GB2161256A

GB2161256A - Refrigerant evaporator for a refrigeration system

Info

Publication number: GB2161256A
Application number: GB08513911A
Authority: GB
Inventors: Jimmie Eurenius; Kjell Hultberg; Arne Nilsson
Original assignee: Stal Refrigeration AB
Current assignee: Stal Refrigeration AB
Priority date: 1984-07-05
Filing date: 1985-06-03
Publication date: 1986-01-08
Also published as: GB2161256B; SE8403575L; GB8513911D0; SE458149B; JPS6124989A; SE8403575D0; DE3522954A1; FR2567254B1; FR2567254A1

Abstract

An evaporator for a refrigeration system is formed as a heat exchanger consisting of a horizontal container (1) with longitudinal tubes (2) traversed by a heat transfer medium, for example water or brine. The container is provided with collection chambers (4, 5) for the tubes at the ends of the inlet and outlet of the heat transfer medium. The liquid refrigerant is passed in through an inlet (8) at one end of the container and is discharged through an outlet (9) at the top of the container at the other end thereof. Somewhere in the centre of the container, the container is divided into two parts by means of a vertical partition (10) so that the first part of the container operates as a so-called flowing evaporator, in which the refrigerant boils up around the tubes. The vertical partition operates as a spillway for the boiling liquid refrigerant, of which a certain part, by means of the boiling, flows over the upper edge of the partition. In this way it is ensured that oil in the refrigerant is forwarded with the evaporated refrigerant back to the compressor. <IMAGE>

Description

SPECIFICATION Refrigerant evaporator for a refrigeration system The present invention relates to an evaporator for a refrigeration system in the form of a heat exchanger consisting of a horizontal container with through-going tubes. The heat exchanger is of the type in which a liquid heat transfer medium flows through the tubes, whereas the refrigerant is evaporated outside the tubes. This type is normally the most practical one since the heat transfer medium often results in a certain degree of fouling and precipitation, and it is considerably more simple to clean the inside of the tubes than the outside thereof.

Evaporators of this type have heretofore been constructed either as flowing evaporators, in which the evaporation takes place by passing the liquid refrigerant into the bottom of the evaporator and boiling it up from the liquid surface, or as dry evaporators, in which the refrigerant is passed through the container in the longitudinal direction and is evaporated during the passage through the container. The first type of evaporators has the disadvantage that accompanying compressor oil is precipitated at the bottom of the container, which is more or less filled up with oil. The other type of evaporators has the disadvantage that it provides poor heat transfer from the gas-liquid mixture to the heat transfer medium in the tubes, and therefore this type has large dimensions to provide the desired heat transfer.

The present invention is based on a combination of the two principles mentioned above by dividing the interior of the container into two parts by means of a vertical partition wall. This partition extends from the bottom of the container more than half-way upwards in the container, the liquid refrigerant being passed into one end of the container and the gaseous meduim leaving the other end of the container. The first part of the container will thus operate as a flowing evaporator, whereas the second part operates as a dry evaporator. The vertical wall will serve as a spillway between the two parts, so that a certain amount of liquid refrigerant constantly flows over into the dry part of the container. The boiling then results in oil-mixed medium being constantly carried along to the dry part, so that the oil is prevented from accumulating to any greater extent in the container.The oil will then sooner or later accompany the gaseous refrigerant back to the compressor for lubrication thereof.

The invention will be described in greater detail with reference to the accompanying drawing, the single figure of which shows a section through an evaporator according to the invention. The evaporator can be used both for proper refrigeration systems and for heat pumps.

The evaporator consists of a horizontal container 1 with longitudinal tubes 2, which are rolled into tube walls 3 at the ends of the container. Collection chambers 4 and 5 are attached to these tube walls by means of flanges and bolts. A heat transfer medium is passed through a lower inlet 6 into th chamber 5, through the lower bundle of tubes 2 and to the turning chamber 4, further through the upper bundle of tubes to the upper part of the chamber 5, which is divided by a vertical partition in the middle, and out through the outlet 7. In ordinary refrigeration systems, the heat transfer medium consists, for example, of brine. In heat pumps, on the other hand, the heat transfer medium consists of the medium, water table or water from a water course or waste water, from which heat is to be recovered.

The liquid refrigerant is passed in through the inlet 8 at the bottom of the container, whereas the gaseous, evaporated refrigerant is discharged through the outlet 9 at the top of the container.

According to the invention, a vertical partition 10 is now placed somewhere to the right of the centre of the container so that the container is divided into one flowing part on the left and one dry part on the right. The partition 10 is suitably moved up to about two-thirds of the height of the container and it will serve as a spillway for the lefthand part so that part of the boiling liquid flows over to the dry part. This causes the oil, suspended or dissolved in the liquid, to also be forwarded to the dry part so that the oil quantity in the flowing part can never exceed the allowed value.

To render the heat transfer in the dry part between refrigerant and heat transfer medium in the tubes more efficient, thus ensuring complete evaporation of the refrigerant while at the same time ensuring that precipitated oil in this part constantly accompanies the gaseous medium back into the compressor, screening walls 11 have been arranged in the dry part so that the gas flow is deflected and a high rate of flow is maintained in the dry part.

