Carbon dioxide rapid icemaking technology to create the "fastest ice surface"

◎ Science and Technology Daily reporter Chen Xi correspondent Liu Xiaoyan

The Beijing Winter Olympics have opened the curtain, and the beautiful and low-carbon Winter Olympic venues have also attracted more and more attention. In order to give the participating athletes a good ice experience and help them play the best level of competition, the team of Ma Yitai and Tian Hua of Tianjin University has developed the international advanced carbon dioxide transcritical direct cold ice making technology through school-enterprise cooperation under the support of the national key research and development plan - Science and Technology Winter Olympics, and built the "most beautiful and fastest ice surface" for athletes from all over the world.

Figure skating and short track speed skating were held at the Capital Gymnasium. For these two events, high-quality ice surface helps athletes to achieve better results, and in addition to the superb skills of the ice maker, the uniformity of the ice surface temperature difference and the uniformity of the soft and hardness determined by the ice making system are the key foundations.

Ice machine is the key core of artificial ice rink construction, from the perspective of ice rink ice machines in previous Winter Olympic Games, mainly using artificial synthetic refrigerant technology such as Freon or ammonia refrigeration technology, the former has a serious greenhouse effect problem, the latter has a safety hazard.

The ice machine technology with carbon dioxide as the refrigerant and direct evaporation under the ice surface is considered to be a green, low-carbon, high-efficiency and energy-saving solution, but its technology has always been in the hands of enterprises in Europe and the United States and other countries. Taking the green and scientific and technological Winter Olympics as an opportunity, through the collaborative research of industry, education and research, Ouyue Ice and Snow Investment Management (Beijing) Co., Ltd., Tianjin University and Est Refrigeration and Solar Energy Technology (Beijing) Co., Ltd. and other 8 units jointly developed, designed and built a carbon dioxide transcritical direct cold ice making unit with independent intellectual property rights, and demonstrated and applied it in the ice rink of the Capital Stadium to serve the Winter Olympics and the national ice and snow strategy.

Tian Hua introduced that the scheme is designed from the four processes of compression, cooling, throttling and evaporation of the carbon dioxide ice making system: for the compression process, the use of two-stage compression to make the source energy consumption achieve "half the work"; for the cooling process, the design of full thermal recovery to recover the cooling heat, to achieve ice rink ice pouring, snow melting and other different temperature hot water demand; for the evaporation process, the use of direct evaporation under the ice surface heat absorption to provide a stable supply of cold rink, and optimize the design of under-ice evaporation coils and civil engineering to ensure uniform ice surface temperature.

It is worth mentioning that the ice machine of this program from the key components to the integration of the whole machine, have realized the domestic design, processing, assembly and operation, especially the water-cooled air cooler is the first application in the world, effectively solving the engineering problem of the long first body cooling circuit.

"The comprehensive energy saving of the system of the program reaches more than 50%, the ice surface temperature difference is controlled within 0.3-0.4 °C, and both the comprehensive energy efficiency and the ice surface temperature difference have reached the international advanced level, so as to provide athletes with a high-quality ice surface with uniform and stable softness and hardness." Tian Hua said.

In addition, since the Capital Stadium hosts both figure skating and short track speed skating, the two have different strict requirements for the thickness of the ice layer and the temperature of the ice surface, and it is necessary to continuously carry out the rapid conversion of the two pieces of ice according to the schedule.

The project team also made full use of the uniform temperature of carbon dioxide ice, combined with a precise control system and linear cooling strategy, to achieve rapid and efficient ice surface conversion within 2 hours, far less than the IOC's 3-hour ice surface conversion requirements.

Tianjin University is one of the earliest teams in China to carry out research on carbon dioxide transcritical refrigeration heat pump technology. The carbon dioxide transcritical direct cold ice making technology used in the equipment is the core result of the "Ice Machine R&D and Application Demonstration" project of the National Key R&D Program for the Winter Olympics of Science and Technology, and Professor Tian Hua is the project leader.

Source: Science and Technology Daily The pictures in the article are provided by Tianjin University

Editor: Zhang Shuang

Review: Julie

Final Judge: He Yi