JP2009041802A - Manufacturing method of supercooled water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent freezing in a supercooler by suppressing deformation of a plate in the supercooler caused by pressure fluctuation of water and brine in manufacturing the supercooled water by heat exchange between the brine and water by using a gasket-type plate heat exchanger. <P>SOLUTION: In the gasket-type plate heat exchanger as the supercooler 4, a flow rate of the water flowing into the supercooler 4 is adjusted by opening and closing a valve 25 in a state the flow rates necessary for manufacturing the supercooled water, of the water and brine are determined, and the water is circulated, and the supercooler 4 is operated while setting differential pressure (measured value of third pressure meter 33 - measured value of second pressure meter 27) such that makes a value (measured value of first pressure meter 23 - measured value (pressure loss) of second pressure meter 27) constant. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing supercooled water at 0 ° C. or lower by exchanging heat between brine and water such as a refrigerator using a gasket type plate heat exchanger.

  In the ice heat storage system, supercooled water of 0 ° C. or lower is continuously produced by a supercooler, and sherbet-like ice is continuously produced by releasing the supercooled state of the supercooled water. In such a case, as a method for producing supercooled water, as in Patent Document 1, for example, water is cooled using a shell-and-tube heat exchanger, and the temperature of the heat transfer surface is set to, for example, -5. A method of maintaining the temperature at 8 ° C. to 0 ° C. has been put into practical use.

  On the other hand, plate-type heat exchangers that can be made smaller than shell-and-tube type heat exchangers and have higher heat exchange efficiency have recently been used from the viewpoint of downsizing and cost reduction of the apparatus. Yes.

JP-A 1-1114682

  However, in a system that produces supercooled water using a plate heat exchanger, when operating in a system configuration / arrangement where the differential pressure between two heat transfer surfaces (differential pressure between plates) is close, even if heat transfer is performed Even if the surface temperature is maintained at −5.8 ° C. to 0 ° C., the supercooling state is broken in the heat exchanger, and as a result, the supercooler is frozen and the production of supercooling water cannot be maintained. It was.

  This is thought to be due to the following. In other words, plate-type supercoolers used in large systems use a structure that separates plates using gaskets, but gasket-type plate heat exchangers use two fluids (water and brine). In order to prevent mixing and leakage to the outside, a gasket is used for the partition between the outer periphery of the plate and the two fluids. By tightening the end plates located at both ends, the gasket is crushed, and a predetermined sealing ability is obtained. It has gained. Gaskets are usually designed so that a predetermined sealing ability can be exerted with a pressing force that is smaller than the pressing force with which the plate surfaces completely come into contact with each other. ing. On the other hand, the plate used for a plate-type heat exchanger uses a very thin metal processed into a corrugated plate for the purpose of improving heat transfer.

  In this way, if there is a gap between the plates, and a plate made of corrugated thin metal is subjected to fluctuations in the pressure of brine or water due to, for example, pump pulsation or automatic valve opening / closing, etc. As a result, the plate surfaces bulge and move and deform, and as a result, the surfaces of the plates collide with each other. Since collisions between solids in supercooled water are known to trigger the release of supercooling (Saito, Taiga, Une, Tanogami, Toshiki: “External factors affecting the solidification of supercooled water According to the Japan Refrigeration Association Proceedings, 8 (2), 151 (1991), the inventors' knowledge, the collision between the plates inside the supercooler as described above causes freezing. It is thought that there is.

  The present invention has been made in view of such a point, and even if a pressure fluctuation occurs for some reason in the brine and water, the subcooler is installed in a state that avoids collision between the plates inside the subcooler. The purpose is to prevent freezing inside the subcooler by operating.

  In order to achieve the above object, the present invention provides a method for producing supercooled water by exchanging heat between cooling brine and water using a gasket-type plate heat exchanger as a supercooler. The subcooling water is produced in a state in which the pressure difference between the plates in the plate heat exchanger is equal to or higher than a predetermined pressure difference.

