Transcript MEC Background

Lightweight 2-kW Diesel-Powered Electric Generator
2005 Joint Service
Power Expo
May 3, 2005
Tampa, FL
Presented by Greg Cole
Photo taken by Army CECOM
Mainstream Generator History
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Engine Development (1991- )
– Customer: U.S. Army RD&E Center (Natick)
– Application: Small, diesel-powered, personal cooling system
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Alternator Development (1994 - )
– Customer: U.S. Army Aberdeen / OST
– Application: Miniature, multi-fueled generator
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Results
– Diesel-cycle is better than Rankine, Stirling, Brayton, and
converted spark ignition (gasoline)
– Mainstream designs and produces integrated, custom machines
2-kW Generator Requirements
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Customer: Marine Corps System Command (MCSC)
Application: Team Portable Collection System (TPCS)
Project Philosophy: Commercial hardware, not Mil-Spec
hardware
Goals:
– Power is expected to exceed 1 kW @ 28 VDC
– Desired weight is less than 50 lbs
– Desired fuel is diesel
2-kW, 28-VDC Generator Evolution
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Phase I – MCSC
– Initial demonstration
– 1.6-kW Generator: 42-lbs unmounted (14” x 11” x 16”)
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Phase II – MCSC
– Revised prototypes
– 2-kW Generator: 48-lbs unmounted
– 2-kW Generator: 65-lbs backpack mounted (18” x 17” x 20”)
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Phase III – ONR
– Two test units delivered to Army CECOM
– 2-kW Generator: 80-lbs roll cage mounted (18” x 18” x 20”)
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Phase III – MCSC
– Additional test units similar to ONR units
– Addresses issues identified during Army CECOM tests
Mainstream’s Generators
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Integrated system designed for military applications
– Alternator integrated into engine flywheel
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resulting in a lighter system
no coupling – eliminates potential failure component
reduces component count and number of wear components
– Air-cooling fan integrated into engine flywheel
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cools power electronics, engine head, oil sump
runs cooler - increases life and reliability
Mainstream designed and fabricated engine and generator
– Sized specifically for application
– Not just packaging of commercial components
2003 Power Expo
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Technology
– Integrated machine
– Light-alloy engine
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Product
– 2-kW, 28-VDC Unmounted Generator – 48 lbs (14”x11”x16”)
– 2-kW, 28-VDC Backpack Generator – 65 lbs (18”x17”x20”)
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Test Results
– Performance tests at Mainstream (Voltage, Fuel, Noise, etc.)
– Life tests at Mainstream (1000+ hrs)
– Field tests at Ft. Drum (U.S. Army 10th Mountain Division & U.S. Air
Force 20th Air Support Operations Squadron)
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Future Work
– Magnesium engine block requires further development
MCSC Field Tests at Ft. Huachuca
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Achievements
– Generator #1 successfully tested from 12/8/03 through 12/12/03
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Issues
– Vibration Mounts
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Too much or too little stiffness
New mounts have been tested for 2000+ hours
– Decompression Lever
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Lever on Generator #2 was over extended, damaged, and repaired
New design includes a stop for lever
– Cover Plate Gasket
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RTV seal on prototypes broke off internally and clogged fuel pump
Production generators have metal gasket
ONR Phase III Program
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Mainstream delivered two 2-kW, 28-VDC generators
Program Goals:
– Government tests to characterize equipment
– Identify remaining issues that need to be addressed
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Mainstream can provide a complete test report to
government personnel upon request
Testing:
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All tests performed by Army CECOM
All tests performed at Ft. Belvoir (Fall 2004)
All tests performed using JP-8
Generators were tested as delivered, no voltage or speed
adjustments were made
Voltage and Speed Adjustments
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Tested Throttle
Loosen knob and rotate
“Voltages are difficult to
adjust on this unit, and not
something that will likely be
attempted in the field by the
user” – Army CECOM
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Revised Throttle
Friction-plate design
Slide lever left-right
Easier access to oil gauge and
plug
Both Designs
 PM Generator: voltage proportional
to speed
 Set screw for maximum setting
Army CECOM Laboratory Tests
(per MIL-STD-705C)
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Physical Characterization
Start and Stop Test (503.1)
Frequency and Voltage Regulation, Stability and, Transient
Response (608.1)
Ripple Voltage (650.1)
Voltage Dip and Rise (619.2)
Fuel Consumption (670.1)
Sound Level (661.2)
Endurance (690.1)
Extreme Cold Start (701.1d)
High Temperature (710.1d)
Physical Characterization
Data provided by Army CECOM
2-kW 28-VDC Mainstream
Dry Weight
80.2 lbs
Wet Weight
84.4 lbs
Size
18”x18”x19.8”
2-kW 28-VDC DoD MTG
Wet Weight
138 lbs
Size
29.5”x16”x21.8”
Frequency and Voltage Regulation, Stability,
and Transient Response Test
Data provided by Army CECOM
Voltage
(max)
Frequency
Regulation
Stability
(30 sec.)
20.90%
6.60%
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N/A
N/A
4%
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Failed
CECOM
Req.
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2%
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Mainstream generator was never
designed to provide voltage
regulation
MCSC Spec. (20-32 VDC)
CECOM Measured (31-37 VDC)
“Most DC-AC inverters require a
voltage range from 24-32
VDC...” - Army CECOM
Mainstream redesigning
alternator to produce same
power, lower voltage
(unregulated)
Voltage regulated machine with
feedback can be designed
Ripple Voltage Test
Data provided by Army CECOM
Percent
Load
Ripple
Voltage
Percent
Ripple
100%
2.63
9.4%
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Failed
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CECOM
Req.
