[TRNSYS-users] Type 460 Kair0 and 1 table

[Camilo Arias <camiloariashenao@yahoo.com>]

Hi, I still working with the Type 460 EAHE, I try to find the table to relation the tube diameter with the Kair0 and Kair1, but i not find him, i´m looking in the Hollmuller work ("Utilisation des echaugeurs air/sol pour chauffage et le refraichissement des batiments") but i´m not find the table too. I know that the variation range of the values but  are only reference (in the example, the .par file values are offset of the recommended range) i send the FAQ file from Type 460 where said that somebody have it (paramdef.txt section, item 4).

regards

Camilo Arias 

Corrected Errors
****************

1) bug in the TYPE460.tmf file from 4.02.2004 wrong number of parameters:
Type 460 has 17 parameters (not 16). You have to insert a parameter 
"temperature accuracy" as a 5th parameter (before surface types), which you 
may define as 0.01 [K].


Help for  paramdef.txt commen mistakes:
*****************************************
1) You defined Nj=11, hence there should be 11 values for DY (instead of 

2). I guess the first values should read 1,1,1 (instead of 1,1), 
corresponding to the first 3 "earth#2 nodes" (soil#2)

2) Since you use symetry in the x-z plane (cutting through the middle of 
the tube), you should set the last DY value to 0.266 (half of 0.531). 
Attention : airflow is to be given for the total pipe !!

Other comments
********************


2)Hint use of the parameter file without a assign statement:
You should give separate values to parameters 1 and 2 (unit number for 
parameter definition/control files), for example 100 and 101. Also, if you 
dont use an assign statement to define the file names, you should give the 
name "paramdef.txt" to the parameter definition file (instead of "Type61.par")


in the deck :
1) You have set airflow to zero (input no 1) ?!
2) Air temperature is coupled directly to the ground (without any air/earth 
resistance). We usually use a standard convective coefficient of about 20 
W/K.m2 (parameters # 12-17 - in particular # 14 corresponding to upper 
surface #3 in paramdef.txt - taking into account conversion from W/K.m2 to 
K.m2.hr/kJ). Should the free surface also be driven by solar radiation, you 
should also take this into account. There is a simple way to do that (just 
ask and I will explain how).
3) as defined, airflow may not exceed 0.1 m3/h (param # 4). Maybe you 
should set this value to zero, so as for the routine to reset this value : 
with your node meshing, it will be set to 81 m3/h (see paramcon.txt, last 
parameter) which means airflow should be zero or greater than 81 m3/h, 
unless you could have oscillation problems. In the same way, because param 
#3 is zero, internal timestep is being calculated by the routine and set to 
0.06 hr (see paramcon.txt, 2ndlast parameter). Hence the "large" 
computational time. If you do want to increase this value, you need to take 
larger nodes around the tubes, but than you might lose in accuracy in air 
output.

in paramdef.txt :
1) It is correct to use longer nodes as you go along the x-axis, but I 
guess 1, 2, 5, 25 m is a bit strong. On the other hand there is no use to 
shorten nodes at the end (unless you use airflow in both directions). So, 
if you keep Ni=11 (7 tube nodes + 4 earth nodes) for a 41 m long tube, I 
would define DX as follows (where parenthesis should of course be dropt): 
(0.5, 0.5), 1, 1, 2, 2, 5, 10, 20, (0.5, 0.5).
2) Since upper surface is driven by ambient air, you might want to define 
shorter DZ nodes close to the surface. Maybe you could cut your first 0.5m 
node into 3 : 0.1, 0.1, 0.3 (which implies setting Nk=11 and adding 2 lines 
in each TypSoil section)
3) Since you don't use water infiltartion, you could set PosInf = 
1,1,1,1,1,1 (this is just for better readability, but wan't change anything 
in calculation)
4) For 60 cm diameter Kair0 and Kair1 should both be set to about 2 W/K.m2 
(resp. W/K.m2 per m/s), i.e : 7.2 kJ/hr.K.m2 (resp. kJ/hr.K.m2 per m/s). If 
needed, I can send a table which gives these values for different diameters.
5) Your CvSoil seems rather low to me? I usually use soils with around 2000 
kJ/K.m3...
6) If your tube is of same material as soil (LamTub=LamSoil, CvTub=CvSoil), 
you may just as well set ThTub to zero...

In attachment a corrected version of "project.dck" and "paramdef.txt" (only 
correction of errors, not of comments). Because of compatibility problems I 
had to drop datareader and onlineploter. Instead I used constant 30°C 40% 
for input and surface and wrote output into a file. Only first 100 hours 
are computed.