  When producing supercooled water, the flow rate of water and brine is always maintained at a constant value by the regulator, so that the resistance coefficient and pressure loss of the plate heat exchanger are constant if there is no movement of the plate. However, since there is actually a gap between the plates, when the water side pressure is higher than the brine side pressure, the water side flow path widens and the brine side flow path narrows. When the pressure is higher than the pressure, the brine side flow path is widened to narrow the water side flow path. According to the inventors' knowledge, if the absolute value of the differential pressure between the plates is not sufficiently large, the resistance coefficient of the plate heat exchanger changes depending on the differential pressure between the plates, and as a result, the pressure loss also changes. However, it has been found that there are places where the resistance coefficient is constant where the pressure difference between the plates is sufficiently large. Therefore, if the cooling brine or water pressure is adjusted to operate under such a differential pressure, the pressure loss can be kept constant, and even if the pressure fluctuation fluctuates during operation due to pump pulsation, etc. The deformation of the plate can be suppressed.

  The predetermined differential pressure is adjusted by adjusting the pressure of the brine flowing into the subcooler in a state where the water and brine are set at a flow rate necessary for the production of the supercooling water and the water is circulated. It is good also as a differential pressure between plates in which the resistance coefficient of entering / exiting becomes constant irrespective of the pressure fluctuation of water or brine.

  The predetermined differential pressure is adjusted by adjusting the pressure of the brine flowing into the subcooler in a state where the water and brine are set at a flow rate necessary for the production of the supercooling water and the water is circulated. On the other hand, the flow rate ratio between the flow rate of the bypass flow path of water flowing in parallel and the flow rate of water flowing through the subcooler may be an inter-plate differential pressure that is constant regardless of the pressure fluctuation of water or brine.

  When adjusting the differential pressure between the plates to be equal to or higher than the predetermined differential pressure, depending on whether the water and brine are heat-exchanged countercurrently or in parallel flow in the supercooler, The method is different.

  According to the inventors' knowledge, when a gasket type plate heat exchanger is used as a supercooler to exchange heat between the cooling brine and water, the two are exchanged in countercurrent or in parallel flow. There are two cases of replacement, and in each case, even if the differential pressure (water pressure and / or brine pressure) changes, the resistance coefficient of the brine or water flow path does not change (ie, the plate does not deform) There are four conditions as shown in the schematic diagram of FIG. In the figure, Br means brine, and the vertical axis shows the pressure value for knowing the pressure loss. Here, the slopes showing the pressure drop of brine and water are depicted differently for brine and water. In general, in the brine-type and water-side, in the sket type plate heat exchanger, each pressure This is because the loss is not the same.

  First, in the case of exchanging heat with brine by AC, there are cases A and B in FIG. 1, and in case A, the pressure at the brine outlet (A3) is larger than the pressure at the water inlet (A4). In such a case, by setting the pressure at the brine outlet (A3)> the pressure at the water inlet (A4), the local pressure difference between the plates always has the same sign in the entire area of the subcooler (supercooler). It was found that the pressure relationship was not reversed inside and out). Therefore, if the magnitude relationship is defined at two points of the brine outlet (A3) and the water inlet (A4), the pressure difference between the plates can be adjusted to be equal to or higher than a predetermined differential pressure.

  Similarly, in case B, if the water outlet (B1)> brine inlet (B2) is satisfied, the water pressure> brine pressure is satisfied in the entire area of the subcooler, and the differential pressure between the plates is equal to or higher than the predetermined differential pressure. Can be adjusted.

  Therefore, when adjusting the pressure of the cooling brine or water so that the differential pressure between the plates becomes equal to or higher than the predetermined differential pressure, when the water and the brine are subjected to heat exchange in a countercurrent, the subcooler It can be proposed to increase the outlet pressure of the brine to the inlet pressure of water (case A) or to increase the outlet pressure of the water to the subcooler higher than the inlet pressure of brine (case B).

  Next, in the case of heat exchange with brine in parallel flow, there are cases C and D in FIG. In case C, in order to make brine pressure> water pressure throughout the subcooler, the pressure at the brine inlet (C1)> the pressure at the water inlet (C2) and the brine outlet (C3) It may be necessary to adjust so that the pressure of the water> the pressure of the water outlet (C4). Similarly, in case D, the pressure of water inlet (D1)> the pressure of brine inlet (D2) and water pressure in order to make brine pressure> water pressure throughout the subcooler. It can be considered that the pressure at the outlet (D3)> the pressure at the outlet (D4) of the brine should be adjusted.

