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HEAT TRANSFER TO A SUNROOM

HEAT TRANSFER TO A SUNROOM. the affect of window type on heat transfer. The Situation. Clear Day Mid June Provo, UT

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HEAT TRANSFER TO A SUNROOM

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  1. HEAT TRANSFER TO A SUNROOM the affect of window type on heat transfer

  2. The Situation • Clear Day • Mid June • Provo, UT • The Pate’s have recently added a sunroom to the exterior of their home. In the summer the temperature rises in that room a considerable amount. Should they have installed double pane windows instead? Should they invest in windows with reflective coating? How much of a difference would these windows make?

  3. What We Know: • Incident Solar Radiation • East Wall: 5015 W/m2 • South Wall: 2997 W/m2 • West Wall: 5015 W/m2 • Temperature Data • Tsur, interior = 20° C • Tsur, exterior = 35° C • Physical Properties • Glass (T=300K) • 1.4 W/mK • Air • K=.0263 W/mK (T=300K) • Areas of Windows: • East Wall • 8.09 m2 • South Wall: • 6.77 m2 (x 2) • 2.60 m2 (x2) • West Wall • 8.09 m2 • Volume of the Room • 60 m3

  4. What We Assume: • Radiation Properties of Glass • Transmissivity = .95 • Absorbtivity = 0 • Reflectivity = .05 • Emissivity = .9 • Neglect radiation out of the room (only consider incident radiation) • No heat transfer through the walls • Tsur stays constant • Window areas are all square (see diagram)

  5. Single Pane Glass • ho,i = 6 W/m2 • qconv+cond = 728 W • qrad= 1606 W • qtotal= 2324 Ho, To Hi , Ti

  6. Double Pane Glass • RaL=91.37 ΔT • RaLmax = 1307 • 1307 < 1708 • Convection between planes is negligible. • Transmissivity: .9 • Reflectivity: .1 • h = 6 W/m2 • qconv+cond= 168 W • qrad= 1522 W • qtotal= 1690 W Ho, To Hi , Ti

  7. Double Pane Glass with Coating • Reflective glass • Reflectivity: .28 • Transmissivity: .72 • Heat transfer from convection and conduction stays the same. • qconv+cond= 168 W • qrad= 1217 W • qtotal= 1385 W Ho, To Hi , Ti

  8. Air Conditioning Cost • Single Pane: $122.07 • Double Pane: $148.09 • Coated Double Pane: $216.12 • $.08/KWhr • COP = 3.4 • Summer Savings: $94.05 • Coating: $36/Window • Estimate: $216 to upgrade, 2.5 Summers to recover the savings

  9. Presented By: • Nathan Honka • Dallin Shaw • Jenny Pate

  10. Appendix A: Radiation Data

  11. Appendix B: Equations • Inside Convection Coefficient • Thermal Resistances

  12. Appendix B: Equations • qconv,i on inner surface: • qcond through window: • qconv,o = qcond = qconv,i • Could not solve that system so we assumed h=6W/m2 to determine qconv,i and qconv,o.

  13. Appendix C: Spreadsheet Solution

  14. Appendix C: Spreadsheet Solution

  15. Appendix C: Spreadsheet Solution

  16. Sources • Incident Solar Radiation Values: http://geology.utah.gov/sep/renewable_energy/solar/images/data_tables/slcbld.jpg

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