ENGR-25_Prob_6-12_Solution.ppt 1 Bruce Mayer, PE Engineering-25: Computational Methods Bruce Mayer, PE Licensed Electrical & Mechanical Engineer Engineering 25 Prob 8-8 Solution Tutorial

ENGR-25_Prob_6-12_Solution.ppt 2 Bruce Mayer, PE Engineering-25: Computational Methods The Conduction Eqn  The General Equation:  Electricity → Ohm’s Law  Heat → Fourier’s Law [FlowRate] = [Conductance]·[PressureChange]

ENGR-25_Prob_6-12_Solution.ppt 3 Bruce Mayer, PE Engineering-25: Computational Methods The Conduction Eqn  The General Equation:  Fluids → Poiseuille's s Law  Diffusion → Fick’s Law [FlowRate] = [Conductance]·[PressureChange]

ENGR-25_Prob_6-12_Solution.ppt 4 Bruce Mayer, PE Engineering-25: Computational Methods U vs R  CONDUTANCE and RESISTANCE are simply INVERSES  So WWhat are the UNITS of “R19” Insulation?

ENGR-25_Prob_6-12_Solution.ppt 5 Bruce Mayer, PE Engineering-25: Computational Methods ANCE vs IVITY  ConductANCE from ConductIVITY: σ  G  ConductANCE from ConductIVITY: k  U th

ENGR-25_Prob_6-12_Solution.ppt 6 Bruce Mayer, PE Engineering-25: Computational Methods ANCE vs IVITY  ConductANCE from ConductIVITY: D  U D  Note that “IVITY” is a MATERIAL Property that is INdependent of material GeoMetry and/or Physical Size

ENGR-25_Prob_6-12_Solution.ppt 7 Bruce Mayer, PE Engineering-25: Computational Methods ANCE vs IVITY i.e.; “IVITY” is intrinsic or inherent to the NATURE of the Material and  “ANCE”, on the other hand, depends on “IVITY” and the Physical SIZE & SHAPE of the Material Object (W/m·K)

ENGR-25_Prob_6-12_Solution.ppt 8 Bruce Mayer, PE Engineering-25: Computational Methods P8.8: Series Heat Flow  Thermodynamically Heat Flows: HiTemp→LoTemp  In this Case the Flow Path  The Conduction Model The SAME amount of heat, q, flows thru ALL Resistances –i.e.: q = ΔT k /R k ; for any k ToTo q T2T2 T2T2 TiTi T1T1 q Heat FLow

ENGR-25_Prob_6-12_Solution.ppt 9 Bruce Mayer, PE Engineering-25: Computational Methods Put Graphic(s) Below on a Blank, wide Screen

ENGR-25_Prob_6-12_Solution.ppt 10 Bruce Mayer, PE Engineering-25: Computational Methods P 8-8

ENGR-25_Prob_6-12_Solution.ppt 11 Bruce Mayer, PE Engineering-25: Computational Methods

ENGR-25_Prob_6-12_Solution.ppt 12 Bruce Mayer, PE Engineering-25: Computational Methods

ENGR-25_Prob_6-12_Solution.ppt 13 Bruce Mayer, PE Engineering-25: Computational Methods

ENGR-25_Prob_6-12_Solution.ppt 14 Bruce Mayer, PE Engineering-25: Computational Methods The MATLAB Code

ENGR-25_Prob_6-12_Solution.ppt 15 Bruce Mayer, PE Engineering-25: Computational Methods The Results

ENGR-25_Prob_6-12_Solution.ppt 16 Bruce Mayer, PE Engineering-25: Computational Methods Bar Chart  Most Temp-Drop Occurs Across the Insulation