  Therefore, when adjusting the pressure of the cooling brine or water so that the differential pressure between the plates is equal to or higher than the predetermined differential pressure, when the water and brine are subjected to heat exchange in parallel flow, the subcooler The brine inlet pressure to the water is greater than the water inlet pressure and the brine outlet pressure to the subcooler is greater than the water outlet pressure (Case C), or the water inlet pressure to the subcooler is It can be proposed that the outlet pressure of the water to the subcooler be greater than the outlet pressure of the brine (Case D) as well as greater than the inlet pressure.

  When realizing the case A and the case C shown in FIG. 1, for example, the position of the expansion tank of the brine is increased, or the closed expansion tank is attached to the piping of the brine, and the gas pressure in the closed expansion tank is adjusted. By adjusting the static pressure of the brine, or by selecting the head of the brine pump to be larger than the rated flow and the resistance of the piping system, the valve installed at the brine outlet of the subcooler is throttled to the rated flow. It can be proposed to adjust.

  Further, in realizing the case B and the case D shown in FIG. 1, the outlet pressure of the water to the supercooler is higher than the sum of the water-side loss pressure and the brine-side loss pressure of the supercooler. It can be proposed to install the supercooler at a position lower than the water surface of the ice heat storage tank that stores ice produced by the supercooled water from the supercooler.

  According to the present invention, when producing supercooled water using a plate heat exchanger, even if pressure fluctuation occurs for some reason in brine or water, the plates are prevented from colliding with each other inside the supercooler. In addition, freezing inside the supercooler can be prevented.

  Hereinafter, preferred embodiments of the present invention will be described. FIG. 2 shows an outline of the entire ice heat storage system in which the method for producing supercooled water according to the embodiment is carried out. Water is taken from the ice heat storage tank 1 by the pump 2, and the ice core is removed by the preheating device 3. After completely disappearing, the water taken from the ice heat storage tank 1 by exchanging heat with the low-temperature brine sent from the refrigerator 5 by the pump 6 in the supercooler 4 composed of a plate heat exchanger. Becomes supercooled water of 0 ° C. or lower.

  The supercooled water is converted into ice water through the propagation preventing device 7, for example, by a closed supercooling release device 8, and returned to the ice heat storage tank 1 again. Ice water is separated from the specific gravity difference between ice and water in the ice heat storage tank 1. By repeating this cycle, the water in the ice heat storage tank 1 is converted to ice, and cold heat is stored. As the subcooler 4, a plate heat exchanger as shown in FIG. 3 is used.

  That is, the supercooler 4 has a structure in which a large number of plates 11 are laminated between end plates 13 and 14 at both ends with a gasket 12 in between, and the end portion of the shaft 15 penetrating the plate 11 and the gasket 12 is the end. They are integrated by tightening with nuts 16 from the outside of the plate 14. And the water from the water flow path 17 which penetrates the upper end vicinity of each plate 11 and the brine from the brine flow path 18 which penetrates the lower end vicinity of each plate 11 are in the space formed by each plate 11 and the gasket 12. The two flow alternately, and both are heat-exchanged via the plate 11.

  Next, the system around the subcooler 4 will be described with reference to FIG. For this supercooler 4, a water piping system 20 that circulates between the ice heat storage tank 1 and the supercooler 4, a brine piping system 30 that circulates between the refrigerator 5 and the supercooler 4, Is piped. Further, in this example, heat exchange is performed between brine and water by alternating current.

  The water piping system 20 includes a water outlet pipe 21 that goes from the supercooler 4 to the ice heat storage tank 1, and a water return pipe 22 that goes from the ice heat storage tank 1 to the supercooler 4. The water outlet pipe 21 is provided with a first pressure gauge 23 for measuring the pressure on the outlet side of water coming out of the supercooler 4, a valve 24, and the supercooling release device 8. In the water return pipe 22, the pump 2, the preheating device 3, the valve 25, the flow meter 26 for measuring the flow rate of water flowing into the subcooler 4, and the pressure on the inlet side of the water flowing into the subcooler 4 are measured. A second pressure gauge 27 is provided. The flow rate of water measured by the flow meter 26 is output to the control device 29, and the control device 29 controls the valve 25 so that a predetermined flow rate value is obtained based on this.

