WO2000071945A1 - Method for removing ice crystals in a heat exchanger generating a diphasic liquid-solid refrigerant - Google Patents

Method for removing ice crystals in a heat exchanger generating a diphasic liquid-solid refrigerant Download PDF

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Publication number
WO2000071945A1
WO2000071945A1 PCT/FR2000/001405 FR0001405W WO0071945A1 WO 2000071945 A1 WO2000071945 A1 WO 2000071945A1 FR 0001405 W FR0001405 W FR 0001405W WO 0071945 A1 WO0071945 A1 WO 0071945A1
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WO
WIPO (PCT)
Prior art keywords
coolant
generator
speed
circuit
ice
Prior art date
Application number
PCT/FR2000/001405
Other languages
French (fr)
Inventor
Michel Barth
Original Assignee
Michel Barth
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Michel Barth filed Critical Michel Barth
Priority to DE60023422T priority Critical patent/DE60023422T2/en
Priority to EP00931340A priority patent/EP1101071B1/en
Priority to AT00931340T priority patent/ATE308021T1/en
Publication of WO2000071945A1 publication Critical patent/WO2000071945A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • F28F19/006—Preventing deposits of ice
    • 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
    • F25C—PRODUCING, WORKING OR HANDLING ICE
    • F25C5/00—Working or handling ice
    • F25C5/02—Apparatus for disintegrating, removing or harvesting ice
    • F25C5/04—Apparatus for disintegrating, removing or harvesting ice without the use of saws
    • 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
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D17/00—Arrangements for circulating cooling fluids; Arrangements for circulating gas, e.g. air, within refrigerated spaces
    • F25D17/02—Arrangements for circulating cooling fluids; Arrangements for circulating gas, e.g. air, within refrigerated spaces for circulating liquids, e.g. brine
    • 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
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/06—Removing frost