5.5%
Ripple is amplitude of the
alternating component of the
DC voltage
Lower ripple is better
“Ripple Voltage leads to EMI,
the higher the ripple the worse
the EMI” – Army CECOM
“Bad Ripple Voltage can
“fatigue” some electronics
components (capacitors,
transistors)” – Army CECOM
“Some fast acting switches can
be damaged by bad ripple
voltage.” – Army CECOM
Resolution of Ripple Voltage Issue
No
Capacitor
With
Capacitor
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Percent
Load
100%
100%
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Ripple
Voltage
2.63
0.81
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Percent
Ripple
9.4%
2.9%
Failed
Passed
5.5%
5.5%
CECOM
Req.
MCSC did not specify
ripple voltage or EMI
MCSC goal was to
minimize weight
Mainstream has added a
commercial capacitor to
reduce ripple voltage
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1.4” dia. x 2.8” long
0.16 lbs
fits in existing enclosure
no cost impact
ripple valleys minimized
resulting in mean voltage
increase and power increase
Voltage Dip and Rise Test
Data provided by Army CECOM
Volts
Volts
Dip
Dropped Gained
Results
(max)
5.92
CECOM Requirement
5.99
Transient
Recovery
Time
24.8% 22.0%
0/0
Passed
30%
Rise
30%
3/3
Fuel Consumption Test
Data provided by Army CECOM
Load (W)
% Rated
Fuel lbs/hr
Fuel Gal/hr
0
0%
0.80
0.120
425
21%
1.04
0.156
975
49%
1.07
0.160
1460
73%
1.23
0.185
1990
100%
1.49
0.223
Passed
2-kW MTG at 100% Load
0.330*
* “The Power Generation Branch has numbers showing some MTGs to
use only 0.26 gal/hr of JP8 at full load. The 0.33 is a fleet maximum.” –
Army CECOM
Sound Level Test
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Generator tested by Army CECOM had same muffler as
that used on the 2-kW MTG
Mainstream has developed a new muffler. Tests indicate
that noise can be reduced by 3 dB.
100.00
95.00
7
6
dBA
90.00
8
85.00
80.00
5
9
75.00
70.00
65.00
1
3
5
7
9
11
13
4
10
Position
No Load LAeq [dB]
Full Load LAeq [dB]
3
11
13
Data provided by Army CECOM
2
12
1
Endurance Test
Data provided by Army CECOM
Load
Hours
50%
36
0%
6
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75%
36
25%
36
100%
36
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Due to limited time and
budget, “conventional”
1000 hr test shortened to
150 hrs
Tested 8 hrs per day
“The unit did not have any
critical failures throughout
the test. The system was
successfully started and
operated throughout the
entire 150 hours.” - Army
CECOM
Passed
Endurance Test – Human Factors Comments
Issue
Mainstream Remark
“The system is very difficult to start at low
temperatures.” - Army CECOM
Electric starter is being added, see Additional
Development Slide
“The system can be cumbersome to turn off
after long hours of operation.” - Army
CECOM
Throttle has changed.
“The exhaust is located aimed directly at the
operator as he/she approaches the control
panel.” - Army CECOM
Exhaust direction has changed with new
muffler.
“The location of the oil fill port is very
difficult to get to, especially while wearing
gloves.” - Army CECOM
Throttle plate has changed allowing easier
access to oil fill port.
Extreme Cold Test
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Every part of system (including fuel and oil) is cold soaked
in an environmental chamber to a specified temperature for
24 hours.
The system is prepared for starting by adding lube oil to
the engine head.
“Mainstream difficult to start below 37°F.” - Army
CECOM
Mainstream generator was designed to start without any
external power supply.
Electric starter is currently being developed.
High Temperature Test
Tests consisted of starting and operating the
system at a specified temperature and ensuring
that the system could stabilize without
overheating.
 “The system was able to stabilize at rated load for
over two hours at 125°F.” - Army CECOM
 “The system was not able to provide 110%.” Army CECOM
 Maximum throttle setting was not changed.
Mainstream’s generator can provide 110%.
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Mainstream’s Life Tests
Number of Generators Tested: 2
 Number of Hours Tested: 2000+ hours each
 Approximate number of starts / stops: 60 each
 Load: variable (0-2000 W)
 Number of Critical Failures: 0
 Number of Hurricanes Survived: 1
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Additional Development
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Electric Start
– Integrated Alternator / Starter
– In development with commercial electronics vendor
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AC Power
– Testing with commercial inverter
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Cost Reduction
– Scaling-up for production
– Completing production fixtures and tooling
Summary
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28-kW 28-VDC dieselpowered electric generator
80-lbs fully instrumented
18” x 18” x 20”
0.22 gph at 2 kW
Improvements
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Throttle
Muffler
Vibration Mounts
Voltage Range (24-32
VDC)
– Voltage Ripple (3%)
– Human Factors
Contact Information
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Company Address
Mainstream Engineering Corp.
200 Yellow Place
Rockledge, FL 32955
(321) 631-3550
http://www.mainstream-engr.com
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Points of Contact
– Technical: Greg Cole, [email protected]
– Contracts: Michael Rizzo, [email protected]