  The brine piping system 30 includes a brine forward pipe 31 from the subcooler 4 toward the refrigerator 5 and a brine return pipe 32 from the refrigerator 5 toward the supercooler 4. The brine forward pipe 31 is provided with a third pressure gauge 33, a valve 34, and a pump 6 that measure the pressure on the outlet side of the brine exiting from the subcooler 4. The brine return pipe 32 is provided with a flow meter 35 for measuring the flow rate of the brine flowing into the subcooler 4 and a fourth pressure gauge 36 for measuring the pressure on the inlet side of the brine flowing into the subcooler 4. ing. An expansion tank 37 is provided in the piping between the pump 6 and the subcooler 4 in the brine outgoing pipe 31 (that is, on the suction side of the pump 6).

  The ice heat storage system shown in FIG. 4 has the above-described configuration. Next, how to obtain a differential pressure at a level at which the plate does not deform or move due to pressure fluctuation in this system will be described. First, the set values in the control devices 29 and 38 for controlling the flow rates of water and brine are set to flow rates necessary for the production of supercooled water, and water is circulated. In this example, the flow rate of water is 700 l / min, and the flow rate of brine is 600 l / min.

  Then, the valve 25 is operated to adjust the flow rate of water to be constant, and the differential pressure ΔP of the plate 11 in the subcooler 4 (that is, the brine pressure-water pressure difference between both surfaces of each plate 11) gradually decreases to the negative side. ΔP (measured value of the third pressure gauge 33−measured value of the second pressure gauge 27, or measured value of the fourth pressure gauge 36−first pressure gauge 23) at the time of lowering and lowering, and supercooling The relationship of the water side pressure loss (measured value of the first pressure gauge 23−measured value of the second pressure gauge 27) of the container 4 is recorded.

  Then, by gradually increasing the flow rate of water, ΔP when the water-side pressure loss of the subcooler 4 (measured value of the first pressure gauge 23−measured value of the second pressure gauge 27) starts to decrease is obtained. ΔPmax, ΔP when the decrease in the water-side pressure loss of the subcooler 4 (measured value of the first pressure gauge 23−measured value of the second pressure gauge 27) stops is assumed to be ΔPmin.

  FIG. 5 shows the difference in pressure ΔP between the plates of the subcooler 4 plate, which is a plate heat exchanger (brine outlet pressure (measured value of the third pressure gauge 33−measured value of the second pressure gauge 23)). The result of having measured the change of pressure loss (the measured value of the 1st pressure gauge 23-the measured value of the 2nd pressure gauge 27) is shown.The measured result was shown with the curve X in the figure.

  According to this, when the inter-plate differential pressure ΔP is changed, the region (1) in FIG. 5, that is, the region where the water pressure is larger than ΔPmin, and the region (3), ie, the brine pressure is larger than ΔPmax. In the region, the pressure loss does not change, but in the region (2), it can be seen that the pressure loss changes as the differential pressure changes. Therefore, it can be seen that if the pressure difference is set to be greater than or equal to ΔPmax or less than or equal to ΔPmin, the pressure loss of the water channel does not change with respect to pressure fluctuation. Since the water flow rate is constant here, the fact that the pressure loss does not change means that the resistance coefficient is constant. If the resistance coefficient of the water flow path does not change due to pressure fluctuation, the plate will not be deformed or moved even if the differential pressure between the plates fluctuates due to pump pulsation, etc. It becomes possible. Therefore, if an appropriate differential pressure operating condition of the supercooler 4 used in the system is set when the ice heat storage system is operated by operating the supercooler 4, the subsequent operation is performed according to the differential pressure operating condition. The ice heat storage system may be operated in a full operation.