Definitions

  • the invention relates to the field of production and distribution of cold by means of a liquid + solid two-phase refrigerant fluid.
  • the secondary refrigerant two-phase liquid + solid consists of a m e lange two liquids, generally a mixture of water and one other liquid miscible with water either ethanol, methanol, ammonia , calcium chloride or other This mixture is cooled to the crystallization temperature of water The crystals then formed are entrained by the coolant in the liquid phase This mixture of crystals and the liquid phase is defined by the term two-phase coolant or "ice coulis"
  • the ice slurry has significant advantages over single-phase f ⁇ goportants fluids
  • these liquid + solid two-phase f ⁇ goporteurs use latent heat of transformation (solid to liquid) and allow cold transport by much larger volume unit which has the advantage of reducing the volume flow rates in circulation
  • Ice grouts are formed in generators whose purpose is to generate ice crystals which are entrained by the liquid phase of the coolant
  • These generators have heat exchange walls swept on the top face by the coolant and on the other side by a f ⁇ go ⁇ gene fluid
  • These heat exchange walls can be the shape of a bundle of flat or cylindrical tubes forming part of a first fluid circuit, this bundle being placed in a chamber forming part of a second fluid circuit
  • the coolant flows in one of the circuits, while the f ⁇ go ⁇ gene fluid flows in the other circuit Ice crystals form on the face of the generator walls swept by the coolant and tend to remain stuck on these walls
  • the invention is based on the idea of intermittently creating turbulence in the coolant by increasing the flow rate, therefore the speed d e circulation
  • the direct consequences of the increase in circulation speed are on the one hand an increase in the pull-out force applied to the crystals in formation and on the other hand a modification of the exchange parameters and therefore a slight wall temperature increase
  • the invention therefore relates to a method for detaching the ice crystals which form on one face of the heat exchange walls of an exchanger generating an ice slurry, said face being in contact with a coolant of a first circuit which flows at nominal speed in said generator exchanger, while the other face of said walls is in contact with a cooling fluid which flows in a second circuit.
  • this process is characterized by the fact that the refrigerant is intermittently circulated in the generator at a speed greater than the nominal speed in order to create turbulence causing the detachment of the ice crystals formed, on the one hand by tearing off and on the other hand by heating of the exchange walls.
  • the nominal speed of the coolant corresponds to the normal operating flow of the installation.
  • the ice crystals formed on the cold walls of the generator are detached by a mechanical-hydraulic and thermal action, for the duration of the increase in flow, and are entrained by the liquid phase of the coolant.
  • the increase in flow has, in effect: a) an increase in the speed of circulation in the turbulent phase, therefore an increase in the pull-out force applied to the crystals; b) a modification of the exchange coefficient parameters, as a result of the increase in speed, and therefore an increase in the temperature of the cold wall which promotes the detachment of the ice crystals.
  • the coolant is circulated by a pump and the speed of rotation of the pump is increased intermittently.
  • the pump is driven for example by a variable speed motor.
  • the basic speed of the motor and the pump, and therefore the normal flow or the nominal speed of the coolant in the generator, as well as the surface temperature of the cold wall are calculated according to the type of exchanger, the refrigerant and the concentration of the mixture, as well as the concentration of the solid particles which it is desired to obtain in the two-phase refrigerant fluid.
  • the ice crystals are detached without mechanical means arranged in the generator as in the prior art.
  • the geometry of the heat exchange walls can be optimized as a function of the thermal conductivity coefficients of the two fluids and of the material of the walls, of the flow rates and of the cooling power required for the installation.
  • the frequency and duration of turbulence, as well as the speed of the coolant during turbulence can be established by test results. They will depend on the type of exchanger, the coolant, the concentration of the mixture, as well as the concentration of solid particles that we want to reach in the coolant.
  • the initiation of turbulence is carried out automatically.
  • the pressure drop undergone by the coolant through the generator is continuously measured and the speed of the pump is increased when the measured pressure drop is greater than a set value.
  • the set value is also a function of the type of exchanger, the coolant, the concentration of the mixture, as well as the concentration of solid particles that one wants to obtain.
  • the temperature of the cooling fluid is increased by increasing the evaporation pressure. This can be achieved by operating the generator inlet and outlet valves on the second circuit, or by injecting hot gas from the gas compressor into the generator.
  • the coolant is a liquid monophasic or biphasic liquid / ice refrigerant, one increases advantageously the temperature of the coolant by recirculating the coolant outside the generator.
  • FIG. 1 shows a diagram of a refrigeration installation comprising an ice slurry generator having a cooling fluid in the evaporation phase in the generator
  • FIG. 2 shows a diagram of a refrigeration installation comprising an ice slurry generator cooled by a liquid or mono- or two-phase coolant liquisol
  • FIG. 3 shows the graph of the speeds of the coolant in the generator for implementing the method according to the invention
  • FIG. 4 shows the generator control system according to a first embodiment of the invention
  • FIG. 5 shows the generator control system according to a second embodiment of the invention.
  • FIG. 1 there is shown by the reference 1 an ice slurry generator which has heat exchange walls 2 separating a first circuit 3 in which a two-phase water / ice coolant flows. a second circuit 4 in which a cooling fluid flows intended to cool the coolant of the first circuit 3.
  • the first circuit 3 comprises, outside the generator 1, a conduit 5 for delivering ice slurry intended to supply exchangers 6 in parallel and a return conduit 7 equipped with a circulation pump 8.
  • the exchangers 6 can be connected directly between conduits 5 and 7, or mounted on branches fitted with autonomous recirculation pumps 9.
  • the exchangers 6 are intended to cool premises or products, the cold being obtained by melting the ice crystals contained in the refrigerant fluid passing through them. The ice concentration of the coolant in the return duct 7 is thus lower than that of the coolant in the delivery duct 5.
  • the temperature of the refrigerant in the return duct 7 is higher than the temperature of the refrigerant in the delivery duct 5 of the ice slurry , and the measurement of these temperatures at the inlet and at the outlet of the generator by the temperature probes 10 and 11 makes it possible to know with good precision the crystal concentrations for a type of mixture used as coolant and the concentration of the mixture.
  • a recirculation tank 12, which can also act as an accumulation, must also be disposed between the delivery pipe 5 and the return pipe 7.
  • a circulation pump 8b is mounted on the pipe 5 downstream of the tank 12.
  • the coolant circulating in the generator 1 is cooled by the coolant, thanks to the heat exchanges which take place through the exchange walls 2. Ice crystals are then formed on the face of the walls 2, which is in contact with the coolant in circuit 3.
  • the circulation pump 8 mounted on the return duct 7 is rotated by a variable speed electric motor 13.
  • the circulation pump 8 is driven at a substantially constant speed, which we call basic speed, and the coolant then flows into the generator 1 with a substantially constant flow which is the normal flow. of generator 1 and at a substantially constant speed which we call the nominal speed Vn.
  • the ice crystals which form on one face of the heat exchange walls 2 are detached, by intermittently circulating, the coolant in the generator 1 at a speed Vs greater than the nominal speed Vn in order to create in the portion of the circuit 1 located in the generator 1 turbulences which slightly heat the walls 2 and cause additional forces for the tearing of the crystals.
  • FIG. 3 shows the graph of the circulation speeds of the coolant in the generator 1.
  • the time interval To between two turbulence phases T1 and T2 and the duration Do of each turbulence phase are obtained for example by the result of tests and are a function of the type of generator, the type of coolant, the proportion of the mixture and the concentration of crystals used.
  • the electric motor 13 is controlled by an automaton 14 into the memory of which four characteristic operating data are introduced: the basic speed corresponding to the nominal speed Vn, the maximum speed corresponding to the speed Vs, l 'time interval To during which the engine turns at its displayed basic speed, and the duration Do of a turbulent phase.
  • the automaton 14 obviously has an internal clock.
  • a differential pressure switch 15 is interposed between the inlet and the outlet of the conduits 5 and 7 in the generator.
  • This pressure switch 15 measures the pressure drop undergone by the coolant through the generator 1. This pressure drop is a function of the quantity of ice crystals deposited on the walls 2 and of the ice concentration of the coolant.
  • the measurement of the pressure switch 15 is transmitted to a calculation unit 16 which compares it to a set value, and when this measurement is greater than the set value, the calculation unit 16 controls the motor 13 to turn , at its speed maximum for a duration Do. Then, the calculating member 16 controls the motor 13 to rotate at its basic speed.
  • three basic characteristics are introduced into the memory of the calculation unit 16: the basic speed of the motor 13, the maximum speed of the motor 13 and the duration Do of a turbulent phase.
  • the measurements of the temperature probes 10 and 11 are also transmitted to the calculation unit 16.
  • the latter is able to correct the set value as a function of the measurements of the temperature waves 10 and 11 which are representative of the concentration of crystals in the coolant at the inlet and at the outlet of the generator 1.
  • the nominal pressure drop of the coolant through the generator 1, in the absence of crystals bonded to the walls 2, is therefore a function of the temperatures measured and the nominal speed of the coolant.
  • the calculating member 16 controls the motor 13 to run at its maximum speed for a duration Do.
  • the calculating member 16 acts on the circulation of the cooling fluid in the exchanger 1 in order to constantly adapt the temperature of the exchange walls 2 with a view to optimizing the efficiency of the installation, and in order to obtain new crystals until the desired crystal concentration is obtained.
  • the invention When the coolant of circuit 1 flows in the generator in turbulence mode in order to detach the ice crystals formed on the walls 2, the invention further provides for rapidly and simultaneously increasing the temperature of the cold walls 2, acting on the coolant side. This is obtained by increasing the temperature of the coolant during the duration Do of the turbulence.
  • the method differs depending on the type of coolant.
  • the cooling fluid which flows in the second circuit 4 is a liquid in the evaporation phase in the generator 1 of ice slurry.
  • the generator 1 thus plays the role of an evaporator for the cooling fluid.
  • the gases produced in the generator 1 are sucked up by a gas compressor 20 mounted in the suction pipe 21 which connects the generator 1 to a condenser 22.
  • a pressure regulating valve 23 is mounted on the suction pipe 21.
  • the refrigerant in the liquid state returns to the generator 1 via a supply conduit 24 on which is mounted a control valve 25 for injecting refrigerant.
  • a branch 26 is provided between the discharge outlet of the compressor 20 and the inlet of the supply duct 24 into the generator 1.
  • a valve 27 for injecting hot gases is mounted on the branch 26.
  • the automaton 14 or the calculation unit 16 also acts on the valves 23 and 25 in particular on the valve 27 for injecting hot gases. This action immediately produces an increase in pressure evaporation in the evaporator, which causes instant warming of the cold walls 2 and detachment of the ice crystals. This action is limited in time to a duration at most equal to the duration Do of the turbulence.
  • the coolant which circulates in the second circuit 4 is itself a coolant cooled in a second generator 30 supplied with coolant by a circuit 4b similar to the circuit 4 of FIG. 1.
  • a three-way valve 40 is mounted on the supply pipe 24 for the fluid of the circuit 4 and a bypass 41 is provided between the three-way valve 40 and the return pipe 42 for the fluid of the circuit 4.
  • the three-way valve 41 is controlled by the automaton 14 or the calculation unit 16, and during the turbulence phases in the first circuit 3, the coolant recirculates through the bypass duct 41, which causes the walls to heat up. 2.
  • the second generator 30 can also be controlled by another automaton or another calculation unit in order to take off the ice crystals which form there, in the case where the refrigerant fluid which circulates in the second circuit 4 is two-phase .

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Other Air-Conditioning Systems (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)
  • Production, Working, Storing, Or Distribution Of Ice (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Abstract

The invention concerns a method for removing ice crystals which are formed on the surface of the heat-exchanging walls (2) of a generator (1), in contact with a diphasic liquid-solid refrigerant fluid. In order to remove the ice crystals formed, it consists in intermittently circulating in the generator (1) the refrigerant fluid at a speed higher than the nominal speed so as to generate turbulent flows which cause the formed ice crystals to be detached, by being pulled off and by heating the heat-exchanging walls. Preferably the rotational speed of the pump (8) circulating the refrigerant fluid is increased intermittently.

