US-12618617-B2 - Heat exchanger and refrigeration system and method

US12618617B2US 12618617 B2US12618617 B2US 12618617B2US-12618617-B2

Abstract

A brazed plate heat exchanger ( 100 ) including a plurality of first and second heat exchanger plates ( 110, 120 ), wherein the first heat exchanger plates ( 110 ) are formed with a first pattern of ridges (R 1 ) and grooves (G 1 ), and the second heat exchanger plates ( 120 ) are formed with a second pattern of ridges (R 2 a , R 2 b ) and grooves (G 2 a , G 2 b ) providing contact points between at least some crossing ridges and grooves of neighbouring plates under formation of interplate flow channels for fluids to exchange heat, said interplate flow channels being in selective fluid communication port openings (O 1 , O 2 , O 3 , O 4 ). The first pattern of ridges and grooves is different from the second pattern of ridges and grooves, so that an interplate flow channel volume on one side of the first heat exchanger plates ( 110 ) is different from the interplate flow channel volume on the opposite side of the first heat exchanger plates ( 110 ). The heat exchanger ( 100 ) is provided with a retrofit port heat exchanger ( 400 ). A system and a method are also disclosed.

Inventors

Sven Andersson
Tomas Dahlberg

Assignees

SWEP INTERNATIONAL AB

Dates

Publication Date: 20260505
Application Date: 20210129
Priority Date: 20200130

Claims (13)

