[TRNSYS-users] HRV Type 667

[Jeff Thornton]

> I was having problems with TRNSYS freezing on occasion during the simulation.  I figured out that this only happened when I was using HRV Type 667 with exterior temperatures below approximately -32ºC. I am using an HRV Type 667 linked with a Type 19 zone model.  It does not matter if the HRV had its flow going to the zone or not.  The only thing that made the program stop crashing is by placing the flow through the HRV at 0. Have other people experienced this problem.  If you want to test it, I suggest using Iqaluit weather data (\Trnsys16\Weather\Meteonorm\North-America\CA-NU-Iqaluit-Frobisher-Bay-719090.tm2).      

Remi,

I found (and fixed) the same problem a few days ago when I was running a Canadian simulation.  The problem is not actually in 667 but in the steam subroutine.  Our 667 model calls steam to get the enthalpy of the water vapor in the air and at low temperatures the steam subroutine gets into some sort of infinite loop.  We have a fix for the problem (sets the enthalpy of the vapor at a constant value below -34 C) so let me know if you'd like me to send you an updated version of the source code.

> Another comment on Type 667, it is very slow.  When the HRV is on it more than doubles the time it takes to run the simulation. 

I've used 667 in numerous projects and have never noticed any sort of slow down.  Are you sure its a 667 problem and not a convergence issue?  Have you checked the time report to see where the slow down is occurring?

Jeff


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Jeff W. Thornton
President - Thermal Energy System Specialists
2916 Marketplace Drive - Suite 104
Madison WI 53719
(608) 274-2577