Cooling system and method for controlling the cooling system

Abstract

The refrigeration system includes a compressor that compresses a gaseous refrigerant to increase its temperature and pressure, a four-way valve that controls whether the refrigeration system is in a cooling mode or a heating mode, a condenser that condenses the gaseous refrigerant from the compressor by exchanging heat with a high-temperature heat transfer medium, an expansion valve that reduces the pressure of the liquid refrigerant from the condenser to lower the boiling point of the refrigerant, an evaporator that vaporizes the refrigerant by exchanging heat with a low-temperature heat transfer medium, and an intake heat exchanger that exchanges heat between the high-temperature liquid refrigerant from the condenser and the low-temperature gaseous refrigerant from the evaporator. A balance valve is positioned to direct the flow of high-temperature liquid refrigerant directly from the condenser to the expansion valve, thereby controlling the amount of heat exchange between the high-temperature liquid refrigerant and the low-temperature gaseous refrigerant in the intake heat exchanger. A method for controlling such a system is also disclosed.

Description

[Technical Field]

[0001] The present invention relates to a refrigeration system including a compressor that compresses a gaseous refrigerant so that its temperature and pressure increase and its boiling point increase, a condenser that condenses the gaseous refrigerant by exchanging heat with a high-temperature heat transfer medium from the compressor, an expansion valve that reduces the pressure of the liquid refrigerant from the condenser to lower the boiling point of the refrigerant, an evaporator that vaporizes the refrigerant by exchanging heat with a low-temperature heat transfer medium from the lowered boiling point, and an intake heat exchanger that exchanges heat between the high-temperature liquid refrigerant from the condenser and the low-temperature gaseous refrigerant from the evaporator. A method for controlling such a system is also disclosed. A heat exchanger, a refrigeration system, and a method are also disclosed. [Background technology]

[0002] In the field of refrigeration, there is a constant striving towards more efficient systems. In fact, the best refrigeration systems approach the Carnot efficiency, the theoretical upper limit of thermal machines. Generally speaking, all refrigeration systems that convert mechanical energy into a temperature difference include a compressor, a condenser, an expansion valve, an evaporator, and piping that allows the transport of refrigerant between the compressor, condenser, expansion valve, and evaporator, and heat is transferred from the evaporator to the condenser.

[0003] However, although the efficiency at some temperature differences may approach the Carnot efficiency, this may not be the case for all operating conditions.

[0004] Generally, all heat exchangers in a cooling system need to be as large and efficient as possible, have as little hold-up as possible, and have low pressure drop. Understandably, it is not possible to meet all of these criteria.

[0005] With regard to the temperature after the evaporator, any increase in temperature above the temperature at which all the refrigerant evaporates (i.e., the refrigerant's maximum boiling point) means a loss of efficiency, but it is also important to actually vaporize all the refrigerant before it enters the compressor, because liquid refrigerant entering the compressor could cause serious damage to the compressor. The condition where all the refrigerant evaporates, but the temperature does not exceed the boiling point, is commonly referred to as "zero superheat" and is a very favorable condition in terms of efficiency.

[0006] One way to achieve "zero superheat" in an evaporator is to "flood" the evaporator with liquid refrigerant and boil the refrigerant off the flooded evaporator. This configuration is common in large chiller applications, i.e., thermal machines with a power of 500-1000 kW. Typically, so-called "plate-and-shell" or "shell-and-tube" heat exchangers are used in such applications.

[0007] As can be seen from the above, such evaporator configurations offer excellent performance, but they are not without drawbacks. First, the bulkiness and weight of all heat exchangers, including the shell, means that the materials costs for their manufacture are high. Second, and more importantly, the amount of refrigerant required to fill the heat exchanger is large. Besides the cost issue, legislation often prohibits excessive refrigerant volumes in thermal machines.

[0008] From a heat transfer / material mass standpoint, by far the most efficient type of heat exchanger is the compact brazed plate heat exchanger (BPHE). As known to those skilled in the art, such heat exchangers include multiple plates made of sheet metal with a pressed pattern of ridges and grooves adapted to maintain the plates at a distance from one another, forming interplate flow paths for the medium to exchange heat. The fact that the plates are brazed together means that each plate pair is activated to pressurize and contain a refrigerant within the heat exchanger. Unlike heat exchangers that include a shell whose sole purpose is to contain the refrigerant, brazed plate heat exchangers have the advantage that virtually all of the material within the heat exchanger is actually active in heat exchange.

[0009] The evaporation process in a BPHE and a flooded shell-and-tube heat exchanger is very different, as mentioned above. Evaporation in a flooded shell-and-tube heat exchanger is similar to pool boiling, but in a BPHE, the refrigerant moves in a nearly straight line through the interplate channels. The closer to the outlet, the less liquid refrigerant is present. The increase in volume due to evaporation increases velocity, and therefore flow resistance, along the length of the heat exchanger.

[0010] As mentioned above, it is important that liquid refrigerant does not enter the compressor, so it is not uncommon for at least a portion of the heat exchanger to contain only gaseous refrigerant, which would absorb heat and become unnecessarily hot, thereby reducing system efficiency.

[0011] It is also advantageous if the liquid refrigerant entering the evaporator is cold, as a cold refrigerant minimizes the flash boiling phenomenon.

[0012] One way to ensure a low refrigerant temperature entering the expansion valve (thus reducing the risk of flash boiling) and a sufficiently high temperature of the gas refrigerant entering the compressor is to use a so-called intake air heat exchanger. In its simplest form, an intake air heat exchanger can be installed simply by placing the piping from the evaporator to the compressor close to the piping from the condenser to the expansion valve and brazing or soldering them together so that heat is transferred between the piping. However, in large systems, it is common to provide a more efficient heat exchanger than simply placing two pipes side by side. Typically, when using larger types of intake air heat exchangers, problems with pressure loss at the evaporator outlet and pressure loss at the intake / outlet of the intake air heat exchanger can destroy overall efficiency and cause control problems for systems equipped with such heat exchangers.

[0013] If superheating of the refrigerant can be minimized while preventing liquid refrigerant from entering the compressor, the BPHE can potentially compete with flooded shell-and-tube heat exchangers in efficiency while retaining their advantages in compactness and material efficiency.

[0014] In refrigeration technology, the so-called "intake air heat exchange" is a method for improving the stability of a refrigeration system. In essence, intake air heat exchange is achieved by providing heat exchange between the high-temperature liquid, high-pressure refrigerant from the condenser outlet and the low-temperature gaseous refrigerant from the evaporator outlet. The intake air heat exchange increases the temperature of the low-temperature gaseous refrigerant and decreases the temperature of the high-temperature liquid. This has two positive effects. First, it reduces the problem of flash boiling after the high-temperature liquid passes through the subsequent expansion valve. Second, it reduces the risk of liquid droplets in the gaseous refrigerant leaving the evaporator.

[0015] Inlet air heat exchange is well known. In many cases, it is achieved simply by brazing or soldering pipes carrying refrigerants of the desired temperature to each other. However, this method of achieving heat exchange is expensive in terms of the amount of refrigerant required, and it is always advantageous if the piping between the different components of the cooling system is as short as possible. Inlet air heat exchange by brazing or soldering piping carrying fluids of different temperatures requires longer piping than would otherwise be required, thereby increasing the internal volume of the piping and therefore requiring more refrigerant in the cooling system. This is disadvantageous not only from an economic standpoint, but also because some jurisdictions limit the amount of refrigerant that can be used.

[0016] Another option is to provide a separate heat exchanger for the intake air heat exchange, which is more efficient than simply brazing different piping sections together. However, providing a separate heat exchanger also requires piping connecting the evaporator and condenser to the intake air heat exchanger, which would increase the amount of refrigerant in the cooling system.

[0017] Furthermore, cooling systems often need to be able to operate in both heating and chilling modes, depending on the required / desired load. Typically, the transition between heating and chilling modes is accomplished by switching a four-way valve so that the evaporator becomes the condenser and vice versa. Unfortunately, this means that the heat exchange in either or both condenser / evaporator units is parallel-flow heat exchange, meaning that the heat exchange medium moves in the same overall direction in either heating or cooling mode. As is well known to those skilled in the art, parallel-flow heat exchange is inferior to counterflow heat exchange. In the evaporator, reduced heat exchange performance can increase the risk of droplets in the refrigerant vapor escaping the heat exchanger. Such droplets are highly undesirable because they can cause serious damage to the compressor. However, devices for switching the flow direction of the medium for heat exchange with the refrigerant in the evaporator are expensive and complicate the cooling system. Summary of the Invention [Problem to be solved by the invention]

[0018] It is an object of the present invention to solve or at least mitigate these and other problems.

