Next-Generation Domestic Refrigerator with Unprecedented Performance using Isobutane as Refrigerant

The primary objective of this project is to design and test the next generation of energy-efficient, hydrocarbon-minimizing (low global warming potential (GWP)) domestic refrigerators with isobutane (R600a) as the refrigerant. The program will focus on achieving overall cycle efficiency with minimal refrigerant charge. This will be accomplished by exploring new and innovative cycle designs and system level improvements to existing vapor compression cycle designs. Due to their operation, domestic refrigerators are a critical appliance in terms of energy consumption and environmental impact. Most existing products today use tetrafluoroethene (R134a) as their working fluid. A major drawback to R134a is its high environmental impact, with a GWP of 1300; as compared to carbon dioxide with a GWP of 1. Thus, there has been tremendous interest in alternative low GWP hydrocarbon refrigerants as a replacement for R134a. R600a has emerged as a promising replacement refrigerant, with its significantly lower GWP of 3. While this is very encouraging, there have been very few studies on the design, testing, and optimization of R600a domestic refrigerator vapor compression cycles. This project seeks to remedy those deficiencies. ORNL's Building Technologies Research and Integration Center (BTRIC) has the proven capabilities in system design and optimization, testing, and technology commercialization to achieve the projects objectives. Within BTRIC, the Building Equipment Group at ORNL features unique facilities that will be used for the project, including several multi-zone environmental chambers and high-performance computational resources. This project will first evaluate various system configurations for performance, footprints, and refrigerant charge and establish potential modifications at component and system level to maximize the performance and reduce charge. ORNL will then optimize the overall system configuration to reduce the total refrigerant charge in the system. Finally, the prototype will be lab scaled and field evaluated over an extended period of time while demonstrating a sustainable performance for at least six months of continuous operation.