Re: [EnergyPlus_Support] Re: Thermal Chimney modelling method

["Kwang Ho Lee" <kwhlee@xxxxxxxxxxxx>]

 Dear Aymeric,

 Actually, I don't have enough experience with AirflowNetwork object to
advise you. Sorry about that.
 But it does look like a good option to use 2 separared zones "as far as"
you put the correct input values to AirflowNetwork object including
pressure coefficients as he mentioned.

 Using AirflowNetwork or Zone:ThermalChimney objects have their own pros
and cons. Zone:ThermalChimney object automatically takes into account all
the processes to compute the natural ventilation enhancement such as
dischrage air temp through the upper opening and the thermal gradient,
etc etc.
 On the other hand, you can get more detailed analysis if you use
AirflowNetwork object.

 I hope this helps.

 Regards, Kwang


> Dear Kwang,
>
> thanks a lot for your advices. I did actually use AirflowNetwork object to
> represent air exchanges between the office, the chimney and outside.
> Another user advices me to represent the chimney with 2 separated zone to
> compute the right pressure at each opening level. Do you think this type
> of discretisation will be efficent?
>
> In the end, do you think the airflow networtk approach is better than the
> thermalchimney object? or the contrary? or equivalent?
>
> Best Regards,
> Aymeric
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Kwang Ho Lee" <kwhlee@...>
> wrote:
>>
>>  Dear Aymeric,
>>
>>  Yes, you need to use Zone:ThermalChimney object to simulate what you
>> want
>> to model. Just simply adding a zone adjacent to the office without using
>> Zone:ThermalChimney object won't induce the natural ventilation that you
>> would expect unless you separately use AirflowNetwork objects.
>>
>>  What Zone:ThermalChimney does is to compute the amount of heat that is
>> aborbed into the thermal chimney air after taking into account all the
>> detailed heat balances taking place inside the thermal chimney zone. And
>> then it calculates the outlet discharge air temperature through the
>> upper
>> opening and the enhanced natural ventilation caused by the thermal
>> gradient within the thermal chimney.
>>
>>  You can also refer to the recently published paper entitled
>> "Enhancement
>> of natural ventilation in buildings using a thermal chimney". It is on
>> the thermal chimney model of EnergyPlus.
>>
>>  Regards,
>>
>>  Kwang
>>
>>
>> > Dear all,
>> >
>> > I am struggeling to know whether or not I did simulate properly a
>> solar
>> > chimney. It is in Jerusalem climate.
>> > I first modelled a zone adjacent to the office I want to cool down. I
>> > positionned a low opening on the partition wall separating the two
>> zones.
>> > This wall is of course composed by a structural part, here concrete,
>> 2.5cm
>> > polyurethan board insulation and a black selective metal plate. The
>> outer
>> > wall of the chimney is a glazed wall with an upper opening.
>> >
>> > Although it seems to work logically, it doesn't match experimental
>> > results. Basically it seems it doesn't enhance enough the natural
>> > ventilation...
>> >
>> > Using this method, I certainly don't take into account the temperature
>> > gradient within the thermal chimney, right? Is it more reliable to use
>> the
>> > object Zone:ThermalChimney?
>> >
>> > Plus, an additional problem I can't explain is that I get some
>> massflow
>> > through ceilings although I do not activate infiltration
>> calculations...
>> >
>> > If anyone has experience modelling thermal chimney, I would be happy
>> to
>> > know more about that!
>> >
>> > Thanks a million
>> > Aymeric
>> >
>> >
>>
>
>
>




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