environmentally conscious design & manufacturing (me592) date: march 29, 2000 slide:1...
Post on 19-Dec-2015
231 views
TRANSCRIPT
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
Mist models - Introduction Predicting cutting fluid mist Experiment Atmospheric aerosols
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000 Slide:3
Introduction
Sources» Cutting fluid
– Condensation– Atomization /
Condensation– Splashing & Drag
out processes» Atmospheric
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000 Slide:4
Condensation - 1
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
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 Relationship between drop size and
droplet suspension 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
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:
Drop formation mode Ligament formation
mode Splatter
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000 Slide:9
Atomization - 4
- Rotating Workpiece:
Wave development followed by drop separation mv
r2
22 -surface tension force
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000 Slide:10
Splashing & Dragout
Splashing 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 CompactNozzle sizes: 0.3175 cm
and 0.635 cmFluid flow rate: 3.4 l/minMass 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)
162
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 morecoarse 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
Relevance in manufacturing
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
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
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
Heterogeneous interaction of gaseous molecules with aerosol particle surfaces
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?
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