Lightweight 2-kW Diesel-Powered Electric Generator

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Lightweight 2-kW Diesel-Powered Electric Generator
2005 Joint ServicePower ExpoMay 3, 2005Tampa,
FLPresented by Greg Cole
Photo taken by Army CECOM
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Mainstream Generator History

• Engine Development (1991- )
• Customer U.S. Army RDE Center (Natick)
• Application Small, diesel-powered, personal
  cooling system
• Alternator Development (1994 - )
• Customer U.S. Army Aberdeen / OST
• Application Miniature, multi-fueled generator
• Results
• Diesel-cycle is better than Rankine, Stirling,
  Brayton, and converted spark ignition (gasoline)
• Mainstream designs and produces integrated,
  custom machines

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2-kW Generator Requirements

• 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 _at_ 28 VDC
• Desired weight is less than 50 lbs
• Desired fuel is diesel

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2-kW, 28-VDC Generator Evolution

• Phase I MCSC
• Initial demonstration
• 1.6-kW Generator 42-lbs unmounted (14 x 11 x
  16)
• Phase II MCSC
• Revised prototypes
• 2-kW Generator 48-lbs unmounted
• 2-kW Generator 65-lbs backpack mounted (18 x
  17 x 20)
• Phase III ONR
• Two test units delivered to Army CECOM
• 2-kW Generator 80-lbs roll cage mounted (18 x
  18 x 20)
• Phase III MCSC
• Additional test units similar to ONR units
• Addresses issues identified during Army CECOM
  tests

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Mainstreams Generators

• Integrated system designed for military
  applications
• Alternator integrated into engine flywheel
• 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
• 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

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2003 Power Expo

• Technology
• Integrated machine
• Light-alloy engine
• Product
• 2-kW, 28-VDC Unmounted Generator 48 lbs
  (14x11x16)
• 2-kW, 28-VDC Backpack Generator 65 lbs
  (18x17x20)
• 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)
• Future Work
• Magnesium engine block requires further
  development

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MCSC Field Tests at Ft. Huachuca

• Achievements
• Generator 1 successfully tested from 12/8/03
  through 12/12/03
• Issues
• Vibration Mounts
• Too much or too little stiffness
• New mounts have been tested for 2000 hours
• Decompression Lever
• Lever on Generator 2 was over extended, damaged,
  and repaired
• New design includes a stop for lever
• Cover Plate Gasket
• RTV seal on prototypes broke off internally and
  clogged fuel pump
• Production generators have metal gasket

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ONR Phase III Program

• Mainstream delivered two 2-kW, 28-VDC generators
• Program Goals
• Government tests to characterize equipment
• Identify remaining issues that need to be
  addressed
• Mainstream can provide a complete test report to
  government personnel upon request
• Testing
• 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

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Voltage and Speed Adjustments

• 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

• 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

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Army CECOM Laboratory Tests(per MIL-STD-705C)

• 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)

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Physical Characterization
Data provided by Army CECOM
2-kW 28-VDC Mainstream 2-kW 28-VDC Mainstream
Dry Weight 80.2 lbs
Wet Weight 84.4 lbs
Size 18x18x19.8
2-kW 28-VDC DoD MTG 2-kW 28-VDC DoD MTG
Wet Weight 138 lbs
Size 29.5x16x21.8
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Frequency and Voltage Regulation, Stability, and
Transient Response Test
Data provided by Army CECOM

• 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

Regulation Stability (30 sec.)
Voltage (max) 20.90 6.60
Frequency N/A N/A
Failed Failed Failed
CECOM Req. 4 2
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Ripple Voltage Test
Data provided by Army CECOM

• 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

Percent Load 100
Ripple Voltage 2.63
Percent Ripple 9.4
Failed
CECOM Req. 5.5
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Resolution of Ripple Voltage Issue

• MCSC did not specify ripple voltage or EMI
• MCSC goal was to minimize weight
• Mainstream has added a commercial capacitor to
  reduce ripple voltage
• 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

No Capacitor With Capacitor
Percent Load 100 100
Ripple Voltage 2.63 0.81
Percent Ripple 9.4 2.9
Failed Passed
CECOM Req. 5.5 5.5
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Voltage Dip and Rise Test
Data provided by Army CECOM
Volts Dropped Volts Gained Dip Rise Transient Recovery Time
Results (max) 5.92 5.99 24.8 22.0 0/0
Passed Passed Passed Passed Passed Passed
CECOM Requirement CECOM Requirement CECOM Requirement 30 30 3/3
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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 2-kW MTG at 100 Load 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
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Sound Level Test

• 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.

Data provided by Army CECOM
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Endurance Test
Data provided by Army CECOM

• 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

Load Hours
50 36
0 6
75 36
25 36
100 36
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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.
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Extreme Cold Test

• 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 37F. -
  Army CECOM
• Mainstream generator was designed to start
  without any external power supply.
• Electric starter is currently being developed.

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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 125F. - Army CECOM
• The system was not able to provide 110. - Army
  CECOM
• Maximum throttle setting was not changed.
  Mainstreams generator can provide 110.

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Mainstreams 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

• Electric Start
• Integrated Alternator / Starter
• In development with commercial electronics vendor
• AC Power
• Testing with commercial inverter
• Cost Reduction
• Scaling-up for production
• Completing production fixtures and tooling

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Summary

• 28-kW 28-VDC diesel-powered electric generator
• 80-lbs fully instrumented
• 18 x 18 x 20
• 0.22 gph at 2 kW
• Improvements
• Throttle
• Muffler
• Vibration Mounts
• Voltage Range (24-32 VDC)
• Voltage Ripple (3)
• Human Factors

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Contact Information

• Company Address
• Mainstream Engineering Corp.
• 200 Yellow Place
• Rockledge, FL 32955
• [phone]
• http//www.mainstream-engr.com
• Points of Contact
• Technical Greg Cole, gsc_at_mainstream-engr.com
• Contracts Michael Rizzo, mar_at_mainstream-engr.com