US20170167810A1 - System and method for dynamic control of a heat exchanger - Google Patents

System and method for dynamic control of a heat exchanger Download PDF

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Publication number
US20170167810A1
US20170167810A1 US15/039,314 US201415039314A US2017167810A1 US 20170167810 A1 US20170167810 A1 US 20170167810A1 US 201415039314 A US201415039314 A US 201415039314A US 2017167810 A1 US2017167810 A1 US 2017167810A1
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Prior art keywords
fluid
local
global
controller
heat exchanger
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US15/039,314
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English (en)
Inventor
Anders Nyander
Klas Bertilsson
Alvaro Zorzin
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Alfa Laval Corporate AB
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Alfa Laval Corporate AB
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Assigned to ALFA LAVAL CORPORATE AB reassignment ALFA LAVAL CORPORATE AB ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BERTILSSON, KLAS, NYANDER, ANDERS, ZORZIN, ALVARO
Publication of US20170167810A1 publication Critical patent/US20170167810A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/30—Expansion means; Dispositions thereof
    • F25B41/31—Expansion valves
    • F25B41/34—Expansion valves with the valve member being actuated by electric means, e.g. by piezoelectric actuators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F27/00—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus
    • F28F27/02—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus for controlling the distribution of heat-exchange media between different channels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B39/00—Evaporators; Condensers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B39/00—Evaporators; Condensers
    • F25B39/02—Evaporators
    • F25B39/028—Evaporators having distributing means
    • F25B41/062—
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/30—Expansion means; Dispositions thereof
    • F25B41/385—Dispositions with two or more expansion means arranged in parallel on a refrigerant line leading to the same evaporator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D9/00—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
    • F28D9/0031—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits for one heat-exchange medium being formed by paired plates touching each other
    • F28D9/0043—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits for one heat-exchange medium being formed by paired plates touching each other the plates having openings therein for circulation of at least one heat-exchange medium from one conduit to another
    • F28D9/005—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits for one heat-exchange medium being formed by paired plates touching each other the plates having openings therein for circulation of at least one heat-exchange medium from one conduit to another the plates having openings therein for both heat-exchange media
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F27/00—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02—Header boxes; End plates
    • F28F9/026—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02—Header boxes; End plates
    • F28F9/026—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits
    • F28F9/027—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits in the form of distribution pipes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02—Header boxes; End plates
    • F28F9/026—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits
    • F28F9/027—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits in the form of distribution pipes
    • F28F9/0273—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits in the form of distribution pipes with multiple holes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/19—Pressures
    • F25B2700/197—Pressures of the evaporator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2117—Temperatures of an evaporator
    • F25B2700/21175—Temperatures of an evaporator of the refrigerant at the outlet of the evaporator
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Definitions

  • the present invention refers generally to a system for dynamic control of the operation of a heat exchanger. Further, the invention refers to a method for dynamic control of the operation of a heat exchanger.
  • the present invention refers generally to a system comprising a heat exchanger and in particular to a heat exchanger in the form of a plate heat exchanger.
  • Different types of heat exchangers are based on different techniques.
  • One type of heat exchanger utilizes evaporation of a fluid, such as a cooling agent, for various applications, such as air conditioning, cooling systems, heat pump systems, etc.
  • the heat exchanger may be used in a two-phase system handling a fluid in a liquid form as well as in an evaporated form.
  • this may include a plate package, which comprises a number of first and second heat exchanger plates.
  • the plates are permanently joined to each other and arranged side by side in such a way that a first plate interspace, forming a first fluid passage, is formed between each pair of adjacent first heat exchanger plates and second heat exchanger plates, and a second plate interspace, forming a second fluid passage, between each pair of adjacent second heat exchanger plates and first heat exchanger plates.
  • the first plate interspaces and the second plate interspaces are separated from each other and provided side by side in an alternating order in the plate package.
  • each heat exchanger plate has at least a first porthole and a second porthole, wherein the first portholes form a first inlet channel to the first plate interspaces and the second portholes form a first outlet channel from the first plate interspaces.
  • the plate package includes a separate space for each of said first plate interspaces, which space is closed to the second plate interspaces.
  • a first fluid such as a cooling agent
  • a partly evaporated fluid at one end of the first inlet channel, i.e. the first port hole, for further distribution along the first inlet channel and further into each of the individual first plate interspaces during evaporation into an evaporated form.
  • the pressure drop of the cooling agent may increase with the distance from the inlet to the first inlet channel, whereby the distribution of the first fluid between the individual plate interspaces will be affected.
  • first plate interspace It is also known that the operation and performance of an individual first plate interspace depends on its position in a plate package. The outermost first plate interspaces on each side of the plate package tend to behave differently than those in the middle of the plate package.
  • the evaporated fluid must have reached superheated state whereby the evaporated fluid comprises dry evaporated fluid only, i.e. the evaporated fluid should have a temperature being higher than the saturation temperature at a prevailing pressure.
  • the superheating being a physical parameter well known in the art, is defined as the temperature difference between the present temperature and the saturation temperature at a prevailing pressure, i.e. when there is not any liquid content remaining in the fluid.
  • the superheating is unique for a given fluid and for a given temperature and pressure.
  • the saturation temperature may be found in conventional graphs or tables.
  • the purpose of operating the evaporator of the heat exchanger as close to a set-point superheating value as possible no matter operation duty is of importance to get as high utilization factor as possible. Thus, it is of economic importance. Further, it has an influence to other components cooperating with the evaporator, such as a compressor, since compressors normally are sensitive to liquid content. Any droplets remaining in the evaporated fluid when reaching the inlet of the compressor may damage the same. Also, there is an economical interest of operating the evaporator with a superheating being as low as possible since once the fluid has reached the superheated state the fluid is completely dry and there is no substantial gain in increasing the temperature additionally.
