[TRNSYS-users] Top control in the Type 56

[Maarten Sourbron]

Dear Héloïse,

If you want to use the ideal heating and cooling option of type56, you can change the set point at wich you want to heat or cool.
e.g. if you want to start heating at T_op=T_set=20°C, determine an input to type56 being T_corrected = 2*Tset-Tmsurf, with Tset = 20 and Tmsurf the mean surface temp which type56 gives as an output.
It comes from T_operative = (T_air+T_mean_surf)/2, or with the symbols of above T_set = (T_corrected+Tmsurf)/2.
So, instead of supplying the required operative temperature T_set as input, you supply the equivalent air temperature, so with T_corrected as air temp and Tmsurf as surface temp you end up with an operative temp = T_set.

Works fine, with no numerical issues, only a small oscillation around T_set, but with a small enough time step, this is neglectable.

Good luck,

Maarten


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________________________________
From: David BRADLEY [mailto:d.bradley at tess-inc.com]
Sent: maandag 8 november 2010 20:48
To: Heloise PELEN
Cc: trnsys-users at engr.wisc.edu
Subject: Re: [TRNSYS-users] Top control in the Type 56

Heloise,
  If you are using the automatic heating and cooling types that are built into Type56/TRNBuild then these only pay attention to the zone air temperature in order to compute the sensible load on the space. The control of those components is assumed to be instantaneous and ideal. If you are simulating a building and an actual HVAC system then you can set up the HVAC system to pay attention to whatever Type56 output variables that you want (including operative temperature). PID control is possible using Type22 but in my experience a lot of portions of the HVAC system are based on ON/OFF control (Type108). When implementing controls of any kind you need to make sure that your timesteps are small (1 to 5 minutes); recall that TRNSYS can make one control decision per timestep and then it must stick with that decision until the next timestep.
Regards,
 David


On 11/8/2010 10:25, Heloise PELEN wrote:
Dear TRNSYS users,

The Type 56 uses a control on the air temperature « TAIR » to compute the sensible heat demand of each thermal zones.
This temperature does not include the surface temperature and doesn't fully describe the temperature actually felt by the human, body.

Is there a way to control the operative temperature, rather than on the air temperature, in type 56 ?
I thought about using Type 22 but the simulation seems rather unstable with more than on Type 22, and I would like to be able to control the operative temperature in each thermal zones.

Thanks for your help !

Best regards,
Héloïse Pelen
ETAMINE
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