[TRNSYS-users] how to get a fixed solar fraction

["Carlos Flores" <karlitro@gmail.com>]

Hello everyone,

I'm simulating a large solar heating system with piping losses and a heat exchanger. I want to fix all the variables but the area of solar collectors in order to achieve a centain solar fraction by varying the total collectors area.

So basically I want to do this: 

- Given a centain ammount of heat I want to transfer to the cold stream in the heat exchanger, I need to find the collector area that does it. 

I've been thinking about it for a while and I can't find the answer. The thing is, after the day ends (i.e at 0:00 AM), I need to decide wheather to increase or decrease the collectors area... and to do that is my main problem (cause there are not if conditions in TRNSYS... which would make it way easier).

Thanks to all,

Carlos Flores
Universidad de Chile