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Modelica: Using temperature sensor to measure temperature of room

Hi, I am trying to model a system where the temperature of the room is measured and fed into a PID to control the air flow rate of the HVAC system. I am trying to use a temperature sensor [senTem]but it is not measuring the temperature of the room[HVAC_Zone] when the initial mass flow rate is 0. I have provided the nominal mass flow rate to be 0.066kg/s. image description. I am trying to model it such that the temperature of the room increases due to the heat load and the temperature sensor measures it and depending on the difference between measured temperature and temperature, the setpoint of the Air flow rate is varied and fed into the air flow inlet [boundary]. \What am I doing wrong or missing? Any help is appreciated. Thank you

sreemohan's avatar
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sreemohan
asked 2020-04-28 14:22:21 -0500
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I suggest using Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor and connect it to the HeatPort of your HVAC_Zone. Would that work?

Thierry Nouidui's avatar
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Thierry Nouidui
answered 2020-04-30 11:28:45 -0500
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This is the right approach. The schematics that is shown above shows that there is no flow through senTem if there is no flow through the volume, so it will not be able to measure the volume's temperature.

Michael Wetter's avatar Michael Wetter (2020-04-30 11:46:17 -0500) edit
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Hi Thankyou for the response. I tried your method and it has worked. Just to clarify and get my concepts right, the temperature measured by the TemperatureSensor at the HeatPort of HVAC_Zone will be the temperature of the fluid in the entire volume right?

sreemohan's avatar sreemohan (2020-04-30 12:44:57 -0500) edit
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Hello, in the documentation for Buildings.Fluid.Sensors.TemperatureTwoPort, I read

Setting transferHeat = true is useful, for example, if the sensor is used to measure the fluid temperature in a system with on/off control on the mass flow rate. If transferHeat were false, then the sensor output T would remain constant if the mass flow rate is set to zero, and hence the controller may never switch the mass flow rate on again.

Maybe this relates to your issue here?

aubr's avatar
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aubr
answered 2020-04-29 04:18:10 -0500
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Hi thanks for the response. I want the temperature sensor to measure the temperature of the room which it isnt doing. In the settings for the temperature sensor I set the transferHeat=true and the TAmb= Mixingvolume.T. This setting is not working since the temperature of the mixing volume is highly varying. I need the sensor to measure the temperature of the room irrespective of the mass flow rate. Is there any way for doing that

sreemohan's avatar sreemohan (2020-04-30 11:01:00 -0500) edit
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