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[EnergyPlus_Support] some questions about E+

  I have some questions about E+.

  1. For the combined conditioned system, such as cooled-ceiling system combined with displacement ventilation system, the simulation sequence (I want it) is that, at a given air supply flow rate, the required air supply temperature is calculated. If the supply temperature is below the preset minimum, the ceiling panels will be 'activated', and the activated panel surface temperature will be calculated, and consequently, the required chilled-water temperature are calculated using a heat-exchanger model. 

  So, can E+ carry out this simulation strategy?

  2. Now, I am simulate a very small office space (5.1m*3.6m*2.64m), served by a plant. For practice, it's not true that a plant only serves a single small space. From simulation point, I only need to investigate the energy consumption of this office and assume a plant serves it. I think it is reasonable, right? During the simulation, the AUTOSIZE can be used for sizing of plant, condenser, etc. However, for the pump and fan, the Rated Pump Head (Pa) and Delta Pressure (Pa) are needed to specify. The question is, at such little flow rate, how to choose these two pressures? Any references for it?

  3. If it's not reasonable for the pressure specifications at such little flow rate, I think I can multiple a single office heat load to a larger one and use the larger flow rate to choose the Rated Pump Head and Delta Pressure from industrial pump or fan parameters. However, the zone list mutliplier is not being applied to internal gains such as LIGHTS and ELECTRIC EQUIPMENT. So, how to consider the light and electric equipment heat load for the total multiple space conditioned load?

  Xu
    ----- Original Message ----- 
    From: zhaicq98 
    To: EnergyPlus_Support@xxxxxxxxxxxxxxx 
    Sent: Tuesday, June 22, 2004 8:30 AM
    Subject: [EnergyPlus_Support] please help with modeling of roof top unit


    Hi,

    I am trying to simulate a roof top unit, which includes a DX cooling 
    coil, heating coil and variable speed fan. I am always getting a lots 
    of warning messages, which 
    said "COIL:DX:COOLINGBYPASSFACTOREMPIRICAL "MAIN COOLING COIL 1" - 
    Air volume flow rate per watt of rated total cooling capacity is out 
    of range." I checked the input output reference, and understood that 
    there is a range for this factor. The range is from 0.00004699 to 
    0.00006041 (m3/s)/W. The rated capacity of my DX coil is 20000 W, and 
    the rated air flow rate is 1.1 m3/s, resulting in a factor inside the 
    required range. 

    I am modeling a VAV system, and the design flow rate of the system is 
    1.1 m3/s. I set the minimum flow fraction of the system to be 0.3. 
    Thus the actual flow rate of the system could go beyond the range 
    required by the DX coil, when the system is operating. If I have to 
    stick to the range, then the actual flow rate of my system can only 
    vary between 0.00004699*1.1 = 0.94 and 0.00006041*1.1 = 1.21 m3/s. I 
    think this is not a real VAV system performs. 

    Can anyone tell me whether these warning messages matter or not? In 
    addition, what is the proper way to deal with the system I am 
    modeling?

    Thanks a lot for your help.

    -Chaoqin



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