Nanoparticles Could Improve Future Chiller Efficiency
New formulations of lubricants and refrigerants blended with nanoparticles could yield increased energy efficiency for chillers, according to research from the National Institute of Standards and Technology (NIST).
New formulations of lubricants and refrigerants blended with nanoparticles could yield increased energy efficiency for chillers, according to research from the National Institute of Standards and Technology (NIST).
In the experiments, heat transfer for the refrigerant R134a was increased between 50 percent and 275 percent by dispersing nanoparticles of copper oxide in a polyester lubricant and adding it to the refrigerant. The copper oxide particles are 30 nanometers in diameter.
NIST scientists are still working to understand just how the improved heat transfer dynamic happens. They speculate the high thermal conductivity of the copper oxide plays a role. In sufficient concentrations, nanoparticles also enhance heat transfer by encouraging more vigorous boiling of the mixture. The increased bubbles carry heat away from the surface.
Continued research will focus on understanding the optimal combination of refrigerant, lubricant and copper oxide particles. If the recipe is optimized, there is a potential for boosting the performance of existing chillers and the creation of smaller next-generation equipment, NIST says.
Chillers account for about 13 percent of the power consumed by the nation’s buildings, and about 9 percent of the overall demand for electric power, according to the Department of Energy.
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