Greening China's high-speed railway with CO₂

With China already established as a global leader in high-speed railway transport, the country is now turning its attention towards making its railways more eco-friendly.

 China-based engineering firm CRRC Dalian Locomotive Research Institute (CRRC Dalian Institute) is playing a key role in this effort, having recently developed one of the world's first CO₂ (R744)-based air-conditioning systems for railway transport. The system will be used by CRRC Changchun Railway Vehicles Co.

The following is an interview with Bai Gang, technology research director for CRRC Dalian Institute.

//R744.com: How did the CO₂ air-conditioning project come about?

Bai Gang: At present, most of the air-conditioning refrigerants for rail vehicles (in China and outside of China) have a high global warming potential (GWP) value. To address this problem, we began our research of the corresponding global policy regulations (such as the Kigali Amendment to the Montreal Protocol, European F-Gas regulations, etc.) and also analyzed the refrigerant replacement process in academia and industry.

Through our research, we found that CO₂ is the world's first choice for the next generation of natural refrigerant-based green air-conditioning technology. It has an ozone depletion potential (ODP) value of zero, a global warming potential (GWP) value of one, is nonflammable, non-explosive, easy to obtain and cheap. R744 is safe, reliable and has good thermodynamic characteristics.

In the field of railway transportation, R744 refrigerant can be used as a new alternative refrigerant. The development of R744-based air-conditioning systems in the field of railway transportation is still new, so there are good market opportunities. The project itself started in January 2016.

//R744.com: What was the goal of the project?

Bai Gang: The project was aimed at designing an R744-based air-conditioning system for the fastest class (G-series) of railway transport vehicles in China. The railway transport vehicle air-conditioning system had to have a compact structure to fit in tight spaces. The system also had high reliability requirements, which brought us great system design challenges.

//R744.com: Can you provide some basic technical details of the system?

Bai Gang: The system has a 45 kW [12.8 TR] cooling capacity and an energy efficiency ratio of 2.3. This is also the world's first high-speed electrical multiple unit (EMU) CO₂ air conditioning system, which reaches a world-class level.

At the same time, the design of the heat exchanger in the system is also very different from traditional refrigerant-based systems. Finally, we installed safety valves to protect the safety of personnel under extreme conditions.

//R744.com: When did CRRC Changchun Railway Vehicles Co., Ltd. agree to use the system?

Bai Gang: They agreed to use the system in December 2016.

//R744.com: What was the main driver of interest in the system?

Bai Gang: In our communication with CRRC Changchun Railway Vehicles Co. — the largest manufacturer of high -speed EMUs [electric multiple units] in China – we found that they have a forward-looking vision.

They fully recognized the technologically advanced nature of our products, so they became really important people in our project. The success of the project is thanks to them and their great effort.

At the same time, the project is in line with the Chinese government's desire to push for more green technology development. The characteristics of this new environmentally friendly refrigerant has aroused their interest. Our project can completely meet the world's most demanding environmental requirements.

//R744.com: What is the status of the project now?

Bai Gang: At present, the project has completed product assembly and ground-test verification and is ready for loading.

//R744.com: What are your goals now?

Bai Gang: We are working on a CO₂solution for vehicles [in Europe], including Germany and Portugal. We also want to provide more efficient and environmentally friendly air-conditioning systems for more customers.