Flooded evaporator

Abstract

A flooded evaporator is provided which can remove floating mist more exactly resulting in that the refrigerant mist is prevented from being sucked into the compressor, and with which heat transfer between the medium to be cooled and refrigerant liquid is improved. The evaporator is composed such that; a tubular housing (3) is provided to erect from a horizontal cylindrical container (1) which forms a heat exchanging section with a heat exchanger (2) accommodated therein, an inner tube (12) for upwardly guiding refrigerant vapor generated in the heat exchanging section is provided, the inner tube (2) is covered by a loose cover (13) so that refrigerant vapor containing refrigerant mist flowed up in the inner tube (12) impinges against the loose cover (13) to be deflected downward to flow out from the inner tube (12), a space (17) is secured in the tubular housing (3) to allow refrigerant mist to fall down utilizing gravitational attraction, a demister (16) is provided in the tubular housing (3) above the space (17), the clearance area between the inner tube (12) and loose cover (13) is smaller than the clearance area between the outer periphery of the loose cover (13) and inner periphery of the tubular housing (3), and circulation paths (20) of refrigerant liquid are formed in the container (1).

Description

TECHNICAL FIELD [0001] The present invention relates to a flooded evaporator further increased in heat transfer performance of flooded evaporators commonly adopted in refrigerating machines, etc. for their superior heat transfer performance and improved in function of separating refrigerant mist in refrigerant vapor volatilized an the evaporator. BACKGROUND ART [0002] A flooded evaporator is an evaporator in which tubes for allowing a medium to be cooled (water for refrigerated air conditioning, for example) to flow are arranged in refrigerant liquid flooded therein to allow heat exchange between the refrigerant liquid and the medium to be cooled so that the medium is cooled by giving heat to the refrigerant liquid to allow it to evaporate. The heat exchange is performed effectively because heat transfer from liquid through the tube wall is superior. [0003] Refrigerant vapor to be introduced into a compressor located downstream of the evaporator must be got rid of refrigerant mist i...

AI Technical Summary

Benefits of technology

[0030] According to the flooded evaporator of the invention, the heat exchanger having a number of cooling tubes in which the medium to be cooled flows is immersed in refrigerant liquid in the container to form the heat exchanging section, good heat transfer performance between the medium to be cooled and refrigerant filled in the heat exchanging section specific to a flooded evaporator can be obtained, and mist separation is performed in three steps. The first step is that refrigerant vapor generated in the heat exchanging section and containing refrigerant mist is introduced to the inner tube to flow up in the inner tube, this fluid impinges against the loose cover provided at the top of the inner tube with a clearance retained between the loose cover and the top end of the inner tube to be deflected there to flow downward, the loose cover being formed such that area A of the clearance between the inside periphery of the downwardly extending parts of the loose cover and the outer periphery of the inner tube is smaller than area B of the clearance between the outer periphery of the downwardly extending parts of the loose cover and the inside periphery of the tubular housing (A<B) so that the refrigerant mist contained in the refrigerant vapor is prevented from flowing upward directly together with the refrigerant vapor after the refrigerant vapor containing refrigerant mist flows out passing through the area B and a part of the mist is separated from the refrigerant vapor and falls down due to gravitational attraction aided by downward velocity thereof to return to the heat exchanging section. The second step is that refrigerant mist remaining in the refrigerant vapor is separated in the course of flowing upward in the space above the loose cover due to gravitational attraction. The third step is that the rest of refrigerant mist is removed in the demister. Therefore, refrigerant mist can be exactly separated from refrigerant vapor, as a result liquid flow-back to a device such as a compressor located downstream of the evaporator can be prevented.

[0031] As the flooded evaporator of the invention is composed of a heat exchanging section and a vapor-liquid separating section provided integral with the heat exchanging section to rise upward, the evaporator does not become large sized, space saving is attained, and can be composed to be hermetically-closed easily by composing as welded construction, it can be applied to an ammonia refrigeration system.

[0032] By composing the flooded evaporator preferably such that the heat exchanger is preferably covered with a cover plate such that an upper part of the cover plate where the inner tube is provided is opened to allow communication of the heat exchanger to the inner tube, lower part is open to the heat exchanging section of the container, and circulation paths are formed between both sides of the cover plate and the inner surface of the container so that refrigerant liquid circulates flowing down the circulation paths, entering the heat exchanger from the opening in the lower part of the cover plate, flowing up in the heat exchanger, and separated refrigerant mist fallen down to the heat exchanging section of the container again flows down the paths as liquid refrigerant, refrigerant liquid filled in the container can flow through the circulation paths which are formed between both sides of the cover plate of the heat exchanger and the container and extending to the lower opening from where the refrigerant liquid enter the heat exchanger, heat exchanging between the medium to be cooled and refrigerant liquid can be performed repeatedly, and heat transfer efficiency is further increased.

[0033] By composing the flooded evaporator preferably such that the container for accommodating the heat exchanger and the heat exchanger has a circular cross section respectively and the heat exchanger is placed in the container offset a little downward, wide area for guiding refrigerant liquid to the circulation paths formed between both sides of the cover plate of the heat exchanger and container can be secured in the upper part of each of the paths at the entrance of refrigerant liquid into the circulation paths. Therefore, circulation of refrigerant liquid through the heat exchanger is enhanced and heat transfer between the medium to be cooled and refrigerant liquid is improved.

[0034] Further, by forming the container for filling refrigerant and the heat exchanger accommodated in the container to have a circular cross section respectively, the volume of the heat exchanger can be increased to a maximum relative to the amount of refrigerant filled in the container, as a result, utilization efficiency of refrigerant is increased. Therefore, the amount of refrigerant liquid retained in the container can be reduced to a minimum and maximum evaporation performance can be attained with minimum amount of refrigerant liquid retained in the container.

[0035] By composing the flooded evaporator preferably such that the heat exchanger is comprised of a number of heat transfer plates arranged parallel to each other at certain spacing and a number of tubes crossing the heat transfer plate, in which tubes the medium to be cooled flows, efficiency of heat transfer between the medium to be cooled and refrigerant liquid can be increased further.

Problems solved by technology

When boiling point of refrigerant liquid rises, temperature difference between the temperature of the medium to be cooled and that of refrigerant liquid ‘a’ becomes small, the amount of heat exchange in the evaporator decreases, and desired low temperature of the medium to be cooled can not be obtained.

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