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I am a beginner who uses trnsys software. Now, I encounter a problem about a control method.

This is a simple system: Two units in parallel provide cold to extremity. When the extremity load is small, open unit 1only; When the extremity load is exceed the cold capability of unit 1,open units 2. It meaning the cold which is unit 2 provided is the part exceeding the cold capability of unit 1. So,how can I achieve this control? how do I need to set the three-way valve? perhaps,are these some better methods to achieve this control method in trnsys?

This problem is important for me. can you give me some advice?

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There are many ways of accomplishing this type of control in TRNSYS. The first question is how are you determining that load is exceeding the capacity of the first unit. If you are determining the load itself, you can add an equation block in your project which compares the load to the capacity and adjusts the flow between the two units. If you are looking at a setpoint temperature and determining that the load exceeds the capacity because the temperature leaving the unit does not meet the setpoint, then you should use a thermostat component to sense the leaving temperature and adjust flows between the units accordingly.

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Thank you! Your methods are very helpful to me. Further, what do "adjust the flow" means? how can I accomplishing "adjust the flow" according to myself . Entering the flow rate(kg/hr) or proportion assignment value in the three-way valve not seems to meet the requirement.

( 2018-02-05 18:51:35 -0600 )edit

You should use pump components and flow diverter components to control the flow in you system.

( 2018-02-09 15:27:02 -0600 )edit

I got it. Thank you!

( 2018-02-09 18:58:16 -0600 )edit