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Published byFrancis Hicks Modified over 8 years ago
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By: Matthew Irvine and Cristina Belew
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Origination and Goals Partnership with Habitat for Humanity Their goal is to lower the overall cost to owner Studied the effect of insulation on energy costs Looked for the effects of different insulations and insulating methods Recommend the insulations with the lowest cost to owner
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Four Different Areas Wall insulation types Framing dimension selection Attic insulation Duct Insulation
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Design Modeling Assumptions h and k values No thermal contact resistance Siding geometry No radiation in attic, theoretical venting
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Decision of appropriate options Wall Insulation Stud Sizing Duct Insulation
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Modeling Techniques We began with a square foot section Moved to a larger section with other elements included Completed our analysis by simulating an entire house (Woodruff House)
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Studied Design Description Small and large wall section for 2X4 and 2X6 Attic Section Duct Section
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2 x 4 Stud, 1 x 1 m 2 Section: Overview Equation for heat flux Q = (T 2 – T 1 )/R total Studied 3 times during the year January – 2.778 ºC April – 15.56 ºC July - 27.2 ºC Desired inside temperature- 22.2 ºC Drywall Insulation Plywood Air Pocket Hardiboard
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2 x 4 Stud, 1 x 1 m 2 Section: R- values R of Convection – 1/h*A h- convection coefficient (W/m·°C) A- area of convection (m 2 ) R of a certain material – L/k*A k- thermal conductivity L- thickness of material (m) A- area of material (m 2 ) R total = R outside,convection + R drywall + R insulation + R hariboard + R air pocket + R siding + R inside,convection R (W/m·°C) RiRi R january R april R july R hardiboard R plywood R insulation R drywall R air pocket R-Total January R-Total April R-Total July 0.042 W/m 2 ·°C 0.1000.02940.03530.04410.05670.1062.120.07130.1562.6362.6422.651 0.03 W/m 2 ·°C 0.1000.02940.03530.04410.05670.1062.960.07130.1563.4833.4893.497 0.046 W/m 2 ·°C 0.1000.02940.03530.04410.05670.1061.930.07130.1562.4522.4582.467
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2 x 4 Stud, 1 x 1 m 2 Section: Theoretical vs. Simulation Heat Flux Heat flux for each insulation and temperature difference was calculated next with Solidworks and compared to the theoretical calculations done. Heat Flux (W-theoretical) JanuaryAprilJuly 0.042 W/m 2 ·°C7.3672.513-1.886 0.03 W/m 2 ·°C5.5771.904-1.430 0.046 W/m 2 ·°C7.92002.701-2.027 Heat Flux (W- simulation) JanuaryAprilJuly 0.042 W/m 2 ·°C 7.42972.5393-1.8999 0.03 W/m 2 ·°C 5.61231.9192-1.4372 0.046 W/m 2 ·°C 7.99252.7312-2.0429 Error (%)JanuaryAprilJuly 0.042 W/m 2 ·°C0.84%0.63%0.91% 0.03 W/m 2 ·°C0.76%0.79%1.11% 0.046 W/m 2 ·°C0.73%0.50%0.78%
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2 x 4 Stud, 1 x 1 m 2 Section: FEA (January) 0.042 W/m 2 ·ºC0.03 W/m 2 ·ºC0.046 W/m 2 ·ºC
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2 x 4 Stud, 1 x 1 m 2 Section: FEA (April) 0.042 W/m 2 ·ºC0.03 W/m 2 ·ºC0.046 W/m 2 ·ºC
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2 x 4 Stud, 1 x 1 m 2 Section: FEA (July) 0.042 W/m 2 ·ºC0.03 W/m 2 ·ºC0.046 W/m 2 ·ºC
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2 x 6 Stud, 1 x 1 m 2 Section: R- values Next Step: How does the heat flux change when more insulation is added with a 2 x 6. The R-values were calculated again when a thicker insulation. R (W/m·°C) RiRi R january R April R july R hardiboard R plywood R insulation R drywall R air pocket R-Total January R-Total April R-Total July 0.042 W/m 2 ·°C 0.1000.02940.03530.04410.05670.1063.330.07130.1563.8463.8523.860 0.03 W/m 2 ·°C 0.1000.02940.03530.04410.05670.1064.660.07130.1563.4833.4893.497 0.046 W/m 2 ·°C 0.1000.02940.03530.04410.05670.1063.040.07130.1562.4522.4582.467