  According to the results shown in FIG. 5, the differential pressure is such that the region (1), that is, the region where the water pressure is higher than ΔPmin, or the region (3), ie, the region where the brine pressure is higher than ΔPmax. Setting conditions will be determined. In order to set the differential pressure so as to be in the region (1), that is, the region where the water pressure is larger than ΔPmin, the water piping system with the amount of water larger than the rated value. In 20 pipes, it can be proposed to provide a throttle valve and an orifice at an appropriate position. Further, the installation position of the supercooler 4 is installed at a position lower than the water surface of the ice heat storage tank 1 for storing ice produced by the supercooled water from the supercooler 4, and the outlet pressure of the water to the supercooler 4 is set. It may be made larger than the inlet pressure of the brine. This region (1) corresponds to case B shown in FIG.

  On the other hand, in order to set the differential pressure so that the pressure of the brine is larger than the region (3), that is, the region where ΔPmax is larger, the sealed expansion tank 37 is provided at a position higher than usual, or the gas pressure in the expansion tank 37 To increase the static pressure of the brine. Furthermore, the head of the pump 6 of the brine piping system 30 is set larger than the rated flow rate and the resistance of the piping system, and the valve 34 installed on the outlet side of the brine outgoing pipe 31 of the subcooler 4 is throttled to the rated flow rate. It can be proposed to adjust. This region (3) corresponds to case A shown in FIG.

  Next, another method for determining the differential pressure between plates will be described. FIG. 6 shows an outline of the system of the ice heat storage system provided with the equipment used at that time. In FIG. 6, the members, equipment, etc. indicated by the same reference numerals as those in FIG. 4 are those shown in FIG. Is the same. In the ice heat storage system shown in FIG. 6, the second pressure gauge 27 and the third pressure gauge 33 are removed from the ice heat storage system shown in FIG. A bypass pipe 41 is provided between the water return pipe 22 and a bypass flow meter 42 for measuring the flow rate of water flowing through the bypass pipe 41 and a valve 43 are provided in the bypass pipe 41. That is, in the water piping system 20, a bypass pipe 41 is piped in parallel to the supercooler 4, and the functions of flow measurement and flow control are provided in the bypass flow path, not the circulation path of the cooling medium to be cooled. Yes. The bypass pipe 41 is made of a highly rigid material such as a steel pipe, a hard PVC pipe, a stainless steel pipe, or a copper pipe. Other configurations are the same as those of the ice heat storage system shown in FIG. Instead of removing the second pressure gauge 27 and the third pressure gauge 33 from the ice heat storage system shown in FIG. 4, the first pressure gauge 23 and the fourth pressure gauge 36 are removed and the second pressure gauge 27 is removed. The pressure gauge 27 and the third pressure gauge 33 may be installed as they are.

In the ice heat storage system shown in FIG. 6, first, the water and brine control devices 29 and 38 are set to the flow rate necessary for the production of the supercooled water and the water and brine to circulate the water. ΔP (measured value of the fourth pressure gauge 36−measured value of the first pressure gauge 23) when the valve 25 is operated to gradually increase the flow rate of water and gradually reduce the differential pressure ΔP; bypass flow meter 42 measurements _{(G 1)} and the flow meter 26 of the measuring values the relationship _{(G 2)} is recorded. The measurement results are plotted in a small circle on the graph of FIG. The left vertical axis in FIG. 5 shows that after adjusting G ₁ / G ₂ to the rated flow rate (G ₁₀ / G ₂ ) by ΔP on the right side of the drawing (G ₁₀ is the rated flow rate of G ₁ ), ΔP was lowered. for _shows a decrease ratio of _{G 1 / G 2 {(G} 1 / G 2) / (G 10 / G 2)}. Here, since G ₂ (flow rate of water) is controlled to 700 L / min, the decreasing rate of G ₁ / G ₂ is expressed as “G ₁ / G ₁₀ ”.

According to this, the _G 1 _{/ G 10} In region (1) and the region (3) does not change, it can be seen that area (2) _{where G} 1 _{/ G 10} in conjunction with a change in the differential pressure is changed. This means that in the region (2), the plate in the subcooler 4 which is a plate heat exchanger moves and deforms as the differential pressure varies. From this, it is understood that the operating pressure may be selected in the regions (1) and (3) so that the collision between the plates does not occur even if the pressure difference between the plates occurs.

