[TRNSYS-users] Ang.: Controling Heatpump system

[Richard Thygesen <richard.thygesen@mdh.se>]

 The only thing the equation should do is letting one of the signals thru. The hysteresis you specified in th controller still works. It only specifies how long the heat pump should run or in other words send a 1 to the equation.
You could try MAX(control_sig1,control_sig2)

Richard

----- Reply message -----
Från: "Amdi Worm" <amdiworm@gmail.com>
Till: "Richard Thygesen" <richard.thygesen@mdh.se>
Kopia: "trnsys-users@cae.wisc.edu" <trnsys-users@cae.wisc.edu>
Rubrik: [TRNSYS-users] Controling Heatpump system
Datum: tis, jan 15, 2013 11:34

Thanks a lot for the quick answers. 

I have been trying to use the equation-method, but im not able to make it work, could you by any change mail me a screen dump of the MAX OR - sentences you recommended? Im also having a hard time figurering out how to integrate a hysteresis when using the functions since they just retur "0" or "1".

Sorry to question you again, I would just really like to make this work.

Best Regards

Amdi Worm  

2013/1/15 Richard Thygesen <richard.thygesen@mdh.se>

Amdi.
I'm simulating a system like yours and I use a equation to allow two control signals to control the heat pump.
One which is based on the return temperature from the heating system and one based on the temperature in a certain place on the DHW tank.
A max or or equation should work. Play around with equations a bit and read chapter 6 in the manual to see which arguments that can be used.

Almost all heat pumps in Sweden prioritize the DHW production.

Richard

----- Reply message -----
Från: "Amdi Worm" <amdiworm@gmail.com>
Till: "trnsys-users@cae.wisc.edu" <trnsys-users@cae.wisc.edu>
Rubrik: [TRNSYS-users] Controling Heatpump system
Datum: tis, jan 15, 2013 10:16

Dear All

I am simulating a heatpump system as attached in the PDF file.

My heatpump system is supplying both roomheating and DHW. As it is for now the heatpump (type 927) is controlled by the temperature in the returnpipe to the heatpump (as it is in many practical cases with a hysteresis) and the temperature in the returnpipe where the heatpump is turned on, depends on the outdoor temperature (lower outdoor temperature = demand for higher return temperature).

But as my system is connected, the DHW system gets the same temperature as the room-heating system, and in summertime due to the outdoor dependence, the temperature is not sufficient for the DHW system. I need the outdoor dependence according to danish law so it is not a solution just to turn it off.

Instead I would like to model the system so that the heatpump turns on if the temperature in the returnpipe in the roomheating curcuit goes below a certain values, and in the same way for the DHW circuit, but here the heatpump must turn on at another value in the returpipe of that circuit. 

Is it possible to give the heatpump 2 control signals, so that it runs if one (or both) of the criterias is met? Which controller could be used in this case? Is it possile to create an "if / else" equation and thereby give the heatpump a control-signal or maybe a Type 108 with roomheating as stage one and DHW as stage two.

It is not an option for me to choose a 2 stage heatpumpe, since I haven't been able to get sufficient cataloge-data as input.   

I hope one is able to help.

Best regards

Amdi Worm

Esbensen A/S