6.108 Cooling to Point C assumes the proper supply condition for our environmental gain balance. The total refrigerant load is l.98x10 8 BTU/hr. The CFM required is l.23xl0 7 cfm, 3.49xlo 5 m 3 /min, or 5810 m 3 /sec . The interior volume of the colony is approximately 7.33xlo 6 m 3 . Thus, the air changes approximately 3 times per hour, which should adequately prevent uncomfortable buildup of odors. VI.10.5: Systems: The specified environmental control process has transferred 100% of the colony heat gain to a refrigerant. This refrigerant must itself be cooled, and provision must be made to move the colony air through the conditioning units. Present air handling units range in size to approximately .75x10 6 cfm with power consumption varying between .19 w/cfm and .86 w/cfm. The environmental control system consists of 20 of these large units whose power consumption is .25 w/cfm. Twenty allows one unit per 36° arc at the edge of each endcap. The precise location of air intake and discharge ports depends on a detailed analysis of air stratification and movement patterns in the colony. An excess of units enables one or more to be serviced without disrupting or upsetting the energy balance. A power consumption rate of .25 w/cfm yields a power requirement of: Pfan = .25 w/cfm x l.23xl0 7 cfm = .3xl0 7 watts This increase is approximately 10% of the total heat gain. The refrigerant is pumped to the outer hull, cooled there by passive radiation to space, and returned to the air conditioning units. The power requirements for pumps depend on the choice of refrigerant and the temperature drop experienced by the refrigerant in the loop. A rough estimate of power consumption is 25% of the air handling requirement: p pump .75xl0 6 watts
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