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At the Heart of Haemostasis: Thermal challenges and heat transfer concept

Custom mini compressor cooling unit controls temperature of reagents in Haemostasis analyzer

In a Haemostasis analyzing instrument various tests are performed to measure blood coagulation or the effect of an anticoagulant treatment that is given to reduce the risk of thrombosis.
Image courtesy of STAGO

Thermal challenges and heat transfer concept

In one area of the instrument the blood samples are kept at a constant temperature of 37°C. Right next to the blood samples there is the area of the reagents that need to be conserved at constant 15°C. The cooling of the reagents is done by forced air flow. This air flow is conditioned by a customized mini compressor cooling unit developed and supplied by AMS Technologies.

The cooling of a few ml of reagents would in theory require only a few Watts of cooling capacity, however it is not an isolated task and area. The reagents are being handled – moved to and from different positions underneath a big cover lid of the instrument. The heat load from the near ambient underneath the lid and the far ambient outside of the instrument as well as the condensation of the air being mixed into the circulating cool air stream define the necessary cooling capacity of the cooling unit.

Empirical approach to fine tune thermal conditions

The cooling capacity requirement was investigated and determined empirically by AMS Technologies during the course of the development of the cooling unit. Its powerful 24 VDC mini compressor has a linear speed control. Small evaporator and condenser heat exchangers, fans, compressor and other components of a refrigeration cycles were placed inside the given restricted space. Air flow rate and duct were optimized to achieve uniform temperatures across the reagents.

Customer statement

STAGO Logo"When we wanted to redesign the reagent cooling system of our equipment STA-R® in order to be more efficient we contacted AMS Technologies. We submitted them our expectations and their experts made a proper thermal analysis and developed a custom micro-compressor unit with precise temperature control and a cooling capacity that allow an accurate and homogenous temperature in all the reagent area. Which is a key parameter for us" Olivier Berthelot, Responsable Développement HW / FW STA-H, STAGO

About Stago a market leader

STA-RStago is a pharmaceutical laboratory, founded in 1945 in France. The group now works in the Vitro Diagnosis (IVD) industry, wholly dedicated to the exploration of the Haemostasis and Thrombosis. Stago invests in research and innovation to develop new and ever more performing reagents, systems and solutions. Stago Group now has almost 2,200 employees, with over half based in France.  With over 350 products commercialised, Stago is a world reference in Haemostasis and a favored partner of medical biology laboratories.

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