Steady-state and dynamic simulation of large thermal systems

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Date

2005-12-24

Authors

Haag, Scott Thomas

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Abstract

The United States Navy has made a corporate decision to develop all-electric technology for inclusion in all future classes of its warships. In anticipation of this, the Office of Naval Research (ONR) continues to support fundamental and applied research in power and thermal management aboard such ships. Thus, as one avenue of activity, ONR is involved in an on-going process to develop transient modeling and simulation tools that may be used to investigate coupled electrical-thermal management issues for its future all-electric ships. The Navy is interested in dynamic models because many of the thermal loads on future all-electric ships have the potential to be heavily dynamic in nature, e.g., electric weaponry and pulsed sensors. The overarching theme of this thesis is thermal management modeling and simulation for large naval ship systems. The work reported here evaluates and utilizes two simulation tools, one steady-state and one dynamic, that were found suitable for modeling surface ship thermal systems. The current Arleigh Burke class destroyer (DDG-51) was used to baseline this modeling activity. The steady-state modeling tool, Cycle-Tempo, was first used in a demonstration – validation problem of a fuel cell – gas turbine hybrid system. Then, as an element of the mainstream work, Cycle-Tempo was used to model and simulate major portions of the DDG-51 thermal management system. Next, Cycle-Tempo was used, along with fundamental thermal analyses, to evaluate a novel cooling scheme that permits heat rejection directly through the hull and into the sea. The dynamic modeling tool of choice, ProTRAX, is a well established commercial product used principally to simulate thermal components and control aspects of conventional power plants. Operation and use of the ProTRAX simulation system is reviewed and discussed. To support the work reported here, the refrigerant R134a was introduced into ProTRAX and validated against established thermodynamic property representations. Finally, ProTRAX was adapted and used to construct a dynamic model of the Navy’s existing 200-ton, vapor compression refrigeration chiller. The model includes the baseline chiller and associated controls and is exercised against sudden and gradual changes in cooling load

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