Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:1 Environmentally Conscious Design & Manufacturing Class 11: Air Quality 2 Prof. S. M. Pandit

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:2 Agenda l Mist models - Introduction l Predicting cutting fluid mist l Experiment l Atmospheric aerosols

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:3 Introduction l Sources »Cutting fluid –Condensation –Atomization / Condensation –Splashing & Drag out processes »Atmospheric

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:4 Condensation - 1 l Heat generated in the workzone may result in cutting fluid jet boiling and evaporation.

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:5 Condensation - 2 l 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

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:6 Atomization - 1 Motivation l Relationship between drop size and droplet suspension l drop size distribution »deposition in the various regions of the human respiratory tract.

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:7 Atomization - 2 l Fluid jet impinging a stationary flat plate »Boundary layer »Splatter

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:8 Atomization - 3 Modes of liquid film disintegration: l Drop formation mode l Ligament formation mode l Splatter

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:9 Atomization Rotating Workpiece: Wave development followed by drop separation  -surface tension force

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:10 Splashing & Dragout l Splashing l Dragout »Ligament formation »Breakup modeling –Force balance

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide: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

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide: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

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:13 Experiment Setup Lathe: Emco Compact Nozzle sizes: cm and cm Fluid flow rate: 3.4 l/min Mass concentration measurement: Aerosol monitor

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide: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)

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:15 Variable Levels for PM10 Experiment

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:16 Sampling Probe Location

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:17 Mass Concentration Measurement

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide: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

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:19 Variable Levels for PM2.5 Experiment

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide: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.

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide: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)

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:22 Atmospheric Aerosols l Relevance in manufacturing l Characterization

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:23

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:24 Atmospheric Aerosols - 1 l 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.

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:25 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.

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:26 Atmospheric Aerosols - 3 l 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

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:27 Aerosol Chemistry l Heterogeneous interaction of gaseous molecules with aerosol particle surfaces l Characterization of atmospheric aerosols, mainly in the free troposphere.

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:28 NOAA

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:29 What happens? l Radiation scattering »Natural »Human activity (industry) –Sulfur emissions from various sources Re. National Oceanic and Atmospheric Administration

Environmentally Conscious Design & Manufacturing (ME592) Date: March 29, 2000 Slide:30 Global Sulfur Emissions