Ultra Slim Air-Moving DeviceME 493 Final Report – Year 2010

June 7, 2010

Group Members

Tim Brodovsky

Joe Eccleston

Joe Frankovich

Paul Marshall

PSU Academic Advisor

Dr. Chien Wern

Intel Corporation Advisor

Jered Wikander

Executive Summary:

The following report is a final summary for the Intel Ultra Slim Air Moving device. This year’s 2010 Capstone team attempted to develop a device which fit requirements set forth by Intel, both in physical dimension as well as power consumption and airflow output.

The Capstone Team, consisting of Paul Marshall, Joseph Eccleston, Joseph Frankovich and Tim Brodovsky explored a number of possible solutions to fit the customer’s specifications. This process had a number of stages, including but not limited to:

Product Design Specification

In this phase of the design project, the Capstone Team collaborated by means of an internal and external search to find methods of producing customer-specified air flow within the physical dimensions set forth by the customer. The internal search included review of designs from last year’s Ultra Slim Air Moving Device team, as well as similar technologies adopted by industry.

House of Quality

The internal and external searches, as well as patent searches to guard against possible infringement, lead to the creation of a house of quality. This “House of Quality” applied a weighted score to the various methods of air flow in a slim package, and directed the team in making an informed decision in terms of design execution. The house of quality took into consideration such segments as air flow, power consumption, size, health concerns and cost. Each segment was assigned a weighted value in terms of importance to the overall design.

Bellows Design

The 2010 capstone team decided to adopt the design of the previous year’s team, pursuing the refinement of a bellows-type air moving device. The team decided to pursue a low cost execution of design, both in terms of the cost of labor and materials. In addition, a passive non-moving design was also pursued in order to reduce the number of moving parts and reduce noise.

Results

The team satisfactorily met the criteria for size, and moving parts worked as expected. The amount of airflow was significantly low compared to what was requested/expected, due in part to the efficiency of the passive air valves incorporated in the design. It is the conclusion of the team that a mechanical check-valve system would need to be incorporated into the design to promote efficient one directional air-flow. The design of such check valves would likely be the focus of continued and successful development.

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Table of Contents

Page

Executive Summary 1

Introduction and Background 3

Mission Statement 3

Design Requirements 3

Top Level Designs 4

Final Design 6

Testing and Results 9

Conclusion and Recommendations 10

Appendix A: Product Design Specifications 12

Appendix B: Concept Evaluations 15

Appendix C: Bill of Materials 16

Appendix D: Tesla valve information 17

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Introduction and Background Information

The increasing demand for portable devices of greater performance and improved battery life (i.e.

CPUs, video cards, chip sets, memory, etc.) gives rise to the problematic issue of heat generation. If the heat

generated by individual electric components cannot be transferred from these devices at a sufficient rate,

serious reduction in performance and life of the device may occur. In many ways, the ability to keep

electrical components at a nominal temperature is one of the major limiting factors in how much portable

electronics can do.

To address these problems it is desirable to provide a convective mode of heat transfer. Forced

(driven) convection is a practical way to dissipate heat quickly and efficiently, given sufficient air flow. This

leads to the desire for an air moving device which itself follows the same governing design criteria as the

portable device that it cools. It should be incorporated into an electronics package such that the air moving

devices dimensions and power consumption have as little impact on the electric device as possible. This

leaves room for extra components to be used in a portable device, while ensuring adequate cooling with

improved battery life and performance.

Mission Statement

The goal of the Ultra-Slim Air Moving capstone team is to design and test an air-moving device,

constrained to be no more than 3 mm thick. The device should output at least 0.075 actual cubic feet per

minute (ACFM) of airflow with a maximum pressure of 0.045 inches of water gauge (IWG).

Design Requirements

The specifications given the highest priority during the design process are as follows:

A maximum thickness of 3 mm

A target air flow of 0.075 ACFM

A maximum air pressure of 0.045 IWG

The following are other specifications that were given consideration during the design process:

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Noise must be within acceptable limits for human comfort

Reasonably easy to install or remove

Operate in a safe fashion

Safe to use near computer components

Not produce any harmful byproducts

Not infringe on any known patents

The specifications are more fully described in the Product Design Specifications (PDS) in Appendix A.

