Transient vapor compression refrigeration cycle for electronics cooling - Part 2: Multi-evaporator dynamics & control

For next-generation sustainable electronic systems, such as high-concentration photovoltaics arrays and high-density supercomputers, two-phase cooling technologies are being explored to significantly reduce heat resistance from electronics' surface to the ambient. Lower electronics operating temperatures lead to higher energy conversion or computation efficiency; therefore, thermal management, especially dynamic thermal management, is able to bring great potential to energy-efficient electronic system operation. These large-scale electronics cooling systems normally include multiple, distributed, and transient heat sources. Multi-evaporator vapor compression refrigeration cycle provides such a promising cooling solution. Due to the complexity of multiple evaporator structure, its transient analysis and active control become very challenging. This paper applies our previous distributed heat exchanger modeling techniques to study the dynamics of multi-evaporator refrigeration cycles. A comprehensive first-principle multi-evaporator vapor compression cycle model is formulated for its transient analysis. Some preliminary expansion valve control results are presented to show the excellent active electronics cooling capability. This general tool is expected to bring instructive guidelines for the optimal design and operation of energy-efficient transient electronics cooling systems with multiple heat loads and hot spots.