Blood plasma quick freezer
High freezing speed of any biological objects guarantees minimum damages thereof, and for blood plasma, significant reduction in the freezing time, that is 14 to 18 minutes as compared to 32 to 50 minutes typical for modern quick freezers, to the temperature of -30 ºС in the core of a container containing blood plasma, increases the content of VIII, IX, and other blood factors therein after its defrosting, thus ensuring the output of “useful” blood other than from the increased number of blood donors that is of great importance for the medicine and human life both in Russia and internationally.
This device (having no world analogues in terms of the technical solution and freezing speed) has been developed for quick freezing of blood plasma and its components.
High freezing speed has become possible as a result of simultaneous use of compressing and thermoelectric freezing methods at direct contact between the freezing surface and refrigerated object.
Both the possibility of refrigeration capacity individual regulation as well as possibility of individual regulated defrosting of earlier refrigerated containers make the blood plasma quick freezer a unique instrument for biological and medical institutions.
Device principal characteristics:
- Consumed power, kWt 1.3
- Temperature range, °С down to -50
- Cooling agent R23
- Dimensions, mm W x D x H 1020х515х800
- Gross weight, kg 75
- Freezing time to -30°С, minute 16
- Contact freezing (compressor + thermal electricity)
By now, a laboratory sample for optimization of freezing regimes for bags of various volume and configuration has been manufactured.
Project key technology
High freezing speed has become possible as a result of the use of two freezing methods: compression refrigerating machine designed for freezing of intermediate heat-transfer agent down to the temperature of minus 5 ºС which procures such aforesaid temperature level of the thermoelectric modules’ hot junction. Current control through the thermoelectric modules ensures their optimum operation at every stage of plasma containers’ freezing from the initial temperature down to minus 30 ºС. The Compression refrigerating machine does not have to procure low subzero temperatures, and consequently it operates with a high refrigerating factor. Maintenance of thermoelectric modules hot junctions’ temperature at the level of 5 ºС considerably reduces the temperature difference of thermoelectric modules’ hot and cold junctions which, in turn, raises their refrigeration capacity and, consequently, reduces the required number of thermoelectric modules.
Project innovative component
To optimize operation modes of thermoelectric modules, it has been proposed to develop thermoelectric modules equipped with sensors which polarity and signal are proportional to the temperature difference of hot and cold junctions. Such aforesaid sensors, controlling power supply sources, allow controlling refrigeration capacity of thermoelectric modules by maintaining the temperature required at a given stage of the refrigerating process.
The device designed to stir the container contents, preventing from ice generation near the walls of the plasma container, in the course of refrigeration from the initial temperature to the temperature when all contents of the container freeze up, and liquid plasma turns into ice, is also intended for the acceleration of the freezing process. The time required for freezing process also reduces when using devices preventing from heat inleakage from the laboratory premises to the cold zone, via power supply cables of thermoelectric modules and temperature control, since the refrigeration capacity of thermoelectric modules is fully used for the object refrigeration, and no expenditures on the compensation of heat inleakage are required. The use of vacuum heat-insulating materials which thermal conductivity is tens of times less than that of the materials used up to now in the refrigeration engineering, in line with the use of the heat-reflective coating as well as meeting of special requirements to laying of heat-insulating materials to the refrigerated zone, also significantly reduces the freezing time, without increase in the number of thermoelectric modules.
Such aforesaid measures, design concepts and construction solutions are expected to reduce the freezing time of 300 ml box down to the temperature of minus 30 ºС in the core of plasma box to no longer than 16 minutes (the freezing time for another volume will remain the same, for it is planned to keep the specific capacity of thermoelectric modules per unit volume).
Additionally to fast freezing, the blood plasma fast freezer providing for individual refrigeration of each container has a number of the following advantages:
- control of each container freezing process, providing for such process registration;
- low noisiness of the process, unlike the installations using turbo compressor units;
- function of plasma containers’ laying and removal in the course of work, without affecting the refrigeration mode of the earlier laid containers;
- function of defroster operation, for efficient defrosting and heating of containers containing biological products in conformity with certain law and up to a desired temperature, instead of the use of a number of thermostats designed for specific purposes;
Low power intensity, circuit design and construction solutions significantly reducing heat losses allow developing a complex for transportation of refrigerated bio-products for all and any distances.
The use of principles and developments implemented in the blood plasma quick freezer will allow developing units for various products needing refrigeration.