  The other method for determining the differential pressure between the plates described above is to observe the movement and deformation of the plate from the change in the flow rate ratio between the subcooler 4 and the bypass pipe 41 which are plate heat exchangers. In such a measurement system, the water flow path is connected in parallel with the subcooler 4 and the bypass pipe 41, but the plate heat exchanger constituting the subcooler 4 and the bypass flow path are separated by a plurality of throttles. When considered as a kind of constructed labyrinth flow path, each resistance coefficient ξ and loss head h is generally expressed by the following equation (1).

That is, h _i = a _i · ξ _i · v _i ² / 2g (1)
i = 1 (flow path of bypass pipe 41) or 2 (water side flow path of subcooler 4) (a: dimensionless constant (constant according to the shape of the flow path), v: flow velocity, g: gravitational acceleration) It is.
Therefore, the loss head h ₁ of the bypass pipe 41 is
h ₁ = a ₁ · ξ ₁ · v ₁ ² / 2g,
The head loss h ₂ water side flow passage of the subcooler 4,
h ₂ = a ₂ · ξ ₂ · v ₂ ² / 2g,
It becomes.

Also, assuming that the cross-sectional areas and flow velocities of the inlet of the subcooler 4 and the bypass pipe 41 of the plate heat exchanger are v and A, respectively, the respective flow rates G are expressed by Expression (2).
G _i = v _i · A _i (2)
i = 1 (flow path of the bypass pipe 41) or 2 (water side flow path of the subcooler 4).
That is,
Flow rate _{G 1} of the bypass pipe 41,
G ₁ = v ₁ · A ₁
Flow rate G ₂ water side flow passage of the subcooler 4,
G ₂ = v ₂ · A ₂
It becomes.

In this measurement system, the loss heads of the subcooler 4 and the bypass pipe 41, which are plate heat exchangers, are always the same (h ₁ = h ₂ ). Therefore, from the equations (1) and (2), the equation (3 ) Is obtained.

  In addition, since the cross-sectional area of the inlet of the subcooler 4 of the plate heat exchanger and the inlet of the bypass pipe 41 is constant, b is a constant as shown in Expression (4).

Here, since the bypass pipe 41 is made of a highly rigid material, the resistance coefficient ξ ₁ does not change. For this reason, if G ₁ and G ₂ are measured, it is possible to detect a change in the resistance coefficient ξ ₂ accompanying the movement and deformation of the plate in the plate heat exchanger.
That is, the variation in the measurement of G ₁ and G ₂ is caused by the change in the resistance coefficient ξ ₂ , and the change in the resistance coefficient ξ ₂ is nothing but an indication that the plate is deformed or moved. Therefore, the differential pressure between the plates such that the resistance coefficient ξ ₂ shows a constant value is used as the operating condition of the subcooler 4, and then the ice storage system is operated in accordance with the differential operating condition. .

  FIG. 7 shows the results of actual measurement of the freezing frequency when the inter-plate differential pressure is changed. The freezing frequency is displayed as a ratio based on the value in the region (2). From this figure, it can be seen that when the operating pressure of the differential pressure between the plates is determined in the region (3), the freezing frequency is reduced as compared with the case where it is determined in the region (2).

  The supercooler 4 employed in the above embodiment is of a type in which water and brine are heat-exchanged in countercurrent, but the present invention is of a type in which water and brine are heat-exchanged in parallel flow. Is also applicable.

  The present invention is useful when supercooled water is produced by a gasket-type plate heat exchanger used in an ice heat storage system or the like.

