How much water is lost from the space suit sublimator during an EVA?Thanks!
Quote from: Dalhousie on 11/18/2015 03:03 amHow much water is lost from the space suit sublimator during an EVA?Thanks!This description of the feed water circuit may help answer your question:B. Feed Water CircuitThe feed water circuit provides the capability to reject the heat from the EMU that has been either generated by the astronaut’s metabolic processes, from the EMU’s avionic systems, from the life support mechanical systems, or from the external environment. Three reservoir tanks (one large and two small) that are initially charged with approximately 10 pounds (aprox. 4.8 quarts) of ultrapure water supply the feed water circuit. A detailed discussion regarding the necessity of the ultrapure water is addressed in subsequent sections. The feed water circuit provides enough water to support cooling for an 8-hour extravehicular activity (EVA). In the event that the 10 pounds of water from the primary tank is prematurely depleted, the reserve tanks can provide an additional 30 minutes of cooling capability at a 1000 British thermal unit (BTU)/hr metabolic rate, enough time to allow the astronaut to return to the ISS airlock.Water flows from the feed water tanks to the sublimator, which acts as a heat exchanger between the feed water circuit and the liquid transport circuit. The sublimator operates at the triple point of water, where the three phases of water are present. Upon exposing the EMU to the vacuum of space, water flow to the sublimator from the feed water system is initiated and forms a layer of ice on the surface of the sublimator that is exposed to vacuum. After the ice layer is formed, water from the feed water circuit remains liquid by picking up the heat from the liquid transport loop via the heat exchanger in the sublimator. The heat removed from the liquid transport loop is dissipated into space via the sublimation of the sublimator ice layer. As the ice sublimates, the voids left behind in the ice layer are filled with additional water from the feed water circuit.Note: 1000 BTU/hr is ~290 watts. The EMU is designed for average/max metabolic rates of 1000 BTU/hr and 2000 BTU/hr respectively
Quote from: AnalogMan on 11/18/2015 01:13 pmQuote from: Dalhousie on 11/18/2015 03:03 amHow much water is lost from the space suit sublimator during an EVA?Thanks!This description of the feed water circuit may help answer your question:B. Feed Water CircuitThe feed water circuit provides the capability to reject the heat from the EMU that has been either generated by the astronaut’s metabolic processes, from the EMU’s avionic systems, from the life support mechanical systems, or from the external environment. Three reservoir tanks (one large and two small) that are initially charged with approximately 10 pounds (aprox. 4.8 quarts) of ultrapure water supply the feed water circuit. A detailed discussion regarding the necessity of the ultrapure water is addressed in subsequent sections. The feed water circuit provides enough water to support cooling for an 8-hour extravehicular activity (EVA). In the event that the 10 pounds of water from the primary tank is prematurely depleted, the reserve tanks can provide an additional 30 minutes of cooling capability at a 1000 British thermal unit (BTU)/hr metabolic rate, enough time to allow the astronaut to return to the ISS airlock.Water flows from the feed water tanks to the sublimator, which acts as a heat exchanger between the feed water circuit and the liquid transport circuit. The sublimator operates at the triple point of water, where the three phases of water are present. Upon exposing the EMU to the vacuum of space, water flow to the sublimator from the feed water system is initiated and forms a layer of ice on the surface of the sublimator that is exposed to vacuum. After the ice layer is formed, water from the feed water circuit remains liquid by picking up the heat from the liquid transport loop via the heat exchanger in the sublimator. The heat removed from the liquid transport loop is dissipated into space via the sublimation of the sublimator ice layer. As the ice sublimates, the voids left behind in the ice layer are filled with additional water from the feed water circuit.Note: 1000 BTU/hr is ~290 watts. The EMU is designed for average/max metabolic rates of 1000 BTU/hr and 2000 BTU/hr respectivelyThank you. II'll work it out. Why can't people use SI units? BTUs? Not even the British use BTUs. Might as well use cubits and bushels.