RU2444324C2 - Liquid nitrogen spraying head - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to medical equipment, particularly, to sprayers of liquid nitrogen in cryohardware. Proposed head consists of multiple through channels arranged at an angle to axis of casing on the side of its case and regularly along the circle, in several rows. Short bent capillary tubes are brazed in all channels of said casing extending a fan-like manner beyond head face. All said tubes are protected against damage by common jacket secured on head casing. Note here that casing outer surfaces and those of said jacket are provided with heat insulation.

EFFECT: possibility to form gas condensate jet of required shape.

1 dwg

Description

The invention relates to medical instruments and can be used in cryosurgical devices with injection of liquid nitrogen into a removable applicator, when a liquid stream of refrigerant must be turned into a formed stream of fine gas condensate in order to use it for cryotherapy, relieve pain shock or stop heavy bleeding.

A number of cryotools are known for the same purpose: to form an open stream of liquid refrigerant for irrigation of damaged biological tissues. A useful analogue may be a cryotool made according to A.S. 1572548 from 08.31.1987. In this tool, a sprinkler is mounted in the form of a wave-curved rod placed in the supply line in the supply line for liquid nitrogen in the area of the heat-insulated tip, and its rear part is in the form of a narrowed flat plate with a slot in which a flat metal shank is placed.

The laminar flow of liquid nitrogen, passing all the way along the highway, acquires an oscillatory motion, excites vibrations of a flat liner, which breaks the flow into separate drops. The disadvantage of this tool is the large dimensional heterogeneity of the droplets, which is a consequence of the inconsistency of the predetermined velocity of the pressure jet of fluid and arbitrary vibrations of the liner (as in devices for spraying water, aperiodicity gives rise to heterogeneity of droplets). In addition, the tip of this tool does not allow to form the desired profile of the gas condensate stream of refrigerant.

Also known is a tool with a tip for spraying a cryoagent for cryotherapy according to A.S. 1602488 from 11/15/1988. This tool contains a rigidly connected housing, a heat exchanger and an open tip with windows on its side surface, which can be taken as a prototype. Delivered to A.S. 1602488 The goal of obtaining a droplet-free gas stream of refrigerant is achieved by introducing at the outlet of the heat exchanger an ejector-air meter made in the form of a cylinder placed coaxially to the body and mounted on the tip with the possibility of changing the window size, and separation plates fixed in the tip in the form of asymmetric truncated cones. The tip in the prototype is, in fact, an additional evaporation chamber, into which a two-phase stream of refrigerant enters after air is taken by the ejector through the side windows, and then the droplet liquid phase of the refrigerant is released on the cone plates with strong turbulization of this process and its final evaporation. Thus, a cold gas stream blows out of the tip. The heat exchanger with the body and the open tip of the prototype are subject to intense heat exchange with atmospheric air, which leads to the loss of the most effective part of the cold storage of liquid nitrogen - its heat of vaporization, which is almost 46% of the enthalpy of liquid nitrogen when it is warmed to room temperature [1]. In addition, a nozzle with an additional external air ejector and conical plates cannot form a refrigerant flow coming out of the atomizer.

An object of the invention is the formation of the desired profile of the gas condensate stream of the refrigerant without losing the heat of vaporization in it.

The essence of the invention lies in the fact that in the head of the liquid nitrogen atomizer, consisting of a housing with many through channels, the channels are made at an angle to the axis of the housing from the side of its end evenly in a circle in several rows, and short capillary tubes are soldered into all the channels of the housing with a fan beyond the end of the head, which are bent, and all capillary tubes are protected from damage by a common cover, are mounted on the head case, and the outer surfaces of the case and cover are protected by thermal insulation.

The design of the head is shown in figure 1, where

1 - head housing,

2 - channels

3 - capillary tubes,

4 - protective cover,

5 - thermal insulation.

The head housing 1 has a threaded hole for connection with a siphon cryotool for supplying liquid nitrogen under pressure. In the housing 1, channels 2 are made at an angle to the axis of the housing from the side of its end and uniformly in a circle in several rows, communicating within the housing 1. The purpose of these channels is to branch the flow of liquid nitrogen injected into the housing 1 into many fine jets. Short capillary tubes 3 are soldered into all channels of the housing.

A short capillary tube 3 of annealed but strong metal (Ni, Cu, cupronickel, etc.), equal in diameter to the channel, is soldered to each channel 2 of the housing 1 at its end. Each of these tubes 3 can be easily bent to orient its output end in the procedure for forming a sheaf profile of the outgoing liquid jets by passing a stream of water. The configuration of capillary tubes 3 formed in this way should be protected from accidental deformation of any of them by a common strong cover 4 on the housing 1. Obviously, a sheaf of refrigerant jets can be formed in a convergent, diverging, round, annular, or other way. And the more jets leaving the head, the more uniform the cloud of atomized gas-condensate refrigerant will be.

In order to prevent the formation of atmospheric condensate on the head and to preserve the complete enthalpy of the refrigerant flow in the head, the entire outer surface of the housing 1 together with the cover 4 and the adjacent zone of the head connecting with the nitrogen supply siphon of the cryotool should be covered with thermal insulation 5.

The spray head of liquid nitrogen works simply. When liquid nitrogen is injected from a cryo-instrument after a short cooling-off stage of all cryogenic parts, the liquid nitrogen stream branches in the housing 1 by channels 2 into a system of thin jets that are emitted through capillary tubes 3 into the atmosphere. In the near zone from the end of the head, the jets are still solid and liquid, but their interaction with atmospheric hot air and the surface tension force them to split into separate homogeneous droplets, which, when further advanced, completely evaporate, and the refrigerant passes into the gas phase.

Thus, the proposed liquid nitrogen atomizer head allows to obtain a formed finely dispersed stream of refrigerant in all its aggregate states and to select a temperature interval during cryotherapy.

Claims (1)

The liquid nitrogen atomizer head, consisting of a body with many through channels, characterized in that the channels are made at an angle to the axis of the body from the side of its end face evenly in a circle in several rows, and short capillary tubes that fan out beyond the end face are soldered into all channels of the body heads that are bent, and all capillary tubes are protected from damage by a common cover attached to the head housing, while the outer surfaces of the housing and cover are protected by thermal insulation.

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