[esp-r] Re: solar chimney

[Ehsan Baharvand]

Dear Achim,

Please see my answers below:

a) what is "massiv" (your back wall)? 
This is the back wall. 

b) how long is your pre-simulation period, how long is your simulation period 
and what does "temperature does not change" mean? "Not at all" or "not as much 
as expected"? Pre-simulation = 12 days
Simulation period = 1 day (24h)
Time-step = 60
Integration per hour = yes
 
The temperatures do not change at all. This holds for all the surface, air node 
temp or thermal db node temperature. 


c) what do you mean "wind effect is not included"? An afn takes wind into 
account by the cp-value table you must define for external nodes.
I excluded the wind effect by using Cp=0 for all the directions. 

d) do the air changes (outside air) change with changed opening sizes?
Yes, see attachtment Infiltration Load / Rate.

e) how large are the air changes befor / after changing the opening sizes?
See attachtment Infiltration Load / Rate.
 
f) do you have a bypass in your stack to allow for downward air flow (night 
time)?
Thanking you in advance. 

Kind regards,
Ehsan 

________________________________
From: Achim.geissler <achim.geissler at intergga.ch>
To: EhsanBaharvand <ebaharvand at yahoo.com>; esp-r at lists.strath.ac.uk
Sent: Fri, April 1, 2011 9:26:47 AM
Subject: AW: [esp-r] solar chimney

Dear Ehsan

some questions for clarification to help understand your model:
a) what is "massiv" (your back wall)?
b) how long is your pre-simulation period, how long is your simulation period 
and what does "temperature does not change" mean? "Not at all" or "not as much 
as expected"?
c) what do you mean "wind effect is not included"? An afn takes wind into 
account by the cp-value table you must define for external nodes.
d) do the air changes (outside air) change with changed opening sizes?
e) how large are the air changes befor / after changing the opening sizes?
f) do you have a bypass in your stack to allow for downward air flow (night 
time)?

Best
Achim


 --------- Original-Nachricht --------
Von: "Ehsan Baharvand" <ebaharvand at yahoo.com>
An: "esp-r at lists.strath.ac.u! k" <esp-r at lists.strath.ac.uk>
Betreff: [esp-r] solar chimney
Datum: 01/04/11 09:05


Dear all,

Problem
The free-floating of a solar chimney is simulated and a upward stream due to the 
solar energy occurs. 
However when increasing the infiltration (colder ambient air) by increasing the 
opening area to outside the backwall inside surface temperature doesn't 
change!  Other thing is that the heat load inside the chimney is being removed 
by the infiltration air exchange. Eventhough I increase the infiltration air 
exchange, the heat load being removed increases, but the surface temperature of 
the backwall remains the same. 


Question
Do I forget something? W! hat can be the problem?
I'm certain about the configurations and the Air Flow Network. 

Model
The 22 zones solar chimney uses a air flow network and has 2 wind pressure 
boundary nodes at the inlet and the outlet. 

Each zone has a separate connection with the outdoors through a air flow network 
connection, which simulates a opening between glazing panels meant for 
infiltration!
The inlet and the outlet areas are connected to the ambient air thourgh a 
orifice with a Cd of 0.67. 

Between the cubic thermal zones fictitious surfaces are used. 
The backwall is a massive construction with adiabatic BC at the surface outside 
node. 

At 1.8 meter distance from the backwall there is a glazing surface with a 
G-value of 0.8 and 80% of glass and it has a external BC. 

The chimney is South oriented for a Cl! imate catagory 3A according to Ashrae 
90.l. 


Not included
Wind effect is not included.


Kind regards,

E. Baharvand 


________________________________

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esp-r mailing list
esp-r at lists.strath.ac.uk
http://lists.strath.ac.uk/mailman/listinfo/esp-r How to do this?But there is no 
control on the air flow inside the chimney. The control is based on 
free-floating. Do I need a bypass?
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