[TRNSYS-users] ROOM TEMPERATURE FOR CONTROL DECISION

[Michaël Kummert]

Edward,

> I'm simulating a solar air heater to heat a house during winter. I have two
> zones: LIVING and BEDROOM. I make a schedule as follows: from 07.00 - 23.00 the
> collector heats the LIVING zone, and from 23.00 - 7.00 the BEDROOM. The house
> is modelled using PREBID, but the schedule is carried out in TYPE 56.
> 
> I need either LIVING or BEDROOM temperature (TAIR) at any time as input to
> control unit. Since I need only one TAIR at any time, I connect the HOUSE (TYPE
> 56) with a mixer (TYPE 11) to get TAIR from either LIVING or BEDROOM zone
> according to the above schedule. However, in Reference manual it is suggested
> not to use the outlet temperature from the mixer for control decision because
> it cannot handle properly the no-flow situation.
> 
> My questions:
> 1. How should I get TAIR from either LIVING or BEDROOM zone as input to my
> control unit without using TYPE 11 ?

I am not sure I understand what you are trying to do, but if you just 
need an input to a controller that is one temperature or another 
depending on a schedule, you can just have:
- schedule that is 1 between 7:00 and 23:00, 0 between 23:00 and 7:00
- equation that is TControl = Sch*TLiving + (1-Sch)*TBedroom
   (where Sch is the value of your schedule)

> 2. When there is no load, there will be no air flow (from the collector) to the
> room. In this situation, is TAIR coming as outputs from TYPE 56 really the true
> air temperature of each room ? I noticed that room temperatures are always much
> higher than the outside temperature even during the winter period. For example,
> room temperature in my simulation can reach as high as 35C even though outside
> temperature is as low as 15 and the irradiance is relatively low.

Type 56 "Tair" outputs are the air temperature in each zone, no matter 
what any flowrate is. If they have unrealistically high values, you are 
probably sending unrealistically high values to Type 56 (gains, 
ventilation flowrate/temperature, etc.).
If you think there is really a problem in one of the components, you 
should simplify the simulation to the minimum required to illustrate the 
problem and then send it to your distributor.

Kind regards,

Michaël Kummert

-- 
_________________________________________________________

Michaël Kummert

Solar Energy Laboratory - University of Wisconsin-Madison
1303 Engr Res Bldg, 1500 Engineering Drive
Madison, WI 53706

Tel: +1 (608) 263-1589
Fax: +1 (608) 262-8464
E-mail: kummert at engr.wisc.edu

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