Optimizing mixtures and cooling systems to improve energy efficiency of domestic and industrial equipment

Two research teams from the Universitat Jaume I and the Public University of Navarra have successfully tested new refrigerant mixtures, systems, and components that significantly enhance energy efficiency in this sector. This industry, which accounts for 7.8% of global greenhouse gas emissions, sees an annual increase of over 170 million new domestic units. The studies are published in Applied Thermal Engineering.

The project "Advanced multi-stage refrigeration systems for low-temperature applications (HELTHA)" is working on three aspects: new high-efficiency refrigeration architectures, new refrigerant mixtures and hybrid applications of two technologies (vapor compression and thermoelectricity), which is currently in the development phase.

In the field of new architectures, the groups consider that the joint cascade system (in which there are two circuits thermally linked and in which one is responsible for lowering the temperature of the other) is a promising technology for ultra-low temperature applications, but that more research is needed to improve its energy efficiency. However, they have tested the use of an internal heat exchanger (IHX) with improvements in the coefficient of performance (COP) of up to 5.6%.

With regard to mixtures, several alternatives to isobutane (R600a), for domestic use, and carbon dioxide, used in industry, have been tested with very positive results. In the first case, the RE170/R600 and R290/R600 mixtures have shown superior energy efficiency together with the maintenance of thermodynamic properties, so they could become, in the long term, an option in vapor compression cycles for domestic refrigeration.

In the case of commercial or industrial refrigeration, the CO₂/R32 and CO₂/R1270 mixtures have shown significant reductions in energy consumption and working pressures, and could be used as an alternative to CO₂ and hydrocarbons in systems where the mass load exceeds the limits of the regulations or for safety reasons, although more tests would be needed to check the non-flammability of the mixtures and for possible leaks.

More information:
Daniel Calleja-Anta et al, Optimizing R152a/R600 and R290/R600 mixtures for superior energy performance in vapor compression systems: Promising alternatives to Isobutane (R600a), Applied Thermal Engineering (2024). DOI: 10.1016/j.applthermaleng.2024.123070

Rodrigo Llopis et al, Energy performance assessment of an auto-cascade cycle for ultra-low temperatures with the pair R1150—R600a, Applied Thermal Engineering (2023). DOI: 10.1016/j.applthermaleng.2023.122255

Ramón Cabello et al, Energy influence of the internal heat exchangers placement in a cascade refrigeration plant. A theoretical and experimental analysis, Applied Thermal Engineering (2024). DOI: 10.1016/j.applthermaleng.2024.122690

Provided by Universitat Jaume I