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Portable cooling systems play an important role in assisting human operations in unfriendly environments, such as soldiers continuously working in a desert area for long hours. Typical cooling system designs utilizing a vapor compression cycle driven by electrical power usually have high weights due to batteries and as a result, compromise the effectiveness of the portable cooling system. A self-contained absorption cycle cooling system design based on micro-scale thermal technology has demonstrated unique advantages in minimizing system weight while providing reasonable thermal efficiency. This system adopts a heat actuated absorption/desorption thermal cycle to raise the pressure of the refrigerant vapor without a heavy battery load. Design challenges exist: 1) multi-physics considerations when integrating the thermodynamic and transport models for the heat pump and peripheral component devices; 2) trade-off among multi-functional design requirements of system weight and thermal efficiency, using the inputs of cooling load, heat rejection temperature, and heat transfer characteristics based on the micro-channel geometry. No existing design automation tools are available on the market to directly support these design tasks. In this work, physics-based system-level models are developed and validated against state-of-the-art prototypes. The use of these models is demonstrated through the design of a 150-watt portable cooling system, typically used by the military in desert training. The system modeling methodology is implemented in Java as a part of an Integrated Design Support Environment, and has been used to generate trade-off study results. These results show that the current implementation is effective, and is a significant step toward a complete integrated design support environment to analyze and synthesize high-quality micro-scale portable cooling systems. |
