Universitat Politècnica de València Background
The current health emergency context has challenged technology in various industrial sectors. In particular, the recent manufacture of vaccines for Covid19 has put the refrigeration industry to the test as some of these vaccines need to be kept at -70°C.
Dry ice or liquid nitrogen is currently used to cool storage containers to such low temperatures. However, this technology is not free from problems such as the difficulty of controlling the temperature, the potential danger of its use in certain types of transport – such as aircraft – due to the CO2 that can be released in the cabin and the limited autonomy it provides by requiring dry ice to be replaced from time to time. In addition, a lack of supply of dry ice is expected worldwide due to the scarcity of pure CO2 production.
Other technologies, such as conventional refrigerant fluid cycles, are not designed to work at such low temperatures and present danger or contamination, due to the fluids they use. In addition, they are more complex as they work with several stages.
These problems can be solved with the UAC which consists of a compact, single-stage system that allows temperatures of up to -200ºC to be obtained at low pressure (3.5 barG) and using natural air as the cooling fluid. To do this it uses an inverse Brayton cycle with air, semi closed, with the stages of compression, expansion, cooling and regeneration.
The compression and expansion stages are carried out either through turbomachines, when high power and low thermal and mechanical inertia are required, or through volumetric machines, when the powers to be covered are low. The cooling and regeneration stages use heat exchangers (plate, shell-tube or cross-flow). The compression stage is carried out in phases, which may include cooling through a closed internal cooling ejector cycle (with refrigerants such as ammonia or carbon dioxide). At the entrance of the first stage (semi-closed) a filter-dryer can be arranged to reduce the humidity of the air ().
With this, 100% autonomous system with electrical supply (AC or DC) is achieved. As it works with only one cycle, operating at low pressure and with no danger it is always low cost, maintaining the robustness of the temperature control in the event of large variations in the ambient temperature.
Stage of Development
A prototype of the Ultra-cooled Autonomous Container (UAC) has been instrumented and is in operation on the UPV test bench at a level of TRL=4. The minimum temperature tested was -135 ºC, with a power consumption of 16.5 kW and a cooling capacity of 1.0 kW using ambient air as the working fluid.
Low acquisition cost (CAPEX), smaller size, low pressure, and no danger.
Speed, greater safety, and cost savings in fluid loads (OPEX).
Possible leaks of working fluid do not involve costs or risks.
The cycle is robust in the face of large variations in ambient temperature.
System based on commercial elements.
100% autonomous system with electrical supply for the motor which can be AC or DC.
The connection with the cold chamber can be adapted to any existing chamber.
Easily scalable to different configurations (small or large transport, storage, etc)
PHARMA: Transport of vaccines and storage of medicines.
LOGISTICS: Ultra-refrigerated transport.
FOOD: Deep-frozen tunnels for food.
HEALTH and SPORT: Medical cryotherapy. Electromedicine. Cryotherapy for high performance sports centres
MOBILITY: Ultra-fast battery charging.
Looking for companies in the field of industrial refrigeration equipment, refrigerated transport, storage logistics platforms, etc., that wish to incorporate ultra-cold technology (-40ºC to -200ºC) into their portfolio through a partnership for the joint development of the solution and a technology licensing option for its exploitation.