This document discusses using mechanical subcooling with ammonia (R718) to improve the efficiency of carbon dioxide (R744) refrigeration processes for industrial and commercial applications. It describes a cascade system where R718 is used to subcool R744, increasing the COP at high ambient temperatures without added complexity. Case studies show such a system can be used to freeze apple pastries by subcooling CO2 with water. Both R718 and R744 are natural refrigerants that can help reduce CO2 equivalent emissions in HVAC&R applications when used together in a cascade arrangement.

2. Mechanical subcooling of R744
processes with R718 in
industrial and commercial
applications
Juergen Suess, Florian Hanslik
Efficient Energy GmbH

3. R718 + R744 = Dream team
Mechanical subcooling installation at efficient energy laboratories

4. Vapor curves
of various
refrigerants

5. Where to
use R718

6. R718 and R744 cascade system layout

7. R718 Applications

8. Mechanical sub cooling of CO2 with water to freeze apple pastries

9. Efficiency
enhancement

10. Summary • Both R718 and R744 are safe and natural
refrigerants
– No critical limitations for global
applications to be expected
– Cascade systems increases the COP of the
CO2 process significantly at high ambient
temperatures
– No added complexity of the R744 process
required
• The combination of both refrigerants will
contribute to the CO2 equivalent reduction
of the HVAC&R industry.
A
fast lane
to sustainability