THE DEVELOPMENT OF AZEOTROPIC AMMONIA REFRIGERANT

It would be desirable to design an azeotropic ammonia mixture with higher pressure to avoid the

disadvantages of pure ammonia. The objective is to determine the appropriate proportions for a

mixture that would allow this blend to be employed for food blast freezing applications in the

temperature range from - 55°C to + 50°C.

Ammonia has a high NBP and low specific heat. Low evaporating temperatures lead to subatmospheric

operation allowing leakage of air into the system, and high compressor discharge

temperatures. The selected blend overcomes these drawbacks by significantly reducing the NBP

and allowing lower discharge temperatures. It will displace liquid nitrogen and carbon dioxide

cryogenic freezers as well as carbon dioxide / ammonia cascade and two stage ammonia systems.

The following findings were made relative to R717:

COP similar

Volumetric refrigerating effect (VRE) higher

Discharge temperature significantly lower, improving reliability

Improved heat transfer

Higher evaporating temperatures

Degradation of COP and refrigerating capacity with increasing temperature lift reduced

Patents have been filed and published and global licensees are now being sought.

Download: The Development of Azeotropic Ammonia Refrigerant Blends for Industrial ProcessApplications.pdf

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