  • the set-point superheating above is determined by the system manufacturer to incorporate a certain wanted safety margin against the risk of receiving liquid into the compressor.
  • the problems discussed above get more pronounced when the load of the evaporator is changed. For example, this may be the case when changing the operation duty of an air conditioning system, from one temperature to another, meaning that the amount of fluid to be supplied to the evaporator is changed.
  • the two documents provide a solution to controlling the operation of a plurality of air-heated evaporators, in which method each evaporator is evaluated as a complete unit and in which method each unit is controlled in view of additional evaporators arranged in the same circuit.
  • the efficiency of heat exchangers, and especially plate heat exchangers, at part load is a raising issue. More focus is put on how the evaporator of the heat exchanger performs at different operation duties instead of being measured at only one operation duty. For example, laboratory scale trials have shown that an air-conditioning system can save 4-10% of its energy consumption just by improved evaporator function at part load for a given brazed plate heat exchanger. Further, a heat exchanger system is typically only operating at full capacity for 3% of the time, while most heat exchangers are designed and tuned for a full capacity operation.
  • the object of the present invention is to provide an improved heat exchanger system remedying the problems mentioned above. Especially it is aimed at a heat exchanger system and a method which allows a better control of the supply of the first fluid, such as the cooling agent, between the fluid passages to thereby improve the efficiency of the plate heat exchanger no matter running condition.
  • a system for dynamic control of the operation of a heat exchanger comprising a heat exchanger, a plurality of injector arrangements, a local sensor arrangement, and a controller
  • the heat exchanger comprises a first global outlet, a first plurality of fluid passages, each fluid passage comprising a local inlet and a local outlet, for the supply of a first fluid to the first global outlet via the first plurality of fluid passages during evaporation of the first fluid
  • the heat exchanger further comprises a second global outlet, a second plurality of fluid passages, each fluid passage comprising a local inlet and a local outlet, for the supply of a second fluid to the second global outlet via the second plurality of fluid passages
  • the first fluid passages and the second fluid passages are arranged separated from each other and side-by-side, in order to enable heat exchange between the first fluid in the first plurality of fluid passages and the second fluid in the second plurality of fluid passages
  • each injector arrangement comprises at least one valve
  • the local adjustment is performed in order to even out any temperature differences in view of the first fluid flowing nearby the local outlets.
  • the overall ambition with the local adjustment may thus be seen as the ambition that all first fluid passages should contribute equally to the overall operation of the evaporator.
  • This is achieved by the inventive system in which the operation of each fluid passage or a subset of fluid passages may be monitored, whereby the contribution from each individual fluid passage to the overall performance of the heat exchanger may be adjusted.
  • the global amount of flow is adjusted if liquid content is detected in the global outlet or downstream from the global outlet.
  • the presence of liquid content in the global flow may be caused by a local overflow in a single fluid passage or in a subset of fluid passages.
  • the first plurality of fluid passages may be utilized more efficiently as compared to known techniques. Further, by optimizing the flow in the plurality of first fluid passages, a higher pressure may be achieved in the global flow downstream from the global outlet. In some systems, the efficiency of the compressor is increased when fed with a higher pressure. Thus, the efficiency of the whole system may be boosted.
  • the plurality of local temperature sensors in the local sensor arrangement may be arranged nearby the local outlets of the first plurality of fluid passages.
  • the plurality of local temperature sensors in the local sensor arrangement may be arranged nearby the local outlets of the second plurality of fluid passages.
  • nearby is meant around the local outlet, i.e. it could be both upstream and downstream from the local outlet in view of the first fluid.
  • the local temperature sensors should be positioned such that they measure on flows of first fluid after the flows have evaporated and before the flows mix with each other to form a global flow.
  • the local temperature sensors may be arranged in through holes having an extension from the exterior of a plate package of the heat exchanger to the interior.
  • the local temperature sensors may be arranged only interior or only exterior of the plate package.
  • the local temperature sensors may be arranged to measure temperatures in connection to one or more fluid passages. Alternatively, the local sensor sensors may be arranged to measure an average temperature value.
  • the controller may be further arranged to determine a compensating local adjustment of the local amount of first fluid supplied by the other than the at least one of the injector arrangements such that the global amount of first fluid in the plurality of first passages remains the same.
  • the controller may be further arranged to communicate the determined compensating local adjustment to said other than the at least one of the injector arrangements.
  • the compensating local adjustment is determined in order to keep the global amount of first fluid in the plurality of first passages unaffected by the local adjustments.
  • the global amount may instead be controlled based on values measured by a global sensor arrangement.
  • the controller may be arranged to determine the difference by at least determining the standard deviation for the measured temperature values. By utilizing the standard deviation for determining the local adjustment, quick and harsh local adjustments are damped such that the adjustment procedure becomes more smooth and even.
  • the difference may be determined in many ways and based on the exact measured temperature values or a modification, such as a mean value or adjustment, of one or more measured temperature values. Moreover, one or more differences may be determined based on a single batch of measured temperature values.
  • the first fluid may be a refrigerant.
  • the second fluid may comprise water.
  • the second fluid may be brine or may consist of only water.
  • the system may be adapted such that different types of first fluids may be supplied through the system.
  • the system may comprise different sections of fluid passages for the supply of different first fluids.