Description

PROCEDE POUR DETACHER LES CRI STAUX DE GLACE D ' UN ECHANGEUR THERMIQUE GENERATEUR D ' UN FRIGOPORTEUR DIPHASIQUE LIQUIDE- SOLIDE " PROCESS FOR DETACHING CRI STALS OF ICE FROM A GENERATOR HEAT EXCHANGER FROM A LIQUID-SOLID DIPHASIC REFRIGERATOR "
L'invention concerne le domaine de la production et distribution du froid au moyen d'un fluide frigoporteur diphasique liquide + solideThe invention relates to the field of production and distribution of cold by means of a liquid + solid two-phase refrigerant fluid.
Le fluide frigoporteur diphasique liquide + solide est constitue d'un mélange de deux liquides, généralement un mélange d'eau, et d'un autre liquide miscible avec l'eau soit de l'ethanol, du methanol, de l'ammoniac, du chlorure de calcium ou autre Ce mélange est refroidi jusqu'à la température de cristallisation de l'eau Les cristaux alors formes sont entraînes par le frigoporteur en phase liquide Ce meiange de cristaux et αe phase liquide est défini par le terme frigoporteur diphasique ou "coulis de glace"The secondary refrigerant two-phase liquid + solid consists of a m e lange two liquids, generally a mixture of water and one other liquid miscible with water either ethanol, methanol, ammonia , calcium chloride or other This mixture is cooled to the crystallization temperature of water The crystals then formed are entrained by the coolant in the liquid phase This mixture of crystals and the liquid phase is defined by the term two-phase coolant or "ice coulis"
Le coulis de glace présente, par rapport aux fluides fπgoporteurs monophasiques, des avantages non négligeables En changeant partiellement d'état, ces fπgoporteurs diphasiques liquide + solide mettent en oeuvre une chaleur latente de transformation (solide en liquide) et permettent un transport de froid par unité de volume beaucoup plus grand ce qui a pour avantage de réduire les débits volumiques en circulation Ceci permet de diminuer notablement le débit des pompes et le diamètre des tuyauteries de distribution Les coulis de glace sont formes dans des générateurs qui ont pour objet de générer des cristaux de glace qui sont entraînes par la phase liquide du fluide frigoporteur Ces générateurs comportent des parois d'échange thermique balayées sur upe face par le fluide frigoporteur et sur l'autre face par un fluide fπgoπgene Ces parois d'échange thermique peuvent se présenter sous la forme d'un faisceau de tubes plats ou cylindriques faisant partie d'un premier circuit de fluide, ce faisceau étant dispose dans une chambre faisant partie d'un deuxième circuit de fluide Le fluide frigoporteur s'écoule dans l'un des circuits, tandis que le fluide fπgoπgene s'écoule dans l'autre circuit Les cristaux de glace se forment sur la face des parois du générateur balayée par le fluide frigoporteur et ont tendance a rester colles sur ces parois Les conséquences directes sont une augmentation des pertes de charge, une baisse des échanges thermiques , le but du générateur étant de fabriquer des cristaux il est donc nécessaire de prévoir des moyens pour détacher les cristaux formes sur les parois En général, on utilise des moyens mécaniques pour arracher la couche de glace formée sur les parois de l'échangeur A cet effet, des lames ou des balais raclent la couche ainsi formée et la glace est entraînée vers le circuit de distribution Cette disposition oblige à utiliser des surfaces d'échange sous forme de cylindres à double paroi, le système racloir agissant soit à l'intérieur du cylindre (circuit fermé), soit à l'extérieur du cylindre (circuit ouvert) Ces générateurs de coulis, dits "à surface raclée", sont limités en dimensions, donc en puissance avec des systèmes mécaniques de racloirs relativement fragiles Ils sont coûteux et un accroissement de puissance exige une mise en parallèle de plusieurs générateurs, ce qui rend le procédé complique et volumineuxThe ice slurry has significant advantages over single-phase fπgoportants fluids By partially changing their state, these liquid + solid two-phase fπgoporteurs use latent heat of transformation (solid to liquid) and allow cold transport by much larger volume unit which has the advantage of reducing the volume flow rates in circulation This allows to significantly reduce the flow rate of the pumps and the diameter of the distribution pipes Ice grouts are formed in generators whose purpose is to generate ice crystals which are entrained by the liquid phase of the coolant These generators have heat exchange walls swept on the top face by the coolant and on the other side by a fπgoπgene fluid These heat exchange walls can be the shape of a bundle of flat or cylindrical tubes forming part of a first fluid circuit, this bundle being placed in a chamber forming part of a second fluid circuit The coolant flows in one of the circuits, while the fπgoπgene fluid flows in the other circuit Ice crystals form on the face of the generator walls swept by the coolant and tend to remain stuck on these walls The direct consequences are an increase in pressure losses, a decrease in heat exchange, the aim of the generator being to make crystals it is therefore necessary to provide means for detaching the crystals formed on the walls In general, mechanical means are used to tear off the layer of ice formed on the walls of the exchanger. For this purpose, blades or brushes scrape off the layer thus formed and the ice is drawn towards the distribution circuit. This arrangement requires that use exchange surfaces in the form of double-walled cylinders, the scraper system acting either inside the cylinder (closed circuit) or outside the cylinder (open circuit) These grout generators, called "with surface scraping ", are limited in size, therefore in power with mechanical systems of relatively fragile scrapers They are expensive and an increase in power requires a paralleling of several generators, which makes the process complicated and bulky
Dans d'autres générateurs de coulis de glace, dits à film tombant, on forme la glace sur une plaque verticale sur laquelle tombe un film d'eau ou de solution La glace fournie en pied de plaque est ensuite broyée Ici aussi, il faut des moyens mécaniques supplémentaires dans le générateur pour broyer les glaces obtenuesIn other ice-slurry generators, known as falling film, ice is formed on a vertical plate onto which a film of water or solution falls. The ice supplied at the bottom of the plate is then crushed. Here too, additional mechanical means in the generator to crush the glass obtained
On peut également réaliser des coulis de glace par le procédé de surfusion Ce procédé consiste à faire baisser la température du fluide frigoporteur en dessous de son point de congélation commerçante, dans des conditions particulières, avant d'initier la cristallisation par des effets tels que les chocs thermiques ou mécaniques, ou par introduction d'agents nucléants Mais cette technique est difficilement exploitable en pratique car elle se traduit par une diminution du rendement de la machine frigorifique L'invention s'est donne pour but de proposer un nouveau procédé pour détacher les cristaux de glace qui se forment sur les parois d'un générateur de coulis de glace et qui puisse être mis en oeuvre facilement sur tous types d'échangeur quelle que soit la forme géométrique de leurs parois d'échange de chaleur L'invention est basée sur l'idée de créer par intermittence des turbulences dans le fluide frigoporteur par augmentation du débit, donc de la vitesse de circulation Les conséquences directes de l'augmentation de vitesse de circulation sont d'une part une augmentation de la force d'arrachement appliquée sur les cristaux en formation et d'autre part une modification des paramètres d'échange et de ce fait une légère augmentation de la température des parois L'invention concerne donc un procédé pour détacher les cristaux de glace qui se forment sur une face des parois d'échange thermique d'un échangeur générateur d'un coulis de glace, ladite face étant en contact avec un fluide frigoporteur d'un premier circuit qui s'écoule à une vitesse nominale dans ledit échangeur générateur, tandis que l'autre face desdites parois est en contact avec un fluide refroidisseur qui s'écoule dans un deuxième circuit.It is also possible to make ice slurries by the supercooling process This process consists in lowering the temperature of the coolant below its commercial freezing point, under special conditions, before initiating crystallization by effects such as Thermal or mechanical shocks, or by the introduction of nucleating agents. However, this technique is difficult to use in practice because it results in a reduction in the efficiency of the refrigerating machine. ice crystals which form on the walls of an ice slurry generator and which can be easily implemented on all types of exchanger whatever the geometric shape of their heat exchange walls The invention is based on the idea of intermittently creating turbulence in the coolant by increasing the flow rate, therefore the speed d e circulation The direct consequences of the increase in circulation speed are on the one hand an increase in the pull-out force applied to the crystals in formation and on the other hand a modification of the exchange parameters and therefore a slight wall temperature increase The invention therefore relates to a method for detaching the ice crystals which form on one face of the heat exchange walls of an exchanger generating an ice slurry, said face being in contact with a coolant of a first circuit which flows at nominal speed in said generator exchanger, while the other face of said walls is in contact with a cooling fluid which flows in a second circuit.
