Page 54 - Apollo Moonships

52 on board apollo moonships
ELECTRICAL POWER SYSTEM (EPS)
The EPS contained the equipment and reactants required to supply, store, and distribute both direct and alternating current electricity for the Apollo mother ship. The electrical power was generated by a set of three fuel cells located within Service Module (SM) Sector 4. These power plants—fed by two oxygen tanks and two hydrogen tanks—combined these chemical elements to generate electricity and water as by-products. Each fuel cell was able to supply from 400 watts to 1420 watts. The excess heat produced by the fuel cells was rejected to space
by eight radiators placed within the 26-inch-high fairing that seals the joint between Command Module (CM) and SM. The EPS also had a secondary source of energy: five batteries situated on the CM, including three rechargeable ones used to provide electricity during Earth’s atmosphere reentry and post-landing maneuvers (after the SM jettison, the ship left behind the power generator equipment). The EPS purveyed 28 V direct current (DC) to two electrical units located inside the fairing section: the Main Bus A and the Main Bus B, which were connected to another two redundant buses placed in the CM, responsible for distributing the energy to all systems. The ship also had two additional buses (AC1 and AC2) to provide energy to any equipment that required alternating current (AC). These buses distributed the energy after the primary 28-volt DC power was converted into 115 V AC power by three solid-
state inverters placed in the CM lower equipment bay.
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EPS- FUEL CELL 13 14
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EPS MAJOR COMPONENTS
1 CSM umbilical (EPS wiring and plumbing)
2 Fuel cell (3)
3 Oxygen (O2) storage
tank (2)
4 Upper hydrogen (H2) storage tank
5 Lower hydrogen storage tank
6 Power distribution block (controls, circuits, main DC buses)
7 EPS radiators (8)
FUEL CELL ACCESSORIES 8 Glycol accumulator
9 Nitrogen (N2) regulator
10 Pressure tank
11 Support cone
12 Glycol, O2, H2 and N2 feed & supply lines
13 Nitrogen vent valve 14 Water purity sensor 15 Oxygen regulator 16 Hydrogen regulator
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APOLLO MOTHER SHIP
Space radiator exposed to the Sun
ENVIRONMENTAL CONTROL SYSTEM
This major system, known as ECS, was designed to offer a livable cabin atmosphere and potable water to the Apollo astronauts. To achieve it, five ECS subsystems operated in conjunction virtually
all the time: the oxygen unit, the water generation unit, the water- glycol unit, the pressure suction circuit (PSC), and the post-landing ventilation unit. Working together, these subsystems performed 23 functions, including regulating the flow and pressure of oxygen into the crew compartment, storing an oxygen reserve for use during Earth’s atmosphere reentry or in emergency cases, providing a conditioned cabin atmosphere, removing debris, moisture, odors, and carbon dioxide from cabin gases, supplying hot and cold drinkable water, and guaranteeing air circulation into the CM crew compartment after the splashdown. To reject the thermal overload caused by ECS subsystems, the ship had two 30-square-foot space radiator panels, which dissipated the heat using water-glycol coolant flow. The radiator arrangement on opposite sides of the SM ensured that one of them was always oriented to deep space, rejecting more heat than the panel warmed by solar radiation. Therefore, the heat- rejection capability of the system could be increased by intensifying the coolant flow to the cold panel.
Space radiator in the shadows