[0019] In one aspect, it is an object of the present invention to provide a plate heat exchanger that provides good fluid distribution and heat transfer between fluids in a cooling system.

[0020] In another aspect, it is an object of the present invention to provide an efficient cooling system.

[0021] In yet another aspect, it is an object of the present invention to provide a BPHE, and a refrigeration system using the BPHE, for achieving zero or near-zero superheat of the refrigerant entering the compressor. [Means for solving the problem]

[0022] In order to achieve some of the above objects, a cooling system according to a first aspect of the present invention includes a compressor that compresses a gaseous refrigerant so that its temperature and pressure increase and its boiling point increase; a four-way valve that controls whether the cooling system is in a cooling mode or a heating mode; a condenser that condenses the gaseous refrigerant from the compressor by exchanging heat with a high-temperature heat transfer medium; an expansion valve that reduces the pressure of the liquid refrigerant from the condenser to lower the boiling point of the refrigerant; an evaporator that vaporizes the refrigerant by exchanging heat with a low-temperature heat transfer medium with the refrigerant whose boiling point has been lowered; and an intake heat exchanger that exchanges heat between the high-temperature liquid refrigerant from the condenser and the low-temperature gaseous refrigerant from the evaporator, and further includes a balance valve arranged to control the amount of heat exchange between the high-temperature liquid refrigerant and the low-temperature gaseous refrigerant in the intake heat exchanger by directing the flow of the high-temperature liquid refrigerant from the condenser to the expansion valve without passing through the intake heat exchanger.

[0023] The invention further relates to a method of controlling such a system, said method comprising: a) measuring the temperature of the hot liquid refrigerant; b) measuring the temperature of the low-temperature gas refrigerant; Step c) calculating the temperature difference between the hot liquid refrigerant and the cold gaseous refrigerant; and d) controlling the balance valve to bypass the intake air heat exchanger if the difference is less than a predetermined threshold. Includes.

[0024] For example, the threshold may be zero.

[0025] In order to achieve some of the above objects, a cooling system according to a second aspect of the present invention includes a compressor that compresses a gaseous refrigerant so that its temperature and pressure increase and its boiling point increase; a condenser that condenses the refrigerant by heat exchange of the gaseous refrigerant from the compressor with a high-temperature heat medium; an expansion valve that lowers the boiling point of the liquid refrigerant from the condenser by reducing the pressure of the refrigerant; an evaporator that vaporizes the refrigerant by heat exchange of the refrigerant with a low-temperature heat medium with the lowered boiling point; and an intake heat exchanger that exchanges heat between the high-temperature liquid refrigerant from the condenser and the low-temperature gaseous refrigerant from the evaporator, wherein the low-temperature gaseous refrigerant entering the intake heat exchanger contains a certain amount of low-temperature liquid refrigerant, and the low-temperature liquid refrigerant is vaporized as a result of heat exchange with the high-temperature liquid refrigerant from the condenser.

[0026] To achieve some of the above objects, a plate heat exchanger according to a third aspect of the present invention comprises a plurality of heat exchange plates provided with pressed patterns adapted to provide contact points maintaining the heat exchange plates at a distance from one another so that inter-plate flow channels are formed between the plates, the inter-plate flow channels being provided for a first medium, the first medium exchanging heat with a second medium in the inter-plate flow channels and a third medium in the inter-plate flow channels, the inter-plate flow channels being in selective fluid communication with port openings for the first medium, the second medium and the third medium, the plate heat exchanger comprising first and second integrated inlet heat exchanger sections provided near the port openings for the second medium and the third medium.

[0027] To achieve some of the above objects, a brazed plate heat exchanger according to a fourth aspect of the present invention includes a plurality of first and second heat exchange plates, the first heat exchange plate having a first pattern of ridges and grooves formed therein, and the second heat exchange plate having a second pattern of ridges and grooves formed therein, the second pattern of ridges and grooves providing contact points between at least some of the intersecting ridges and grooves of adjacent plates under the formation of interplate flow passages for a fluid to exchange heat, the interplate flow passages selectively corresponding to first, second, third and fourth large port openings and first and second small port openings. 1. A brazed plate heat exchanger comprising: first and second heat exchange plates in fluid communication, each having a dividing surface formed thereon that divides the heat exchange plate into a first heat exchange portion and a second heat exchange portion, such that fluid passing between the first and second large port openings exchanges heat with fluid passing between the third and fourth port openings on (over) the first heat exchange portion of each plate and with fluid passing between the first and second small port openings on the second heat exchange portion of each plate; wherein the ridges and grooves are formed such that inter-plate flow passages between different plate pairs have different volumes. Optionally, the first pattern defines, at least in part, a first angle, such as a first chevron angle, and the second pattern defines, at least in part, a second angle, such as a second chevron angle, that is different from the first angle.

[0028] The small port openings and dividing surfaces create an integrated intake heat exchanger. The combination of the small port openings, dividing surfaces, and at least two different plate patterns, optionally with different chevron angles and different interplate flow volume, creates a BPHE with desirable characteristics for use in cooling systems. The combination of different chevron angles and interplate flow volume balances fluid flow distribution and pressure loss to achieve efficient heat exchange, which has been found to be particularly favorable for cooling. Such BPHEs have been found to result in substantially zero or near-zero superheat of the refrigerant entering the compressor of a refrigeration system. Evaporation occurs with near-zero superheat, and superheat is added to the water side (secondary side) without evaporation. Superheat and carryover are added in the intake heat exchange process, and the carryover droplets evaporate, resulting in superheat that does not affect the evaporation process by reducing the heat transfer in the heat exchanger from the gas to the water / brine, which occurs when adding superheat in a standard heat exchanger. This allows for temperatures to be approached using parallel flow.

[0029] The invention further relates to a cooling system and a cooling method including such a plate heat exchanger.

[0030] To achieve some of the above objects, a brazed plate heat exchanger according to a fifth aspect of the present invention includes a plurality of first and second heat exchange plates, the first heat exchange plate having a first pattern of ridges and grooves and the second heat exchange plate having a second pattern of ridges and grooves, the second pattern of ridges and grooves providing contact points between at least some of the intersecting ridges and grooves of adjacent plates to form interplate channels for heat exchange between fluids, the interplate channels being selectively in fluid communication through port openings, wherein the first pattern of ridges and grooves differs from the second pattern of ridges and grooves, such that a volume of the interplate channels on one side of the first heat exchange plate differs from a volume of the interplate channels on the opposite side of the first heat exchange plate. Optionally, the first pattern of ridges and grooves defines a first angle and the second pattern of ridges and grooves defines a second angle different from the first angle.

[0031] The combination of different interplate flow channel volumes on both sides of the plates and at least two different plate patterns with different angles results in a BPHE with favorable fluid distribution characteristics, balancing fluid flow distribution and pressure drop for efficient heat exchange. This allows different characteristics to be achieved in the interplate flow channels on both sides of the same plate, so that the flow and pressure drop on one side can be different from that on the other side. The different flow channel volumes on both sides of the plate can also be used for different types of media, e.g., one channel volume for liquids and the other for gases. The combination of different interplate flow channel volumes between adjacent plates and at least two different plate patterns with different angles also allows for different brazed joint shapes, such as the width of the brazed joint relative to the flow direction, to control the flow and pressure drop of the media.

[0032] When a refrigerant starts to evaporate, it transitions from a liquid state to a vapor state. The liquid density is much higher than the vapor density. For example, for R410A at Tdew=5°C, the liquid density is 32 times higher than the vapor density. This also means that the vapor moves through the channels 32 times faster than the liquid. This automatically means that the dynamic pressure loss of the vapor is 32 times higher than the dynamic pressure loss of the liquid, meaning that the vapor has a much higher pressure loss than all types of refrigerants.