Selon l'invention, ce procédé est caractérisé par le fait que l'on fait circuler par intermittence dans le générateur le fluide frigoporteur à une vitesse supérieure à la vitesse nominale afin de créer des turbulences entraînant le détachement des cristaux de glace formés, d'une part par arrachement et d'autre part par échauffement des parois d'échange.According to the invention, this process is characterized by the fact that the refrigerant is intermittently circulated in the generator at a speed greater than the nominal speed in order to create turbulence causing the detachment of the ice crystals formed, on the one hand by tearing off and on the other hand by heating of the exchange walls.
La vitesse nominale du fluide frigoporteur correspond au débit normal de fonctionnement de l'installation. Ainsi selon l'invention, les cristaux de glace formés sur les parois froides du générateur sont détachés par une action mécano-hydraulique et thermique, pendant la durée de l'augmentation de débit, et sont entraînés par la phase liquide du fluide frigoporteur.The nominal speed of the coolant corresponds to the normal operating flow of the installation. Thus according to the invention, the ice crystals formed on the cold walls of the generator are detached by a mechanical-hydraulic and thermal action, for the duration of the increase in flow, and are entrained by the liquid phase of the coolant.
L'augmentation du débit a, en effet pour conséquence : a) une augmentation de la vitesse de circulation en phase turbulente, donc une augmentation de la force d'arrachement appliquée sur les cristaux ; b) une modification des paramètres de coefficient d'échanges, par suite de l'augmentation de la vitesse, et donc une augmentation de la température de la paroi froide qui favorise le détachement des cristaux de glace.The increase in flow has, in effect: a) an increase in the speed of circulation in the turbulent phase, therefore an increase in the pull-out force applied to the crystals; b) a modification of the exchange coefficient parameters, as a result of the increase in speed, and therefore an increase in the temperature of the cold wall which promotes the detachment of the ice crystals.
De préférence, le fluide frigoporteur est mis en circulation par une pompe et l'on augmente par intermittence la vitesse de rotation de la pompe. La pompe est entraînée par exemple par un moteur à vitesse variable.Preferably, the coolant is circulated by a pump and the speed of rotation of the pump is increased intermittently. The pump is driven for example by a variable speed motor.
La vitesse de base du moteur et de la pompe, et par le fait même le débit normal ou la vitesse nominale du fluide frigoporteur dans le générateur, ainsi que la température de surface de la paroi froide sont calculées en fonction du type d'echangeur, du frigoporteur et de la concentration du mélange, ainsi que de la concentration des particules solides que l'on veut obtenir dans le fluide frigoporteur diphasique.The basic speed of the motor and the pump, and therefore the normal flow or the nominal speed of the coolant in the generator, as well as the surface temperature of the cold wall are calculated according to the type of exchanger, the refrigerant and the concentration of the mixture, as well as the concentration of the solid particles which it is desired to obtain in the two-phase refrigerant fluid.
Ainsi, grâce à l'invention, les cristaux de glace sont détachés sans moyens mécaniques disposés dans le générateur comme dans l'art antérieur.Thus, thanks to the invention, the ice crystals are detached without mechanical means arranged in the generator as in the prior art.
La géométrie des parois d'échange thermique peut être optimisée en fonction des coefficients de conductivité thermiques des deux fluides et du matériau constitutif des parois, des débits et de la puissance frigorifique demandée pour l'installation. La fréquence et la durée des turbulences, ainsi que la vitesse du fluide frigoporteur pendant les turbulences peuvent être établies par des résultats de tests. Elles seront fonction du type d'echangeur, du frigoporteur, de la concentration du mélange, ainsi que de la concentration des particules de solide que l'on veut atteindre dans le frigoporteur.The geometry of the heat exchange walls can be optimized as a function of the thermal conductivity coefficients of the two fluids and of the material of the walls, of the flow rates and of the cooling power required for the installation. The frequency and duration of turbulence, as well as the speed of the coolant during turbulence can be established by test results. They will depend on the type of exchanger, the coolant, the concentration of the mixture, as well as the concentration of solid particles that we want to reach in the coolant.
Selon une autre caractéristique avantageuse de l'invention, le déclenchement d'une turbulence est réalisé automatiquement. A cet effet, on mesure en continu la perte de charge subie par le fluide frigoporteur à travers le générateur et on augmente la vitesse de la pompe lorsque la perte de charge mesurée est supérieure à une valeur de consigne.According to another advantageous characteristic of the invention, the initiation of turbulence is carried out automatically. For this purpose, the pressure drop undergone by the coolant through the generator is continuously measured and the speed of the pump is increased when the measured pressure drop is greater than a set value.
La valeur de consigne est également fonction du type d'echangeur, du frigoporteur, de la concentration du mélange, ainsi que de la concentration des particules solides que l'on veut obtenir.The set value is also a function of the type of exchanger, the coolant, the concentration of the mixture, as well as the concentration of solid particles that one wants to obtain.
Afin de renforcer l'action mécano-hydraulique et thermique des turbulences, on provoque en outre une augmentation de la température du fluide refroidisseur dans le générateur, lorsque l'on crée des turbulences dans le fluide frigoporteur.In order to reinforce the mechanical-hydraulic and thermal action of the turbulence, an increase in the temperature of the cooling fluid in the generator is also caused, when turbulence is created in the coolant.
Dans le cas où le fluide refroidisseur est un liquide en phase d'évaporation dans le générateur, et le deuxième circuit comporte un compresseur de gaz, on augmente la température du fluide refroidisseur en augmentant la pression d'évaporation. Ceci peut être obtenu en manoeuvrant les vannes d'entrée et de sortie du générateur sur le deuxième circuit, ou en injectant dans le générateur des gaz chauds issus du compresseur de gaz. Dans le cas où le fluide refroidisseur est un frigoporteur liquide monophasique ou diphasique liquide/glace, on augmente avantageusement la température du fluide refroidisseur en recirculant le fluide refroidisseur en dehors du générateur.In the case where the cooling fluid is a liquid in the evaporation phase in the generator, and the second circuit comprises a gas compressor, the temperature of the cooling fluid is increased by increasing the evaporation pressure. This can be achieved by operating the generator inlet and outlet valves on the second circuit, or by injecting hot gas from the gas compressor into the generator. In the case where the coolant is a liquid monophasic or biphasic liquid / ice refrigerant, one increases advantageously the temperature of the coolant by recirculating the coolant outside the generator.
D'autres avantages et caractéristiques de l'invention ressortiront à la lecture de la description suivante faite à titre d'exemple et en référence aux dessins annexés dans lesquels :Other advantages and characteristics of the invention will emerge on reading the following description given by way of example and with reference to the appended drawings in which:
- la figure 1 montre un schéma d'une installation frigorifique comportant un générateur de coulis de glace ayant un fluide refroidisseur en phase d'évaporation dans le générateur,FIG. 1 shows a diagram of a refrigeration installation comprising an ice slurry generator having a cooling fluid in the evaporation phase in the generator,
- la figure 2 montre un schéma d'une installation frigorifique comportant un générateur de coulis de glace refroidi par un fluide refroidisseur mono- ou diphasique liquisol,FIG. 2 shows a diagram of a refrigeration installation comprising an ice slurry generator cooled by a liquid or mono- or two-phase coolant liquisol,
- la figure 3 montre le graphique des vitesses du fluide frigoporteur dans le générateur pour la mise en oeuvre du procédé selon l'invention,FIG. 3 shows the graph of the speeds of the coolant in the generator for implementing the method according to the invention,
