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a burst of humidity in Energyplus

asked 2020-07-24 12:15:41 -0500

updated 2020-07-25 04:49:25 -0500

Hi, I would like to input [gH2O/h] in Energyplus simulation to take into account burst of humidity within 9 hours. Thank you.

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What causes this burst of humidity? Is it a water draw like a shower or sink connected to a domestic hot water system or something similar? Is it something inside of a zone that uses electricity or gas? More information would be helpful.

Aaron Boranian gravatar imageAaron Boranian ( 2020-07-24 14:22:36 -0500 )edit

i want to validate an experimental results; it just a an increase of humidity in the zone!!! gravatar ( 2020-07-25 04:38:43 -0500 )edit

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answered 2020-07-25 10:11:49 -0500

First off, you have many options to define latent moisture gain entering a zone in EnergyPlus. If some electricity consumption causes this latent moisture gain, then you should use the ElectricEquipment object in your input file. There are other objects to use if latent moisture gain is caused by using gas, or as @rraustad pointed out in their answer the OtherEquipment object that will add moisture without consuming any energy.

No matter what option you use to define the latent moisture gain, you cannot directly define moisture addition to a zone in terms of water mass rate like $g_{water}/hr$. You will instead need to define multiple inputs that will together set this water mass rate gain:

  • Energy use of the equipment (total design level in $W$, power per area in $\frac{W}{m^2}$, or power per person in $\frac{W}{person}$
  • Fraction of the equipment's energy use that becomes latent gain. As @rraustad says, this should be set to 1 so that all of the energy use becomes latent gain to the zone.

The basic calculation for the "power" of latent gain into a zone is:

$$ Power_{latent} = \dot{m}_{water}*h_{fg} $$

Where $h_{fg}$ is the heat of vaporization of water (2256 $\frac{kJ}{kg}$ at 100 $^oC$). So, you should multiply your desired $g_{water}/hr$ by $h_{fg}$ to calculate the equivalent $W$ of latent gain to enter as an EnergyPlus input for Design Level.

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thank you so much this is so hopeful @Aaron Boranian gravatar ( 2020-07-25 11:32:18 -0500 )edit

answered 2020-07-24 14:44:15 -0500

You could use the OtherEquipment object with a Latent Fraction = 1 to add moisture to a zone based on a schedule.

  MoistureInjector,        !- Name
  None,                    !- Fuel Type
  ZONE ONE,                !- Zone or ZoneList Name
  MySchedule,              !- Schedule Name
  EquipmentLevel,          !- Design Level Calculation Method
  352,                     !- Design Level {W}
  ,                        !- Power per Zone Floor Area {W/m2}
  ,                        !- Power per Person {W/person}
  1,                       !- Fraction Latent
  0,                       !- Fraction Radiant
  0;                       !- Fraction Lost
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thank you sir but i didn't find any column to put 500g/h how can convert g/h to watt? gravatar ( 2020-07-25 04:47:57 -0500 )edit

and what is the mean of design level gravatar ( 2020-07-25 05:21:23 -0500 )edit

Design level is the max output and this value is multiplied by the schedule. So if your schedule is all 0 except for a time period of your choosing then the moisture generator will be off most of the time.

rraustad gravatar imagerraustad ( 2020-07-27 07:49:19 -0500 )edit

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Asked: 2020-07-24 12:15:41 -0500

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Last updated: Jul 25