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.

Engineering Corporation

Lightweight 2-kW Diesel-Powered Electric Generator

2005 Joint ServicePower Expo

May 3, 2005Tampa, FL

Presented by Greg Cole

Photo taken by Army CECOM


Mainstream Generator History

Engine Development (1991- )– Customer: U.S. Army RD&E 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


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 @ 28 VDC

– Desired weight is less than 50 lbs

– Desired fuel is diesel


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


Mainstream’s 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


2003 Power Expo

Technology– Integrated machine– Light-alloy engine

Product– 2-kW, 28-VDC Unmounted Generator – 48 lbs (14”x11”x16”)– 2-kW, 28-VDC Backpack Generator – 65 lbs (18”x17”x20”)

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


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


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


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


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)


Physical Characterization

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”

Data provided by Army CECOM


Frequency and Voltage Regulation, Stability, and Transient Response Test

Regulation Stability (30 sec.)

Voltage (max)

20.90% 6.60%

Frequency N/A N/A

Failed

CECOM Req.

4% 2%

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 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%



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%


Voltage Dip and Rise Test

Volts Dropped

Volts Gained

Dip Rise Transient Recovery Time

Results (max)

5.92 5.99 24.8% 22.0% 0/0

Passed

CECOM Requirement 30% 30% 3/3



Fuel Consumption Test

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

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.

65.00

70.00

75.00

80.00

85.00

90.00

95.00

100.00

1 3 5 7 9 11 13

Position

dBA

No Load LAeq [dB] Full Load LAeq [dB]

78

9

10

11

121

2

3

4

5

6

13



Endurance Test

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



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

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%.


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


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


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


Contact Information Company Address

Mainstream Engineering Corp.

200 Yellow Place

Rockledge, FL 32955

(321) 631-3550

http://www.mainstream-engr.com

Points of Contact– Technical: Greg Cole, [email protected]

– Contracts: Michael Rizzo, [email protected]

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.

Documents

program r mainstream

reliability r mainstream

request r testing

vdc unmounted generator

r issues vibration mounts

vdc generators r program

vdc backpack generator

army cecom tests