Top Level Designs

Extensive internal and external research was done in order to fulfill the requirements listed above. There

were three top level designs; Piezoelectric, ionic air flow, and bellows design. After much consideration the

team chose the below design with explanation as to why below. A choice then had to be made between

different coils, magnets, and flow management.

Piezoelectricity is the ability of some materials such as crystals to generate electric potential in response to

applied mechanical stress. This process can also be reversed by applying electricity, which causes the

material to expand and contract (as seen in Figure 1). The idea was to use flat oscillating fan blade inside the

3mm constraint. The benefit to this design was that it consumes relatively low power. The disadvantages to

using piezoelectricity was that it can be loud, expensive, and at its best case the volume of the material can

only have a 4% change.

Figure 1: Demonstration of a piezoelectric crystal expanding and contracting because of electricity.

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Our second choice was the Ionic airflow which is commonly used for air purifier filters. It charges air

particles and attracts them to a surface as shown in Figure 2. This device could be designed to pass air

through a 3mm device. The great thing about this system is it would have no moving parts and be

completely silent. The problem is it produces ozone. The ozone produced could be filtered out but the extra

material and space would conflict with our space requirements. Ionic air also corrodes plastics and requires

high voltage. Our team created a prototype that worked and had airflow that could be felt by the hand.

Figure 2: Computer generated demonstration of ionic airflow.

Our third and chosen design was the bellows design. The bellows design is essentially a magnet in a

diaphragm closed by two plates. There is a coil on the outside that pulses the magnet to get air flow. The

bellow design had the most pros over cons compared to any other design. It is cheap to manufacture, easy to

build, has great potential for optimization, and fits dimension specs. On the other hand it can be loud at

certain frequencies and can draw more power relative to the other designs.

Our three main decisions we had to make for the bellow design was what type of magnet/shape, coil

gauge/shape, and valve type and case design. There were 4 different magnet size and shapes we

experimented with as shown in figure 3. The final shape and size was chosen to be two magnets with 1/4

inch diameter each by testing of best airflow. We tested 5 different coil diameters and found that 32-gauge

wire has the greatest attraction to the magnet for the specific coil diameter we used. Our most difficult

decision was choosing the airflow path. Our initial design had passively actuated “flapper” valves. This

system would have the advantage of being efficient, but may potentially cause noise and have fatigue issues.

The design we went with was a modified Tesla valve system. This system takes advantage of certain

properties of air such as inertia, viscosity and vacuum/compression “tension”, in order to compel airflow in

one direction. This system has the advantage of using no moving parts and is quiet, but it is potentially

inefficient.5

Figure 3: Multiple casings with different magnet size and placement configurations.

Final Design

The final bellows design consisted of four main parts: a top and bottom casing, a diaphragm, and a

flat solenoid electromagnet. The top and bottom casings were designed in Solidworks and the diaphragm

and coil were hand-made by the capstone team.

The casing: The casing was designed using the CAD program Solidworks and was sent to Solid Concepts

for rapid prototyping. The dimensions of the combined casings are 51mm by 45mm by 3mm. The modified

Tesla channels that were implemented were arranged in two rows of seven on both the entrance and exit

edges, with a cavity in the center for the diaphragm, as shown in Figure 4. Alignment pegs and holes were

created to facilitate proper aligning during assembly, and dimples were created in line with the magnets on

the diaphragm to allow the maximum lateral movement (see Figure 5). The size of the Tesla valves were

selected to allow air to enter and exit freely, but to impose more directionality by discouraging two-way

airflow in a single channel.

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Figure 4: One half of the device casing.

Figure 5: Model showing alignment using magnet frame and pins.

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The diaphragm: The diaphragm was made using a latex sheet less than 0.050” in thickness. The team

decided that for a more secure fit that the diaphragm would be attached in slight tension via adhesive to the

bottom of the casing, using a quick-dry glue gel. The same gel was used to attach the ¼” magnets to the

latex. The team had Solid Concepts rapid prototype an alignment frame so that the magnets would fit

perfectly into the dimples in the casing. Once the magnets were attached, the frame was removed. The

magnets used were purchased from K&J Magnetics and were rated at N42 strength. Two smaller magnets

were chosen as opposed to one large magnet to facilitate a greater amount of airflow through the cavity.