  • the controller may be a P regulator, a PI regulator or a PID regulator. These regulator types are well known in the field of automatic control engineering.
  • the PID regulator may be used to relatively fast process and react on values, such as measured temperature and/or pressure values, without causing any self-oscillation of the system.
  • the system may further comprise a global sensor arrangement being arranged to measure the global temperature and the global pressure, or the presence of any liquid content, of the evaporated first fluid downstream from the first global outlet.
  • the controller may be arranged to communicate with the valves of the plurality of injector arrangements, or with a global valve, to control, based on information received from the global sensor arrangement, the global amount of the first fluid to be supplied to the first plurality of fluid passages in order for the heat exchanger to operate towards a set-point superheating value.
  • liquid content is in the context of this application defined as fluid being in a liquid phase or a mixed liquid/gaseous phase. It may for example be in the form of droplets.
  • the purpose of the global sensor arrangement is to determine the presence of any liquid content in the evaporated first fluid, or to determine the so called superheating of the evaporated first fluid.
  • the measurements are transmitted to the controller which, in turn, determines a global adjustment of the flow of first fluid in the first plurality of fluid passages.
  • the local flow in a subset of the first plurality of fluid passages may be controlled by measuring local temperature values by the local sensor arrangement, and the global flow in the first plurality of fluid passages may be controlled by measuring global temperature and/or pressure values by the global sensor arrangement.
  • the global adjustment may be described as an adjustment in order to operate towards a set-point superheating or towards the non-presence of liquid content, whereas the local adjustment may be described as an adjustment for evening out the temperature differences within the heat exchanger. Both adjustments are performed in order to optimize the performance of the heat exchanger.
  • the adjustments complement each other but may also function alone.
  • a system may comprise the local sensor arrangement and perform the local tuning of the first plurality of fluid passages without utilizing the global sensor arrangement and global adjustment.
  • the global adjustment may be performed by another arrangement than the global sensor arrangement.
  • the two processes of local adjustment and global adjustment are preferably performed continuously for the system during operation thereof.
  • the local flow and the global flow are adjusted continuously whereby the heat exchanger is continuously optimized in view of current running conditions and operation duty.
  • the heat exchanger thus becomes more flexible and adapts to different running conditions.
  • the heat exchanger will run in an optimized manner regardless of the running conditions.
  • the two processes may be performed as parallel loops in the controller.
  • the global sensor arrangement may comprise a global temperature sensor and a global pressure sensor. Based on a measured global temperature value and a measured global pressure value, the superheating may be determined by the controller.
  • the two global sensors must not have the same position within the system. However, it may be preferred that the global sensor arrangement is arranged at essentially the same position, such that the global sensors measures on the same portion of evaporated first fluid.
  • the set-point superheating value may for example be the superheating for the specific fluid used as first fluid in the system.
  • the superheating value may be the calculated superheating for the specific fluid used in the system as adjusted with a pre-determined safety margin.
  • the set-point superheating value may be handled in a “digital” manner, wherein presence of any liquid content is an indicator of the amount of fluid supplied to the evaluated fluid passage being too high for a complete evaporation, or alternatively, no presence of any liquid content is an indicator of the amount of fluid supplied to the fluid passage being insufficient and may be increased.
  • the global sensor arrangement may be at least one global temperature sensor.
  • the global temperature sensor may be used for determining a tendency of decreasing global temperature as seen over a measuring period or be used for determining an unstable global temperature as seen over a measuring period. Both a tendency of decreasing global temperature and an unstable global temperature may be used as input to the controller to establish the presence of any liquid content in the evaporated fluid since the liquid content, i.e. a fluid flow being in liquid phase or in a mixed liquid/gaseous phase will indicate a lower temperature on the global temperature sensor than a fully evaporated, dry gaseous fluid flow.
  • This principle is also applicable to the local temperature sensors, i.e. the local temperature sensors may be utilized to detect the presence of any liquid content in one or a subset of fluid passages in the first plurality of fluid passages.
  • the local sensor arrangement may in some embodiments function on its own without the global sensor arrangement.
  • the invention relates to the use of a system according to any of the above disclosed embodiments of the system.
  • the invention relates to a method for dynamic control of the operation of a heat exchanger in a system according to any of the above disclosed embodiments, the method comprising the steps of:
  • the method may further comprise the step of determining a compensating local adjustment of the local amount of first fluid supplied by the other than the at least one of the injector arrangements in order to keep the global amount of first fluid in the plurality of first passages unaffected by the local adjustments.
  • the method may further comprise the step of communicating, by the controller, with the valves of the plurality of injector arrangements to adjust the local amount of first fluid supplied by said other than the at least one of the plurality of injector arrangements according to the determined compensating local adjustment.
  • the step of determining the difference may comprise determining the standard deviation for the measured temperature values.
  • the method may be performed in a system further comprises a global sensor arrangement comprising a global temperature sensor and a global pressure sensor, wherein the method further comprising the steps of:
  • the steps b)-f) and the steps g)-l) may be performed in parallel.
  • the steps b)-f) and the steps g)-l) may be continuously performed.
  • the steps b)-f) and the steps g)-l) may be performed as parallel loops in the controller.
  • FIG. 1 schematically illustrates a prior art refrigeration circuit being a mechanical vapor compression system.
  • FIG. 2 schematically illustrates a side view of a typical plate heat exchanger.
  • FIG. 3 schematically illustrates a front view of the plate heat exchanger of FIG. 2 .
  • FIG. 4 schematically illustrates a cross section along an edge of a prior art plate heat exchanger.
