[TRNSYS-users] Measured heat loads and air-water heat pump control

[David BRADLEY]

Dear Zhe,
   In addition to Jean Marais' response, I thought that I would mention 
that if you have precalculated loads, you can impose them either on an 
air stream or on a water stream using components from the TESS Loads and 
Structures Libraries (Type682 and 693). Jean is quite correct that it is 
best to have the weather data for the same year for which the loads were 
generated since the heat pump performance depends on ambient conditions.

   As for the second part of your question. There are two ways of 
modeling buildings and systems. The first way is that you calculate the 
loads and then impose them on the HVAC equipment. When you do this, 
however, you presuppose the zone temperatures. You no longer have any 
control over when the heat pump turns on and when it turns off. If there 
is a load (whether heating or cooling) it must be imposed on the heat 
pump. All of the control algorithms are built in to determining the 
space load.

   The other way of modeling a building is to allow the building 
temperature to float, to define a thermostat model that senses the room 
temperature and which is then used to command equipment to turn on and 
off to keep the space at its temperature. In this case there is no load. 
The conditioned air or water stream from the heat pump is delivered to 
the zone by whatever means are appropriate (a VENTILATION type in 
Type56, an active layer in Type56, a fan coil model, the heat pump 
itself...) and the zone temperature responds accordingly. The thermostat 
senses the room temperature change and decides whether to keep the 
equipment on or turn it off.
Kind regards,
  david



On 7/2/2012 07:00, Zhe Li wrote:
>
> Dear all,
>
> I am having two problems.
>
> I have a measured hourly domestic heat loads for a year, I would like 
> to implement it in TRNSYS simulation. Which component is best for this 
> application? And how to actually implement it?
>
> Also, I would like to utilise air-water heat pump.  However, I want to 
> turn the heating mode on only, and completely turn off the cooling 
> mode. How could I achieve this?
>
> I would like to set room temperature at 22oC. I would want to turn on 
> the heat pump at temperature below 20oC and turn it off when room 
> temperature arrives at 24oC. I notice there are a few controllers are 
> capable to do this, however, which one is the easiest in controlling 
> this function?
>
> Thank you very much in advance.
>
> Zhe Li
>
>
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com



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