[0033] The performance of a heat exchanger (temperature approach, TA) is defined as the water outlet temperature (at the inlet of the heat exchanger flow channel) minus the evaporating temperature (Tdew) at the outlet of the heat exchanger flow channel. High pressure losses along the heat exchanger surface result in different local saturation temperatures, resulting in a relatively large total refrigerant temperature difference between the inlet and outlet of the flow channel. This temperature rise at the inlet of the flow channel directly impacts the performance of the heat exchanger, since a high inlet refrigerant temperature (due to high flow channel pressure loss) makes it difficult to cool the outlet water to the correct temperature. The only way a system can compensate for a high inlet refrigerant temperature is to lower the evaporating temperature until the correct outlet water temperature can be reached. Heat exchanger performance can be improved by creating a heat exchanger flow channel pattern with high heat transfer characteristics and low pressure loss characteristics. Lowering the overall refrigerant pressure loss within the flow channel not only improves the performance of the heat exchanger, but also has a positive impact on the overall system performance and, therefore, energy consumption.

[0034] The use of brazed plate heat exchangers with or without an inlet air heat exchanger, with different interplate flow volume and different angles for evaporating or condensing a medium is also disclosed.

[0035] To achieve some of the above objects, a brazed plate heat exchanger according to a sixth aspect of the present invention includes a plurality of first and second heat exchange plates, the first heat exchange plate having a first pattern of ridges and grooves and the second heat exchange plate having a second pattern of ridges and grooves, the second pattern of ridges and grooves providing contact points between at least some of the intersecting ridges and grooves of adjacent plates to form interplate channels for heat exchange of fluid, the interplate channels being in selective fluid communication with port openings. The brazed plate heat exchanger is characterized in that the first pattern of ridges and grooves differs from the second pattern of ridges and grooves, thereby providing interplate channel volumes on one side of the first heat exchange plate that differ from interplate channel volumes on the opposite side of the first heat exchange plate. Optionally, the first pattern exhibits a first angle and the second pattern exhibits a second angle different from the first angle. The heat exchanger is provided with an additional inlet port heat exchanger.

[0036] The present invention further relates to a cooling system and method comprising such a heat exchanger, which comprises two different plates with different patterns and angles, and in which an extra inlet port heat exchanger is provided. [Brief explanation of the drawings]

[0037] The present invention will now be described with reference to the accompanying drawings.

[0038] [Figure 1] 1 is an exploded perspective view of a heat exchanger according to an embodiment of the present invention; [Figure 2] 2 is an exploded perspective view of a portion of the heat exchanger of FIG. 1, showing a first heat exchange plate and a second heat exchange plate of the heat exchanger. [Figure 3] 5 is a schematic cross-sectional view of another portion of the first heat exchanger plate according to an embodiment, showing the same depth of the grooves of the first heat exchanger plate. FIG. [Figure 4] 4 is a schematic cross-sectional view of a portion of a second heat exchanger plate according to one embodiment, illustrating the alternating depth of the grooves in the second heat exchanger plate. [Figure 5]1 is a schematic cross-sectional view of a portion of a heat exchanger including alternating first and second heat exchange plates according to one embodiment; [Figure 6a] FIG. 2 is a schematic front view of a first heat exchanger plate according to one embodiment, showing a corrugated herringbone pattern of the first heat exchanger plate with a first chevron angle. [Figure 6b] FIG. 10 is a schematic front view of a first heat exchanger plate according to an alternative embodiment, showing a corrugation pattern of the first heat exchanger plate having a first angle. [Figure 7a] FIG. 10 is a schematic front view of a second heat exchanger plate according to one embodiment, showing a corrugated herringbone pattern of the second heat exchanger plate with a second chevron angle. [Figure 7b] FIG. 10 is a schematic front view of a second heat exchange plate according to an alternative embodiment, showing a corrugation pattern of the second heat exchange plate having a second angle. [Figure 8] 6 is a schematic diagram of a first heat exchange plate placed on top of a second heat exchange plate, showing the contact points between the first and second heat exchange plates according to the example of FIG. 5. FIG. [Figure 9] 6 is a schematic diagram of a second heat exchange plate placed on top of a first heat exchange plate, showing the contact points between the first and second heat exchange plates according to the example of FIG. 5. FIG. [Figure 10a] 1 is a schematic plan view showing a cooling system according to a first embodiment of the present invention in a heating mode. [Figure 10b] FIG. 6 is a schematic plan view showing a cooling system according to a second embodiment of the present invention in a heating mode. [Figure 11a] 1 is a schematic plan view showing a cooling system according to a first embodiment in a cooling mode. [Figure 11b] FIG. 6 is a schematic plan view showing a cooling system according to a second embodiment in a cooling mode. [Figure 12] 1 is an exploded perspective view of a heat exchanger to which an additional introduction port heat exchanger according to an embodiment of the present invention is attached; FIG. [Figure 13] FIG. 1 is a schematic perspective view of an additional inlet port heat exchanger according to one embodiment. [Figure 14] FIG. 10 is a schematic perspective view of an alternative embodiment of an additional inlet port heat exchanger. [Figure 15] FIG. 6 is a schematic cross-sectional view of a portion of a heat exchanger including first and second heat exchange plates according to another embodiment. [Figure 16] FIG. 6 is a schematic cross-sectional view of a portion of a heat exchanger including first and second heat exchange plates according to another embodiment. [Figure 17] FIG. 10 is a schematic cross-sectional view of a portion of a heat exchanger including first and second heat exchange plates according to yet another embodiment. [Figure 18] 4 is a schematic cross-sectional view of a portion of a heat exchanger plate stack of first and second heat exchanger plates having different corrugation depths according to another embodiment. FIG. [Figure 19] FIG. 1 is a schematic exploded perspective view of a true double heat exchanger including dual integrated intake heat exchangers according to one embodiment of the present invention. [Figure 20] 10 is a schematic perspective view of another embodiment of the corrugation pattern of the heat exchange plate, showing a corrugation pattern in which the angle of the corrugation pattern in the central main heat exchange section is different from the angle of the port opening portion of the heat exchange plate. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0039] Referring to FIG. 1, a brazed plate heat exchanger 100 according to one embodiment is shown, a portion of which is shown in more detail in FIG. 2. The heat exchanger 100 includes a plurality of first heat exchange plates 110 and a plurality of second heat exchange plates 120 stacked to form the heat exchanger 100. The first and second heat exchange plates 110, 120 are arranged alternately, with every other plate being a first heat exchange plate 110 and every other plate being a second heat exchange plate 120. Alternatively, the first and second heat exchange plates may be arranged in other configurations with additional plates. The heat exchanger 100 is an asymmetric plate heat exchanger.

[0040] The heat exchange plates 110, 120 are made from sheet metal and are provided with a pressed pattern of ridges R1, R2a, R2b and grooves G1, G2a, G2b to provide contact points between intersecting ridges and grooves on at least some of adjacent plates 110, 120, thereby forming interplate flow paths for fluids to exchange heat when the plates are stacked to form the heat exchanger 100. The pressed pattern in FIGS. 1 and 2 is a herringbone pattern. However, the pressed pattern may also be in the form of diagonally extending straight lines. In either case, the pressed pattern of ridges and grooves is a wave pattern. The pressed pattern is adapted to maintain the plates 110, 120 spaced apart from each other except at the contact points.

[0041] In the illustrated embodiment, each of the heat exchange plates 110, 120 is surrounded by a skirt S that extends approximately perpendicular to the plane of the heat exchange plate and is adapted to contact the skirt of an adjacent plate to provide a seal along the periphery of the heat exchanger 100.

