Two Phase Thermal Energy Management System 2011-01-2584

The Air Force Research Laboratory (AFRL), in cooperation with the University of Dayton Research Institute (UDRI) and Fairchild Controls Corporation, is building a test facility to study the use of advanced vapor cycle systems (VCS) in an expanded role in aircraft thermal management systems (TMS). It is dedicated to the study and development of VCS control and operation in support of the Integrated Vehicle ENergy Technology (INVENT) initiative. The Two Phase Thermal Energy Management System (ToTEMS¹) architecture has been shown through studies to offer potential weight, cost, volume and performance advantages over traditional thermal management approaches based on Air Cycle Systems (ACS). The ToTEMS rig will be used to develop and demonstrate a control system that manages the system capacity over both large amplitude and fast transient changes in the system loads. In addition, it will be used to develop control strategies that continuously seek the highest possible coefficient of performance (COP) under varying operational and load requirements. Finally, the system will be used to analyze methods for fault detection and mitigation based on a minimum number of temperature and pressure measurements, as well as to provide a way to validate thermal models. The ToTEMS rig is a flexible system that presently consists of two independent liquid-heated evaporators with provisions for three additional evaporators that can be either electrically or liquid-heated. The compressor is a state-of-the-art 30 kW twin screw device provided by Fairchild Controls. The condenser can reject heat at a rate up to 50 kW to the facility chiller. Realistic cooling duty cycles for cooling fast loops, avionics, crew cabin, and re-circulated fuel can be evaluated with dynamic and steady-state heat loads with energy acquired at different heat fluxes and temperatures. This paper describes the test facility, objectives, approach to the control development, and preliminary results.