The properties of hydrocarbons make them the best-performing refrigerants for light commercial applications, Professor Cláudio Melo of the Polo research lab in Brazil told the 13th Gustav Lorentzen Conference on Natural Refrigerants this week.
“Hydrocarbons have equal or better heat transfer performance and lower pressure drop compared to R22 and R134a,” Melo told his audience at the Polytechnic University of Valencia.
“Hydrocarbons mix very well with mineral oils both in the liquid and vapour phases,” said Melo, adding: “The hygroscopic synthetic oils used with HFCs can thus be avoided.”
The professor pointed out that most of the materials used in HFC refrigeration systems can also be used for hydrocarbons. These include neoprene, Viton, nitrile rubber and nylon.
The world-renowned Polo research laboratories at the Federal University of Santa Catarina, located in the Brazilian city of Florianópolis, works on emerging technologies in cooling and thermophysics.
“Hydrocarbons don’t harm the ozone layer and have a negligible climate impact,” Melo said.
“Hydrocarbons such as isobutane and propane are substantially less expensive than HFCs.”Professor Cláudio Melo
Business case for hydrocarbons
There is also a strong business case for adopting hydrocarbons over HFCs, the professor argued. “Hydrocarbons such as isobutane and propane are substantially less expensive than HFCs,” he said.
“Typically a refrigeration system designed for hydrocarbons will need 50-60% less refrigerant by mass when charged with hydrocarbons,” Melo said.
“The energy efficiency of hydrocarbon units is frequently claimed to be up to 30-40% better than comparable HFC units,” he said.
“5-10% of this improvement can be accredited to better thermodynamic and transport properties,” Melo said. “The rest is most likely due to component modifications such as improved compressor or heat exchanger design, as well as variable speed drives.”
Isobutane, with its boiling point of -12°C (R600a), is used mostly in small coolers and domestic appliances. Propane (R290) has a boiling point of -42°C and is typically used in light commercial refrigeration and heat pumps, Melo said.
“Due to lower pressure levels and pressure ratios, R600a compressors run more quietly than comparable R134a units,” Melo said.
The 13th Gustav Lorentzen Conference on Natural Refrigerants took place at the Polytechnic University of Valencia from 18-20 June.
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