26aip - Air Independent Propulsion For non-nuclear...

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Air Independent Propulsion This is an ever moving technology. These notes represent an overview but may For non-nuclear submarines, submersibles and unmanned vehicles; not represent the latest AUV, UUV, torpedoes parameters. Torpedo propulsion was originally stored high pressure air.** It evolved to heated air at the turn of the century using kerosene, alcohol or Otto fuel. Current torpedoes employ electrical storage or lithium sulphur hexafluoride systems. (Sulphur hexafloridegas is sprayed over a block of lithium which generates heat. As is well known typical submarine propulsion uses a storage battery with engine recharging. In all the stored systems, the challenge is storage of the oxygen component, ** The initiative behind the self-propelled torpedo was provided by an Austrian frigate captain Giovanni Luppi. After some unsuccesful attempts to propel a charge laden boat with a springdriven clockwork. In 1864 he turned to Robert Whitehead (1823-1905), then technical manager in an Italian factory to design an improved version. The result was a torpedo in October 1886: length 3.35 m, diameter 25.5 cm, weight 136 kg. Propulsion was provided by 20 to 25 kg of compressed air, driving a reciprocating engine with a high and low pressure cylinder. Taken from "Swedish Torpedo 100 Years; 1876 - 1976. Secondary Batteries Lead acid- discharges 2 - 1.8 V per cell solid solid liquid => solid liquid charges 2.1 - 2.6 V per cell electrolyte H 2 SO 4 Pb + Pb O 2 + O 4 = 2Pb S O 4 + 2H 2 O energy density 67 lb/kW*hr 2 S lbf kgf check 67 = 30.391 (2 + 8 ) O 2S kW hr kW hr 4H = (8 + 2 O 1 Whr = 14.925 lbf lbf 67 Silver - Zinc kW hr discharges 1.1 - 0.8 V per cell lbf kgf charges 1.6 - 2.0 V per cell 20 kW hr = 9.072 kW hr electrolyte KOH energy density 20 lb/kW*hr 1 = 50 lbf lbf 20 kW hr problem (both cells): hydrogen release in charging. New developments: NiCd, Li rechargeable Fuel Cell originally developed by Roger Bacon. H 2 and O 2 are supplied to special electrodes with various electrolytes. KOH in the alkaline cells, proton exchange membranes (PEM) and high temperature carbonate in the molten carbonate cells, solid oxides in other cells. Energy conversion is relatively high ~ 60% H 2H 2 + 2electons figure later overall reaction H 2 + 1 O 2 = H 2 O complete H 2 + 2O = O 2 1 H 2 O O 2 + = 2electrons + 2 O H 2 theoretical voltage: 1.23 V, practical voltage ~ 0.8 V 12/11/2006 1
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maximum power at w_dot max = = = Δ G G = Gibbs_function constant T 1 m_dot h 1 T 1 s 1 ( h 2 T 1 s 2 ) G 1 G 2 h 1 h 2 = heating_value_of_fuel Δ G = 0.825_to_ 0.95 depending on T 1 and state of H 2 O liquid or vapor with internal hhv losses ( ~ 60% conversion) H 2 consumption: 0.111 lbf = 0.05 kgf kW hr kW hr O 2 consumption: 0.889 lbf = 0.403 kgf kW hr kW hr lbf kgf 1.0 = 0.454 reactants kW hr kW hr the volume is important and depends on the storage method: as cryogenic liquids: O 2 sp_gr = 1.14 71 lbf = 1.137 × 10 3 kgf 3 3 ft m H 2 sp_gr = 0.064 4.0 lbf = 64.074 kgf 3 3 ft m
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26aip - Air Independent Propulsion For non-nuclear...

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