Design of an Automobile Cabin Ventilation System Krista Cowan John Fearncombe Nathaniel Greene Brad Holtsclaw Katie Iaizzo ME 414: Thermal Fluid System Design Mechanical Engineering, IUPUI Professor: Dr. Toksoy Fall 2006

Design Parameters Satisfy space constraints dictated by other system components Satisfy space constraints dictated by other system components Minimize pressure drops in each of the three sections of the system Minimize pressure drops in each of the three sections of the system Equalize these pressure drops Equalize these pressure drops Minimize cost of the system Minimize cost of the system

System Modeling Flow evaluation performed within AFT Fathom software based upon geometry constraints Flow evaluation performed within AFT Fathom software based upon geometry constraints Evaluated potential materials based on price, density, and cost Evaluated potential materials based on price, density, and cost Utilized fluid properties dictated by the given fluid and operating temperature Utilized fluid properties dictated by the given fluid and operating temperature

Summary Table Desired Values Actual Values Flow Rate 0.05 m 3 /s Material Weight Minimize 477 g Flow Distribution 33.3%33.3%

Analysis Tools AFT Fathom for flow distribution and flow rate analysis AFT Fathom for flow distribution and flow rate analysis Microsoft Excel orifice diameter analysis Microsoft Excel orifice diameter analysis

Design Parameters 3D Pipes with 1D Analysis 3D Pipes with 1D Analysis Create 3 separate models with constant pressure Create 3 separate models with constant pressure No Elevation No Elevation Define cross-sectional area Define cross-sectional area No pump No pump Verify reasonable flow rate and velocity Verify reasonable flow rate and velocity K=3.42 at system vents K=3.42 at system vents

Initial Model

Design Process Optimized bend dimensions to reduce pressure losses Optimized bend dimensions to reduce pressure losses Selected an appropriate orifice diameter Selected an appropriate orifice diameter Experimented with sudden vs. conical contractions Experimented with sudden vs. conical contractions Experimented with venturi Experimented with venturi

Selection of Orifice Diameter

Bill of Materials

Final Model

Conclusion Total Material Costs= $12.43 Total Material Costs= $12.43 Equalized flow distribution Equalized flow distribution Equalized pressure drops Equalized pressure drops –Side Branches= Pa –Center Branch= Pa –Difference= 0.49% Minimized weight Minimized weight

Sources Class Notes and Handouts Class Notes and Handouts Idelchik, I.E. (1989). Flow Resistance: A Design Guide for Engineering Idelchik, I.E. (1989). Flow Resistance: A Design Guide for Engineering

Questions