[0042] The heat exchanger plates 110, 120 are provided with large port openings O1-O4 and small port openings SO1, SO2 for allowing heat exchange fluid to enter and exit the inter-plate flow channels. In the illustrated embodiment, the heat exchanger plates 110, 120 are provided with a first large port opening O1, a second large port opening O2, a third large port opening O3, and a fourth large port opening O4. The heat exchanger plates 110, 120 are also provided with a first small port opening SO1 and a second small port opening SO2. The areas surrounding the large port openings O1-O4 are provided at different heights to achieve selective communication between the large port openings and the inter-plate flow channels. In the heat exchanger 100, the areas surrounding the large port openings O1-O4 are arranged so that the first and second large port openings O1, O2 are fluidly connected to each other through some of the inter-plate flow channels, and the third and fourth large port openings O3, O4 are fluidly connected to each other through adjacent inter-plate flow channels. In the illustrated embodiment, the heat exchanger plates 110, 120 are rectangular with rounded corners, and the large port openings O1-O4 are located near the corners. Alternatively, the heat exchanger plates 110, 120 are, for example, square with rounded corners. Alternatively, the heat exchanger plates 110, 120 are circular, elliptical, or arranged in any other suitable shape, with the large port openings O1-O4 distributed in any suitable manner. In the illustrated embodiment, four large port openings O1-O4 are formed in each of the heat exchanger plates 110, 120. In other embodiments of the present invention, as described below, the number of large port openings may be greater than four, i.e., six, eight, or ten. For example, the number of large port openings is at least six, and the heat exchanger is configured to exchange heat between at least three fluids. Thus, in one embodiment, the heat exchanger is a three-circuit heat exchanger having at least six large port openings and configured with or without at least one integrated intake heat exchanger.

[0043] In the illustrated embodiment, each of the heat exchange plates 110, 120 is formed with two small port openings SO1, SO2. The small port openings SO1, SO2 are arranged to provide an integrated intake heat exchanger. Thus, the first and second heat exchange plates 110, 120 are formed with a dividing plane DW that divides the heat exchange plates 110, 120 into a first heat exchange portion 130 and a second heat exchange portion 140. As a result, fluid passing between the first and second large port openings O1, O2 exchanges heat with fluid passing between the third and fourth port openings O3, O4 on the first heat exchange portion 130 of each plate 110, 120 and with fluid passing between the first and second small port openings SO1, SO2 on the second heat exchange portion 140 of each plate 110, 120.

[0044] The dividing plane DW is provided to divide the heat exchange area into the first heat exchange portion 130 and the second heat exchange portion 140. For example, the dividing plane DW is disposed between one long side of the heat exchange plate 110, 120 and its adjacent short side. For example, the dividing plane DW extends from the long side to the short side. Alternatively, the dividing plane DW is disposed between two long sides, for example, from one long side to the other long side. In the illustrated embodiment, the dividing plane DW is curved between the long side and the short side of the plate. Alternatively, the dividing plane DW is straight or has an angle.

[0045] The dividing planes DW include elongated flat surfaces provided at different heights on different plates 110, 120. When the flat surfaces of adjacent plates 110, 120 contact each other to form the dividing plane DW, the inter-plate flow passages are sealed, and otherwise open. In this case, the dividing plane DW being provided at the same height as the area surrounding the first and second large port openings O1, O2 means that the dividing plane DW is open to the inter-plate flow passages fluidically connecting the first and second large port openings O1, O2, but blocks the inter-plate flow passages fluidically connecting the third and fourth large port openings O3, O4.

[0046] The dividing surface DW blocks the flow of fluid in the interplate passages communicating with the third and fourth large port openings O3 and O4, so separate interplate passages exist on both sides of the dividing surface DW. The interplate passages on the side of the dividing surface DW that do not communicate with the third and fourth large port openings O3 and O4 communicate with the two small port openings SO1 and SO2. The dividing surface DW does not block the interplate passages communicating with the first and second large port openings O1 and O2. Therefore, the medium flowing through the interplate passages communicating with the small port openings SO1 and SO2 exchanges heat with the medium flowing through the passages communicating with the first and second large port openings O1 and O2, just like the medium flowing through the interplate passages communicating with the third and fourth large port openings O3 and O4.

[0047] In the embodiment shown in FIGS. 1 and 2, the dividing plane DW extends between the first large port opening O1 and the third large port opening O3. The small openings SO1 and SO2 are located on both sides of the first large port opening O1. The first large port opening O1 is positioned so that the medium flowing through the interplate flow passages communicating with the small port openings SO1 and SO2 passes through both sides of the first large port opening O1. The dividing plane DW extends between the first large port opening O1 and the remaining large port openings O2 to O4. The first and second small openings SO1 and SO2 are located on the same side of the dividing plane DW as the first large port opening O1, i.e., within the second heat exchange section 140, and the other large port openings O2 to O4 are located on the other side of the dividing plane DW, i.e., outside the dividing plane DW, within the first heat exchange section 130.

[0048] In the illustrated embodiment, the heat exchanger 100 includes only first and second heat exchange plates 110, 120. Alternatively, the heat exchanger 100 may include a third heat exchange plate, and optionally a fourth heat exchange plate, with the third and optional fourth heat exchange plates being arranged with a different pressed pattern than the first and second heat exchange plates 110, 120, and the heat exchange plates being arranged in the appropriate order.

[0049] In the illustrated embodiment, the heat exchanger 100 further includes a start plate 150 and an end plate 160. The start plate 150 has openings formed therein that correspond to the large port openings O1 to O4 and the small port openings SO1 and SO2 for allowing fluid to enter and exit the inter-plate flow paths formed by the first and second heat exchange plates 110 and 120. For example, the end plate 160 is a conventional end plate.

[0050] Referring to FIG. 3, a cross-sectional view of a first heat exchanger plate 110 according to one embodiment is schematically shown. A first pattern of ridges R1 and grooves G1 is formed in the first heat exchanger plate 110. The grooves G1 of the first heat exchanger plate are formed to the same depth D1, as shown schematically in FIG. 3. Accordingly, all grooves G1 are formed to the same depth D1. For example, the depth D1 is 0.5 to 5 mm, e.g., 0.6 to 3 mm, or 0.8 to 3 mm. For example, all ridges R1 are formed to the same height in a corresponding manner. In other words, the corrugation depth of the first heat exchanger plate 110 is symmetrical and similar across the plate, or at least substantially across the plate. In one embodiment, at least the first heat exchanger portion 130 of the first heat exchanger plate 110, e.g., the entire first heat exchanger portion 130, is formed to the same corrugation depth, and each groove G1 is formed to the depth D1. For example, the first heat exchange portion 130 and the second heat exchange portion 140 of the first heat exchange plate 110, for example, the entire first heat exchange portion 130 and the entire second heat exchange portion, are formed with the same corrugation depth, and each groove portion G1 is formed with a depth D1.

[0051] 4, a cross-sectional view of a second heat exchanger plate 120 according to one embodiment is shown. For example, all the second heat exchanger plates 120 are the same. The second heat exchanger plates 120 are formed with a second pattern of first and second ridges R2a, R2b and first and second grooves G2a, G2b. The first and second grooves G2a, G2b of the second heat exchanger plate 120 are formed with different depths. The first groove G2a is formed with a first depth D2a, and the second groove G2b is formed with a second depth D2b, which is different from the first depth D2a. For example, the first depth D2a is 0.5 to 5 mm, e.g., 0.6 to 3 mm or 0.8 to 3 mm, and the second depth D2b is 30 to 80%, e.g., 40 to 60%, of the first depth D2a. The ridges R2a, R2b have different heights in a corresponding manner. In the illustrated embodiment, the first depth D2a is greater than the second depth D2b. The first and second grooves G2a, G2b are alternately arranged. Alternatively, the first and second grooves G2a, G2b, and optional additional grooves having other depths, may be arranged in any desired pattern.

[0052] For example, the pattern of ridges and grooves of the second heat exchange plate 120 is asymmetric, i.e., the second heat exchange plate 120 forms an asymmetric heat exchanger when combined with the first heat exchange plate 110, as shown below with reference to FIG. 5. In one embodiment, at least the first heat exchange portion 130 of the second heat exchange plate 120, e.g., the entire first heat exchange portion 130, is formed with a second pattern of ridges and grooves having at least two different corrugation depths D2a, D2b of the grooves. For example, the first heat exchange portion 130 and the second heat exchange portion 140 of the first heat exchange plate 110, e.g., the entire first heat exchange portion 130 and the entire second heat exchange portion, are formed with at least two corrugation depths, where the first grooves G2a are formed with a first depth D2a and the second grooves G2b are formed with a second depth D2b.

