Ultra low temperature cascade refrigeration system

Za potrebe skladištenja medicinskih preparata projektiran je rashladni spremnik s integriranim rashladnim sustavom. Potrebno je proračunati komponente za postizanje temperature u ULT hladnjaku od -90°C pi okolišnoj temperaturi od 20°C. Za postizanje traženih uvjeta u spremniku odabran je kaskadni sustav s radnom tvari R290 u gornjoj kaskadi te R170 u donjoj kaskadi. Rashladni sustav hladi zrak u spremniku koji se slobodnom konvekcijom rasprostranjuje u prostoru. Kondenzator rashladnog sustava hlađen je okolišnim zrakom. U sklopu rada napravljen je termodinamički proračun toplinskog opterećenja spremnika, termodinamički proračun pojedinih komponenti, poput kapilarnih cjevčica u svrhu određivanja njihovih dimenzija te dispozicijski crtež isparivača. Također napravljena je shema spajanja i regulacije.A cooling tank with an integrated cooling system was designed for the storage of medical preparations. It is necessary to calculate the components to achieve a temperature in the ULT refrigerator of -90°C in an ambient temperature of 20°C. To achieve the required conditions in the tank, a cascade system was chosen with the refrigerant R290 in the upper cascade and R170 in the lower cascade. The cooling system cools the air in the tank, which spreads in the room by free convection. The condenser of the cooling system is cooled by ambient air. As part of the assignment, a thermodynamic calculation of the thermal load of the tank was made, a thermodynamic calculation of individual components, such as capillary tubes for the purpose of determining their dimensions, and a layout drawing of the evaporator. A connection and regulation scheme was also made