- la figure 4 montre le système de pilotage du générateur selon un premier mode de réalisation de l'invention,FIG. 4 shows the generator control system according to a first embodiment of the invention,
- la figure 5 montre le système de pilotage du générateur selon un deuxième mode de réalisation de l'invention.- Figure 5 shows the generator control system according to a second embodiment of the invention.
Dans la description faite ci-après, les éléments identiques portent les mêmes références. Sur les figures 1 et 2, on a représenté par la référence 1 un générateur de coulis de glace qui comporte des parois d'échange thermique 2 séparant un premier circuit 3 dans lequel s'écoule un fluide frigoporteur diphasique eau/glace, . d'un deuxième circuit 4 dans lequel s'écoule un fluide refroidisseur destiné à refroidir le fluide frigoporteur du premier circuit 3.In the description given below, identical elements have the same references. In Figures 1 and 2, there is shown by the reference 1 an ice slurry generator which has heat exchange walls 2 separating a first circuit 3 in which a two-phase water / ice coolant flows. a second circuit 4 in which a cooling fluid flows intended to cool the coolant of the first circuit 3.
Le premier circuit 3 comporte en dehors du générateur 1 un conduit 5 de délivrance de coulis de glace destiné à alimenter en parallèle des échangeurs 6 et un conduit de retour 7 équipé d'une pompe de circulation 8. Les échangeurs 6 peuvent être branchés directement entre les conduits 5 et 7, ou montés sur des dérivations équipées de pompes de recirculation 9 autonomes. Les échangeurs 6 sont destinés à refroidir des locaux ou des produits, le froid étant obtenu par fusion des cristaux de glace contenu dans le fluide frigoporteur les traversant. La concentration en glace du fluide frigoporteur dans le conduit de retour 7 est ainsi inférieure à celle du fluide frigoporteur dans le conduit de délivrance 5. Du fait que la température d'un fluide frigoporteur diphasique décroît lorsque la concentration en cristaux de glace augmente, la température du fluide frigoporteur dans le conduit de retour 7 est supérieure à la température du fluide frigoporteur dans le conduit de délivrance 5 du coulis de glace, et la mesure de ces températures à l'entrée et à la sortie du générateur par les sondes de température 10 et 11 permet de connaître avec une bonne précision les concentrations en cristaux pour un type de mélange utilisé en tant que fluide frigoporteur et la concentration du mélange. Une bâche 12 de recirculation, pouvant également faire office d'accumulation, doit en outre être disposée entre le conduit de délivrance 5 et le conduit de retour 7. Une pompe de circulation 8b est montée sur le conduit 5 en aval de la bâche 12.The first circuit 3 comprises, outside the generator 1, a conduit 5 for delivering ice slurry intended to supply exchangers 6 in parallel and a return conduit 7 equipped with a circulation pump 8. The exchangers 6 can be connected directly between conduits 5 and 7, or mounted on branches fitted with autonomous recirculation pumps 9. The exchangers 6 are intended to cool premises or products, the cold being obtained by melting the ice crystals contained in the refrigerant fluid passing through them. The ice concentration of the coolant in the return duct 7 is thus lower than that of the coolant in the delivery duct 5. Because the temperature of a two-phase refrigerant decreases when the concentration of ice crystals increases, the temperature of the refrigerant in the return duct 7 is higher than the temperature of the refrigerant in the delivery duct 5 of the ice slurry , and the measurement of these temperatures at the inlet and at the outlet of the generator by the temperature probes 10 and 11 makes it possible to know with good precision the crystal concentrations for a type of mixture used as coolant and the concentration of the mixture. A recirculation tank 12, which can also act as an accumulation, must also be disposed between the delivery pipe 5 and the return pipe 7. A circulation pump 8b is mounted on the pipe 5 downstream of the tank 12.
Le fluide frigoporteur circulant dans le générateur 1 est refroidi par le fluide refroidisseur, grâce aux échanges thermiques qui se font à travers les parois d'échange 2. Des cristaux de glace se forment alors sur la face des parois 2, qui est en contact avec le fluide frigoporteur du circuit 3.The coolant circulating in the generator 1 is cooled by the coolant, thanks to the heat exchanges which take place through the exchange walls 2. Ice crystals are then formed on the face of the walls 2, which is in contact with the coolant in circuit 3.
La pompe de circulation 8 montée sur le conduit de retour 7 est entraînée en rotation par un moteur électrique à vitesse variable 13.The circulation pump 8 mounted on the return duct 7 is rotated by a variable speed electric motor 13.
En exploitation normale de l'installation, la pompe de circulation 8 est entraînée à une vitesse sensiblement constante, que nous appelons vitesse de base, et le fluide frigoporteur s'écoule alors dans le générateur 1 avec un débit sensiblement constant qui est le débit normal du générateur 1 et à une vitesse sensiblement constante que nous appelons la vitesse nominale Vn.In normal operation of the installation, the circulation pump 8 is driven at a substantially constant speed, which we call basic speed, and the coolant then flows into the generator 1 with a substantially constant flow which is the normal flow. of generator 1 and at a substantially constant speed which we call the nominal speed Vn.
Selon la présente invention, on détache les cristaux de glace qui se forment sur une face des parois d'échange thermique 2, en faisant circuler par intermittence, le fluide frigoporteur dans le générateur 1 à une vitesse Vs supérieure à la vitesse nominale Vn afin de créer dans la portion du circuit 1 située dans le générateur 1 des turbulences qui réchauffent légèrement les parois 2 et entraînent des forces supplémentaires pour l'arrachement des cristaux.According to the present invention, the ice crystals which form on one face of the heat exchange walls 2 are detached, by intermittently circulating, the coolant in the generator 1 at a speed Vs greater than the nominal speed Vn in order to create in the portion of the circuit 1 located in the generator 1 turbulences which slightly heat the walls 2 and cause additional forces for the tearing of the crystals.
L'augmentation de vitesse du fluide frigoporteur est obtenue en agissant sur la vitesse de rotation du moteur 13 qui entraîne la pompe 8. La figure 3 montre le graphique des vitesses de circulation du fluide frigoporteur dans le générateur 1. L'intervalle de temps To entre deux phases de turbulence T1 et T2 et la durée Do de chaque phase de turbulence sont obtenus par exemple par le résultat de tests et sont fonction du type de générateur, du type de frigoporteur, de la proportion du mélange et de la concentration de cristaux utilisés.The increase in the speed of the coolant is obtained by acting on the speed of rotation of the motor 13 which drives the pump 8. FIG. 3 shows the graph of the circulation speeds of the coolant in the generator 1. The time interval To between two turbulence phases T1 and T2 and the duration Do of each turbulence phase are obtained for example by the result of tests and are a function of the type of generator, the type of coolant, the proportion of the mixture and the concentration of crystals used.
Selon un premier mode de réalisation, le moteur électrique 13 est piloté par un automate 14 dans la mémoire duquel on introduit quatre données caractéristiques de fonctionnement : la vitesse de base correspondant à la vitesse nominale Vn, la vitesse maximum correspondant à la vitesse Vs, l'intervalle de temps To pendant lequel le moteur tourne à sa vitesse de base affichée, et la durée Do d'une phase turbulente. L'automate 14 comporte évidemment une horloge interne.According to a first embodiment, the electric motor 13 is controlled by an automaton 14 into the memory of which four characteristic operating data are introduced: the basic speed corresponding to the nominal speed Vn, the maximum speed corresponding to the speed Vs, l 'time interval To during which the engine turns at its displayed basic speed, and the duration Do of a turbulent phase. The automaton 14 obviously has an internal clock.