[0053] Referring to FIG. 5 , a plurality of first and second heat exchange plates 110, 120 are stacked to schematically illustrate the formation of inter-plate channels according to one embodiment. In the illustrated embodiment, every other plate is a first heat exchange plate 110 and the remaining plates are second heat exchange plates 120. The first and second heat exchange plates are alternately arranged to form an asymmetric heat exchanger 100, and the inter-plate channels are formed with different volumes. Alternatively, the different volumes of the inter-plate channels are formed by expansion profiles with the same press depth or corrugation depth. For example, the first and second heat exchange plates have different corrugation depths. For example, the first and / or second heat exchange plates are asymmetric heat exchange plates. Alternatively, the first and / or second heat exchange plates are symmetric heat exchange plates.

[0054] Referring to FIG. 6a, a first pattern of ridges R1 and grooves G1 of the first heat exchanger plate 110 is schematically shown. The pattern is a pressed herringbone pattern, in which the ridges R1 and grooves G1 have two slanted legs that meet at a centrally located apex, forming an arrow shape. For example, the apexes are distributed along an imaginary centerline, such as the longitudinal centerline of a rectangular heat exchanger plate. For example, the herringbone pattern is such that, in at least the central portion of the first heat exchanger plate 110, the ridges R and grooves G extend from one long side of the first heat exchanger plate 110 to the other long side, with all apexes facing one of the short sides. The pattern of the first heat exchanger plate 110, i.e., the first pattern of ridges R1 and grooves G1, exhibits a first chevron angle β1. The chevron angle is the angle between the ridge and an imaginary line across the plate that is perpendicular to the long side of the rectangular plate, the imaginary line being diagrammatically indicated by dashed line C. The chevron angle is therefore the angle between the ridge and the short side of the heat exchange plate toward which the apex faces. Because the long side of the heat exchange plate extends perpendicular to the short side, the ridge and groove pattern is arranged so that the ridges are also angled relative to the long side. For example, the chevron angle is the same on both sides of the apex. For example, the entire or substantially the entire first pattern of ridges and grooves is formed at a first chevron angle β1 across the plate, or at least across the first heat exchange portion 130 and, for example, the second heat exchange portion 140. For example, the first chevron angle β1 is between 5° and 85°, between 25° and 70°, or between 30° and 45°.

[0055] 6b, a first pattern of ridges R1 and grooves G1 of a first heat exchanger plate 110 according to an alternative embodiment is shown, in which the pressed pattern is in the form of diagonally extending straight lines. Thus, the pressed pattern of ridges and grooves is a wave pattern of diagonally extending straight lines. The diagonally extending straight lines of the first heat exchanger plate 110 are arranged at an angle β1. For example, the pattern is arranged such that the ridges R1 and grooves G1 extend from one long side of the first heat exchanger plate 110 to the other long side, e.g., parallel to each other.

[0056] Referring to FIG. 7a, a second pattern of ridges R2a, R2b and grooves G2a, G2b on the second heat exchanger plate 120 is shown schematically. The second pattern is a pressed herringbone pattern, as described above with reference to the first heat exchanger plate 110, but with a second chevron angle β2 that is different from the first chevron angle β1. Thus, the second heat exchanger plate 120 is provided with a herringbone pattern with a different angle than the angle on the first heat exchanger plate. For example, the second chevron angle β2 may be between 0° and 90°, between 25° and 70°, or between 30° and 45°. For example, the entire or substantially the entire pattern of ridges and grooves on the second heat exchanger plate 120 may be formed at the second chevron angle β2 across the plate, or across at least the first heat exchanger portion 130 and, for example, the second heat exchanger portion 140. For example, the difference between the first and second chevron angles β1 and β2 is 2° to 35°.

[0057] 7b, a second pattern of ridges R2a, R2b and grooves G2a, G2b of a second heat exchanger plate 120 according to an alternative embodiment is shown, in which the pressed pattern is in the form of diagonally extending straight lines. Thus, the pressed pattern of ridges and grooves is a wave pattern of diagonally extending straight lines. The diagonally extending straight lines of the second heat exchanger plate 120 are arranged at an angle β2. For example, the pattern is arranged such that the ridges R2a, R2b and grooves G2a, G2b extend from one long side of the second heat exchanger plate 120 to the other long side, e.g., parallel to each other.

[0058] Therefore, the first and second heat exchange plates 110, 120 are formed with different chevron angles β1, β2 and different pressed patterns, resulting in different inter-plate volumes. For example, the first and second heat exchange plates 110, 120 have different corrugation depths. Alternatively, or in addition, the first and second heat exchange plates 110, 120 have different corrugation frequencies. For example, the first and second heat exchange plates 110, 120 have the same corrugation depth but different corrugation frequencies. Therefore, the first and second heat exchange plates 110, 120 have different corrugation depths and / or different corrugation frequencies. For example, one of the first and second heat exchange plates 110, 120 is a symmetric heat exchange plate and the other is an asymmetric heat exchange plate. Alternatively, both the first and second heat exchange plates 110, 120 are asymmetric. Alternatively, both the first and second heat exchange plates 110, 120 are symmetric.

[0059] 8 and 9, the contact points between the first and second heat exchange plates 110, 120 are shown schematically using the example of FIG. 5. Brazed joints 170 are formed in and / or around the contact points 170 between intersecting ridges and grooves. In the embodiment of FIGS. 8 and 9, the brazed joints 170 are formed in all of the contact points. Alternatively, the brazed joints 170 are formed in only some of the contact points. In FIG. 8, the first heat exchange plate 110 is placed on the second heat exchange plate 120, and the contact points are formed in a first pattern. In FIG. 8, all intersections of the ridges R1 of the first heat exchange plate 110 and the ridges or grooves of the second heat exchange plate 120 form contact points.

[0060] 9 is a schematic diagram of a second heat exchange plate 120 disposed on the first heat exchange plate 110, with contacts formed in a second pattern. In FIG. 9, only the intersections between the first ridges R2a of the second heat exchange plate 120 form contacts that can form brazed joints 170, while the second ridges R2b are spaced apart from the intersecting ridges or grooves of the first heat exchange plate 110. Therefore, no contacts or brazed joints are formed between the second ridges R2b of the second heat exchange plate 120 and the first heat exchange plate 110. In FIG. 9, all contacts are shown as brazed joints 170.

[0061] In one embodiment, the brazed joints 170 between the first and second heat exchange plates 110, 120 are elongated, such as oval, and the brazed joints 170 are positioned in a first orientation in the larger volume interplate flow passages and in a second orientation in the smaller volume interplate flow passages to provide a favorable pressure drop in the desired interplate flow passages. For example, the brazed joints 170 are positioned at a first angle relative to the longitudinal direction of the plates 110, 120 in the larger volume interplate flow passages and at a second angle in the remaining interplate flow passages. In one embodiment, the first angle is greater than the second angle.

[0062] 10a, 10b and 11a, 11b show embodiments of a chiller system in which a heat exchanger 100 according to any one of the above heat exchanger embodiments can be used, in a heating mode and a cooling mode, respectively. A chiller system can also be referred to as a refrigeration system.

[0063] The chiller system according to the embodiment of Figures 10a, 10b, 11a, and 11b includes a compressor C, a four-way valve FWV, a payload heat exchanger PLHE connected to a brine system requiring heating or cooling, a first controllable expansion valve EXPV1, a first one-way valve OWV1, a dump heat exchanger DHE connected to a heat source that may release unwanted heat or cold, a second expansion valve EXPV2, and a second one-way valve OWV2. Each of the heat exchangers PLHE and DHE has four large openings O1-O4 and two small openings SO1 and SO2, as described above. The large openings O1 and O2 of each heat exchanger communicate with each other, the large openings O3 and O4 of each heat exchanger communicate with each other, and the small openings SO1 and SO2 of each heat exchanger communicate with each other. Heat exchange occurs between the fluid flowing from O1 to O2 and the fluid flowing between O3 and O4 and between SO1 and SO2. However, no heat exchange takes place between the fluid flowing from O3 to O4 and the fluid flowing from SO1 to SO2. The payload heat exchanger PLHE and / or the dump heat exchanger DHE are plate heat exchangers 100 as described herein.