1 . A brazed plate heat exchanger assembly comprising a plurality of first and second heat exchanger plates, wherein the first heat exchanger plates are formed with a first pattern of ridges and grooves, and the second heat exchanger plates are formed with a second pattern of ridges and grooves providing contact points between at least some crossing ridges and grooves of neighbouring plates under formation of interplate flow channels for fluids to exchange heat, said interplate flow channels being in selective fluid communication with port openings, the first pattern of ridges and grooves is different from the second pattern of ridges and grooves, so that an interplate flow channel volume on one side of the first heat exchanger plates is different from the interplate flow channel volume on the opposite side of the first heat exchanger plates, the second pattern of ridges and grooves has first and second grooves, wherein the first grooves are formed with a first depth and the second grooves are formed with a second depth different from the first depth, brazing joints are formed at said contact points between crossing ridges and grooves of the first and second heat exchanger plates, and said brazing joints are elongated, and a retrofit port heat exchanger, wherein the first and second heat exchanger plates are arranged alternatingly so that every other of the heat exchanger plates are the first heat exchanger plates, and the remaining heat exchanger plates are the second heat exchanger plates, wherein ridges and grooves of the first heat exchanger plates, at least in a central main heat exchanging section of the first heat exchanger plates, extend in a first angle, and ridges and grooves of the second heat exchanger plates, at least in a central main heat exchanging section of the second heat exchanger plates, extend in a second angle different from the first angle, wherein a difference between the first angle and the second angle is 2° to 35°, wherein the elongated brazing joints are arranged in a first orientation in the interplate flow channel volume on the one side of the first heat exchanger plates, and in a second orientation in the interplate flow channels on the opposite side of first heat exchanger plates, wherein the first orientation and the second orientation are different, and wherein the interplate flow channel volume on the one side of the first heat exchanger plates is larger than the interplate flow channel volume on the opposite side of the first heat exchanger plates.
2 . The brazed plate heat exchanger assembly of claim 1 , wherein the retrofit port heat exchanger comprises a pipe extending into a port opening of a plurality of heat exchanger plates.
3 . The brazed plate heat exchanger assembly of claim 2 , wherein the pipe of the retrofit port heat exchanger comprises a portion bent in the form of a semi helix, said portion extending into the port opening.
4 . The brazed plate heat exchanger assembly of claim 1 , wherein the first pattern is a first herringbone pattern or a first pattern of obliquely extending straight lines and the second pattern is a second herringbone pattern or a second pattern of obliquely extending straight lines, and wherein some of the ridges and grooves of the first and second patterns extend from one side of the heat exchanger plates to the other.
5 . The brazed plate heat exchanger assembly of claim 1 , wherein the interplate flow channels on the one side of the first heat exchanger plates have a different cross section area than on the opposite side.
6 . The brazed plate heat exchanger assembly of claim 1 , wherein at least the second heat exchanger plates are asymmetric.
7 . The brazed plate heat exchanger assembly of claim 1 , wherein the first heat exchanger plates are symmetric.
8 . A refrigeration system comprising a compressor for compressing a gaseous refrigerant, such that the temperature, pressure and boiling point thereof increases; a condenser, in which the gaseous refrigerant from the compressor exchanges heat with a high temperature heat carrier, said heat exchange resulting in the refrigerant condensing; an expansion valve reducing the pressure of liquid refrigerant from the condenser, hence reducing the boiling point of the refrigerant; an evaporator, in which the low boiling point refrigerant exchanges heat with a low temperature heat carrier, such that the refrigerant vaporizes; and a retrofit port heat exchanger exchanging heat between high temperature liquid refrigerant from the condenser and high temperature gaseous refrigerant from the evaporator, wherein the evaporator is formed by a brazed plate heat exchanger comprising a plurality of first and second heat exchanger plates, wherein the first heat exchanger plates are formed with a first pattern of ridges and grooves, and the second heat exchanger plates are formed with a second pattern of ridges and grooves providing contact points between at least some crossing ridges and grooves of neighbouring plates under formation of interplate flow channels for fluids to exchange heat, said interplate flow channels being in selective fluid communication with port openings, wherein the first pattern of ridges and grooves is different from the second pattern of ridges and grooves, so that an interplate flow channel volume on one side of the first heat exchanger plates is different from an interplate flow channel volume on an opposite side of the first heat exchanger plates, the second pattern of ridges and grooves has first and second grooves, wherein the first grooves are formed with a first depth and the second grooves are formed with a second depth different from the first depth, brazing joints are formed at said contact points between crossing ridges and grooves of the first and second heat exchanger plates, and said brazing joints are elongated, wherein the first and second heat exchanger plates are arranged alternatingly so that every other of the heat exchanger plates are the first heat exchanger plates, and the remaining heat exchanger plates are the second heat exchanger plates, wherein ridges and grooves of the first heat exchanger plates, at least in a central main heat exchanging section of the first heat exchanger plates, extend in a first angle and ridges and grooves of the second heat exchanger plates, at least in a central main heat exchanging section of the second heat exchanger plates, extend in a second angle different from the first angle, wherein a difference between the first angle and the second angle is 2° to 35°, wherein the elongated brazing joints are arranged in a first orientation in the interplate flow channel volume on the one side of the first heat exchanger plates, and in a second orientation in the interplate flow channels on the opposite side of first heat exchanger plates, wherein the first orientation and the second orientation are different, and wherein the interplate flow channel volume on the one side of the first heat exchanger plates is larger than the interplate flow channel volume on the opposite side of the first heat exchanger plates.
9 . The refrigeration system of claim 8 , comprising means for controlling the amount of heat exchange in the retrofit port heat exchanger.
10 . The refrigeration system of claim 9 , wherein the means for controlling the amount of heat exchange in the retrofit port heat exchanger is a controllable balance valve, which controls the amount of refrigerant bypassing the retrofit port heat exchanger.
11 . The refrigeration system of claim 10 , wherein the balance valve bypasses liquid refrigerant from the condenser past the retrofit port heat exchanger.
12 . The refrigeration system of claim 9 , wherein the means for controlling the amount of heat exchange in the retrofit port heat exchanger comprises dual expansion valves, wherein a first of the expansion valves is connected between an inlet of the evaporator and the retrofit port heat exchanger and a second of the expansion valves is connected between the inlet of the evaporator and the condenser.
13 . The refrigeration system of claim 8 , comprising a four-way valve, so that the refrigeration system is reversible.