Selon un deuxième mode de réalisation de l'invention, montré sur la figure 5, un pressostat différentiel 15 est interposé entre l'entrée et la sortie des conduits 5 et 7 dans le générateur. Ce pressostat 15 mesure la perte de charge subie par le fluide frigoporteur à travers le générateur 1. Cette perte de charge est fonction de la quantité de cristaux de glace déposés sur les parois 2 et de la concentration en glace du fluide frigoporteur. La mesure du pressostat 15 est transmise à un organe de calcul 16 qui la compare à une valeur de consigne, et lorsque cette mesure est supérieure à la valeur de consigne, l'organe de calcul 16 commande le moteur 13 à tourner, à sa vitesse maximum pendant une durée Do. Ensuite, l'organe de calcul 16 commande le moteur 13 à tourner à sa vitesse de base. Ici trois caractéristiques de base sont introduites dans la mémoire de l'organe de calcul 16 : la vitesse de base du moteur 13, la vitesse maximum du moteur 13 et la durée Do d'une phase turbulente.According to a second embodiment of the invention, shown in FIG. 5, a differential pressure switch 15 is interposed between the inlet and the outlet of the conduits 5 and 7 in the generator. This pressure switch 15 measures the pressure drop undergone by the coolant through the generator 1. This pressure drop is a function of the quantity of ice crystals deposited on the walls 2 and of the ice concentration of the coolant. The measurement of the pressure switch 15 is transmitted to a calculation unit 16 which compares it to a set value, and when this measurement is greater than the set value, the calculation unit 16 controls the motor 13 to turn , at its speed maximum for a duration Do. Then, the calculating member 16 controls the motor 13 to rotate at its basic speed. Here three basic characteristics are introduced into the memory of the calculation unit 16: the basic speed of the motor 13, the maximum speed of the motor 13 and the duration Do of a turbulent phase.
Les mesures des sondes de température 10 et 11 sont également transmises à l'organe de calcul 16. Ce dernier est apte à corriger la valeur de consigne en fonction des mesures des ondes de température 10 et 11 qui sont représentatives de la concentration de cristaux dans le fluide frigoporteur à l'entrée et à la sortie du générateur 1. La perte de charge nominale du fluide frigoporteur à travers le générateur 1 , en l'absence de cristaux collés sur les parois 2, est donc fonction des températures mesurées et de la vitesse nominale du fluide frigoporteur. Lorsque la différence entre la perte de charge mesurée par le pressostat différentiel 15 et la perte de charge nominale est supérieure à la valeur de consigne, l'organe de calcul 16 commande le moteur 13 à tourner à sa vitesse maximum pendant une durée Do. Au fur et à mesure que la concentration en cristaux augmente dans le fluide frigoporteur, la température de formation des cristaux diminue. L'organe de calcul 16 agit sur la circulation du fluide refroidisseur dans l'échangeur 1 afin d'adapter en permanence la température des parois d'échange 2 en vue de l'optimisation du rendement de l'installation, et afin d'obtenir de nouveaux cristaux jusqu'à l'obtention de la concentration de cristaux désirée.The measurements of the temperature probes 10 and 11 are also transmitted to the calculation unit 16. The latter is able to correct the set value as a function of the measurements of the temperature waves 10 and 11 which are representative of the concentration of crystals in the coolant at the inlet and at the outlet of the generator 1. The nominal pressure drop of the coolant through the generator 1, in the absence of crystals bonded to the walls 2, is therefore a function of the temperatures measured and the nominal speed of the coolant. When the difference between the pressure drop measured by the differential pressure switch 15 and the nominal pressure drop is greater than the set value, the calculating member 16 controls the motor 13 to run at its maximum speed for a duration Do. As the crystal concentration increases in the coolant, the temperature of crystal formation decreases. The calculating member 16 acts on the circulation of the cooling fluid in the exchanger 1 in order to constantly adapt the temperature of the exchange walls 2 with a view to optimizing the efficiency of the installation, and in order to obtain new crystals until the desired crystal concentration is obtained.
Lorsque le fluide frigoporteur du circuit 1 s'écoule dans le générateur en mode de turbulence afin de détacher les cristaux de glace formés sur les parois 2, l'invention prévoit en outre d'augmenter rapidement et simultanément la température des parois froides 2, en agissant du côté du fluide refroidisseur. Ceci est obtenu en augmentant la température du fluide refroidisseur pendant la durée Do des turbulences. La méthode diffère selon le type de fluide refroidisseur.When the coolant of circuit 1 flows in the generator in turbulence mode in order to detach the ice crystals formed on the walls 2, the invention further provides for rapidly and simultaneously increasing the temperature of the cold walls 2, acting on the coolant side. This is obtained by increasing the temperature of the coolant during the duration Do of the turbulence. The method differs depending on the type of coolant.
Dans l'installation frigorifique montrée sur la figure 1 , le fluide refroidisseur qui s'écoule dans le deuxième circuit 4 est un liquide en phase d'évaporation dans le générateur 1 de coulis de glace. Le générateur 1 joue ainsi le rôle d'un évaporateur pour le fluide refroidisseur. Les gaz produits dans le générateur 1 sont aspirés par un compresseur de gaz 20 monté dans le conduit d'aspiration 21 qui relie le générateur 1 à un condenseur 22. Une vanne de régulation de pression 23 est montée sur le conduit d'aspiration 21. Le fluide frigorigène à l'état liquide retourne vers le générateur 1 par un conduit d'alimentation 24 sur lequel est montée une vanne de régulation 25 d'injection de fluide frigorigène. Une dérivation 26 est prévue entre la sortie de refoulement du compresseur 20 et l'entrée du conduit d'alimentation 24 dans le générateur 1. Une vanne 27 d'injection de gaz chauds est montée sur la dérivation 26.In the refrigeration installation shown in FIG. 1, the cooling fluid which flows in the second circuit 4 is a liquid in the evaporation phase in the generator 1 of ice slurry. The generator 1 thus plays the role of an evaporator for the cooling fluid. The gases produced in the generator 1 are sucked up by a gas compressor 20 mounted in the suction pipe 21 which connects the generator 1 to a condenser 22. A pressure regulating valve 23 is mounted on the suction pipe 21. The refrigerant in the liquid state returns to the generator 1 via a supply conduit 24 on which is mounted a control valve 25 for injecting refrigerant. A branch 26 is provided between the discharge outlet of the compressor 20 and the inlet of the supply duct 24 into the generator 1. A valve 27 for injecting hot gases is mounted on the branch 26.
Au début des phases de turbulence du fluide frigoporteur dans le générateur 1, l'automate 14 ou l'organe de calcul 16 agit également sur les vannes 23 et 25 notamment sur la vanne 27 d'injection de gaz chauds. Cette action produit immédiatement une augmentation de la pression d'évaporation dans l'évaporateur, qui entraîne un réchauffement instantané des parois froides 2 et un décollement des cristaux de glace. Cette action est limitée dans le temps à une durée au plus égale à la durée Do des turbulences. Dans l'exemple montré sur la figure 2, le fluide refroidisseur qui circule dans le deuxième circuit 4 est lui-même un fluide frigoporteur refroidi dans un deuxième générateur 30 alimenté en fluide refroidisseur par un circuit 4b semblable au circuit 4 de la figure 1.At the start of the turbulence phases of the coolant in the generator 1, the automaton 14 or the calculation unit 16 also acts on the valves 23 and 25 in particular on the valve 27 for injecting hot gases. This action immediately produces an increase in pressure evaporation in the evaporator, which causes instant warming of the cold walls 2 and detachment of the ice crystals. This action is limited in time to a duration at most equal to the duration Do of the turbulence. In the example shown in FIG. 2, the coolant which circulates in the second circuit 4 is itself a coolant cooled in a second generator 30 supplied with coolant by a circuit 4b similar to the circuit 4 of FIG. 1.
Une vanne trois voies 40 est montée sur le conduit d'alimentation 24 du fluide du circuit 4 et une dérivation 41 est prévue entre la vanne trois voies 40 et le conduit de retour 42 du fluide du circuit 4.A three-way valve 40 is mounted on the supply pipe 24 for the fluid of the circuit 4 and a bypass 41 is provided between the three-way valve 40 and the return pipe 42 for the fluid of the circuit 4.
La vanne trois voies 41 est commandée par l'automate 14 ou l'organe de calcul 16, et pendant les phases de turbulence dans le premier circuit 3, le fluide refroidisseur recircule par le conduit de dérivation 41 , ce qui provoque le réchauffement des parois froides 2. Le deuxième générateur 30 peut également être piloté par un autre automate ou un autre organe de calcul afin de décoller les cristaux de glace qui s'y forment, dans le cas où le fluide frigoporteur qui circule dans le deuxième circuit 4 est diphasique. The three-way valve 41 is controlled by the automaton 14 or the calculation unit 16, and during the turbulence phases in the first circuit 3, the coolant recirculates through the bypass duct 41, which causes the walls to heat up. 2. The second generator 30 can also be controlled by another automaton or another calculation unit in order to take off the ice crystals which form there, in the case where the refrigerant fluid which circulates in the second circuit 4 is two-phase .