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2 x 6 Stud, 1 x 1 m 2 Section: Theoretical vs. Simulation Heat Flux Here are the heat flux numbers for the SolidWorks simulations compared to the theoretical calculations done: Heat Flux (W-theoretical) JanuaryAprilJuly 0.042 W/m 2 ·°C7.3672.520-1.886 0.03 W/m 2 ·°C5.5771.904-1.430 0.046 W/m 2 ·°C7.9202.701-2.027 Heat Flux (W- simulation) JanuaryAprilJuly 0.042 W/m 2 ·°C7.42972.5393-1.8999 0.03 W/m 2 ·°C5.61231.9192-1.4372 0.046 W/m 2 ·°C7.99252.7312-2.0429 Error (%)JanuaryAprilJuly 0.042 W/m 2 ·°C0.61%0.80%0.51% 0.03 W/m 2 ·°C0.47%0.69%0.38% 0.046 W/m 2 ·°C0.65%0.85%0.55%
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2 x 6 Stud, 1 x 1 m 2 Section: FEA (January) 0.042 W/m 2 ·ºC0.03 W/m 2 ·ºC0.046 W/m 2 ·ºC
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2 x 6 Stud, 1 x 1 m 2 Section: FEA (April) 0.042 W/m 2 ·ºC0.03 W/m 2 ·ºC0.046 W/m 2 ·ºC
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2 x 6 Stud, 1 x 1 m 2 Section: FEA (July) 0.042 W/m 2 ·ºC0.03 W/m 2 ·ºC0.046 W/m 2 ·ºC
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Conclusions from Theoretical and SolidWorks Studies of 1 x 1 m 2 Section Based upon this data, fiberglass is the insulation to choose. The heat flow through the section of wall is the lowest compared to the other insulation choices.
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3 Sections of Wall with 2 x 4 Studs: Overview The next step: A bigger section of wall with studs included. The R-values had to be calculated for the sections of wall next to the studs and next to the insulation. Drywall Insulation Studs Plywood Hardiboard
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3 Sections of Wall with 2 x 4 Studs: R-values RiRi R January R April R July R hardiboard R plywood R insulation R drywall R studs 1/R-Total January 1/R-Total April 1/R-Total July 0.042 W/m 2 ·°C 0.0380.01130.01360.01700.06490.0410.810.02751.0020.98330.9966 0.03 W/m 2 ·°C 0.0380.01330.01360.01700.06490.0411.140.02750.75450.75430.7524 0.046 W/m 2 ·°C 0.0380.01330.01360.01700.06490.0410.740.02751.0771.0761.073 Studs0.27640.08130.09750.12180.46630.29250.19721.75510.32590.32410.3216
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3 Sections of Wall with 2 x 4 Studs: Heat Flux Comparisons Heat Flux (W-simulation) 0.042 W/m 2 ·°C0.03 W/m 2 ·°C0.046 W/m 2 ·°C January 25.7920.9827.24 April 8.6807.1619.300 July -6.590-5.370-6.971 Heat Flux (W-Theoretical) 0.042 W/m 2 ·°C0.03 W/m 2 ·°C0.046 W/m 2 ·°C January 25.8521.5727.57 April 8.8807.4149.414 July -6.685-5.585-7.138 Error (%)0.042 W/m 2 ·°C0.03 W/m 2 ·°C0.046 W/m 2 ·°C January 0.21%2.73%1.20% April 2.25%3.41%1.21% July 1.43%3.85%2.34%
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3 Sections of Wall with 2 x 4 Studs: FEA (January) 0.046 W/m 2 ·ºC 0.03 W/m 2 ·ºC 0.042 W/m 2 ·ºC
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3 Sections of Wall with 2 x 4 Studs: FEA (April) 0.046 W/m 2 ·ºC0.03 W/m 2 ·ºC 0.042 W/m 2 ·ºC
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3 Sections of Wall with 2 x 4 Studs: FEA (July) 0.046 W/m 2 ·ºC0.03 W/m 2 ·ºC0.042 W/m 2 ·ºC
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Duct Insulation: Overview Next step: Determine what size fiberglass insulation is best Assumptions: Air flowing through is 22.2 °C Air surrounding duct is the temperature of the outside since placed in attic Three fiberglass insulation size choices of 2 inches, 4 inches and 6 inches. The analysis in Solidworks was performed on a three foot section of duct. Reflective Barrier Fiberglass insulation Aluminum Core Air Flow
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Duct Insulation: R-values For a cylinder, the equation for the total r-value changes. It is dependent on the radius of each section of material. R-Values R convection, inside R aluminum R fiberglass R reflective barrier R ouside,convection 2 inch 0.13710.00070763.5290.000024530.1523 4 inch 0.13710.00070765.7143121.69064E-050.1054695 6 inch 0.13710.00070767.2980.000012190.08072