  • FIG. 5 illustrates a refrigeration circuit relating to the inventive system.
  • FIG. 6 illustrates injector arrangements for providing a fluid into the first plurality of fluid passages.
  • FIGS. 7-9 illustrate the positioning of the local sensor arrangement in different embodiments of the present invention.
  • FIG. 10 illustrates a method for controlling the local flow in the heat exchanger according to one embodiment of the present invention.
  • FIG. 11 illustrates a method for controlling the global flow in a heat exchanger.
  • a heat exchanger 1 may typically be included as an evaporator in a refrigeration circuit.
  • a prior art refrigeration system see FIG. 1 , being a mechanical vapor compression system, typically comprises a compressor 51 , a condenser 52 , an expansion valve 53 and an evaporator 54 .
  • the circuit may further comprise a pressure sensor 55 and a temperature sensor 56 arranged between the outlet of the evaporator and the inlet of the compressor.
  • the refrigeration circle of such system starts when a cooling agent enters the compressor 51 in evaporated form with a low pressure and with a low temperature.
  • the cooling agent is compressed by the compressor 51 to a high pressure and high temperature evaporated state before entering the condenser 52 .
  • the condenser 52 precipitates the high pressure and high temperature gas to a high temperature and high pressure liquid by transferring heat to a lower temperature medium, such as water or air.
  • the high temperature liquid then enters the expansion valve 53 where the expansion valve allows the cooling agent to enter the evaporator 54 .
  • the expansion valve 53 has the function of expanding the cooling agent from the high to the low pressure side, and to fine tuning the flow. In order for the higher temperature to cool, the flow into the evaporator must be limited to keep the pressure low and allow evaporation back into the evaporated form.
  • the expansion valve 53 may be operated by a controller 57 based on signals received from the pressure sensor 55 and the temperature sensor 56 . The information may be used to indicate the overall operation of the evaporator 54 based on a so called superheating being indicative of any liquid content remaining in the fluid after leaving the evaporator 54 .
  • FIGS. 2 to 4 in which an evaporator in the form of a plate heat exchanger 1 is illustrated.
  • the heat exchanger 1 may be of any type, such as a plate heat exchanger, a pipe and shell heat exchanger, a spiral heat exchanger etc.
  • the invention will however in the following be discussed as applied to a plate heat exchanger 1 , although the invention is not to be limited thereto.
  • local refers to a subset of the total system.
  • a local amount of flow in the first plurality of fluid passages refers to an amount of flow in a subset of the first plurality of fluid passages, such as one fluid passage in the first plurality of fluid passages.
  • each fluid passage has a local inlet and a local outlet.
  • local temperature of the first fluid refers to a temperature at a certain position in the first fluid, such as the temperature of the first fluid flowing in one fluid passage in the first plurality of fluid passages.
  • the term global refers to the total system.
  • the global amount of flow of the first fluid in the first plurality of fluid passages refers to the total amount of flow of the first fluid in the evaporator.
  • all injector arrangements are adjusted, by increasing or decreasing the flow, to an equal amount.
  • the heat exchanger has a global outlet, meaning the outlet where the local flows from subsets of the first plurality of fluid passages comes together to a single flow.
  • a global temperature of the first fluid refers to the temperature at a position where the first fluid is flowing as a single flow.
  • the plate heat exchanger 1 includes a plate package P, which is formed by a number of heat exchanger plates A, B, which are provided side by side.
  • the heat exchanger plates include two different plates, which in the following are referred to as a first heat exchanger plate A and a second heat exchanger plate B.
  • the heat exchanger plates A, B are provided side by side in such a manner that a first fluid passage 3 is formed between each pair of adjacent first heat exchanger plates A and second heat exchanger plates B, and a second fluid passage 4 is formed between each pair of adjacent second heat exchanger plates B and first heat exchanger plates A.
  • the heat exchanger comprises a first plurality of fluid passages 3 and a second plurality of fluid passages 4 .
  • Each fluid passage has a local inlet 41 and a local outlet 42 .
  • Each local inlet and local outlet may in turn comprise a plurality of entrances to or exits from the space between a pair of adjacent heat exchanger plates forming the fluid passage.
  • local inlet to a fluid passage is meant one or more entrances to the fluid passage
  • local outlet from a fluid passage is meant one or more exits from the fluid passages.
  • the plate package P further includes an upper end plate 6 and a lower end plate 7 provided on a respective side of the plate package P.
  • each heat exchanger plate A, B has four portholes 8 .
  • the first of the portholes 8 forms a first inlet channel 9 to the first plurality of fluid passages, including first fluid passage 3 , which extends through substantially the whole plate package P, i.e. all plates A, B and the upper end plate 6 .
  • the second of the portholes 8 forms a first outlet channel 10 from the first plurality of fluid passages, which also extends through substantially the whole plate package P, i.e. all plates A, B and the upper end plate 6 .
  • the third of the portholes 8 forms a second inlet channel 11 to the second plurality of fluid passages, including the second fluid passage 4 .
  • the fourth of the portholes 8 forms a second outlet channel 12 from the second plurality of fluid passages. Also these two channels 11 and 12 extend through substantially the whole plate package P, i.e. all plates A, B and the upper end plate 6 .
  • the system comprises an evaporator 54 in the form of a plate heat exchanger.
  • the evaporator 54 comprises heat exchanger plates A, B configured as discloses above in connection to FIGS. 2-4 .
  • the evaporator 54 comprises a first plurality of fluid passages 3 and a second plurality of fluid passages 4 .
