Numerical Study of Ammonia Leak and Dispersion in the International Space Station

Abstract

Management of off-nominal situations on-board the International Space Station (ISS) is important to its continuous operation. One situation of concern is an accidental release of a chemical into the ISS atmosphere. In particular, introduction of ammonia into the cabin atmosphere can occur via the interface heat exchangers (IFHX) between the external thermal control system containing ammonia and internal thermal control system that uses water as a coolant to remove heat from ISS subsystems. Breach of the water/ammonia barrier of the IFHX can lead to a catastrophic rupture. Once the liquid water/ammonia mixture exits the ITCS, it instantly vaporizes and mixes with the U.S. Laboratory cabin atmosphere that results in rapid contamination of the cabin. The goal of the study is to assess the amount of ammonia in the Russian Segment by the time the crew is able to isolate the U.S. Segment. A Computational Fluid Dynamics (CFD) model for an accurate prediction of airflow and ammonia transport in the frozen flow field within the assembly complete ISS cabin was developed. The localized effects of ammonia dispersion are examined and discussed.

Unsteady RANS Simulation of Air Distribution in a Ventilated Classroom with Numerous Jets

“…RANS approach has been applied to solve complex ventilation problems such as design of HVAC systems in airplane cabins [4,5], indoor swimming pools [6,7], a solar house [8], and an ice rink arena [9]. RANS-based CFD studies aimed at development of life support systems on board of the International Space Station (ISS), especially in case of off-nominal operation and other contingency scenarios, are presented, e.g., in [10][11][12]. RANS approach solves a set of transport equations obtained from the Navier-Stokes equations by means of the averaging procedure that results in the unknown Reynolds stress tensor emergence.…”