Claims

REVENDICATIONS
1. Procédé pour détacher les cristaux de glace qui se forment sur une face des parois (2) d'échange thermique d'un échangeur générateur (1 ) de coulis de glace, ladite face étant en contact avec un fluide frigoporteur d'un premier circuit (3) qui s'écoule à une vitesse nominale (Vn) dans ledit échangeur générateur (1 ), tandis que l'autre face est en contact avec un fluide refroidisseur qui s'écoule dans un deuxième circuit (4), caractérisé par le fait que l'on fait circuler, par intermittence, dans le générateur (1 ) le fluide frigoporteur à une vitesse (Vs) supérieure à la vitesse nominale (Vn) afin de créer des turbulences qui entraînent le détachement des cristaux de glace formés, d'une part par arrachement et d'autre part par réchauffement des parois d'échange (2). 1. Method for detaching the ice crystals which form on one face of the heat exchange walls (2) of an exchanger generating (1) ice slurry, said face being in contact with a coolant of a first circuit (3) which flows at a nominal speed (Vn) in said generator exchanger (1), while the other face is in contact with a cooling fluid which flows in a second circuit (4), characterized by the fact that the coolant is circulated intermittently in the generator (1) at a speed (Vs) greater than the nominal speed (Vn) in order to create turbulences which cause the detachment of the ice crystals formed, on the one hand by tearing off and on the other hand by heating the exchange walls (2).
2. Procédé selon la revendication 1 , caractérisé par le fait que le fluide frigoporteur est mis en circulation par une pompe (8), et que l'on augmente par intermittence la vitesse de rotation de la pompe (8).2. Method according to claim 1, characterized in that the coolant is circulated by a pump (8), and that the rotation speed of the pump (8) is intermittently increased.
3. Procédé selon la revendication 2, caractérisé par le fait que l'on mesure en continu la perte de charge subie par le fluide frigoporteur à travers le générateur (1 ), lorsque le fluide frigoporteur s'écoule à la vitesse nominale (Vn), et par le fait que l'on augmente la vitesse de la pompe (8) lorsque la perte de charge mesurée dépasse une valeur de consigne.3. Method according to claim 2, characterized in that the pressure drop undergone by the coolant is continuously measured through the generator (1), when the coolant flows at nominal speed (Vn) , and by the fact that the speed of the pump (8) is increased when the measured pressure drop exceeds a set value.
4. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé par le fait que l'on provoque en outre une augmentation de la température du fluide refroidisseur dans le générateur, lorsqu'on crée des turbulences dans le fluide frigoporteur.4. Method according to any one of claims 1 to 3, characterized in that one further causes an increase in the temperature of the coolant in the generator, when turbulence is created in the coolant.
5. Procédé selon la revendication 4 dans lequel le fluide refroidisseur est un liquide en phase d'évaporation dans le générateur (1 ) et le deuxième circuit (4) comporte un compresseur de gaz (20), caractérisé par le fait que l'on modifie la température d'évaporation, en modifiant la pression.5. Method according to claim 4 wherein the coolant is a liquid in the evaporation phase in the generator (1) and the second circuit (4) comprises a gas compressor (20), characterized in that one changes the evaporation temperature, by changing the pressure.
6. Procédé selon la revendication 5, caractérisé par le fait que l'on modifie la pression dans le générateur (1 ) en y injectant des gaz chauds issus du compresseur. 6. Method according to claim 5, characterized in that the pressure is changed in the generator (1) by injecting hot gases from the compressor.
7. Procédé selon la revendication 4 dans lequel le fluide refroidisseur est un frigoporteur liquide monophasique ou diphasique liquide/glace, caractérisé par le fait que l'on augmente la température du fluide refroidisseur en recirculant le fluide refroidisseur en dehors du générateur (1).7. The method of claim 4 wherein the coolant is a liquid refrigerant monophasic or two-phase liquid / ice, characterized in that one increases the temperature of the coolant by recirculating the coolant outside the generator (1).
8. Générateur de coulis de glace pour la mise en oeuvre du procédé selon l'une quelconque des revendications 1 à 7, comportant des parois (2) d'échange thermique entre un premier circuit (3) comportant une pompe de circulation (8) pour l'écoulement d'un fluide frigoporteur à une vitesse nominale (Vn) dans le générateur (1 ) et un deuxième circuit (4) dans lequel circule un fluide refroidisseur, caractérisé par le fait qu'il comporte en outre des moyens (14, 16) pour augmenter par intermittence la vitesse d'écoulement du fluide frigoporteur afin de créer des turbulences entraînant le détachement des cristaux de glace formés sur les parois (2) d'échange thermique, d'une part par arrachement et d'autre part par réchauffement des parois d'échange.8. Ice slurry generator for implementing the method according to any one of claims 1 to 7, comprising walls (2) for heat exchange between a first circuit (3) comprising a circulation pump (8) for the flow of a coolant at nominal speed (Vn) in the generator (1) and a second circuit (4) in which a coolant circulates, characterized in that it also comprises means (14 , 16) to intermittently increase the flow speed of the coolant in order to create turbulence resulting in the detachment of the ice crystals formed on the heat exchange walls (2), on the one hand by tearing off and on the other hand by heating the exchange walls.
9. Générateur selon la revendication 8, caractérisé par le fait que lesdits moyens comportent des capteurs de pression (15) du fluide frigoporteur à l'entrée et à la sortie du générateur reliés à un organe de calcul (16) qui comprend des moyens pour calculer la perte de charge du fluide frigoporteur à travers le générateur, des moyens pour comparer la perte de charge calculée à une valeur de consigne, et des moyens pour augmenter la vitesse de rotation de la pompe de circulation lorsque la perte de charge calculée est supérieure à la valeur de consigne. 9. Generator according to claim 8, characterized in that said means comprise pressure sensors (15) of the coolant at the inlet and at the outlet of the generator connected to a calculating member (16) which comprises means for calculating the pressure drop of the coolant through the generator, means for comparing the calculated pressure drop with a set value, and means for increasing the rotation speed of the circulation pump when the calculated pressure drop is greater at the setpoint.
10. Générateur selon l'une quelconque des revendications 8 ou10. Generator according to any one of claims 8 or
9, caractérisé par le fait qu'il est en outre prévu des moyens pour augmenter la température du fluide refroidisseur dans le générateur, lorsqu'on crée des turbulences dans le fluide frigoporteur. 9, characterized in that means are further provided for increasing the temperature of the coolant in the generator, when turbulence is created in the coolant.
PCT/FR2000/001405 1999-05-25 2000-05-23 Method for removing ice crystals in a heat exchanger generating a diphasic liquid-solid refrigerant WO2000071945A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DE60023422T DE60023422T2 (en) 1999-05-25 2000-05-23 METHOD FOR SOLVING ICE CRYSTALS IN A HEAT EXCHANGER WITH TWO-PHASE SOLID FLUID COOLING CARRIER
EP00931340A EP1101071B1 (en) 1999-05-25 2000-05-23 Method for removing ice crystals in a heat exchanger generating a diphasic liquid-solid refrigerant
AT00931340T ATE308021T1 (en) 1999-05-25 2000-05-23 METHOD FOR DISSOLVING ICE CRYSTALS IN A HEAT EXCHANGER WITH A TWO-PHASE SOLID-LIQUID COLD CARRIER