[0064] In heating mode, as shown in Figures 10a and 10b, compressor C delivers high-pressure gas refrigerant to the four-way valve FWV. In this heating mode, the four-way valve is controlled to transport the high-pressure gas refrigerant to the large opening O1 of the payload heat exchanger PLHE. The high-pressure gas refrigerant then passes through the payload heat exchanger PLHE and exits through the large opening O2. As the high-pressure gas refrigerant passes through the payload heat exchanger PLHE, it exchanges heat with a brine solution connected to the payload that needs to be heated, which flows from the large opening O4 to the large opening O3, i.e., in a countercurrent direction compared to the refrigerant flowing from the large opening O1 to the large opening O2. The high-pressure gas refrigerant condenses during heat exchange with the brine solution and is fully condensed, i.e., in a liquid state, when it exits the payload heat exchanger PLHE through the large opening O2.

[0065] In heating mode, the first expansion valve EXPV1 is fully closed and the flow of liquid refrigerant leaving the payload heat exchanger passes through the first one-way valve OWV1, which allows refrigerant flow in this direction and blocks flow in the other direction (as will be described later in connection with the description of cooling mode).

[0066] After passing through the first one-way valve OWV1, the liquid refrigerant (still relatively hot) enters the dump heat exchanger DHE through a small opening SO2 and exits the heat exchanger DHE through a small opening SO1. During its passage between the small openings SO and SO1, the temperature of the refrigerant drops significantly due to heat exchange with the cooler, primarily gaseous, refrigerant exiting the dump heat exchanger DHE.

[0067] For example, during cold start-up, i.e., before the system reaches the desired operating conditions, it may be necessary to balance the heat exchange rate of the intake air heat exchanger. This can be achieved by controlling the balancing valve BV, which is a three-way valve arranged to control the heat exchange rate of the intake air heat exchanger, for example, by allowing control of liquid refrigerant from the condenser to the small opening SO2 and / or the expansion valve EXPV2.

[0068] After leaving the dump heat exchanger DHE through the small opening SO1, the liquid refrigerant passes through the second expansion valve EXPV2, where its pressure is reduced and some of the refrigerant flash boils, lowering its temperature. From the second expansion valve, the refrigerant passes through a branch connected to both sides of the second one-way valve OWV2, which is connected between the high-pressure and low-pressure sides of the refrigerant circuit and is closed to refrigerant flow due to the pressure difference between the high-pressure and low-pressure sides. After passing through the branch, the low-temperature, low-pressure, semi-liquid refrigerant enters the large opening O2 and passes through the dump heat exchanger DHE in heat exchange with a brine solution connected to a low-temperature heat collection source, such as an outdoor air collector, a solar thermal collector, or a hole in the ground. The liquid refrigerant is mainly vaporized by heat exchange with the brine solution flowing from the large opening O4 to the large opening O3. Heat exchange between the brine solution and the refrigerant occurs under parallel flow conditions, which are known to have poorer heat exchange performance than counterflow heat exchange.

[0069] Just before exiting the dump heat exchanger DHE through large opening O1, the refrigerant (now almost completely vaporized) enters the dump heat exchanger through small opening SO2 and exchanges heat with the relatively hot liquid refrigerant that exited the dump heat exchanger through small opening SO1. In one embodiment of the present invention, approximately 85-98%, preferably 90-95%, more preferably 91-94%, e.g., 93%, of the refrigerant is vaporized when it begins to exchange heat with the hot liquid refrigerant.

[0070] As a result, the temperature of the refrigerant exiting the dump heat exchanger DHE through opening O1 increases, thus ensuring that all of this refrigerant is completely vaporized.

[0071] Therefore, the low-temperature gas refrigerant entering the intake heat exchanger contains a certain amount of low-temperature liquid refrigerant, which is vaporized as a result of heat exchange with the high-temperature liquid refrigerant from the condenser. For example, the certain amount of low-temperature liquid refrigerant is 2 to 15 mass%, preferably 5 to 10 mass%, more preferably 6 to 9 mass%, for example, 7 mass%.

[0072] It is well known to those skilled in the art that parallel-flow heat exchange is inferior to counter-flow heat exchange in terms of heat exchange performance. However, because heat exchange occurs between the relatively high-temperature liquid brine entering the small opening SO2 and the primarily gaseous refrigerant exiting the dump heat exchanger DHE (i.e., the so-called "intake air heat exchange"), the refrigerant does not need to be fully vaporized during the heat exchange between the brine and the refrigerant. Instead, the refrigerant only needs to be partially vaporized when it enters the intake air heat exchanger along with the high-temperature liquid refrigerant, because the remaining liquid refrigerant evaporates during this heat exchange. It is well known that liquid-liquid heat exchange is much more efficient than gas-liquid heat exchange. Parallel-flow heat exchange also has the added advantage of reducing the risk of freezing. This is because the refrigerant enters the heat exchanger at a location where the medium exchanging heat with the refrigerant is at a high temperature, reducing the risk of freezing at this location, which is the most critical location for freezing.

[0073] Testing showed that there may be issues with cold start-up of the chiller system in cold environments.

[0074] From the dump heat exchanger opening O1, the gaseous refrigerant enters a four-way valve FWV which is controlled to direct the flow of gaseous refrigerant to the compressor where it is compressed again.

[0075] In Figures 11a and 11b, this chiller system is shown in cooling mode. To switch from heating mode to cooling mode, four-way valve FWV is controlled so that the compressor supplies compressed gas refrigerant to opening O1 of dump heat exchanger DHE. Expansion valve EXPV2 is fully closed, one-way valve OWV2 is open, one-way valve OWV1 is closed, and expansion valve EXPV1 is open, controlling the pressure of the refrigerant before and after passing through expansion valve EXPV1.

[0076] Thus, in cooling mode, the dump heat exchanger functions as a counterflow condenser and its "inlet air heat exchanger" does not exchange heat, while the payload heat exchanger (PLHE) functions as a parallel flow evaporator. However, the efficiency of the parallel flow heat exchange can be maintained at an acceptable level because of the inlet air heat exchange between the hot liquid refrigerant and the semi-vaporized refrigerant exiting the payload heat exchanger (PLHE).

[0077] Note that the intake heat exchange section is integrated with the dump heat exchanger DHE and the payload heat exchanger PLHE in Figures 10 and 11. However, in other embodiments, the intake heat exchanger may be separated from the dump heat exchanger and / or the payload heat exchanger.

[0078] Different climate zones have different cooling and heating needs. In warmer climates, the cooling need is higher, and the cooling system is used closer to full cooling effectiveness, requiring a corresponding capacity of the inlet air heat exchanger to evaporate the refrigerant droplets that would otherwise leave the evaporator. For example, the evaporator is the payload heat exchanger PLHE, as described above, when the cooling system is in cooling mode, and its integrated inlet air heat exchanger is used accordingly by the balancing valve BV. When the cooling system is used at a reduced effectiveness, such as 25% or 50% of full effectiveness, the inlet air heat exchanger is controlled via the balancing valve BV. The cooling system is reversible and can be switched between cooling and heating modes by the four-way valve FWV, as described above. As shown in the drawings, both the payload and dump heat exchangers include integrated inlet air heat exchangers that can be activated and controlled by the balancing valve BV to ensure evaporation of the refrigerant before it leaves the evaporator with zero superheat in either cooling or heating mode, depending on the effectiveness at which the system is operating. Thus, the amount of refrigerant directed to the intake air heat exchanger can be adapted to the system requirements in both heating and cooling modes to provide an efficient reversible cooling system for various types of climates.

[0079] In other embodiments of the present invention, a "standard" heat exchanger 100, as shown for example in FIG. 12, may be provided with a retrofit port heat exchanger 400 (see FIGS. 13 and 14) that includes some structure that fits within or just outside the port openings O1-O4 of the standard heat exchanger.

[0080] In the embodiment shown, the additional introduction port heat exchanger 400 includes a pipe 410 that fits within the port opening, and the pipe is bent into a semi-helical shape to allow hot liquid refrigerant to flow through the pipe, similar to the refrigerant flowing between the small port openings SO1, SO2 in the previous embodiment exchanging heat with the cold gaseous (or semi-gaseous) refrigerant exiting the dump heat exchanger DHE or payload heat exchanger PLHE.