  • the first plurality of fluid passages are represented by the first fluid passages denoted 3 a and 3 b .
  • Each first fluid passage 3 a , 3 b has a local inlet and a local outlet.
  • the evaporator 54 has a global inlet and a global outlet 13 .
  • the fluid passages 3 a , 3 b are arranged such that a first fluid may be supplied through the evaporator 54 from the global inlet to the global outlet 13 via the fluid passages 3 a , 3 b.
  • each injector arrangement 25 a , 25 b comprises a valve 22 a , 22 b and a nozzle 27 a , 27 b.
  • an injector arrangement may be constituted by a valve providing a fluid distribution.
  • the injector arrangements 25 a , 25 b are connected to one or more local inlets of a first fluid passage 3 a , 3 b in the first plurality of fluid passages of the evaporator 54 .
  • a closed circulation system is provided.
  • Each injector arrangement 25 a , 25 b in the plurality of injector arrangements is arranged to supply a flow of a first fluid to a local inlets of a first fluid passage 3 a , 3 b for evaporation of the first fluid before leaving the evaporator 54 via its global outlet 13 .
  • one or more of the injector arrangements may be arranged to supply a flow of a first fluid to the local inlets of more than one of the first fluid passages in the first plurality of fluid passages.
  • the flow is directed essentially in a direction in parallel with the flow direction through the first plurality of fluid passages 3 . Thereby any undue re-direction of the fluid flow may be avoided.
  • the heat exchanger being a plate heat exchanger this means in parallel with the general plane of the first and the second heat exchanger plates.
  • valves 22 a , 22 b of the injector arrangements 25 a , 25 b are positioned exterior of the evaporator 54 and of the plate package P making up the same, whereas the nozzles 27 a , 27 b of the injector arrangements 25 a , 25 b are arranged to extend to the interior of the evaporator 54 via evaporator inlets 26 a , 26 b , in a wall portion of the plate package.
  • the evaporator inlets 26 a , 26 b are in the form of through holes having an extension from the exterior of the plate package P to the interior of the plate package and more precisely to the local inlets of the first plurality of fluid passages.
  • the through holes may be formed by plastic reshaping, by cutting or by drilling.
  • plastic reshaping refers to a non-cutting plastic reshaping method such as thermal drilling.
  • the cutting or drilling may be made by a cutting tool. It may also be made by laser or plasma cutting.
  • each injector arrangement 25 a , 25 b may comprise only a valve which both controls the flow and functions as a nozzle.
  • the nozzles 27 a , 27 b may be omitted whereby the flow of fluid may be provided from a through hole (not disclosed) or a pipe (not disclosed).
  • FIG. 6 A cross-section of the inlet area of an evaporator possible to be used in the inventive system is disclosed in FIG. 6 .
  • the inlet channel 9 of the embodiment of FIG. 4 has been replaced by each first fluid passage, in the first plurality of fluid passages 3 , receiving an injector arrangement 25 a , 25 b.
  • each injector arrangement 25 a , 25 b may comprise a plurality of nozzles, wherein the plurality of nozzles are provided with fluid from a single valve. It is also to be understood that each injector arrangement 25 a , 25 b may comprise a plurality of valves.
  • each injector arrangement 25 a , 25 b may be lower than the number of first fluid passages 3 .
  • each injector arrangement may be arranged to supply its flow of the first fluid to more than one of the local inlets of the first fluid passages 3 .
  • each injector arrangement 25 a , 25 b being arranged in a through hole having a diameter extending across two or more first fluid passages, whereby one and the same injector arrangement 25 a , 25 b may supply fluid to more than one fluid passage in the first plurality of fluid passages 3 .
  • the inventive system further comprises a local sensor arrangement 29 comprising local temperature sensors.
  • the local temperature sensors are represented by the local temperature sensors denoted 31 a and 31 b.
  • the local temperature sensors 31 a , 31 b are arranged to measure temperature values corresponding to the local temperature of the evaporated first fluid flowing nearby the local outlets of the first plurality of fluid passages 3 .
  • nearby is meant around the local outlet, i.e. it could be either upstream or downstream from the local outlet in view of the first fluid.
  • the local temperature sensors 31 a , 31 b should be positioned such that they measure on flows of first fluid after the flows have evaporated and before the flows mix with each other to form a global flow.
  • the local temperature sensors 31 a , 31 b may be arranged in through holes having an extension from the exterior of the plate package P to the interior of the plate. Alternatively, the local temperature sensors 31 a , 31 b may be arranged only interior or only exterior of the plate. The local temperature sensors 31 a , 31 b may be arranged separated from each other or in connection to each other by for example attachment to a flute shaped device extending along an outlet channel common for the local outlets of the first plurality of fluid passages 3 .
  • the local temperature sensors 31 a , 31 b may be arranged to measure temperatures in connection to one or more fluid passages 3 a , 3 b .
  • the local sensor sensors 31 a , 31 b may be arranged to measure an average temperature value.
  • the local sensor arrangement 29 does not need to be arranged to measure the temperature corresponding to the local temperature of the first fluid in all in the first plurality of fluid passages 3 .
  • the local temperature sensors 31 a , 31 b may be arranged such that the temperatures corresponding to the local temperatures of the first fluid flowing nearby the local outlets of every tenth pair of fluid passages in the first plurality of fluid passages 3 are measured.
  • the local temperature sensors 31 a , 31 b are connected to a controller 57 .
  • the controller 57 is arranged to communicate with the local sensor arrangement 29 and with the individual valves 22 a , 22 b of the injector arrangements 25 a , 25 b .
