[TRNSYS-users] 4 way valve

[Danny Jonas]

Dear trnsys users,

 

I would like to simulate a SDHW System in which a 4 way valve is used to
discharge the 

store (Type 340) with a fixed mixing temperature from 3 temperature zones.

 

I’ve attached a project file I’ve used to test the controller. 

 

I’ve tried to use two flow diverter and two tee pieces to realize the
system.

 

Double Port 3 is placed in the top of the storage

Double Port 2 between top and middle of the storage

Double Port 1 in the middle of the storage  

 

Flow diverter 1 outlet flow rate 1 is connected to Double Port 1

Flow diverter 1 outlet flow rate 2 is connected to flow diverter 2 Inlet
flow rate

Flow diverter 2 outlet flow rate 1 is connected to Double Port 2

Flow diverter 2 outlet flow rate 2 is connected to Double Port 3 

 

(in the complete system the temperatures are also connected, but in the
attached file

I have no system between Flow diverter and mixers
 and the input
temperatures to the

tee pieces have fixed values to simulate an example for storage
temperatures) 

 

The double ports outlet flow rates and temperatures are connected to two tee
pieces 

 

Tee Piece 1 inlet temperature 1 and flow rate 1 is connected to Double Port
2

Tee Piece 1 inlet temperature 2 and flow rate 2 is connected to Double Port
3

Tee Piece 2 inlet temperature 1 and flow rate 1 is connected to Double Port
1

Tee Piece 2 inlet temperature 2 and flow rate 2 is connected to outlet
temperature and outlet flow

rate of tee piece 1

 

In the attached file the outlets of the flow diverters are connected to the
inlets of the tee pieces.

 

I’ve tried to control the outlet flow rates from the flow diverters with
iterative feedback controllers

to reach the set point temperature as mixing temperature of tee piece 1 and
2.

 

The first flow diverter is controlled by an iterative feedback controller
monitoring the

outlet temperature of tee piece 2 (setpoint 40°C)

 

the second flow diverter is controlled by a second iterative feedback
controller monitoring

the outlet temperature of tee piece 1 (setpoint also 40°C)

 

the inlet flow rate of flow diverter 1 is fixed

 

inlet temperature 1 of tee piece 1 is 50°C

inlet temperature 2 of tee piece 1 is 70°C

inlet temperature 1 of tee piece 1 is 30°C

 

To reach the setpoint the control function of flow diverter 1 has to be zero
and 

the control function of flow diverter 2 has to be 0.5.

 

The first iterative feedback controller works fine, control function is set
to zero, but the second iterative 

Feedback controller doesn’t work, but I don’t know why.

 

I hope someone can help me or can tell me an easier way to realize the
system.

 

 

Thanks 

 

Danny 

 

 

 

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