RE: [EnergyPlus_Support] EnergyPlus Validation

I would just like to point out, while the test is very interesting on a theoretical level, the conditions you are simulating do not exist in the real world.

Since your walls have an absorption of zero (I am assuming a radiant absorption), they must have a reflectance of one. Or 100% of the radiant energy is reflected back into the space, or more precisely, reflected back to the air in the space which will be able to absorb it. The radiant source heats the air, THEN the air will lose some heat to conduction to the walls.

With the convective source, while it is convectively heating up the air, the air is also transferring heat to the outside by conduction. Thus, the air is constantly having both the convection from the source added, while losing heat through conduction to the walls.

A basic text book on heat transfer will give you all the relevant equations for each type of source.

Michelle Smith
Belle Engineering, LLC
Ph: 314.631.8447
Fx: 314.631.9102
www.belleengineering.com

-----Original Message-----
From: Alexander Beisteiner [mailto:alexander.beisteiner@xxxxxxxxxxxxxxxxxx]
Sent: Friday, October 25, 2002 1:18 AM
To: 'Energy Plus Support'
Subject: [EnergyPlus_Support] EnergyPlus Validation

Dear Sir/Madam

I am validating EnergyPlus according to the VDI directive 6020. Tests require surfaces which absorption coefficients are zero, a constant external temperature and no solar radiation. In the case of one example a room has to be simulated with a load of 1000 W, one time 100% convective, the other time 100 % radiant. While the radiant load produces an equilibrium temperature of about 52 °C (conform to the reference results of the directive) the convective load raises the room temperature to only 36 °C (reference temperature in the directive is about 50 °C).

There is no doubt that the convective load causes the room temperature to increase quicker, but I wonder why the same load of 1000 W (either radiant or convective) produces such different equilibrium temperatures at constant external conditions.

I would appreciate your help.

Alexander Beisteiner
__________________________________

alexander.beisteiner@xxxxxxxxxxxxxxxxxx
Forschungs- und Technologietransfer
Pinkafeld GmbH
Steinamangerstrasse 21
7423 Pinkafeld

http://www.fh-pinkafeld.ac.at
Tel.: 0043/3357/45370-1324
Fax: 0043/3357/45370/1010

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