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Duct Insulation: Heat Flux Heat Flux- SimulationJanuaryAprilJuly 2 inch 5.0741.7351.3057 4 inch 3.30251.13230.8393 6 inch 2.5840.8830.6652 Heat Flux- TheoreticalJanuaryAprilJuly 2 inch 5.0901.7441.304 4 inch 3.2601.1150.8492 6 inch 2.62020.898350.67376 Error (%)JanuaryAprilJuly 2 inch -0.31%-0.52%0.13% 4 inch 1.30%1.55%-1.17% 6 inch -1.38%-1.71%-1.27%
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Duct Insulation: FEA Simulation (January) January Analysis: Temperature flow through the center at 22.2 ºC and the surrounding temperature 2.778 ºC 2 inches 4 inches6 inches
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Duct Insulation: FEA Simulation (April) 6 inches4 inches 2 inches April Analysis: Temperature flow through the center at 22.2 ºC and surrounding temperature at 15.56 ºC
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Duct Insulation: FEA Simulation (July) July Analysis: Temperature flow through the center at 22.2 ºC and the surrounding temperature 27.2ºC 2 inches 4 inches6 inches
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Attic Insulation: Overview Next Step: Which insulation is the best choice for the attic Assumptions: Attic temperature is the outside temperature Inside temperature is 22.2 °C Drywall Insulation
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Attic Insulation: R-values R-Values R inside R january R april R July R insulation R drywall R- Total January R- Total April R-Total July 0.042 W/m 2 ·°C 0.108 0.1632.120.07132.407 2.518 0.03 W/m 2 ·°C 0.108 0.1632.960.07133.247 3.358 0.046 W/m 2 ·°C 0.108 0.1631.930.0713 2.217 2.328
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Attic Insulation: Heat Flux Heat Flux- TheoreticalJanuaryAprilJuly 0.042 W/m 2 ·°C 8.0682.758-1.986 0.03 W/m 2 ·°C 5.9812.045-1.489 0.046 W/m 2 ·°C 8.7592.995-2.148 Heat Flux- SimulationJanuaryAprilJuly 0.042 W/m 2 ·°C 8.08842.7731-1.9886 0.03 W/m 2 ·°C 5.98162.0508-1.4877 0.046 W/m 2 ·°C 8.75923.003-2.1457 Error (%)JanuaryAprilJuly 0.042 W/m 2 ·°C 0.25%0.55%0.13% 0.03 W/m 2 ·°C 0.01%0.28%-0.09% 0.046 W/m 2 ·°C 0.00%0.27%-0.11%
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House Model: Overview Next Step: Move from a small section of wall or attic to a full wall or ceiling. Each section of wall was simulated separately and then the heat flux of all were added together.
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House Model: Layout
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House Model: FE Analysis Here are the results for the heat flux traveling through each wall of the house model. Heat Flux (W) 0.042 W/m 2 ·ºC for January 0.042 W/m 2 ·ºC for April 0.042 W/m 2 ·ºC for July Back Wall329.03110.04-80.303 Front Wall276.6493.284-68.72 Left Wall489164.81-121.35 Right Wall484.78163.55-120.32 Ceiling852.16292.7-210 Heat Flux Total2431.61824.384-600.693
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House Model: FEA Simulation Right and Left Walls
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House Model: FEA Simulation Front Wall
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Quantitative Results Insulation Type (30%) Duct Thickness (36% compared to 20%) Stud Sizing (~30%)
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Future Work Determine thermal conductivities for each insulation Find quantitative difference of heat flux for different insulation choices Compare cost difference between insulations with energy savings or loses
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References Heat and Mass Transfer (Cengel; McGraw-Hill) www.engineeringtoolbox.com www.engineeringtoolbox.com www.matweb.com www.matweb.com www.energysavers.com www.energysavers.com Engineering Analysis with SolidWorks Simulation 2010 (Kurowski; SDC Publications) http://www.ornl.gov/sci/roofs+walls/insulation/ins_01.html http://www.ornl.gov/sci/roofs+walls/insulation/ins_01.html http://www.jameshardie.com/ http://www.jameshardie.com/ www.lowes.com www.lowes.com Habitat for Humanity
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