[0081] Referring to FIG. 15 , a cross section of a portion of a heat exchanger including first and second heat exchange plates 110 and 120 according to another embodiment is shown. In the embodiment of FIG. 15 , the first heat exchange plate 110 is a symmetric heat exchange plate, and the second heat exchange plate 120 is an asymmetric heat exchange plate as described above. Therefore, the corrugation depth of the first heat exchange plate 110 is constant, while the corrugation depth of the second heat exchange plate 120 varies. At least two different corrugation depths are formed on the second heat exchange plate 120. Furthermore, the first and second heat exchange plates 110 and 120 are formed with corrugation patterns having different angles, such as chevron angles, as described above. In the embodiment of FIG. 15 , the chevron angle of the first heat exchange plate 110 is 54 degrees, and the chevron angle of the second heat exchange plate 120 is 61 degrees. For example, the inter-plate volume between adjacent plates is different, so that the inter-plate volume on one side of the first heat exchange plate 110 is different from the inter-plate volume on the opposite side of the first heat exchange plate 110. Of course, the same is true for the second heat exchange plate 120. Therefore, the inter-plate volume between the first and second heat exchange plates is different from the inter-plate volume between the second and first heat exchange plates. Similarly, the cross-sectional area on one side of the first heat exchange plate 110 is different from the cross-sectional area on the opposite side of the first heat exchange plate 110.

[0082] 16, a cross section of a portion of a heat exchanger according to yet another embodiment is shown, including first and second heat exchange plates 110, 120. In the embodiment of FIG. 16, the first heat exchange plate 110 is a symmetric heat exchange plate, and the second heat exchange plate 120 is an asymmetric heat exchange plate as described above. In the embodiment of FIG. 16, the chevron angle of the first heat exchange plate 110 is 45 degrees, and the chevron angle of the second heat exchange plate 120 is 61 degrees.

[0083] Referring to FIG. 17 , a cross section of a portion of a heat exchanger including first and second heat exchange plates 110 and 120 according to yet another embodiment is shown. In the embodiment of FIG. 17 , the first heat exchange plate 110 is an asymmetric heat exchange plate, and the second heat exchange plate 120 is also an asymmetric heat exchange plate. In the embodiment of FIG. 17 , the chevron angles of the first heat exchange plate 110 and the second heat exchange plate 120 are different, as described above. Furthermore, the interplate flow passages have different volumes, as described above. For example, the brazed joints have elongated shapes, such as ellipses, and are arranged in a first orientation in the interplate flow passages with larger volumes and in a different second orientation in the interplate flow passages with smaller volumes.

[0084] Referring to Figure 18, a cross section of a portion of a stack of first and second heat exchange plates 110, 120 according to yet another embodiment is shown. In the embodiment of Figure 18, the first and second heat exchange plates 110, 120 have different corrugation depths. The first heat exchange plate 110 is a symmetric heat exchange plate, and the second heat exchange plate 120 is an asymmetric heat exchange plate. Alternatively, both the first and second heat exchange plates 110, 120 are symmetric or asymmetric. The chevron angles of the first heat exchange plate 110 and the second heat exchange plate 120 are different, resulting in different interplate flow passage volumes when the first and second heat exchange plates 110, 120 are brazed together at the brazed joint.

[0085] Heat exchangers according to various embodiments of the present invention are used, for example, for condensation or evaporation, where at least one medium is in a gas phase at some point. For example, the heat exchanger is used for heat exchange, where condensation or evaporation occurs in the interplate channels with a large volume. For example, a liquid medium, such as water or brine, is conducted through the interplate channels with a small volume.

[0086] 19, an exemplary brazed true double heat exchanger 500 is shown in an exploded view, including two separate integrated inlet air heat exchangers ISGHX1 and ISGHX2. True double heat exchangers are used in heat pumps or chillers that require a high power ratio. Systems for true double heat exchangers are well known to those skilled in the art, and these systems typically consist of two separate heat pump systems that use true double heat exchangers rather than two separate heat exchangers.

[0087] The true double heat exchanger 500 includes six heat exchange plates 510, 520, 530, and 540. Each heat exchange plate is provided with a pressed pattern of ridges and grooves adapted to maintain the plates spaced apart so that interplate flow channels 510-520, 520-530, 530-540, 540-510, and 510-520 are formed between the heat exchange plates for heat exchange of a medium. Each heat exchange plate also has port openings 550, 560, 570, 580, 590, 600, and 610 for a refrigerant and two port openings 620 and 630 for a water or brine solution. The port openings are in selective fluid communication with the interplate flow channels as follows:

[0088] Port openings 630, 640 are in fluid communication with interplate channels 510-520, 530-540, port openings 550, 560 are in fluid communication with interplate channels 520-530, port openings 570, 580 are in fluid communication with interplate channels 540-510, and port openings 590, 600, 610, 620 are in fluid communication with interplate channels 510-520.

[0089] The heat exchange plates 510, 520, 530, 540 are divided into small sections, and in this embodiment, the inter-plate flow paths are connected and restricted in a specific way, and in the main section 650, all inter-plate flow sections are used for heat exchange of media, and in the first integrated intake heat exchanger section ISGHX1, the inter-plate flow paths 520-530 are fluidly connected to the inter-plate flow paths 520-530 of the main section, and either or both of the inter-plate flow paths 510-520 and / or 530-540 are connected to the port openings 610, 620, and in the second integrated intake heat exchanger section ISGHX2, the inter-plate flow paths 540-510 are fluidly connected to the inter-plate flow paths 540-510 of the main section, and either or both of the inter-plate flow paths 510-520 and / or 530-540 are fluidly connected to the port openings 590, 600.

[0090] The main section is separated from the integrated intake heat exchanger sections ISGHX1 and ISGHX2 by a divider wall 660 extending from one long side to the other long side of each heat exchanger plate. The divider wall includes plate surfaces arranged at different heights such that adjacent plate surfaces cooperate to block communication between the inter-plate flow passages 510-520 and 530-540 and the corresponding inter-plate flow passages of the integrated intake heat exchanger sections ISGHX1 and ISGHX2. Furthermore, the plate surfaces of the divider wall 660 are configured such that adjacent plate surfaces cooperate to block communication between the inter-plate flow passages 520-530 of the main section and the corresponding inter-plate flow passages of the second integrated intake heat exchanger section ISGHX2, and to block communication between the inter-plate flow passages 540-510 of the main section and the corresponding inter-plate flow passages of the first integrated intake heat exchanger section ISGHX1. The dividing wall 660 divides the heat exchange plates 510-540 into a main portion 650 and integrated intake heat exchanger sections ISGHX1 and ISGHX2. Thus, four of the port openings, namely, port openings 550, 570, 630, and 640, are located in the main portion 650, and the first and second integrated intake heat exchanger sections ISGHX1 and ISGHX2, including port openings 560 and 580 and port openings 610, 620, 590, and 600, are located on the other side of the dividing wall 660.

[0091] A second divider wall 670 is provided between the integrated intake heat exchanger sections ISGHX1 and ISGHX2 and extends from the short sides of the heat exchanger plates and the divider wall 660. The plate surfaces of this divider wall are arranged so that the plate surfaces of adjacent plates contact each other, blocking communication between all inter-plate flow passages of the integrated intake heat exchanger sections ISGHX1 and ISGHX2. Thus, the first integrated intake heat exchanger section, including port opening 560 and port openings 610 and 620, is located on one side of the divider wall 670, and the second integrated intake heat exchanger section, including port opening 580 and port openings 590 and 600, is located on the other side of the divider wall 670. Thus, the main section 650, the first integrated intake heat exchanger section ISGHX1, and the second integrated intake heat exchanger section ISGHX2 are separated by the divider walls 660 and 670.

[0092] Finally, each heat exchanger plate is provided with a skirt 680 extending around the entire periphery of the heat exchanger plate 510, 520, 530, 540, with the skirts 680 of adjacent plates adapted to contact each other to create a circumferential seal that prevents the medium from escaping through the inter-plate flow paths. Furthermore, the heat exchanger 500 of the present invention is preferably provided with start and / or end plates (not shown) located on either side of the stack of heat exchanger plates. Port openings are provided in one of the start or end plates, but not in the other, to create a seal on the port opening side that does not have connections for transferring heat exchange fluid into or out of the heat exchanger.

[0093] With the above arrangement, a true double heat exchanger has separate inter-plate flow passages between port openings 630, 640 on (over) the inter-plate flow passages 510-520, 530-540 of the main section 650, between port openings 550, 560 on the inter-plate flow passages 520-530 of the main section and the first integrated intake heat exchanger section ISGHX1, between port openings 570, 580 on the inter-plate flow passages 540-510 of the main section 650 and the second integrated intake heat exchanger section ISGHX2, between port openings 610, 620 on the inter-plate flow passages 520-530 of the first integrated intake heat exchanger section ISGHX1, and between port openings 590, 600 on the inter-plate flow passages 540-510 of the second integrated intake heat exchanger section ISGHX2.

