[EnergyPlus_Support] one about vav system

["Xu H.T" <02900046r@xxxxxxxxxxxx>]

  Like the following email.

  I do a simulation for VAV system. The design day is used for sizing of zone, system and plant.
  I set the supply air temperature to 19C. I find with the design day simulation, the supply air temperature isn't 19 (20.5 actually) and the air flowrate is constant. However, for the run period simulation, the supply air temperature is actually 19 and the supply air flowrate is also constant. Why? Any suggestion for this problem. Thanks.

  Xu 

  ----- Original Message ----- 
    From: zhaicq98 
    To: EnergyPlus_Support@xxxxxxxxxxxxxxx 
    Sent: Thursday, June 24, 2004 8:51 AM
    Subject: [EnergyPlus_Support] questions about dx vav system


    I have two questions here.

    First, I am simulating a VAV system with no terminal reheat. I 
    specify the supply air temperature to be 12.8oC in cooling season and 
    35oC in heating season. According to results I got, it works well in 
    cooling season, trying to keep the indoor temperature under 23oC by 
    varing the supply air flow rate. While in winter, it keeps heating 
    the space to a high temperature. In heating season, the supply air 
    flow rate is always at its maximum value. I can not understand why 
    the supply air flow rate in heating season does not vary.

    Second question is about the iteration. I am using a multispeed DX 
    coil. The program terminates when simulating the system in May. There 
    is a fatal error which says the iteration limit is exceeded when 
    calculating the speed of the compressor. I have no idea how to 
    resolve the problem.

    I have uploaded the file named BOX4_VAV.idf to the files area.

    Thanks.



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