RU2509281C1 - Evaporator-condense with intermediate coolant - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: in an evaporator-condenser of cascade refrigerating machines, comprising two coil heat exchangers connected to each other by heat conducting lamels, fixed on the common frame, the coils are submerged into an intermediate liquid coolant contained in the heat insulated body.

EFFECT: accumulation of cold in an intermediate coolant, which makes it possible to exclude synchronous start of compressors of both branches of a cascade and to reduce load at electric network and accordingly load at electric motors of compressors during their ramp-up time.

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Description

The invention relates to refrigeration and can be used as an evaporator-condenser in cascade refrigeration units.

Known condenser-evaporator shell-and-tube type with a vertical arrangement of tubes [1], in which their inner surface has a hydrophobic coating, and to enhance heat transfer between the working media, the middle part of the tubes has a star-shaped cross section. The condensing medium enters the annulus, and the boiling medium enters the annulus.

Also known is a condenser-evaporator [2], located in the distillation column housing and containing a plate-fin heat exchanger, consisting of a heat exchange section with alternating boiling and condensation channels. The supply of boiling medium and the removal of refrigerant vapor of the upper cascade is carried out through the low pressure column, and the supply of vapor and the collection of condensate of the refrigerant of the lower cascade is carried out through the high pressure column.

The disadvantage of both schemes is the need for synchronous operation of both branches of the cascade, which increases the load on the electrical equipment of the refrigeration unit, reduces its reliability and reduces the temperature range of its application.

Closest to the claimed invention is a regenerative-recuperative heat exchanger [3], in a thermally insulated casing of which there are two coils for liquid heat carriers, arranged so that the heat exchange elements of the first circuit alternate in layers with the heat exchange elements of the second circuit. The space between the coils and the casing is filled with a working fluid, the melting temperature of which is selected so that it is in the range of operating temperatures of one of the circuits. To compensate for the deformations of the working fluid associated with a change in its physical conditions, there is a cavity above the working fluid inside the casing, filled with gas that is neutral with respect to the working fluid and structural materials, connected to a chamber made of an elastic material located outside the casing.

The disadvantages of this apparatus are the design complexity due to the need for an expansion chamber, as well as the possible risk of damage to the pipes during solidification of the working fluid.

The basis of the invention is the task of reducing the load on the compressor motors during start-up and the load on the protective switching equipment of the cascade refrigeration machine.

The problem is solved due to the fact that in the evaporator-condenser of cascade refrigeration machines, consisting of two coil heat exchangers interconnected by heat-conducting lamellas, mounted on a common frame, the coils are immersed in an intermediate liquid coolant contained in a heat-insulated casing.

The technical result, which consists in the independent operation of both branches of the cascade to exclude the synchronous start of compressors of the upper and lower branches of the cascade, increasing the operating range of the cascade refrigeration machine and optimizing the operating mode of the refrigeration unit, is achieved by immersing the evaporator-condenser coils in the intermediate liquid coolant contained in a thermally insulated housing.

The proposed installation (Fig. 1), made on the basis of an air three-row condenser, includes a thermally insulated housing 2 with a cover 1 filled with a coolant 3. The coils 4, 6 are connected into the coolant, interconnected by heat-conducting lamellas 5. The lower stage cascade is condensed in two rows of pipes of the coil 4, and the boiling of the refrigerant of the upper cascade occurs in one row of pipes of the coil 6.

The evaporator-condenser operates as follows. In the coil 4, the refrigerant of the lower cascade is condensed by transferring heat to the refrigerant of the upper cascade circulating in the coil 6, where it boils. Thus, the coil 4 is a condenser of the lower cascade of the refrigeration unit, and the coil 6 is the evaporator of the upper cascade.

The use of the inventive evaporator-condenser in cascade refrigeration units due to the accumulation of cold necessary to maintain the condensation temperature of the lower cascade, allows to reduce inrush currents when starting the compressors, which in turn leads to increased reliability. Along with this, the presence of an intermediate coolant allows you to expand the temperature range of the cascade refrigeration machine.

Sources of literature

1. Patent No. 20133749, Russian Federation, IPC F28F 1/40. Condenser-evaporator / Movchan E.P. - Omsk Scientific and Production Association "Sibkriotekhnika". - No. 4924503/06; declared 04/02/1991; publ. 05/30/1994 (analogue).

2. Patent No. 2100715, Russian Federation, IPC F25B 39/00, F28D 9/00. Condenser-evaporator / Poznyak V.E., Saveliev V.N. - Open Joint-Stock Company of Cryogenic Engineering. - No. 95118254/06; declared 10/27/1995; publ. 12/27/1997 (analogue).

3. Patent No. 2101645, Russian Federation, IPC F28D 17/02. Regenerative-regenerative heat exchanger / Kryshchenko K.I., Dzegilenok V.N., Neyland A.B. - No. 96103971/06; declared 03/05/1996; publ. 01/10/1998 (prototype).

Claims (1)

The evaporator-condenser of cascade refrigeration machines, consisting of two coil heat exchangers interconnected by heat-conducting lamellas, mounted on a common frame, and characterized in that the coils are immersed in an intermediate liquid coolant contained in a thermally insulated casing.

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