  • the controller 57 may be for example a P regulator, a PI regulator or a PID regulator.
  • the temperatures at local positions within the heat exchanger may be determined.
  • the purpose of the local sensor arrangement 29 is to determine the local temperatures in or nearby the local outlets of one or several first fluid passages 3 a , 3 b in order to enabling determining and executing a local adjustment of the flow of first fluid in the first plurality of fluid passages 3 .
  • the controller 57 is arranged to receive the measured local temperature values from the local sensor arrangement 29 .
  • the controller 57 determines a difference between the measured temperature values. One or more differences may be determined based on a single batch of measured temperature values.
  • the controller 57 determines a local adjustment of the local amount of first fluid supplied by at least one of the injector arrangements 25 a , 25 b .
  • the controller 57 may determine one or more local adjustments based on a single batch of measured temperature values received from the local sensor arrangement 29 . Different injector arrangements 25 a , 25 b may be adjusted to a different degree.
  • the difference may be determined by determining the standard deviation of the measured temperature values received from the local sensor arrangement 29 .
  • the standard deviation By utilizing the standard deviation for determining the local adjustment, quick and harsh local adjustments are damped such that the adjustment procedure becomes more smooth and even.
  • the controller 57 does not need to base the adjustment on all of the received measured temperature values.
  • the controller 57 may determine an adjustment in flow in view of a particular injector arrangement based on a selected number of measured temperature values, such as those corresponding to the adjacent injector arrangements, or of a mean value of a number of measured temperature values.
  • the local adjustment is performed in order to even out any temperature differences in view of the first fluid flowing nearby the local outlets.
  • the overall ambition with the local adjustment may thus be seen as the ambition that all first fluid passages 3 should contribute equally to the overall operation of the evaporator.
  • the global amount of flow is adjusted if liquid content is detected in the global outlet or downstream from the global outlet 13 .
  • the presence of liquid content in the global flow may be caused by a local overflow in a single fluid passage or in a subset of fluid passages.
  • the presence of any liquid content in a local flow may be detected by means of the local sensor arrangement 29 if the local sensors 31 a , 31 b are arranged to measure directly on the first fluid nearby the local outlets of the first plurality of fluid passages 3 . If any liquid content is present nearby a local temperature sensor 31 a , 31 b , the liquid substance will attach to the sensor and evaporate there from. Due to the evaporation, the affected local temperature sensor 31 a , 31 b will measure a temperature value being lower than temperature values from local temperature sensors which measure on a fully evaporated first fluid.
  • the amount of first fluid in the first fluid passage or passages in which the measured local temperature values are low is adjusted such that all fluid supplied thereto may become evaporated and thus the measured temperature values should increase towards the measured local temperature value of other first fluid passages.
  • the first plurality of fluid passages 3 may be utilized more efficiently as compared to known techniques. Further, by optimizing the flow in the plurality of first fluid passages 3 , a higher pressure may be achieved in the global flow downstream from the global outlet. In systems such as the one illustrated in FIG. 5 , the efficiency of the compressor 51 is increased when fed with a higher pressure. Thus, the efficiency of the whole system may be boosted.
  • the system further comprises a global sensor arrangement 28 .
  • the global sensor arrangement 28 comprises a global pressure sensor 30 a and a global temperature sensor 30 b .
  • the global sensor arrangement 28 may be arranged in the tube system 15 connecting the global outlet 13 of the evaporator 54 with the inlet 14 of the compressor 51 and more precisely in or downstream from the global outlet 13 of the evaporator but before the inlet 14 of the compressor 51 .
  • the two global sensors 30 a , 30 b must not have the same position within the system. However, it is preferred that the global sensor arrangement 28 is arranged at essentially the same position, such that the global sensors 30 a , 30 b measures on the same portion of evaporated first fluid.
  • the global pressure sensor 30 a is preferably arranged after the global outlet 13 of the evaporator 54 in a more or less straight section of the tube system 15 connecting the evaporator 54 with the compressor 51 .
  • the global pressure sensor 30 a is arranged on a distance after a tube bend corresponding to at least ten times the inner diameter of the tube, and on a distance before a tube bend corresponding to more than five times the inner diameter of the tube.
  • the global sensor arrangement 28 is arranged nearby the inlet 14 of the compressor 51 .
  • the global pressure sensor 30 a is arranged to measure the global pressure value of the evaporated first fluid, in the following identified as the measured global pressure.
  • the global pressure sensor 30 a may for example be a 4-20 mA pressure sensor with a range from 0 to 25 bars.
  • the global temperature sensor 30 b is preferably arranged in the tube system 15 after a tube bend. It is preferred that the temperature sensor 30 b is arranged closer to the inlet 14 of the compressor 51 than to the global outlet 13 of the evaporator 54 . By positioning the temperature sensor 30 b after a tube bend it is more likely that any remaining liquid content in the evaporated first fluid is evaporated while meeting the walls of the tube bend and thereby being forced to change its flow direction. There is also an evaporation taking place by the remaining liquid contents absorbing heat from the surrounding superheated fluid flow.
  • the global temperature sensor 30 b may be a standard temperature sensor measuring the temperature, in the flowing identified as the measured temperature.
  • the measured values regarding global pressure and global temperature are communicated to the controller 57 which is arranged to regulate the system on a global level based on the determined superheating.
  • the controller 57 may base the regulation on a detection of presence of liquid content which may be performed by at least one temperature sensor included in the global sensor arrangement 28 .
