Regeneration of the “older” refrigerant
Carbon dioxide is not “new expensive” in refrigeration. In fact, because of their ease of access and their low cost, carbon dioxide was used as a refrigerant more than 100 years ago when steam compressed refrigeration technologies were emerging in europe. However, with the development of synthetic refrigerant technology, co2 has gradually been replaced by a high critical temperature, liquidized synthetic refrigerant, freon. By the 1970s and 1980s, countries had come to realize that the two major environmental problems of ozone layer damage and greenhouse effects were related to synthetic refrigerants and had begun to stop using them。
Professor, faculty of mechanical engineering, tianjin university under the montreal protocol signed by the international community in 1987, by 2010 we had phased out refrigerants that had a significant effect on the ozone layer, representative of freon r12, and by 2030 we would have phased out refrigerants that had a slight effect on the ozone layer, representative of freon r22。
Because of the disadvantages of synthetic refrigerants, carbon dioxide, a “year-old” refrigerant, is back in sight。
Professor maathai, faculty of mechanical engineering, tianjin university: co2 as a component of the atmosphere does not damage the ozone layer. Carbon dioxide is a greenhouse gas, but the greenhouse effect is much lower than other synthetic refrigerants。
Because of this environmental properties of co2 cooling, 7 of the 15 ice sheets in the beijing area of this winter olympics will be based on carbon dioxide trans-critical straight-cool ice-making techniques. This will make the beijing winter games 2022 the first olympic games in history to use carbon dioxide refrigerants on a large scale。
Is it made like a refrigerator?
Small home-to-home refrigerators, large enough to be commercial refrigerators, are at the core of all refrigeration activities. Refrigerators consist mainly of compressors, condensers, swelling valves, and evapotors, the key substance of which is refrigerants, with different minimum temperatures that can be achieved by different refrigerants。
Professor maathai, faculty of mechanical engineering, university of tianjin: co2 can be used as a refrigerant like freon or ammonia. It has the same cooling cycle as normal refrigerants, which are steam compressed refrigeration (or heat pumps) cycles, but vary in detail。
Typically, more liquid co2 is stored in a co2 liquid tank, which is supplied with 1. 5 to 2. 5 times as much as the cooling demand, which ensures more even temperatures across the ice field; compressors have more than a few units, which can be used to control the number of stations depending on the changes in cooling volumes; and computer-controlled electro-inflation valves can accurately control co2 evaporation temperature depending on the size of the cooling volume and changes in ambient temperature。
In mid-november, the capital stadium, which is a short-track skating and skating stadium, completed ice-making, with an ice size of 31 metres x 61 metres. In the process of making the ice, multiple co2 compressors operate simultaneously, low-temperature co2 and ice sheet concrete are replaced by heat in the ice sheet pipeline, the temperature of ice plate concrete is gradually reduced to less than 10 degrees celsius, the chillers are constantly pouring water on the ice sheet, freezing to a few millimeters of ice per layer, many times after which tens of millimeters of ice are frozen。
Save the cooling of second pass
Carbon dioxide, known as one of the most advanced current ice-making technologies, is by no means a false name. In addition to green, accessible, etc., carbon dioxide across critical straight-cooling technologies have the advantage of temperature control, ice quality and ice efficiency. This technique enables accurate control of ice temperature and assures ice quality, which is closely related to its use of direct evaporation cooling。
In the past, some stadiums used indirect refrigeration, i. E. Refrigerant refrigeration, to make ice sheets. Indirect refrigeration is the process by which the amount of cold obtained from direct evaporation cooling is passed to the ice by the carrier. Ma-tae described the advantage of having a low intensity requirement for an ice-filled tube, as long as it was not leaking, and usually using a plastic tube. The stress-resisting parts are in the chillers. This is a good choice for temporary ice fields, such as stage shows or winter ice carnivals. But the biggest problem with ice fields for official competitions is the inconsistent temperature of the ice. Because the substances normally used as refrigerants, be they salt water or ethanol water solution, are not heated at a relatively fixed temperature, there must be a temperature difference in the coolant pipeline. When the temperature differentials between imports and exports are too high, the ice is very soft and hard, while reducing the temperature differentials between imports and exports will result in a greater flow of refrigerants and higher energy consumption for refrigeration。
