1993-07-01

U.S. Lab-A Module Cabin Air Distribution in Space Station 932192

This paper presents the basic test data obtained from tests of a cabin air distribution system in a simulated Space Station U.S. Lab-A module.
The cabin air distribution system controls the flow of air in the open space of a Space Station module. In order to meet crew comfort criteria the local velocities for this cabin air are required to be distributed within a specified range with upper and lower limits. Achieving this desired velocity distribution is dependent upon the: (1.) design of the cabin air supply equipment and cabin air return equipment, (2.) total flowrate of air supplied to and subsequently returned from the cabin, and (3.) interactive effects of any other additional air flow streams which enter and exit the cabin.
The basic Space Station design for the cabin air supply and air return equipment was used in this test program. Only directional adjustments to vanes in supply air diffusers were made during the test. This equipment is included in the Temperature and Humidity Control (THC) subsystem for the Space Station. Two other air streams, in addition to what is defined as THC cabin airflow, which were involved in the test program were:
  1. 1.
    Standoff airflow – Standoffs are described in the paper. Briefly, they are enclosures within the cabin which formerly included ventilation fans. The consequent standoff airflow interacted with THC cabin airflow. The present baseline THC subsystem does not include the standoff fans.
  2. 2.
    Intermodule Ventilation (IMV) Airflow – IMV assemblies are used to interchange airflow between Space Station modules. These modules include the U.S. Lab-A module, the nodes, and, later in the Space Station program, the international modules.
Test results from eight (8) of the test runs which demonstrate the ability for the air distribution system to meet its objectives are presented. These test run results are compared with each other with respect to their standing relative to meeting the test objectives.
The test program investigated the effects of the variables noted above in meeting the test objectives. The basic variable in these test runs was the THC airflow. This airflow varied from 300 cfm to 500 cfm in the 8 test runs presented here. Some changes were made in supply air diffuser vane directional settings. Standoff airflow was used in one test run (number 4) and IMV airflow was used in test runs 5, 6, 7, and 8. Based on the test results, the desired velocity range and an engineering evaluation of the test results, a THC airflow rate for U.S. Lab-A is recommended.

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