Description

This application is a National Stage Application of PCT/SE2021/050068, filed 29 Jan. 2021, which claims benefit of Serial No. 2050096-3, filed 30 Jan. 2020 in Sweden, and which applications are hereby incorporated by reference in their entireties. To the extent appropriate, a claim of priority is made to each of the above disclosed applications. FIELD OF THE INVENTION The present invention relates to a brazed plate heat exchanger comprising a plurality of heat exchanger plates having a pattern of ridges and grooves providing contact points between at least some crossing ridges and grooves of neighboring plates under formation of interplate flow channels for fluids to exchange heat. The interplate flow channels are in selective fluid communication with four port openings for fluids to exchange heat. This type of heat exchangers also comprises a so called suction gas heat exchanger, in the form of a retrofit port heat exchanger. The present invention is also related to a refrigeration system comprising at least one such heat exchanger. The present invention is also related to a refrigeration method using at least one such heat exchanger. Disclosed is also heat exchangers and refrigeration systems and methods. PRIOR ART A plurality of brazed plate heat exchangers with a pressed corrugated pattern having ridges and grooves in a herringbone pattern is known in the prior art. It is also known to provide heat exchangers with an integrated suction gas heat exchanger and to use such a heat exchanger in a refrigeration system. In the refrigeration field, there is a constant strive towards more efficient systems. Actually, the best refrigeration systems approach the Carnot efficiency, which is the theoretical upper limit for a heat machine. Generally speaking, all refrigeration systems transforming mechanical energy to a temperature difference comprises a compressor, a condenser, an expansion valve, an evaporator, and piping enabling transport of refrigerant between the compressor, the condenser, the expansion valve and the evaporator, wherein heat is transferred from the evaporator to the condenser. However, although the efficiency at some temperature differences may approach the Carnot efficiency, this is far from true for all running conditions. In general terms, all heat exchangers comprised in a refrigeration system should be as large and efficient as possible. Also, they should have an as low hold-up volume as possible, and a low pressure drop. As could be understood, these criteria cannot all be met. When it comes to the temperatures after the evaporator, every temperature increase over the temperature at which all refrigerant is evaporated (i.e. the highest boiling point of the refrigerant) will mean a loss in efficiency—however, since liquid refrigerant entering the compressor may seriously damage the compressor, it is also crucial that all refrigerant actually is vaporized before entering the compressor. A state where all the refrigerant is evaporated, although its temperature does not exceed the boiling temperature, is generally referred to as “zero superheat”, and is a state being very beneficial in terms of efficiency. One way of achieving “zero superheat” in the evaporator is to “flood” the evaporator with liquid refrigerant and let refrigerant boil off from the flooded evaporator. This configuration is common in large chiller applications, i.e. heat machines having a power of 500-1000 kW. Usually, so-called “plate and shell” or “shell and tube” heat exchangers are used for such applications. As could be understood from the above, such evaporator configurations give great performance, but they are far from free from drawbacks. First, all heat exchangers comprising a shell are bulky and heavy, meaning that the material cost for manufacturing them are high. Secondly, and even more important, the refrigerant volume required for flooding the heat exchanger is large. Except from the cost issue, legislation often bans too large refrigerant amounts in a heat machine. The by far most efficient heat exchanger type in terms of heat transfer/material mass is the compact brazed plate heat exchanger (BPHE). As known by persons skilled in the art, such heat exchangers comprise a number of plates made from sheet metal and provided with a pressed pattern of ridges and grooves adapted to keep the plates at a distance from one another under formation of interplate flow channels for the media to exchange heat. The plates are brazed to one another, meaning that each plate pair will be active in containing the refrigerant under pressure in the heat exchanger. Brazed plate heat exchangers have the benefit that virtually all material in the heat exchanger actually is active for heat exchange, unlike the heat exchangers comprising a shell, wherein the shell has the sole purpose of containing the refrigerant. The evaporation processes in BPHE:s and flooded shell and tube heat exchangers are very different—as mentioned, the evapo