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR99/06559 1999-05-25
FR9906559A FR2794228B1 (en) 1999-05-25 1999-05-25 METHOD FOR DETACHING ICE CRYSTALS FROM A GENERATOR HEAT EXCHANGER FROM A LIQUID-SOLID DIPHASIC REFRIGERATOR

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
FR2835600A1 (en) * 2002-02-01 2003-08-08 Michel Barth Method of detaching ice crystals on the internal surface of an heat exchanger, especially a heat exchanger used in ice crystal generators

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2960630B1 (en) * 2010-05-25 2012-05-04 Michel Barth PROCESS FOR PRODUCING AND SEPARATING ICE CRYSTALS FROM A LIQUID-SOLID DIPHASIC REFRIGERATOR
FR3004797B1 (en) * 2013-04-23 2018-05-18 Axima Refrigeration France PROCESS FOR DETACHING WATER CRYSTALS ON THE INTERNAL SURFACE OF A HEAT EXCHANGER WITHOUT REMOVING THE TEMPERATURE OF THE FRIGOPORATOR AT THE ENTRY OF THE EXCHANGER

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US4401449A (en) * 1982-04-29 1983-08-30 Refrigeration Engineering Corporation Slush ice maker
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JPH02161293A (en) * 1988-12-13 1990-06-21 Hisaka Works Ltd Plate type heat exchanger
US4936114A (en) * 1989-06-23 1990-06-26 Chicago Bridge & Iron Technical Services Company Apparatus and method of freeze concentrating aqueous waste and process streams to separate water from precipitable salts
US4970869A (en) * 1989-01-13 1990-11-20 Shimizu Construction Co., Ltd. Tube type freezing unit and in-tube freezing method
US5139549A (en) * 1991-04-05 1992-08-18 Chicago Bridge & Iron Technical Services Company Apparatus and method for cooling using aqueous ice slurry
US5402650A (en) * 1994-05-03 1995-04-04 The Curators Of The University Of Missouri Thermal storage composition for low energy ice harvesting, method of using same
US5743110A (en) * 1994-03-04 1998-04-28 Laude-Bousquet; Adrien Unit for distribution and/or collection of cold and/or of heat
US5894734A (en) * 1996-05-14 1999-04-20 Hoshizaki Denki Kabushiki Kaisha Water-circulating type ice maker

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US4075863A (en) * 1976-08-23 1978-02-28 Storm King Products, Inc. Freeze-harvest control system for a tubular ice maker
US4401449A (en) * 1982-04-29 1983-08-30 Refrigeration Engineering Corporation Slush ice maker
US4656836A (en) * 1983-08-26 1987-04-14 Gilbertson Thomas A Pressurized, ice-storing chilled water system
US4865251A (en) * 1987-05-12 1989-09-12 Steinemann Ag Receiving station for long-distance heating
JPH02161293A (en) * 1988-12-13 1990-06-21 Hisaka Works Ltd Plate type heat exchanger
US4970869A (en) * 1989-01-13 1990-11-20 Shimizu Construction Co., Ltd. Tube type freezing unit and in-tube freezing method
US4936114A (en) * 1989-06-23 1990-06-26 Chicago Bridge & Iron Technical Services Company Apparatus and method of freeze concentrating aqueous waste and process streams to separate water from precipitable salts
US5139549A (en) * 1991-04-05 1992-08-18 Chicago Bridge & Iron Technical Services Company Apparatus and method for cooling using aqueous ice slurry
US5743110A (en) * 1994-03-04 1998-04-28 Laude-Bousquet; Adrien Unit for distribution and/or collection of cold and/or of heat
US5402650A (en) * 1994-05-03 1995-04-04 The Curators Of The University Of Missouri Thermal storage composition for low energy ice harvesting, method of using same
US5894734A (en) * 1996-05-14 1999-04-20 Hoshizaki Denki Kabushiki Kaisha Water-circulating type ice maker

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
FR2835600A1 (en) * 2002-02-01 2003-08-08 Michel Barth Method of detaching ice crystals on the internal surface of an heat exchanger, especially a heat exchanger used in ice crystal generators

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EP1101071B1 (en) 2005-10-26
FR2794228A1 (en) 2000-12-01
EP1101071A1 (en) 2001-05-23
FR2794228B1 (en) 2001-09-07
ATE308021T1 (en) 2005-11-15
DE60023422T2 (en) 2006-07-27
DE60023422D1 (en) 2005-12-01

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