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Communication Dans Un Congrès Année : 2015

Thermodynamic analysis of secondary refrigeration loops: effects of slurry type and flow conditions

Hong-Minh Hoang
Anthony Delahaye
Laurence Fournaison

Résumé

The refrigeration industry must face more and more restrictive regulations about the volume of refrigerant contained in the units. Those regulations aim to reduce the leaks of refrigerant toward the atmosphere, a serious hazard with respect to global warming potential. In the many cases when one central cooling unit distributes cold between several cold heat-exchangers with a long refrigerant circuit, inserting a secondary refrigeration loop, filled with a fluid most often neutral with respect to the environment, between the evaporator and the distributed heat-exchangers is a good way to reduce the refrigerant volume. When the secondary refrigerant is a two-phase fluid, namely a slurry, large enthalpy changes can be achieved over reduced temperature glides. Ice slurries have indeed been used for long in industrial environment. New classes of slurries are currently under study: the clathrate-hydrates. These ice-like crystalline compounds mainly made of water molecules arranged around host molecules, attract attention because their fusion temperatures lie over zero Celsius and can be adjusted to the application. A numerical model of a two-phase secondary refrigeration loop was built-up for addressing the basic issues and all the energy transports and conversion processes involved from final use (herein air conditioning) to heat release to the atmosphere. Global analysis involves total energy consumption altogether with flow constraints in terms of turbulence (for avoiding crystal sedimentation) or pressure drops (not too high), so that each simulation is self-consistent. Exergy analysis of the whole process is also developed. Performance of various slurries, ranging from glycol-water mixture to clathrate-hydrate of CO2+TBPB, are compared, first in terms of global performance, second in terms of irreversibility: that analysis evidences which parameters have the most influence on design and results, and how.
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Dates et versions

hal-01836581 , version 1 (12-07-2018)

Identifiants

  • HAL Id : hal-01836581 , version 1

Citer

Michel Pons, Hong-Minh Hoang, Anthony Delahaye, Laurence Fournaison. Thermodynamic analysis of secondary refrigeration loops: effects of slurry type and flow conditions. International Conference on Efficiency, Cost, Optimization Simulation and Environmental Impact of Energy Systems, J.-P. Bédécarrats, Jan 2015, Pau, France. ⟨hal-01836581⟩
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