DRIVING FUEL CHOICES
manufacturers, such as Tesla, have chosen to use Li-ion batteries.
Te conversion devices considered were combustion engines, electric motors and fuel cells. Teir performance characteris- tics can be seen in Figure 3, Page 104, which shows a measurement of the actual performance of each power source versus its power output. Electric motors have the highest level of performance, but, as we saw earlier, they are connected to batter- ies that don’t have enough stored energy to last for military applications. Gasoline and diesel combustion engines are next, with methane engines at the lowest level.
ENERGY CARRIERS TAKE UP SPACE Another important factor when consider- ing alternative energy carriers is how much vehicle space will be required to transport the requisite fuel as well as all of the ancil- lary equipment necessary to operate and adequately power the vehicle system.
In order to assess and compare approx- imately how much onboard space each alternative would require, researchers evaluated the approximate space claims by comparing the energy carrier volume and powertrain mass associated with each carrier with regard to the Humvee and Family of Medium Tactical Vehicles (FMTV) platforms. Figure 4, Page 105,
FLYWHEEL POWER
The flywheel of a Cummins engine, at lower right, is hooked up to a dynamometer, above, that measures its mechanical force, torque or power—torque being a force that produces or tends to produce rotation or torsion. A flywheel is an energy carrier; it’s a heavy wheel attached to a rotating shaft so as to smooth out delivery of power. As it spins, the inertia of the flywheel opposes and moderates fluctuations in the speed of the engine and stores the excess energy for intermittent use. (Photo by Dr. Pete Schihl, U.S. Army Combat Capabilities Development Command Ground Vehicle Systems Center)
There is a good reason the Army hasn’t unilaterally decided to switch to alternative fuels.
102 Army AL&T Magazine Fall 2020
illustrates the predicted total powertrain mass and energy carrier volume for vari- ous single and dual hybrid energy carriers for the two vehicle systems. Te results indicate that diesel and gasoline fuels are clearly the optimal energy carriers for both vehicle systems, with the lowest total powertrain masses and low energy carrier volumes.
Tis is true of the results for both single energy carriers in the left-side graphs of Figure 4 and for dual hybrid carri- ers (diesel + battery or supercapacitor) in the right-side graphs. Of the dual hybrid
energy carriers, diesel fuel + Li-air hybrid is clearly optimal, yielding the greatest rate of hybridization (50 percent diesel and 50 percent Li-air) considering the rela- tively small mass and volume increases. Tese results also clearly indicate the dramatic benefits of Li-ion and Li-air battery technology over more tradition- ally used NiMH.
A prime candidate for an alternative- energy carrier for military vehicles would include an optimized fuel source and conversion device, a high level of commer- cialization, as well as a system mass and
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196