As mentioned above, the partition is positioned somewhat to the right of the centre of the container so that the flowing part, which has the best heat transfer, is the greatest one. The dry part is then to serve as some kind of superheater and should be dimensioned so as to ensure complete evaporation of the refrigerant before the refrigerant, in gaseous state, leaves the outlet 9 at the top of the container.

1. An evaporator for a refrigeration system in the form of a heat exchanger consisting of a horizontal container (1) with through-going tubes (2) for passage of a heat transfer medium, the container being divided into two parts by means of a vertical partition (10) up to a certain height, a liquid refrigerant being passed into one end (8) of the container, evaporated in the space between the tubes and the container wall and the evaporated refrigerant being discharged from the other end (9) of the ontainer, characterized in that the vertical partition (10) serves as a spillway for the liquid refrigerant in the first part of the container.

2. Evaporator according to claim 1, characterized in that the height of the vertical partition (10)

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Refrigerant evaporator for a refrigeration system The present invention relates to an evaporator for a refrigeration system in the form of a heat exchanger consisting of a horizontal container with through-going tubes. The heat exchanger is of the type in which a liquid heat transfer medium flows through the tubes, whereas the refrigerant is evaporated outside the tubes. This type is normally the most practical one since the heat transfer medium often results in a certain degree of fouling and precipitation, and it is considerably more simple to clean the inside of the tubes than the outside thereof. Evaporators of this type have heretofore been constructed either as flowing evaporators, in which the evaporation takes place by passing the liquid refrigerant into the bottom of the evaporator and boiling it up from the liquid surface, or as dry evaporators, in which the refrigerant is passed through the container in the longitudinal direction and is evaporated during the passage through the container. The first type of evaporators has the disadvantage that accompanying compressor oil is precipitated at the bottom of the container, which is more or less filled up with oil. The other type of evaporators has the disadvantage that it provides poor heat transfer from the gas-liquid mixture to the heat transfer medium in the tubes, and therefore this type has large dimensions to provide the desired heat transfer. The present invention is based on a combination of the two principles mentioned above by dividing the interior of the container into two parts by means of a vertical partition wall. This partition extends from the bottom of the container more than half-way upwards in the container, the liquid refrigerant being passed into one end of the container and the gaseous meduim leaving the other end of the container. The first part of the container will thus operate as a flowing evaporator, whereas the second part operates as a dry evaporator. The vertical wall will serve as a spillway between the two parts, so that a certain amount of liquid refrigerant constantly flows over into the dry part of the container. The boiling then results in oil-mixed medium being constantly carried along to the dry part, so that the oil is prevented from accumulating to any greater extent in the container.The oil will then sooner or later accompany the gaseous refrigerant back to the compressor for lubrication thereof. The invention will be described in greater detail with reference to the accompanying drawing, the single figure of which shows a section through an evaporator according to the invention. The evaporator can be used both for proper refrigeration systems and for heat pumps. The evaporator consists of a horizontal container 1 with longitudinal tubes 2, which are rolled into tube walls 3 at the ends of the container. Collection chambers 4 and 5 are attached to these tube walls by means of flanges and bolts. A heat transfer medium is passed through a lower inlet 6 into th chamber 5, through the lower bundle of tubes 2 and to the turning chamber 4, further through the upper bundle of tubes to the upper part of the chamber 5, which is divided by a vertical partition in the middle, and out through the outlet 7. In ordinary refrigeration systems, the heat transfer medium consists, for example, of brine. In heat pumps, on the other hand, the heat transfer medium consists of the medium, water table or water from a water course or waste water, from which heat is to be recovered. The liquid refrigerant is passed in through the inlet 8 at the bottom of the container, whereas the gaseous, evaporated refrigerant is discharged through the outlet 9 at the top of the container. According to the invention, a vertical partition 10 is now placed somewhere to the right of the centre of the container so that the container is divided into one flowing part on the left and one dry part on the right. The partition 10 is suitably moved up to about two-thirds of the height of the container and it will serve as a spillway for the lefthand part so that part of the boiling liquid flows over to the dry part. This causes the oil, suspended or dissolved in the liquid, to also be forwarded to the dry part so that the oil quantity in the flowing part can never exceed the allowed value. To render the heat transfer in the dry part between refrigerant and heat transfer medium in the tubes more efficient, thus ensuring complete evaporation of the refrigerant while at the same time ensuring that precipitated oil in this part constantly accompanies the gaseous medium back into the compressor, screening walls 11 have been arranged in the dry part so that the gas flow is deflected and a high rate of flow is maintained in the dry part. As mentioned above, the partition is positioned somewhat to the right of the centre of the container so that the flowing part, which has the best heat transfer, is the greatest one. The dry part is then to serve as some kind of superheater and should be dimensioned so as to ensure complete evaporation of the refrigerant before the refrigerant, in gaseous state, leaves the outlet 9 at the top of the container. CLAIMS

2. Evaporator according to claim 1, characterized in that the height of the vertical partition (10) somewhat exceeds half the height of the container (1).

3. Evaporator according to claim 1, characterized in that the second part of the container (1) is divided by means of other vertical partitions (11), extending upwards and downwards in the container, into interconnecting chambers for deflecting the flow of evaporated refrigerant.

4. Evaporator according to claim 1, characterized in that the first partition (10) is so positioned that the first part of the container, the boiler part which contains liquid refrigerant, is greater than the second part.

5. An evaporator substantially as hereinbefore described with reference to and as shown in the accompanying drawing.