[0094] Selective fluid communication between the port openings and the inter-plate channels can be achieved in various ways, for example, by providing surfaces around the port openings at different heights so that the surfaces of adjacent plates either touch or do not touch each other. Alternatively, selective fluid communication can be achieved by providing separate sealing rings at the port openings, with openings in the sealing ring to allow communication as required.

[0095] Although described as a brazed heat exchanger, it is possible to design a true double heat exchanger according to the present invention as a gasketed heat exchanger.

[0096] The true double heat exchanger 500 of the present invention is particularly useful in heat pump or chiller applications where dual compressors are used to achieve a large ratio between low and high power.

[0097] The heat exchange plates 510-540 are provided with first and second patterns of ridges R1, R2a, R2b and grooves G1, G2a, G2b, as described above with reference to Figures 2-9. For example, every other heat exchange plate is provided with the first pattern, and the other heat exchange plates are provided with the second pattern. For example, the heat exchange plates 510, 530 are provided with the first pattern and the heat exchange plates 520, 540 are provided with the second pattern, or the heat exchange plates 510, 530 are provided with the second pattern and the heat exchange plates 520, 540 are provided with the first pattern. The pressed first and second patterns are, for example, herringbone patterns with different chevron angles or pressed diagonal patterns with different angles, as described above with reference to Figures 6a, 6b, 7a, and 7b. The main portion 650 is provided with such a pattern, and for example, the first and second integrated intake heat exchanger sections ISGHX1 and ISGHX2 are also provided with such a pattern. For example, the angle β1, e.g., chevron angle β1, of every other heat exchanger plate, such as the heat exchanger plates 510 and 530, is 25° to 70° or 30° to 45°. For example, the angle β2, e.g., chevron angle β2, of every other heat exchanger plate, such as the heat exchanger plates 520 and 540, is 25° to 70° or 30° to 45°. Since the first and second patterns are opposite in direction, the angles or chevron apexes alternately point in opposite directions throughout the heat exchanger. For example, the difference between the first and second chevron angles β1 and β2 is 2° to 35°.

[0098] For example, the grooves G1 of every other heat exchanger plate are formed with the same depth D1, as described above with reference to Figure 3, while the other heat exchanger plates having first and second grooves G2a, G2b are formed with different depths, with the first grooves G2a being formed with a first depth D2a and the second grooves G2b being formed with a second depth D2b, as described above with reference to Figure 4. Thus, every other inter-plate channel has a larger volume than the rest, as also described above.

[0099] For example, as described above with reference to Figures 8 and 9, the contacts and brazed joints are arranged in an alternating pattern so that the brazed joints between the heat exchange plates 510-540 have an elongated, oval-like shape, with the brazed joints oriented in a first direction in the interplate flow passages with larger volumes and in a second direction in the interplate flow passages with smaller volumes.

[0100] Referring to FIG. 20 , a first pattern of ridges R1 and grooves G1 of a first heat exchanger plate 110 is shown. In FIG. 20 , the first heat exchanger plate 110 includes small port openings SO1 and SO2 and a dividing surface DW to provide the first and second heat exchanger portions 130 and 140 that form an integrated intake heat exchanger, as described above. Alternatively, the first heat exchanger plate 110 includes dividing walls 660 and 670 and small port openings 590-620 to provide two integrated intake heat exchangers ISGHX1 and ISGHX2, as described with reference to FIG. 19 . The pressed pattern according to the embodiment of FIG. 20 is a herringbone pattern, but may alternatively be a diagonal pattern, so that the central main heat exchanger portion of the heat exchanger plate 110 exhibits a first angle β1, as generally described above with reference to FIGS. 6 a and 6 b. Thus, the first pressed pattern partially includes the first angle β1. For example, the central main heat exchange section extends from one side to the opposite side of the first heat exchange plate 110. The central main heat exchange section is disposed between the first and second heat exchange sections of the port openings (referred to herein as ends) of the heat exchange plate. The first and second ends are disposed, for example, at opposite ends of the first heat exchange plate 110. For example, the first and second ends extend from one side to the opposite side of the first heat exchange plate 110. The first end includes port openings, such as the first port opening O1 and the third port opening O3, and the small port openings SO1 and SO2, as well as a dividing surface DW, forming an intake heat exchanger. The second end includes port openings, such as the second and fourth port openings O2 and O4. The pressed pattern of ridges R1 and grooves G1 is disposed at an angle β1' at at least one end, such as the first and second ends, and the angle β1' is different from the angle β1 of the pressed pattern in the central main heat exchange section. For example, the pressed pattern direction is the same at the central main portion as at the ends. For example, the angle is the same at the two ends. Alternatively, the angle at the first end is different from the angle at the second end. Optionally, the second heat exchange portion 140 is arranged in a different pattern or angle than the first end.In Figure 20, the first heat exchange plate 110 is shown as an example, but it should be understood that the second pressed pattern of the second heat exchange plate 120 is designed in a corresponding manner, and the second pattern of ridges R2a, R2b and grooves G2a, G2b is arranged at an angle β2 in the central main heat exchange section, and the ends are arranged at a different angle β2' (not shown).

Claims

[Claim 1] 1. A method of controlling a cooling system, comprising: a compressor (C) that compresses the gas refrigerant so that its temperature, pressure, and boiling point increase; a four-way valve (FWV) that controls whether the refrigeration system is in cooling mode or heating mode; a condenser (PLHE) that condenses the gas refrigerant from the compressor into a high-temperature liquid refrigerant by heat exchange with a high-temperature heat medium; a first expansion valve (EXPV1) and a first one-way valve (OWV1); a second expansion valve (EXPV2) that reduces the boiling point of the high-temperature liquid refrigerant by decompressing the high-temperature liquid refrigerant from the condenser; an evaporator (DHE) that vaporizes the high-temperature liquid refrigerant having a lowered boiling point into a low-temperature gas refrigerant by heat exchange between the high-temperature liquid refrigerant having a lowered boiling point and a low-temperature heat medium; an intake heat exchanger (SO2, SO1) for exchanging heat between the high-temperature liquid refrigerant from the condenser and the low-temperature gas refrigerant from the evaporator; the cooling system further includes a balance valve (BV) arranged to control the amount of heat exchange between the high-temperature liquid refrigerant and the low-temperature gaseous refrigerant in the intake air heat exchanger by directing a flow of high-temperature liquid refrigerant from the condenser to the second expansion valve (EXPV2) without passing through the intake air heat exchanger; The system comprises: a) measuring the temperature of the high-temperature liquid refrigerant; b) measuring the temperature of the low-temperature gas refrigerant; c) calculating a temperature difference between the hot liquid refrigerant and the cold gaseous refrigerant; and step d) controlling the balance valve to bypass the intake air heat exchanger when the temperature difference is less than a predetermined threshold, and further comprising: in a heating mode, controlling the four-way valve to deliver high-pressure gas refrigerant from the compressor (C) of the condenser to a large opening (O1) and discharge it through another large opening (O2) while condensing the high-pressure gas refrigerant into a high-temperature liquid refrigerant by heat exchange with the high-temperature heat transfer medium in a countercurrent flow; closing the first expansion valve (EXPV1) and passing the high-temperature liquid refrigerant through the first one-way valve (OWV1); directing a portion of the hot liquid refrigerant through the intake air heat exchanger integrated with the evaporator (DHE) by means of the balance valve (BV) while exchanging heat with the cold gaseous refrigerant exiting the evaporator (DHE); directing the remaining portion of the high-temperature liquid refrigerant to the second expansion valve (EXPV2) and further to the large opening (O2) of the evaporator without passing through the intake air heat exchanger by the balance valve; directing the liquid refrigerant from the intake air heat exchanger to the second expansion valve (EXPV2) and further to the large opening (O2) of the evaporator; exchanging heat between the high-temperature liquid refrigerant and the low-temperature heat transfer medium in parallel flow in the evaporator; 12. A method for controlling a cooling system, comprising:

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