Gustav Lorentzen: NH₃/CO₂ system development in China

Through its 2014 Gustav Lorentzen (GL 2014) papers, Yantai Moon discussed the different stages leading up to the to the development of an NH₃/CO₂ system, and demonstrated that such systems can achieve a higher COP than other types of refrigeration systems. Yantai Moon’s NH₃/CO₂ cascade research received support from the UNDP (United Nations Development Program) and the Chinese government. 

 

“Our goal in attending Gustav Lorentzen this year is to convey our message of building an environmental friendly refrigeration technology and to share knowledge on green, low-carbon solutions,” continues Mr. Wang Liqun, from the marketing department of Yantai Moon, “We will  keep promoting sustainable solutions.”

 

 

In their first GL 2014 presentation, Yantai Moon reviewed the different steps towards the development of an NH₃/CO₂ system. The project began in May 2011, when the UNDP and the Ministry of Environmental Protection chose Yantai Moon’s NH₃/CO₂ cascade refrigeration system development plan as a global HCFC-22 phase-out project.  On the 23 July 2013, the Chinese Government acknowledged that Yantai Moon’s development results filled a technological gap in Chinese national refrigeration technology. Following this, from September to November 2013, Yantai Moon organised a road show to promote CO₂ refrigeration technology as a solution ready for large-scale application across China. 

 

The presentation also highlighted some technical aspects of the NH₃/CO₂ cascade system. For safety, ammonia is confined to the refrigeration unit within an equipment room. This reduces ammonia charge to 10% compared to traditional ammonia systems. What is more, the cascade system, takes full advantage the different heat transfer, mass transfer and refrigeration properties of NH₃ and CO₂, in particular the fact that CO₂ has a higher heat exchange efficiency at lower temperatures. The system cascade systems can supply temperatures between 0°C and -52°C. 

 

Yantai Moon recommends that the NH₃/CO₂ system applied to quick freezing applications (-45°C to -40°C) and large cold storage (-33°C to -28°C) to maximise energy saving potential of the system.  

 

 

In a second Yantai Moon paper titled “Research on CO₂ Refrigeration System” by Ge Changwei, Jiang Shaoming and Yu Zhiqing, data analysis shows that a CO₂ refrigeration system has a very high running efficiency in a temperature range of -55 °C to 5 °C. 

 

In the comparative study of an NH₃/CO₂ cascade refrigeration system with a two-stage ammonia compression refrigeration system, the COP of the NH₃/CO₂ cascade refrigeration system was between 8.8 and 10% higher, at an evaporating temperature of -45 °C. 

 

With regards to COP, when compares to an NH₃ single stage refrigeration system, and NH₃ double stage refrigeration systems, and R22 single stage refrigeration system, and an R22 double refrigeration system, the NH₃/CO₂ system achieved a COP of 2.18 at -40°C/+25°C and 1.78 at -50°C/+25°C, higher than any of the other refrigeration systems. 

 

 

Yantai Moon also introduced some installation examples of NH₃/CO₂ systems in China.