IES-VE User Forum

Posted: **Wed Sep 30, 2015 7:43 am**

Hi,

I am trying to do cfd analysis for casting shop. In this process ,after completing Apache simulation, i have imported the boundary conditions in to Microflo. But here i am facing the problem. Surface temperature of walls and roof are ok but room internal temperature is around 22 deg C where as the boundary temperatures are between 42 - 49 deg C. i have chosen the boundary conditions at peak summer and the location is chennai. As i am simply dumping ambient air into the room.

I have cross checked the room temperature conditions in Vista pro results and it is showing around 50 deg C for the chosen time period. How to export this room conditions to Microflo.

I would really appreciate any clarification on this topic. Thank you!

Posted: **Tue Oct 13, 2015 9:57 am**

Was this the room temperature observed after simulation or in the initial conditions dialogue in the CFD settings before running the simulation? if it is latter, ignore that value and run the simulation to find out actual air temperature. If it is the former follow the steps below.

Did you import only boundary conditions or the internal gains as well? what was the temperature of air being supplied to the space in the cfd model?

I have feeling you have not imported the internal gains and/or have the supply temperature set to the wrong value.

Posted: **Wed Oct 14, 2015 11:34 am**

Thanks for your reply. This problem occurs after the simulation only.

1. I have imported internal heat gains.
2. Supply air temperature is set to 35 deg C ( ambient air)

If i am not wrong, even if there is no internal heat gain, (after the simulation) space temperature should not be less than the supply air temperature because there is a heat gain from building envelope.

Even without providing any supply air in to the space, due to heat gain from the building envelope, inside air temperature should be +/-5 deg C of ambient temp. ( assuming that Microflo considers heat gain from the building envelope )

Finally In the results the inside temperature is 22 deg C in most of the areas except near the supply diffusers and walls. where as the ambient temp is around 42 deg C ( Chennai location ).

Thanks!

Posted: **Wed Oct 21, 2015 10:44 am**

You are right, even if internal gains are absent and supply temperature is set to 35C, room temperature should be around that value. Further checking:

1) How long have you run the simulation for?
2) Did the residuals converge when before you looked at the results?

Just as a note, MicroFlo does not simulate gain through building envelope as ApacheSim. MicroFlo recognises the internal surface as a wall with a temperature assigned to it only. It has no idea about the ambient.

rajeevsam wrote:
Finally In the results the inside temperature is 22 deg C in most of the areas except near the supply diffusers and walls. where as the ambient temp is around 42 deg C ( Chennai location ).

Thanks!

This would suggest the simulation has not converged.

Posted: **Tue Oct 27, 2015 11:55 am**

hi,

1. Simulation run for 5000 iterations (around 36 hours).
2. Residuals are very much converged, also i ve taken screenshot at the end of simulation but i am unable to find an option to post here.

harshadj wrote:
Just as a note, MicroFlo does not simulate gain through building envelope as ApacheSim. MicroFlo recognises the internal surface as a wall with a temperature assigned to it only. It has no idea about the ambient.

i too agree that it recognizes internal wall surface temperate. what about the temperature of air in the space which is away from the walls? How MicroFlo recognizes initial space air temperature?

i feel.. once the model is ready for the simulation ( after Apache sim and importing the boundary conditions), the inside room air temperature should be around +/- ambient temp.

thanks

Posted: **Tue Oct 27, 2015 12:21 pm**

Since you have run the simulation for such a long time, initial conditions should really not matter. This is a steady state calculation, so boundary conditions will eventually override the initial conditions.

Can you copy the contents of the part of the boundary condition file here if possible? I think we are missing something simple with regards to the setup.

Posted: **Tue Oct 27, 2015 1:08 pm**

I ve copied some contents of the file.

LOCATION,CHENNAI,-,IND,IWEC Data,432790,13.00,80.18,5.5,16.0
DESIGN CONDITIONS,1,Climate Design Data 2009 ASHRAE Handbook,,Heating,1,20,20.7,14.5,10.3,28.6,15.9,11.3,27.9,8.3,27.6,7.7,28.2,0.6,320,Cooling,5,8.8,38.5,25.7,37.2,25.6,36.2,25.6,28.3,32.9,27.9,32.3,27.5,31.9,4.2,270,27.2,23.1,30.5,26.8,22.5,30.2,26.5,22,29.9,91.7,33.1,89.5,32.3,87.7,31.9,1,Extremes,8.3,7.5,6.5,31.8,18.5,41.6,0.8,1.5,17.9,42.7,17.5,43.6,17,44.4,16.5,45.5
TYPICAL/EXTREME PERIODS,7,No Dry Season - Week Near Average Annual,Typical,9/10,9/16,Summer - Week Nearest Max Temperature For Period,Extreme,5/22,5/28,Summer - Week Nearest Average Temperature For Period,Typical,7/17,7/23,Winter - Week Nearest Min Temperature For Period,Extreme,1/18,1/24,Winter - Week Nearest Average Temperature For Period,Typical,1/ 4,1/10,Autumn - Week Nearest Average Temperature For Period,Typical,10/10,10/16,Spring - Week Nearest Average Temperature For Period,Typical,3/15,3/21
GROUND TEMPERATURES,3,.5,,,,25.10,24.79,25.33,26.19,28.42,30.14,31.30,31.66,31.06,29.72,27.93,26.27,2,,,,26.23,25.68,25.79,26.25,27.74,29.09,30.17,30.75,30.63,29.87,28.64,27.33,4,,,,27.16,26.60,26.48,26.65,27.50,28.40,29.24,29.82,29.96,29.63,28.90,28.02
HOLIDAYS/DAYLIGHT SAVINGS,No,0,0,0
COMMENTS 1,"IWEC- WMO#432790 - Asia -- Original Source Data (c) 2001 American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), Inc., Atlanta, GA, USA. http://www.ashrae.org All rights reserved as noted in the License Agreement and Additional Conditions. DISCLAIMER OF WARRANTIES: The data is provided 'as is' without warranty of any kind, either expressed or implied. The entire risk as to the quality and performance of the data is with you. In no event will ASHRAE or its contractors be liable to you for any damages, including without limitation any lost profits, lost savings, or other incidental or consequential damages arising out of the use or inability to use this data."
COMMENTS 2, -- Ground temps produced with a standard soil diffusivity of 2.3225760E-03 {m**2/day}
DATA PERIODS,1,1,Data,Sunday, 1/ 1,12/31

