ORNL fridge uses PCMs to maintain temperatures
27th May 2024
USA: Scientists have developed a new household refrigeration technology that cycles once overnight and uses a phase change material (PCM) to maintain temperature.
The technology developed by the USA’s Oak Ridge National Laboratory uses advanced evaporators with PCMs installed in each compartment for cold energy storage.
PCMs are useful for heating and cooling because they store and release energy when changing from solids to liquids or vice versa.
Researchers applied porous metals, direct-contact defrosting technology and a refrigerant with low global warming potential to enhance performance and minimise environmental impact.
“PCMs are integrated with evaporator coils to keep temperature constant, requiring one operating cycle and allowing refrigerators to operate almost 100% at night-time, when energy use is lower,” ORNL’s Zhiming Gao said. “This reduces electricity demand, saves costs and maintains efficiency.”
It uses advanced evaporators with PCM–based long-duration cold energy storage, PCM heat conduction enhancement using a metal foam material, direct-contact defrosting technology, and a low GWP alternative refrigerant to achieve flexible load demand management. Energy efficiency improvements are said to be in excess of 20%.
ORNL claims that this will enable a 30% reduction in CO2 emissions and almost 100% load shift from daytime to nighttime operation.
The PCM is organic based and can be integrated with evaporator coils and keep temperature constant for fresh and frozen food. It only requires one cycle on, and one cycle off, unlike current technology that cycles on and off repeatedly throughout the day.
According to ORNL, replacing the current 100 million current refrigerators in the US with the proposed new refrigerator would save up to 167 TBtu (49 billion kW) of primary energy consumption and reduce CO2 emissions by 7.2 million tons.
