Experimental and numerical investigation of a compact vapor compression refrigeration system for cooling of avionics in harsh environments

Abstract

The power density and heat dissipation requirements of electric/electronics devices have significantly increased due to miniaturization. This is especially critical with the emergence of the more electric aircraft concept (MEA), which demands higher heat dissipation. The future thermal management systems must possess high heat removal capability and effectively handle heat loads of individual components in line with MEA objectives. Moreover, they should perform optimally in the highly dynamic and harsh aviation environments, e.g. elavated temperatures. Compact vapor compression refrigeration (VCR) systems have garnered interest as they excel in eliminating high heat flux and keeping device temperatures lower to ensure better performance in challenging environments. This paper presents the design, development, and testing of a compact VCR system applicable at the device level. The studied compact refrigeration system, with dimensions of 600 mm x 400 mm x 250 mm and weighing 2.8 kg, utilizes R134a as its working fluid and incorporates a miniature refrigeration compressor. It achieves heat dissipation of up to 623 W at an ambient temperature of 50 degrees C, attaining a COP of 2.7 while maintaining device temperatures lower than or close to ambient levels. Through simulations and experiments, the system's dynamic performance is assessed under varying heat loads and ambient temperatures. Experimental validation of the model has been carried out at various conditions. Overall, the proposed compact vapor compression system proves to be an excellent solution for thermal management in harsh conditions, aligning well with the requirements of the modern electric aircraft concepts.