  • the superheating being a physical parameter well known in the art, is defined as the temperature difference between the present temperature and the saturation temperature at a prevailing pressure, i.e. when there is not any liquid content remaining in the fluid.
  • the superheating is unique for a given fluid and for a given temperature and pressure.
  • the superheating may be found in conventional graphs or tables.
  • the superheating may be regarded as being digital—either there is a complete evaporation without any liquid content, or there is an incomplete evaporation with liquid content contained in the evaporated flow downstream the evaporator.
  • a compressor In order to optimize the operation of an evaporator it is desired to have as low superheating as possible.
  • a compressor is sensitive to liquid content and may be damaged thereby, its common praxis to use a safety margin of some degrees when designing an evaporation system.
  • a normal safety margin for a prior art evaporator is 5° K, i.e. the superheating should be at least 5° K.
  • another value of the safety margin may be elected.
  • the safety margin is to be regarded as a constant decided by the intended use of the evaporator. It is however to be understood that there is also a desire to use as low safety margin as possible since there is an economical interest of operating the evaporator as close to the saturation temperature as possible. During the operation of the system this constant will be used as a set-point superheating, i.e. a target value, towards which the operation of the evaporator 54 will be dynamically controlled.
  • the global amount of first fluid in the first plurality of fluid passages 3 are thus adjusted in order to reach the set-point superheating, or in order to remove the presence of any liquid content.
  • the global tuning works as an optional complement to the local tuning of the local flows within the heat exchanger which is controlled based on values measured by the local sensor arrangement 28 .
  • the purpose of the global sensor arrangement 28 is thus to determine the presence of any liquid content in the evaporated first fluid, or to determine the so called superheating of the evaporated first fluid.
  • the measurements are transmitted to the controller 57 which, in turn, determines a global adjustment of the flow of first fluid in the first plurality of fluid passages 3 .
  • the local flow in a subset of the first plurality of fluid passages 3 is controlled by measuring local temperature values by the local sensor arrangement 29
  • the global flow in the first plurality of fluid passages 3 is controlled by measuring global temperature and/or pressure values by the global sensor arrangement 28 .
  • the global adjustment may be described as an adjustment in order to operate towards a set-point superheating or towards the non-presence of liquid content, whereas the local adjustment may be described as an adjustment for evening out the temperature differences within the heat exchanger. Both adjustments are performed in order to optimize the performance of the heat exchanger.
  • the adjustments complement each other but may also function on their own.
  • a system may comprise the local sensor arrangement 29 and perform the local tuning of the first plurality of fluid passages 3 without utilizing the global sensor arrangement and global adjustment.
  • the local adjustment and optionally the global adjustment are preferably performed continuously for the system during operation thereof.
  • the local flow and optionally also the global flow are adjusted continuously whereby the heat exchanger is continuously optimized in view of current running conditions and operation duty.
  • the heat exchanger thus becomes more flexible and adapts to different running conditions.
  • the heat exchanger will run in an optimized manner regardless of the running conditions.
  • the two processes may be performed as parallel loops in the controller 57 .
  • FIGS. 7-9 both the first plurality of fluid passages and the second plurality of fluid passages are illustrated highly schematically.
  • the local sensor arrangement is arranged to measure temperature values corresponding to the local temperatures of the evaporated first fluid flowing nearby the local outlets of the first plurality of fluid passages.
  • the sensors 31 a , 31 b of the local sensor arrangement 29 may measure directly or indirectly on the evaporated first fluid flowing nearby the local outlets.
  • a first fluid is supplied to a first plurality of fluid passages by injector arrangements 25 a , 25 b .
  • the flow of first fluid through the first plurality of fluid passages is indicated by 74 .
  • a second fluid is supplied to a second plurality of fluid passages.
  • the flow of second fluid through the second plurality of fluid passages is indicated by 75 .
  • the second fluid enters the heat exchanger via a global inlet 71 and exits the heat exchanger via a global outlet 72 . When flowing through the respective fluid passages, heat is transferred between the first fluid and the second fluid.
  • the local temperature sensors 31 a , 31 b are in FIG. 7 arranged nearby the local outlets of the first plurality of fluid passages, and the local temperature sensors 31 a , 31 b are arranged within the housing of the heat exchanger.
  • the local outlets of the first plurality of fluid passages exits in a common outlet channel ending in a global outlet 76 from the heat exchanger.
  • the global outlet 76 corresponds to the first outlet channel 10 of FIG. 3 .
  • the local temperature sensors 31 a , 31 b is in this embodiment attachment to a flute shaped device 73 extending along common outlet channel.
  • the local temperature sensors 31 a , 31 b are in FIG. 8 arranged also nearby the local outlets of the first plurality of fluid passages, but instead in a position exterior of the plate package P and outside the housing of the heat exchanger.
  • the local temperature sensors 31 a , 31 b are arranged in so called ports 80 a , 80 b located between the housing and a common outlet.
  • the local temperature sensors 31 a , 31 b are in FIG. 9 arranged nearby the local outlets of the second plurality of fluid passages.
  • the local sensors are in this embodiment not arranged in direct or even indirect connection to the first fluid.
  • the local temperature of the second fluid flowing nearby the local outlets of the second plurality of fluid passages and the local temperature of the first fluid flossing nearby the local outlets of the first plurality of fluid passages.
  • the local temperature of the second plurality of fluid passages reflects the local temperature of the first fluid.
  • the measured temperature values at the second plurality of fluid passages may therefore in this embodiment be utilized in the controller for determining local adjustments in order to even out differences between the measured temperature values.
