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Environmentally Conscious Design & Manufacturing Class 11: Air Quality 2

This class covers mist models, predicting cutting fluid mist, atmospheric aerosols, atomization, splashing & dragout processes, mist control strategies, and experimental investigation for minimizing cutting fluid mist.

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Environmentally Conscious Design & Manufacturing Class 11: Air Quality 2

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  1. Environmentally Conscious Design & Manufacturing Class11: Air Quality 2 Prof. S. M. Pandit

  2. Agenda • Mist models - Introduction • Predicting cutting fluid mist • Experiment • Atmospheric aerosols

  3. Introduction • Sources • Cutting fluid • Condensation • Atomization / Condensation • Splashing & Drag out processes • Atmospheric

  4. Condensation - 1 • Heat generated in the workzone may result in cutting fluid jet boiling and evaporation.

  5. Condensation - 2 • Estimate evaporation rate through the heat flux prediction. • Analytical Techniques • Closed form solutions of temperature distributions (temporal & spatial) due to conduction and convection with a moving heat source • Experimental validation

  6. Atomization - 1 Motivation • Relationship between drop size and droplet suspension • drop size distribution • deposition in the various regions of the human respiratory tract.

  7. Atomization - 2 • Fluid jet impinging a stationary flat plate • Boundary layer • Splatter

  8. Atomization - 3 Modes of liquid film disintegration: • Drop formation mode • Ligament formation mode • Splatter

  9. Atomization - 4 - Rotating Workpiece: Wave development followed by drop separation s-surface tension force

  10. Splashing & Dragout • Splashing • Dragout • Ligament formation • Breakup modeling • Force balance

  11. Mist Control Strategies • Enclosing the machine tool • - restrict to access to the machine tool • Using air filters and mist collectors • - expensive to maintain and operate • Adding antimisting agents to cutting fluid • - be effective in suppressing mist formation • - added cost

  12. Experimental Investigation • Purpose: • Examine the underlying process conditions that • affect the mass concentration level of cutting fluid mist • Identify significant factors to lead to modifications in the • machining process as an alternative solution for • minimizing cutting fluid mist • Underlying process: • Turning

  13. Experiment Setup Lathe: Emco Compact Nozzle sizes: 0.3175 cm and 0.635 cm Fluid flow rate: 3.4 l/min Mass concentration measurement: Aerosol monitor

  14. PM10 Experiment Design • Two level fractional factorial design • Investigated variables: • Spindle speed • Workpiece diameter • Nozzle diameter • Cutting fluid oil concentration • Sampling locations (X, Z)

  15. Variable Levels for PM10 Experiment

  16. Sampling Probe Location

  17. Mass Concentration Measurement

  18. PM10 Experiment Analysis • Significant effects: • Spindle speed • - Increase speed produces a mechanical energy • and Lead to the formation of droplets. • Workpiece diameter • - A large diameter results in a great surface velocity • X-location

  19. Variable Levels for PM2.5 Experiment

  20. PM2.5 Experiment Analysis • Significant effects: only spindle speed • Fine particles are uniformly distributed in • the air around the machine tool. • A larger workpiece diameter results in more • coarse particles, but has little effect on the • number of fine particles.

  21. Summary of Experiments • Spindle speed is the most significant variable affecting • PM10 and PM2.5 mass concentration. • Workpiece diameter has a significant effect on PM 10 but • not on PM2.5 mass concentration. • X-location is significant for PM10 but not for PM2.5 mass • concentration. • Attention should be focused on high speed machining • operation (turning, face milling, and boring)

  22. Relevance in manufacturing Characterization Atmospheric Aerosols

  23. Atmospheric Aerosols - 1 • Aerosols impact the chemistry and physical processes of the troposphere in several ways: • Cloud condensation nuclei (CCN), they directly impact the earth's radiative budget via light scattering • Serve as sites for heterogeneous reactions.

  24. Atmospheric Aerosols - 2 Aerosol > 1microns serve as ice nuclei, and may contain the bulk of the aerosol mass; Submicron aerosol become CCN in the ambient atmosphere and are efficient light-scatterers.

  25. Atmospheric Aerosols - 3 • Need - Composition of aerosols as a function of size • Measurement of sulfate and soluble organics as a function of aerosol size • Example: • Quantify the fate of emitted anthropogenic and biogenic sulfur compounds

  26. Aerosol Chemistry • Heterogeneous interaction of gaseous molecules with aerosol particle surfaces • Characterization of atmospheric aerosols, mainly in the free troposphere.

  27. NOAA

  28. What happens? • Radiation scattering • Natural • Human activity (industry) • Sulfur emissions from various sources Re. National Oceanic and Atmospheric Administration

  29. Global Sulfur Emissions

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