<div>I need help translating SRCC OG-100 ratings into TRNSYS. Specifically, I have questions (listed below background info) on what the units are and if they are positive or negative.</div><div><br></div>I'm currently translating the SRCC OG-100 ratings of a flat plate collector used in domestic solar water heating into my TRNSYS program. I'm using at Type 539 under the Tess Solar Library - Glazed Flat Plate Collector - OG100 Quadratic Efficiency Approach.<div>
<br></div><div>My solar collector has the following specs:</div><div><a href="https://securedb.fsec.ucf.edu/srcc/coll_detail?srcc_id=2007032A">https://securedb.fsec.ucf.edu/srcc/coll_detail?srcc_id=2007032A</a></div><div>
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<td colspan="6" align="left" style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt"><b style="font-size:8pt"> Efficiency Equation [NOTE: Based on gross area and (P)=Ti-Ta]</b></td><td align="center" style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">
<b style="font-size:8pt">Y INTERCEPT</b></td><td align="center" style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt"><b style="font-size:8pt">SLOPE</b></td></tr><tr style="font-size:8pt"><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">
</td><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt"><b style="font-size:8pt">SI Units:</b></td><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">η= 0.718</td><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">
-2.29060 (P)/I</td><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">-0.04398 (P)<sup style="font-size:8pt">2</sup>/I</td><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt"> </td>
<td align="center" style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">0.744</td><td align="left" style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">-5.151 W/m<sup style="font-size:8pt">2</sup>.°C</td>
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<tbody style="font-size:8pt"><tr style="font-size:8pt"><td colspan="3" style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt"> <b style="font-size:8pt">Incident Angle Modifier [(S)=1/cosθ - 1, 0°<θ<=60°]</b></td>
</tr><tr style="font-size:8pt"><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt"> <b style="font-size:8pt">Kτα</b> = 1</td><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">-0.322 (S)</td>
<td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">0.031 (S)<sup style="font-size:8pt">2</sup></td></tr><tr style="font-size:8pt"><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">
<b style="font-size:8pt">Kτα</b> = 1</td><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt">-0.29 (S)</td><td style="font-family:Geneva,Arial,Helvetica,sans-serif;font-size:8pt"> Linear Fit</td></tr>
</tbody></table></div><div><br></div><div>TRNSYS states, Efficiency = a0 - a1*(T-T_Ambient)/G - a2*(T-T_Ambient)^2/G</div><div> where T = fluid temperature</div><div> T_Ambient = ambient air temperature</div>
<div> G = total solar radiation incident on the surface [kJ/hr]</div><div><br></div><div>Parameter a1 is the first-order parameter of the collector efficiency equation. Its units are [kJ/hr-m2-K].</div><div>
<div>Parameter a2 is the second-order parameter of the collector efficiency equation. Its units are [kJ/hr-m2-K2].</div></div><div><br></div><div><br></div><div>-and for IAM coefficients -</div><div><div>Modifier = 1 - b0 * S - b1 * S^2</div>
<div><br></div><div>where S=1/cos(Incidence angle)-1</div></div><div>b0 and b1 correspond to the two IAM coefficients</div><div><br></div><div><font face="arial, helvetica, sans-serif"><br></font></div><div><font face="arial, helvetica, sans-serif">Here is what I am doing, but would like confirmation:</font></div>
<div><font face="arial, helvetica, sans-serif"><u>TRNSYS Parameter TRNSYS Value ... from SRCC value</u></font></div><div><font face="arial, helvetica, sans-serif">Intercept efficiency (a0) +0.718 (no units, <span style="background-color:rgb(255,255,255)">η from SRCC specs)</span></font></div>
<div><font face="arial, helvetica, sans-serif">1st order efficiency coefficient (a1) +2.29060 (W/m^2*K?) (P)/I (-2.29060) from SRCC specs, but input as a positive value in TRNSYS?</font></div><div><font face="arial, helvetica, sans-serif">2nd order efficiency coefficient (a2) +0.04398 (W/m^2*K)? <span style="background-color:rgb(255,255,255)">(P)</span><sup style="background-color:rgb(255,255,255)">2</sup><span style="background-color:rgb(255,255,255)">/I (-0.04398)from SRCC specs, but input as a positive value in TRNSYS?</span></font></div>
<div><font face="arial, helvetica, sans-serif">1st order IAM coefficient +0.332 (no units) S (-0.322) from SRCC specs, but input as a positive value in TRNSYS, or should this be negative</font></div>
<div><font face="arial, helvetica, sans-serif">2nd order IAM coefficient -0.031 (no units) <span style="background-color:rgb(255,255,255)">(S)</span><sup style="background-color:rgb(255,255,255)">2 </sup></font><span style="background-color:rgb(255,255,255)"><font face="arial, helvetica, sans-serif">(+0.031)from SRCC specs, but I input as negative value in TRNSYS since it's the opposite of all others</font></span></div>
<div><br></div><div><ul><li>I want to confirm that the W/m^2.C that is noted on the SRCC webpage next to the slope is what I'm using for a1 and a2 units, instead of the kJ/hr.m^2.K^2 that TRNSYS has as default. Or are the SRCC units posted in kJ/hr.m^2.K^2 ?</li>
<li>I also want to know which units are positive and which are negative, as it seems SRCC states them opposite of how they are inputted into TRNSYS, but I'm not 100% certain, especially for the IAM coefficients.</li>
</ul>
</div><div><br></div><div>Thanks!</div><div>Tom</div><div><br></div><div><br></div>
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