  • the second plurality of fluid passage may provide a friendlier environment for the sensors in case the second fluid is water. Secondly, it may be easier to arrange temperature sensors in the second plurality of fluid passages without affecting the fluid. Thirdly, the measured temperature values on the second fluid may be utilized for further purposes, such as providing information regarding the outgoing second fluid temperature to a user.
  • the measurement on the second fluid may be performed inside the heat exchanger or outside of the heat exchanger in analogy with the arrangement of the local sensors 31 a , 31 b when arranged to measure on the first fluid (i.e. FIGS. 7 and 8 ).
  • the local sensor arrangement may be arranged to measure directly on the fluid or indirectly, such as by measuring on heat-conducting pipes in which the fluid flows.
  • a method according to one embodiment of the present invention for performing the local adjustment of the heat exchanger, based on the measurement of the local sensor arrangement, will now be disclosed with reference to FIG. 10 .
  • the heat exchanger system as such has the same general design as that previously described with reference to FIG. 5 whereby reference is made thereto.
  • a first fluid and a second fluid is supplied 1001 .
  • the first fluid is supplied by the plurality of injector arrangements to the first plurality of fluid passages 3 .
  • the second fluid is supplied to the second plurality of fluid passages 4 .
  • temperature values corresponding to local temperatures of the evaporated first fluid flowing nearby the local outlets of the first plurality of fluid passages 3 are measured 1002 .
  • the measured temperature values are transmitted 1003 to the controller 57 .
  • a difference between the measured temperature values is determined 1004 .
  • the difference may for example be determined by determining the standard deviation for the measured temperature values.
  • a local adjustment is determined 1005 .
  • the local adjustment is an adjustment of the local amount of fluid supplied by at least one of the plurality of injector arrangements, in order to even out the determined difference.
  • One or more local adjustments may be determined based on the same batch of measured temperature values. For example, a first local adjustment to be applied to a first injector arrangement may be determined together with a second local adjustment to be applied to a second injector arrangement and to a third injector arrangement.
  • the method may further comprise a step of determining a compensating local adjustment of the local amount of first fluid supplied by the other injector arrangements for which no local adjustment has been determined.
  • a compensating local adjustment may be determined for a fourth injector arrangement.
  • the compensating local adjustment is determined in order to keep the global amount of first fluid in the plurality of first passages unaffected by the local adjustments.
  • the global amount is instead controlled based on the values measured by the global sensor arrangement.
  • the local adjustment is communicated 1006 from the controller 57 to the valves of the affected injector arrangement.
  • the local amount of first fluid supplied by that specific injector arrangement is adjusted according to the determined local adjustment.
  • the compensating local adjustment if any, is also communicated to the valves of the affected injector arrangements.
  • the method may be performed continuously in the heat exchanger.
  • the method may further be performed in parallel with global adjustment of the global amount of flow of first fluid.
  • a global adjustment method will in the following be disclosed with reference to FIG. 11 .
  • the system as such has the same general design as that previously described with reference to FIG. 5 whereby reference is made thereto.
  • the global sensor arrangement 28 downstream the global outlet 13 of the heat exchanger measures 1101 the presence of any liquid content in the global flow of first fluid or measured global pressure Pm and global temperature Tm.
  • the signal generated by the global sensor arrangement 28 is received 1102 by the controller 57 .
  • the controller may be a P regulator, a PI regulator or a PID regulator.
  • the controller 57 evaluates 1103 the received signal.
  • the signal When measuring the presence of any liquid content, the signal may in its most simple form be a digital signal: 1—no liquid content detected; 0—liquid content detected. More precisely, a signal having the value 1 indicates that the evaporated fluid has a measured temperature corresponding to or being above the superheating. Likewise, a signal having the value 0 indicates that the evaporated fluid has a temperature being below the superheating.
  • the superheating may be determined by firstly converting the measured global pressure value to a saturation temperature and secondly establish the superheating by comparing the measured global temperature value with the determined saturation temperature.
  • the controller 57 determines 1104 a suitable global adjustment of first fluid supplied by the plurality of injector arrangement, based on the determined liquid content or determined superheating.
  • the controller 57 communicates with the valves of the injector arrangements, or with a global valve, to adjust the global flow according to the determined global adjustment.
  • the global valve may be a main valve arranged upstream from the injector arrangements, which valve controls the total supply of first fluid to all injector arrangements.
  • the injector arrangements are disclosed as being arranged in through holes extending from the exterior of the plate package into the individual fluid passages. It is to be understood that this is only one possible embodiment.
  • the injector arrangements may extend into any inlet port or the like depending on the design of the evaporator. This may for example be made by a flute device arranged along an inlet channel.
  • the invention has generally been described based on a plate heat exchanger having first and second plate passages and four port holes allowing a flow of two fluids. It is to be understood that the invention is applicable also for plate heat exchangers having different configurations in terms of the number of plate passages, the number of port holes and the number of fluids to be handled.
  • controller may be used for other purposes as well, such as control of the refrigerant circuit as such.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
US15/039,314 2013-11-28 2014-11-03 System and method for dynamic control of a heat exchanger Abandoned US20170167810A1 (en)

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PCT/EP2014/073533 WO2015078661A1 (en) 2013-11-28 2014-11-03 System and method for dynamic control of a heat exchanger

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JP6134068B2 (ja) 2017-05-24
WO2015078661A1 (en) 2015-06-04
JP2017502238A (ja) 2017-01-19
EP2878912A1 (en) 2015-06-03
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CN105745510A (zh) 2016-07-06
TWI542847B (zh) 2016-07-21

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