The solenoid: The flat electromagnetic solenoid was constructed using a 34-gauge enamel magwire. It

proved to be very difficult to make a tight, flat solenoid that had no overlap, which was of utmost

importance because overlap would significantly increase the thickness. Eventually, the team designed a

“coil jig,” which aided greatly in the construction of the solenoid. The jig was essentially a ¼” aluminum

bar with a ½” shallow groove cut into it. A flat plastic disk was attached over the groove, which would

allow the wire to seat on the disk and one end could be drawn through the groove. A second plastic disk

was then placed against the first, and was supported from behind by a compression spring. The disks would

allow the wire to wrap but would discourage overlap. The jig could then be placed into a hand drill to aid

with winding. Lastly, a canal was cut into the bottom disk (the attached one) so that, when the coil was

finished, a piece of tape or adhesive could be applied to prevent the coil from coming undone when the top

disk was removed.

Figure 6: A sketch of the coil jig.

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Figure 7: A completed coil made using the coil jig.

Testing and Results

Pertaining to the PDS requirements, we have succeeded in creating a device that was approximately

3mm thick. The form-factor was reduced to 45x51mm as well. In this respect, we succeeded. Our design

was also substantially quieter than last year’s design, as well as safe to handle and operate.

With regards to the performance of the device, we were unable to achieve reliable results. The goals

were based off of last year’s achieved performance, which was effective enough to distort the flame from a

lighter. In the laboratory, we were certainly able to deform a flame in a similar fashion, but we were not able

to record numerical results at the Intel testing facility. It is noteworthy that the LFE (Laminar Flow Element)

used in last year’s test was in another part of the country during our testing period. As a result of

intermittent reliance on our device and inconsistent testing circumstances, we could not obtain a benchmark

value to compare to last year’s design.

For a cost analysis, our magnets could be obtained for 11 cents each, in bulk from K&J Magnetics.

The coil needs only several feet of wound 34-gauge copper wire. At $10.09 per 770 ft, we used about 6.5

cents worth of wire. The latex was 2x2 inches in area out of a 24”x15” that cost $13.12, implying a cost of

14.58 cents. No doubt latex rubber sheeting can be found cheaper elsewhere though. Our plastic parts cost

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$62 each to produce. Each prototype model had 3 parts made for it, but only two ended up being used once

the frames aligned the magnets properly (meaning they may be reused indefinitely). As such, the two halves

cost $124. This cost would be dramatically reduced if a mold of the prototype was created and this design

was made in mass production.

Conclusion and Recommendations

Thickness of the device was our primary form factor restraint followed by the mode of operation.

The team was heavily discouraged from using a rotating blade for the basis of our design, but we needed to

produce 0.075 AFCM of air flow at 0.045 IWG of pressure. Barring continuous flow from rotating blades,

one supposes that a pulsed device of some sort must be utilized. Considering our size restraints, this would

imply that our device (assuming 2”x2”) would need to displace 4.6 times its own volume every second.

While this is certainly achievable, one must take into account the real world limitations of this device. Our

final design used a substantial portion of the available space for the valve portion, the magnet and the

diaphragm. What was left was a substantially smaller working space. Even so, if the operating frequency

had been above approximately 60 Hz, it could have had a chance. However, late in the prototyping phase,

we discovered that our “Tesla valve” design worked on a concept called diodicity; or output/backflow. In

some scholarly articles we later discovered, we found that the optimal diodicity of our design would be

around 1.2 at best, meaning that we could expect less than 16.7% the efficiency of an ideal on/off check

valve. Now our 60 Hz becomes at least 360 Hz to produce such a volume of airflow. While we were finding

some resonant frequencies in that neighborhood, the amplitudes were far short of being effective. The

voltage required to produce such amplitude were excessive to the point of warping the device. Next year’s

design team would do well to consider requesting more thermally resistant material for rapid prototyping.

