.
> > As I said the measurements were made with specific
> > intervals. I found the areas of these intervals
> and
> > multiplied by measured velocities. I found the
> total
> > by adding all these. At last I divided this value
> to
> > total area in order to get mean velocity.
> > When I multiply mean velocity with window open
> area I
> > get volume flow rate. Is it wrong?
> >
> >
> > --- Lixing Gu <gu@xxxxxxxxxxxx> wrote:
> >
> >> Neslihan:
> >>
> >> My answers are below your questions.
> >>
> >> ----- Original Message ----- 
> >> From: "neslihanturkmenoglu"
> >> <neslihanturkmenoglu@xxxxxxxxx>
> >> To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
> >> Sent: Wednesday, April 16, 2008 6:23 AM
> >> Subject: [EnergyPlus_Support] Re: temperature
> >> gradient
> >>
> >>
> >> > Hi Lixing
> >> >
> >> >
> >> > I calculated wind speed profile exponent with
> the
> >> values  got from
> >> > wind tunnel measurements in front of the scale
> >> model.
> >> > In order to understand,  I change the values
> one
> >> by one in weather
> >> > station object or site atmospheric variation
> >> object, nothing changed
> >> > in the results of airflow volume flow rate 2 to
> 1.
> >> > The only change occured when I enter my wind
> speed
> >> profile exponent
> >> > to airflow network-site wind conditions object.
> >> >
> >> Your observation is correct. The wind speed
> >> calculation in the airflow
> >> network model is independent of inputs of weather
> >> station object and has its
> >> own inputs.
> >>
> >> > I understood that one exponent is for weather
> site
> >> conditions,
> >> > the other exponent is for building site
> >> conditions.Why is there the
> >> > third one with another default value in airflow
> >> network site wind
> >> > conditions?
> >> >
> >> The field of Wind velocity profile exponent in
> the
> >> AIRFLOWNETWORK SIMULATION
> >> object and the field of Exponent of Wind Velocity
> >> Profile in the
> >> AIRFLOWNETWORK:MULTIZONE:SITE WIND CONDITIONS
> object
> >> are used for wind speed
> >> calculation. Could you let me know which is the
> >> third one specifically?
> >
> >
> >
> >>
> >> > when I compare the results of energyplus with
> my
> >> manually calculated
> >> > volume flow rates, they are not the same. So in
> >> order to define the
> >> > wind tunnel conditions in Energyplus, what do
> you
> >> suggest me to do?
> >> >
> >>
> >> What is your definition of manual calculation
> >> results? If you compare your
> >> testing results, you have to ensure the input
> values
> >> used in the EnergyPlus
> >> match your testing conditions. I have no
> knowledge
> >> of convertion from wind
> >> tunnel conditions to EnergyPlus inputs.
> >
> >
> >
> >>
> >
> >
> >> > And which velocity should I enter to design
> object
> >> wind velocity
> >> > field- u mean calculated from measured data in
> >> front of the scale
> >> > model or the wind tunnel's 2.5 m/s Gradient
> >> velocity %10 Motor
> >> > velocity.
> >> >
> >> When you got the calaculated wind velocity using
> the
> >> scale model, the
> >> velocity used in weather data should be at the
> >> height consistent with the
> >> input value of Reference height for recorded wind
> >> data in the AIRFLOWNETWORK
> >> SIMULATION object.
> >
> >>
> >> > I hope you answer in a short time.
> >> > thank you very much
> >> >
> >>
> >
> >
> >
> > 
> >
>
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> >
> > ------------------------------------
> >
> > The primary EnergyPlus web site is found at:
> > http://www.energyplus.gov
> >
> > The group web site is:
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> >
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> >
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> > Documentation link and press the "search" button.
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> >
> >
> >
> > 
> 
> 



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References:
- Re: [EnergyPlus_Support] Re: temperature gradient
  - From: Lixing Gu

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