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 r Engine Development (1991- ) –Customer: U.S. Army RD&E Center (Natick) –Application: Small, diesel-powered, personal cooling system r Alternator Development ( ) –Customer: U.S. Army Aberdeen / OST –Application: Miniature, multi-fueled generator r 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 r Customer: Marine Corps System Command (MCSC) r Application: Team Portable Collection System (TPCS) r Project Philosophy: Commercial hardware, not Mil-Spec hardware r Goals: –Power is expected to exceed 1 28 VDC –Desired weight is less than 50 lbs –Desired fuel is diesel

2-kW, 28-VDC Generator Evolution r Phase I – MCSC –Initial demonstration –1.6-kW Generator: 42-lbs unmounted (14” x 11” x 16”) r Phase II – MCSC –Revised prototypes –2-kW Generator: 48-lbs unmounted –2-kW Generator: 65-lbs backpack mounted (18” x 17” x 20”) r Phase III – ONR –Two test units delivered to Army CECOM –2-kW Generator: 80-lbs roll cage mounted (18” x 18” x 20”) r Phase III – MCSC –Additional test units similar to ONR units –Addresses issues identified during Army CECOM tests

Mainstream’s Generators r Integrated system designed for military applications –Alternator integrated into engine flywheel l resulting in a lighter system l no coupling – eliminates potential failure component l reduces component count and number of wear components –Air-cooling fan integrated into engine flywheel l cools power electronics, engine head, oil sump l runs cooler - increases life and reliability r Mainstream designed and fabricated engine and generator –Sized specifically for application –Not just packaging of commercial components

2003 Power Expo r Technology –Integrated machine –Light-alloy engine r Product –2-kW, 28-VDC Unmounted Generator – 48 lbs (14”x11”x16”) –2-kW, 28-VDC Backpack Generator – 65 lbs (18”x17”x20”) r 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) r Future Work –Magnesium engine block requires further development

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

ONR Phase III Program r Mainstream delivered two 2-kW, 28-VDC generators r Program Goals: –Government tests to characterize equipment –Identify remaining issues that need to be addressed r Mainstream can provide a complete test report to government personnel upon request r 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 r Tested Throttle r Loosen knob and rotate r “Voltages are difficult to adjust on this unit, and not something that will likely be attempted in the field by the user” – Army CECOM r Revised Throttle r Friction-plate design r Slide lever left-right r Easier access to oil gauge and plug Both Designs r PM Generator: voltage proportional to speed r Set screw for maximum setting

Army CECOM Laboratory Tests (per MIL-STD-705C) r Physical Characterization r Start and Stop Test (503.1) r Frequency and Voltage Regulation, Stability and, Transient Response (608.1) r Ripple Voltage (650.1) r Voltage Dip and Rise (619.2) r Fuel Consumption (670.1) r Sound Level (661.2) r Endurance (690.1) r Extreme Cold Start (701.1d) r High Temperature (710.1d)

Physical Characterization 2-kW 28-VDC Mainstream Dry Weight80.2 lbs Wet Weight84.4 lbs Size18”x18”x19.8” 2-kW 28-VDC DoD MTG Wet Weight138 lbs Size29.5”x16”x21.8” Data provided by Army CECOM

Frequency and Voltage Regulation, Stability, and Transient Response Test RegulationStability (30 sec.) Voltage (max) 20.90%6.60% FrequencyN/A Failed CECOM Req. 4%2% r Mainstream generator was never designed to provide voltage regulation r MCSC Spec. (20-32 VDC) r CECOM Measured (31-37 VDC) r “Most DC-AC inverters require a voltage range from VDC...” - Army CECOM r Mainstream redesigning alternator to produce same power, lower voltage (unregulated) r Voltage regulated machine with feedback can be designed Data provided by Army CECOM

Ripple Voltage Test r Ripple is amplitude of the alternating component of the DC voltage r Lower ripple is better r “Ripple Voltage leads to EMI, the higher the ripple the worse the EMI” – Army CECOM r “Bad Ripple Voltage can “fatigue” some electronics components (capacitors, transistors)” – Army CECOM r “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% Data provided by Army CECOM

Resolution of Ripple Voltage Issue r MCSC did not specify ripple voltage or EMI r MCSC goal was to minimize weight r 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% Ripple Voltage Percent Ripple 9.4%2.9% FailedPassed CECOM Req. 5.5%

Voltage Dip and Rise Test Volts Dropped Volts Gained DipRiseTransient Recovery Time Results (max) %22.0%0/0 Passed CECOM Requirement30% 3/3 Data provided by Army CECOM

Fuel Consumption Test Load (W)% RatedFuel lbs/hrFuel Gal/hr 00% % % % % Passed 2-kW MTG at 100% Load0.330* * “ 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 Data provided by Army CECOM

Sound Level Test r Generator tested by Army CECOM had same muffler as that used on the 2-kW MTG r Mainstream has developed a new muffler. Tests indicate that noise can be reduced by 3 dB Data provided by Army CECOM

Endurance Test r Due to limited time and budget, “conventional” 1000 hr test shortened to 150 hrs r Tested 8 hrs per day r “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 r Passed LoadHours 50%36 0%6 75%36 25%36 100%36 Data provided by Army CECOM

Endurance Test – Human Factors Comments IssueMainstream 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 r Every part of system (including fuel and oil) is cold soaked in an environmental chamber to a specified temperature for 24 hours. r The system is prepared for starting by adding lube oil to the engine head. r “Mainstream difficult to start below 37°F.” - Army CECOM r Mainstream generator was designed to start without any external power supply. r Electric starter is currently being developed.

High Temperature Test r Tests consisted of starting and operating the system at a specified temperature and ensuring that the system could stabilize without overheating. r “The system was able to stabilize at rated load for over two hours at 125°F.” - Army CECOM r “The system was not able to provide 110%.” - Army CECOM r Maximum throttle setting was not changed. Mainstream’s generator can provide 110%.

Mainstream’s Life Tests r Number of Generators Tested: 2 r Number of Hours Tested: hours each r Approximate number of starts / stops: 60 each r Load: variable ( W) r Number of Critical Failures: 0 r Number of Hurricanes Survived: 1

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

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

Contact Information r Company Address Mainstream Engineering Corp. 200 Yellow Place Rockledge, FL (321) r Points of Contact –Technical: Greg Cole, –Contracts: Michael Rizzo,