Power, Metallurgical and Chemical Mechanical Engineering Cryogenic Instrument Refrigerating by Liquid Nitrogen in Underheated Conduction

Abstract

Objectives. Cryogenic surgical instruments have been successfully used to conduct tumor ablation. For a long time, cryoablation procedures in Russia were carried out using cryodestructors cooled with liquid nitrogen, which are able to remove heat from the ablation object with high heat flux density and quickly form a cryoablation zone, while being relatively cheap and easy to operate. However, these instruments turned out to be unsuitable for minimally invasive surgeries; therefore, they are squeezed out of practical medicine and cryosurgical instruments are cooled by throttling argon gas. This led to the purpose of the study - the choice of equipment for the organization of local supercooling of pathological tissue.Method. To solve the problem of optimizing the cryogenic pipeline, a method was chosen for finding the Pareto-optimal solution. To solve this problem, it is sufficient to increase the pressure in the fluid flow directed to the NCS using a liquid micropump. In the role of quality criteria in this task, we selected: hydraulic loss power and heat loss power.Result. The following results were obtained: the minimum pressure in the vessel, which ensures the movement of the fluid in a single-phase state, according to the magi-line of 1 m length is 0.75 MPa; With this pressure, through a line with a diameter of 1 mm, the flow rate is maintained up to 6 kg / h; heat dissipation ability of the instrument reaches 608 watts. The thermal load on the cooling system of the heatdissipating device of the device for CA is unsteady and is formed due to the heat reserve accumulated in the patient's tissues.Conclusion. The use of liquid nitrogen in the undersized cryosurgical equipment makes it possible to overcome the noted drawbacks of liquid cryodestructors.

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