New system developed in Spain to transport Covid vaccine at -200ºC
The supply of the doses of Pfizer's vaccine against Covid-19 starts across Spain and the Canary Islands tomorrow, Sunday December 27th, and one of the obstacles that must be overcome to distribute it is the temperature at which the dose vials must remain at all times (-70 ºC), for which researchers from the Polytechnic University of Valencia (UPV) have developed a new ultra-cold system that allows transport in very low temperatures.
The system reaches up to -200ºC, stays stable and is one hundred percent autonomous with electrical supply. In fact, the autonomous ultra-cold container-CAU, as they have called it, is capable of reaching the extreme temperature using "exclusively ambient air as cooling fluid".
As the vaccines already arrive in insulated boxes loaded with dry ice, this container only maintains the cold chain by compensating for heat losses to the environment. This allows the storage or indefinite transport of the vaccine boxes, within the CAU chamber, and without the need to replenish or monitor the dry ice.
"The current health emergency situation and the new vaccine manufacturing techniques require new refrigeration techniques at very low temperatures. Industrial and fiscal limitations for the manufacture and commercialization of traditional refrigerant fluids make it necessary to seek new efficient ultra-refrigeration technologies , but at the same time respectful with the environment and that minimize CO2 emissions ", explains José Ramón Serrano, researcher at the UPV CMT-Thermal Engines and member of the team that has developed this system.
This container, created by the experts of the CMT-Thermal Motors Institute of the UPV, is scalable for all types of transportation, so it can be adapted for installation in medical-pharmaceutical delivery vans or industrial refrigerators, to large freight containers or logistics storage and distribution centres .
"With this system we could cover the entire process from the transport phase to its subsequent storage, and thus ensure, at all times, that the chambers are kept at the required temperature to guarantee their correct conservation", highlights Vicente Dolz, researcher at UPV.
In order to maintain the cold chain in the transport of vaccines, "air expansion is used in a reverse ‘Brayton cycle’. Thus "the rotational speed of the cycle compressors is controlled with a frequency variator, the power is controlled and, therefore, the process temperature is controlled," says Serrano.
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The latest technologies applied to the manufacture of vaccines involve the conservation of genetic material of the virus at cryogenic temperatures (-70 ° C). The solution today is to use dry ice , which sublimates at -78ºC, or liquid nitrogen , which evaporates at -196ºC, to refrigerate the vaccine containers.
However, according to the researchers from the CMT-Thermal Engines of the UPV, this technology has some drawbacks: "It is not easy to control the temperature and the vials, as if they are subjected to too extreme temperatures, they can be damaged".
In addition, in certain transports like planes, "the CO2 of the dry ice that sublime in the cabin can be dangerous". To this must be added that a lack of supply of dry ice is expected due to the shortage in production of pure CO2.
"You only have to provide electrical power to the machine. It could also be an alternative to dry ice if the CAU is used directly to store the vaccines in the production centre," emphasizes José Ramón Serrano.
At present, the CMT-Thermal Engines team of the UPV has a prototype of this container, instrumented and in operation in one of the test benches of its laboratories.