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*Date*: Thu, 16 Jan 2003 10:15:55 -0600*Date*: Thu, 16 Jan 2003 11:16:49 -0600*From*: Michaël Kummert <kummert@xxxxxxxxxxxxx>*Subject*: RE: how to use incident angle modifiers

Dear Timo, The short answer is to make a matrix with all possible combinations between the values for longitudinal and transversal angles and give that matrix to DATA in Type71. A longer explanation: Let's assume you have the following data for the IAM: Dir. | 0° | 15° | 30° | 45° | 60° | 75° | 90° | ------------------------------------------------------------- Trans. IAM | 1.00 | 1.01 | 1.03 | 1.05 | 1.04 | 1.02 | 0.00 | Long. IAM | 1.00 | 1.00 | 0.98 | 0.96 | 0.90 | 0.71 | 0.00 | (so in this case, 7 values for the longitudinal direction and 7 values for the transversal direction) I assume that those values are given for "the other angle = 0", i.e. the first line is for a null longitudinal angle. You are right that Type 71 (i.e. the DATA subroutine called by Type 71) needs 49 values Type 71 calculates the longitudinal angle and transversal angle corresponding to any incidence angle and needs the IAM for that particular combination. We have to assume that the IAM value for any angle of incidence is: (IAM for the corresp. trans. angle and for a 0 long. angle) * (IAM for the corresp. long. angle and for a 0 trans. angle) E.g. the value for a transversal incidence angle = 15° and a longitudinal incidence angle=30° is simply 1.01*0.98=0.99 The file you have to give to Type71 must include the following data: --- First line includes the 7 values of transversal angle: 0 15 30 45 60 75 90 --- Then the 7 values of longitudinal angle: 0 15 30 45 60 75 90 --- Then a matrix of IAM values for different angles. The value in line i, column j corresponds to transversal angle i, longitudinal angle j. --- The matrix is written in one long column, line after line --- 1 st value: IAM for Transversal angle = 0° and Longitudinal angle = 0 (1.00*1.00=1.00) 1.00 --- 2 nd value: IAM for Transversal angle = 0° and Longitudinal angle = 15 (1.00*1.00=1.00) 1.00 --- 3 rd value: IAM for Transversal angle = 0° and Longitudinal angle = 30 (1.00*0.98=0.98) 0.98 --- Etc. --- 8th value: IAM for Transversal angle = 15° and Longitudinal angle = 0 (1.01*1.00=1.01) 1.01 --- 9th value: IAM for Transversal angle = 15° and Longitudinal angle = 15 (1.01*1.00=1.01) 1.01 --- 10th value: IAM for Transversal angle = 15° and Longitudinal angle = 30 (1.01*0.98=0.99) 0.99 --- Etc. I attached an example file. Please note that subroutine DATA does not extrapolate if a value falls outside of the given range. E.g., this means that if you start your data for the longitudinal angle at 30°, DATA will use 0.98 for all values smaller than 30°. For this reason, I recommend you to always add (0°, 1.00) to your data. For high incidence angle values, you can also add (90°, 0.00). This is especially true for flat-plate collectors or for the longitudinal direction in vacuum-tubes collectors. However, you have to be careful for the transversal direction, because the IAM curve is often flat for that direction up to anlges very close to 90°. If you only have the value (45°, 1.05) and you add (90°, 0.00), the value at 60° will be interpolated as 0.53, which is probably not realistic. You can either NOT add the last value (90, 0.00) or add another value that you think to be realistic (e.g. 80°, 1.00). I hope this helps. Again, I hope some solar collector experts will correct me if I am wrong! Cheers, Michaël P.S. I noticed that some outputs (including the calculated transversal and longitudinal angles and the IAM) are missing in the Type71 proforma. They will be added in the next Trnsys release. > -----Original Message----- > From: owner-trnsys@relay.doit.wisc.edu > [mailto:owner-trnsys@relay.doit.wisc.edu] On Behalf Of Timo Sengewald > Sent: Thursday, January 16, 2003 04:18 > To: TRNSYS group > Subject: RE: how to use incident angle modifiers > > > Michaël, > > thank you for your help. > > I found b0 and b1 for my flat plate collector using the MS > Excel solver. > > The K_diff I wrote about is the modifier for diffuse > radiation. I think the types 1 and 71 are calculating it by > themselves. > > The detailed test protocol for the tube collector I want to > use contains the IAMs for the transversal and longitudinal > angles 30, 45, 50, 60 and 70 degrees. There are 10 values: 5 > transversal, 5 longitudinal. But it seems that the subroutine > DATA needs 5*5=25 values. > > Could You (or any other) help me once more? > > Best regards, > > Timo Sengewald > > ------------------------------------------ > Phönix Sonnenwärme AG > Am Treptower Park 28-30 > D-12435 Berlin, Germany > e-mail: timo.sengewald@sonnenwaerme-ag.de > www.sonnenwaerme.ag > Tel.: +49-(0)30-53 00 07-237 > Fax.: +49-(0)30-53 00 07-17 > ------------------------------------------ > -----Ursprüngliche Nachricht----- > Von: owner-trnsys@relay.doit.wisc.edu > [mailto:owner-trnsys@relay.doit.wisc.edu]Im Auftrag von > Michaël Kummert > Gesendet: Dienstag, 7. Januar 2003 22:18 > An: trnsys@relay.doit.wisc.edu > Betreff: RE: how to use incident angle modifiers > > > Dear Timo, > > First, I must say that I am not sure how K_diff is assessed > in experimental tests according to EN 12975. I suspect it is > the value of KTauAlpha for an "equivalent angle" close to > 60°. Hopefully someone will correct me if I am wrong! > > For the flat-plate collector (Type 1), optical modes 2 and 3 > allow you to take into account experimental data. > > Mode 2 requires b0 and b1, the two parameters of an equation > giving KTauAlpha vs. Theta: K = > 1-bo*(1/cos(Theta)-1)-b1*(1/cos(Theta)-1)^2 > b1 can often be neglected so you could fit a b0 value using > only the value of K for 50°. If my assumption about K_Diff is > right, you can use a second data point in your regression > (K_diff for 60°). > > Mode 3 allows you to enter data in a file. In this case, you > would have at least 3 data points: (Theta, KTauAlpha) (0 , > 1.0) (50 , your value KTauAlpha50°) (90 , 0.0) (you could add > (60 , K_diff) if my assumption on K_diff is correct). Note > that the subroutine DATA will interpolate linearly between > these values. > > I would suggest to use Mode 2 with a fitted b0 value but I > don't think you would notice a big difference between the two > options. For the vacuum tube collector, you have to give data > in a file (see section 4.2.3 of the main manual). You can > enter the 3 (or 4) data points I mentioned here above for > each direction (longitudinal & transversal). I don't think it > would be a good idea to fit a "b0" parameter for this type of > collector. Be careful not to mix transversal and longitudinal IAM's. > > I hope this helps, > > Michaël Kummert _________________________________________________ > > Michaël Kummert > > Solar Energy Laboratory - University of Wisconsin-Madison > 1303 Engr Res Bldg, 1500 Engineering Drive > Madison, WI 53706 > > Tel: +1 (608) 263-1589 > Fax: +1 (608) 262-8464 > E-mail: kummert@engr.wisc.edu (NEW!) > > SEL Web Site: http://sel.me.wisc.edu > TRNSYS Web Site: http://sel.me.wisc.edu/trnsys > > > > -----Original Message----- > > From: owner-trnsys@relay.doit.wisc.edu > > [mailto:owner-trnsys@relay.doit.wisc.edu] On Behalf Of Timo > Sengewald > > Sent: Monday, January 06, 2003 04:32 > > To: TRNSYS group > > Subject: how to use incident angle modifiers > > > > > > Hello! > > > > I have got the test protocol (according to DIN EN 12975) of > the german > > ISFH for two different solar collectors: a flate plate and > a evacuated > > tube collector. Can I use the given incident angle > modifiers with Type > > 1 and Type 71? For the flat plate collector the IAMs are called > > K_taualpha_dir(45°) and K_taualpha_dif. The IAMs for the tube > > collector are > > K_long(50°) and K_rad(50°). Which values do I have to > provide by the > > IAM files? > > > > Thanks a lot, > > > > Timo Sengewald > > > > > > > > ------------------------------------------ > > Phönix Sonnenwärme AG > > Am Treptower Park 28-30 > > D-12435 Berlin, Germany > > e-mail: timo.sengewald@sonnenwaerme-ag.de > > www.sonnenwaerme.ag > > Tel.: +49-(0)30-53 00 07-237 > > Fax.: +49-(0)30-53 00 07-17 > > ------------------------------------------ > > > > Timo Sengewald > ------------------------------------------ > Phönix Sonnenwärme AG > Am Treptower Park 28-30 > D-12435 Berlin, Germany > e-mail: timo.sengewald@sonnenwaerme-ag.de > www.sonnenwaerme.ag > Tel.: +49-(0)30-53 00 07-237 > Fax.: +49-(0)30-53 00 07-17 > ------------------------------------------ >

**Attachment:
IAM.dat**

**Follow-Ups**:**RE: how to use incident angle modifiers***From:*Timo Sengewald

**References**:**RE: how to use incident angle modifiers***From:*Timo Sengewald

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