Another observation is that multiple, smaller magnets is a poor choice when dealing with a flat coil

design. The smaller magnets offer less reactive force and are often too far away from the center of the

electromagnetic coil’s center where the only practically useful part of the field is found. Even worse, we

noticed that in the two magnet setup, one magnet would tend to vibrate exuberantly while the second would

lay unperturbed. At a different frequency, the magnets would switch roles. This implies that the two

magnets would act as two separate mass/spring/damper systems, rather than the hoped for unified system.

Even if connected via a link of some sort, it is suspected that the connecting link would be under a varying

moment, causing reciprocating torsion like a diving board, rather than joining the magnets in their force

expression.

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In conclusion, the bellows design still has a chance of working. It is the end of the term, and thus too

late for us to make the radical changes necessary to achieve full functionality, but next year’s team of

engineers may benefit from the knowledge that maximizing the working volume of the device will lower the

frequency requirements. Further, if at all possible, seek to have a valve system with near 100%

effectiveness.

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Appendix A: Product Design Specifications

PerformanceCustomer Requirements Metrics Targets Basis Verification

Intel Air flow ACFM 0.075 Customer testingIntel Air pressure IWG 0.045 Customer testing

Intel Noise Comparative low Customer testing

Size and ShapeCustomer Requirement Metric Target Basis Verification

Intel thickness mm 3 or less Customer measure

InstallationCustomer Requirement Metric Target Basis Verification

Intel installableconformation to typical fans installable Customer testing

Quality and ReliabilityCustomer Requirement Metric Target Basis Verification

Intelworking model working yes Customer testing

MaintenanceCustomer Requirements Metrics Targets Basis Verification

Intel removable remove yes Customer testing

SafetyCustomer Requirement Metric Target Basis Verification

Intel safe operationinjuries or damage 0 Customer testing

MaterialsCustomer Requirement Metric Target Basis Verification

Intel

safe for use near

computer components

interference with other

components 0 Customer

study of material

properties

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DocumentationCustomer Requirement Metric Target Basis Verification

PSU

entire process properly

documentedundocumente

d processes 0Course

Requirements Grade

TimelinesCustomer Requirement Metric Target Basis Verification

ME 492Progress Report

Reports Submitted 1 report

Course Requirements Grade

ME 493 Design ReportReports

Submitted 1 reportCourse

Requirements Grade

IntelCompleted Retrofitting

Device completed 1 device

Customer Feedback and

Course Requirement Grade

LegalCustomer Requirement Metric Target Basis Verification

IntelNo patent violations

Patents violated 0 violations Customer

Patent research

EnvironmentCustomer Requirement Metric Target Basis Verification

IntelNo harmful byproducts

Harmful byproducts 0 Customer testing

TestingCustomer Requirement Metric Target Basis Verification

IntelMust be testable

Tests unable to be performed 0 tests Customer

Intel test procedures

WeightCustomer Requirement Metric Target Basis Verification

IntelAcceptable

weight grams 300 or less Customer testing

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Not ApplicableCriteria Reason

Applicable codes and Standards None required for prototyping

Ergonomics Internal componentCompany constraints and Procedures None required for prototyping

Cost of production per part None required for prototyping

Life in service Not requiredManufacturing Facilities None required for prototyping

Shipping None required for prototyping

Aesthetics There are no requirementsPackaging None required for prototyping

Disposal Not requiredQuantity None required for prototyping

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Appendix B: Concept Evaluation and Selection

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Appendix C: Bill of Materials

Beginning Budget $ 2,520.00 Expenses $ 981.11 Encumbered $ - Balance $ 1,538.89

Date Account PO/IV# Amount Vendor 2/22/2010 20103 $144.39 Norvac Electronics3/11/2010 20103 Reimbursement $58.88 Joseph

Eccleston 1/20/2010 20103 IV014096 $136.00 Omega - thermocouples and

adhesive tape 4/27/2010 20215 I0660956 $614.88 Solid

Concepts 4/8/2010 20103 Reimbursement $16.96 Tim Brodovsky Reimbursement--Michael's-adhesive

testing supplies 4/12/2010 20103 Reimbursement $10.00 Joseph Eccleston--K&J

Magnetics, magnets

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Appendix D: Tesla valve information

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