Posted: **Tue Oct 27, 2015 1:39 pm**

That's the weather file.

Look under the Vista folder of the project for a '.bcf' file. Copy the contents of that file.

Posted: **Wed Oct 28, 2015 8:44 am**

here is the file content..

File [1][2] Vista BCF Tab-delimited
Date 28 May 15:00 60 mins.
Note All fields are tab-delimited
Note All indices are zero-based
Note 'Var. Values...' denotes a list of tab delimited variable data values on following lines
Note 'Neutral plane upper fraction' = fraction of the window height above the neutral plane.
Note 'Direction of upper flow' = +1.0 for in-flow, -1.0 for out-flow.
Note
Note Line Formats, based on 4 character starting Key Name...
Note
Note Atmo Num.Var.Values
Note Room Room handle Room ID Num.Surfs. Num.Var.Values
Note Surf Surface index Description Num.IAdjs Num.Opens Num. Ext.Adjacency Var.Values
Note IAdj Adjacency index Description Num.Var.Values
Note Open Opening index Description Num.Var.Values
Note # Variable Name Data Value
Atmo 5
# Temperature 41.150002
# Atmospheric pressure 99700.000000
# Wet bulb temperature 24.929955
# External moisture content 0.013296
# External relative humidity 26.498936

Room 6 LD000001 10 23
# Room air temperature 41.505295
# Humidity ratio 0.003465
# Relative humidity 6.882705
# Room CO2 concentration 399.999969
# Room radiant temperature 44.597633
# MacroFlo internal vent 0.000000
# MacroFlo external vent 0.000000
# MacroFlo int vent gain 0.000000
# MacroFlo ext vent gain 0.000000
# MacroFlo int vent lat gain 0.000000
# MacroFlo ext vent lat gain 0.000000
# Casual gains 0.000000
# Lighting gain 0.000000
# Equipment gain 0.000000
# People gain 0.000000
# Equipment latent gain 0.000000
# People latent gain 0.000000
# Number of people 0.000000
# Convective plant load 0.000000
# Room latent load 69.922905
# Convective lighting gain 0.000000
# Convective equipment gain 0.000000
# Convective people gain 0.000000
Surf 0 ceil. 0 0 1
# Surface temperature 49.676033
Surf 1 wall 0 0 1
# Surface temperature 45.008926
Surf 2 ceil. 0 0 1
# Surface temperature 49.675228
Surf 3 wall 0 0 1
# Surface temperature 45.008926
Surf 4 ceil. 0 0 1
# Surface temperature 50.009262
Surf 5 wall 0 0 1
# Surface temperature 51.405300
Surf 6 wall 0 0 1
# Surface temperature 45.008926
Surf 7 floor 0 0 1
# Surface temperature 40.264061
Surf 8 wall 0 0 1
# Surface temperature 47.025814
Surf 9 wall 0 0 1
# Surface temperature 45.008926

Thanks!

Posted: **Thu Oct 29, 2015 2:17 pm**

There don't seem to be any flows assigned to this room. Quick glance at the boundary condition file shows all MacroFlo related numbers to be zero. That means there is no flow coming in/out of the room. Also all the gains are at zero, which means no gains were applied to the rooms while running ApacheSim.

That is why the sim is running for such a long time and not producing results. Since there is no flow moving the air, the flow is already steady. That is why there the initial temperature is shown overriding the results.

I would suggest you to go back and fix the inputs to the building model, before you get to MicroFlo.

IES-VE User Forum

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How to Export Room Internal temp from Vistapro to Microflo

Re: How to Export Room Internal temp from Vistapro to Microf

Re: How to Export Room Internal temp from Vistapro to Microf

Re: How to Export Room Internal temp from Vistapro to Microf

Re: How to Export Room Internal temp from Vistapro to Microf

Re: How to Export Room Internal temp from Vistapro to Microf

Re: How to Export Room Internal temp from Vistapro to Microf

Re: How to Export Room Internal temp from Vistapro to Microf

Re: How to Export Room Internal temp from Vistapro to Microf

Re: How to Export Room Internal temp from Vistapro to Microf