You’ll probably be better off using a simple feedback controller rather than an equation block because you can get frequent starts and stops or non-convergence warnings.
Also, that’s a pretty large temperature range to operate over. Are you driving an absorption chiller with those temperatures?
You might be better off controlling a variable speed pump to maintain your temperature range rather than shutting the pump off when the temperature exceeds 80C. If you shut off the pump when the temperature is over 80C, you risk exceeding the stagnation temperature of your panels in the real world.
There is a solar thermal panel in the TESS libraries that has a built in controller that has an output for a variable speed pump that works really well.
Good luck!
Fred
Fred Betz PhD., LEED AP
Sustainable Systems Analyst | | AEI | AFFILIATED ENGINEERS, INC.
5802 Research Park Blvd. | Madison, WI 53719
P: 608.236.1175 | F: 608.238.2614
fbetz@aeieng.com | www.aeieng.com |
From: Shahrdad JavidRad [mailto:shahrdad@live.de]
Sent: Tuesday, February 22, 2011 12:11 PM
To: TRNSYS USERS
Subject: [TRNSYS-users] acceptable temperature range
Hello,
in my solar thermal system I want to define an acceptable interval for the collector outlet temperature [65-80°C] by giving an output signal=1 for the pump in the collector loop. For any other temperatures out of this range the signal should be=0
For this purpose I am using an Equation block!! (Is there any controller, that is able to do it?)
I have defined these variables as:
T_min=65
T_max=80
T_out= collector outlet temperature
Signal=AND(GT(T_out,T_min),LT(T_out,T_max))*1+(1-AND(GT(T_out,T_min),LT(T_out,T_max)))*0
I have plotted the signal. It works fine but I am experiencing a very long simulation time. More than 15 minutes just for a week.
Is there any idea?
Thanks,
Shahrdad