Transcript Environmentally Conscious Design & Manufacturing ME592E-1

Environmentally Conscious
Design & Manufacturing
Class 11: Air Quality 2
Prof. S. M. Pandit
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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Agenda
Mist models - Introduction
 Predicting cutting fluid mist
 Experiment
 Atmospheric aerosols

Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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Introduction

Sources
» Cutting fluid
– Condensation
– Atomization /
Condensation
– Splashing & Drag
out processes
» Atmospheric
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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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
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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
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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
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Atomization - 2

Fluid jet impinging a
stationary flat plate
» Boundary layer
» Splatter
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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Atomization - 3



Modes of liquid film
disintegration:
Drop formation mode
Ligament formation
mode
Splatter
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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Atomization - 4
- Rotating Workpiece:
Wave development followed by drop separation
mv 2
 2 r
2
-surface tension force
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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Splashing & Dragout


Splashing
Dragout
» Ligament formation
» Breakup modeling
– Force balance
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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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
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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
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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
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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PM10 Experiment Design
Two level 2
6 1
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
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Variable Levels for PM10
Experiment
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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Sampling Probe Location
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Mass Concentration Measurement
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Date: March 29, 2000
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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
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Variable Levels for PM2.5
Experiment
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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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
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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
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Atmospheric Aerosols

Relevance in manufacturing

Characterization
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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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
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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 lightscatterers.
Environmentally Conscious Design & Manufacturing (ME592)
Date: March 29, 2000
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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
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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
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NOAA
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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
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Global Sulfur Emissions
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