It is explanatory drawing which showed typically the pressure conditions which do not change a resistance coefficient even if a differential pressure changes in this invention about a countercurrent and a parallel flow. It is explanatory drawing which showed typically the outline | summary of the ice thermal storage system to which this invention is applied. It is explanatory drawing which showed typically the structure of the gasket type plate-type heat exchanger used for the ice thermal storage system of FIG. 2, the figure of the left side shows the front, and the figure of the right side has shown the right side. It is explanatory drawing which showed typically the outline of the system | strain at the time of determining a differential pressure by pressure loss in the ice thermal storage system of FIG. It is a graph which shows the relationship between the brine outlet pressure-water inlet pressure in the supercooler of the ice thermal storage system of FIG. 4, water side pressure loss, and bypass flow rate / water flow rate of the subcooler. In the ice thermal storage system of FIG. 2, it is explanatory drawing which showed typically the outline of the system | strain at the time of determining a differential pressure with the water flow rate of a bypass flow rate / supercooler. It is a graph which shows the relationship between the differential pressure between plates of brine and water, freezing frequency, and total ice making time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ice thermal storage tank 2, 6 Pump 4 Supercooler 5 Refrigerator 8 Supercooling release device 11 Plate 12 Gasket 15 End plate 20 Water piping system 21 Water outflow pipe 22 Water return pipe 23 First pressure gauge 24, 25 Valve 26 35 Flow meter 27 Second pressure gauge 28 Expansion tank 30 Brine piping system 31 Brine outgoing pipe 32 Brine return pipe 33 Third pressure gauge 36 Fourth pressure gauge 37 Expansion tank 41 Bypass pipe 42 Bypass flow meter

Claims (13)

In a method for producing supercooled water by exchanging heat between cooling brine and water using a gasket type plate heat exchanger as a supercooler,
A method for producing supercooled water, wherein the pressure of the cooling brine or water is adjusted to produce supercooled water in a state where the interplate differential pressure in the plate heat exchanger is equal to or higher than a predetermined differential pressure. The predetermined differential pressure is adjusted by adjusting the pressure of the brine flowing into the subcooler in a state where the water and brine are set at a flow rate necessary for the production of the supercooling water and the water is circulated. The method for producing supercooled water according to claim 1, wherein the resistance coefficient of the water flow path is a differential pressure between plates that is constant regardless of pressure fluctuation or flow rate fluctuation of water or brine. The predetermined differential pressure is adjusted by adjusting the pressure of the brine flowing into the subcooler in a state where the water and brine are set at a flow rate necessary for the production of the supercooling water and the water is circulated. The flow rate ratio between the flow rate of the bypass flow path of the water flowing in parallel and the flow rate of the water flowing through the subcooler is a differential pressure between the plates that is constant regardless of the pressure fluctuation of the water or brine, The method for producing supercooled water according to claim 1. When adjusting the pressure of the cooling brine or water so that the pressure difference between the plates is equal to or higher than the predetermined pressure difference, when heat is exchanged between the water and the brine in countercurrent, the water inlet pressure to the subcooler is 2. The method for producing supercooled water according to claim 1, wherein the outlet pressure of the brine is increased or the outlet pressure of the water to the subcooler is made larger than the inlet pressure of the brine. When adjusting the pressure of the cooling brine or water so that the differential pressure between the plates becomes equal to or higher than the predetermined differential pressure, when heat and water are exchanged in parallel flow, the inlet pressure of the brine to the subcooler is set to Make the outlet pressure of the brine to the subcooler greater than the outlet pressure of the water, or make the inlet pressure of the water to the subcooler greater than the inlet pressure of the brine and the subcooler The method for producing supercooled water according to claim 1, wherein an outlet pressure of water with respect to water is larger than an outlet pressure of brine. The supercooled water according to claim 4, wherein the position of the expansion tank of the brine is increased so that the brine outlet pressure is larger than the water inlet pressure to the supercooler and heat is exchanged in countercurrent. Manufacturing method. Increase the position of the brine expansion tank so that the brine outlet pressure to the subcooler is greater than the water outlet pressure and the brine inlet pressure to the subcooler is greater than the water inlet pressure. The method for producing supercooled water according to claim 5, wherein heat exchange is performed by a flow. A closed expansion tank is attached to the piping of the brine, and the static pressure of the brine is adjusted by adjusting the gas pressure in the closed expansion tank so that the outlet pressure of the brine is larger than the inlet pressure of water to the supercooler. The method for producing supercooled water according to claim 4, wherein heat exchange is performed in a counterflow. A closed expansion tank is attached to the piping of the brine, and the static pressure of the brine is adjusted by adjusting the gas pressure in the closed expansion tank so that the outlet pressure of the brine to the subcooler is more than the outlet pressure of water. 6. The method for producing supercooled water according to claim 5, wherein the heat is exchanged in parallel flow by increasing the inlet pressure of the brine to the supercooler larger than the inlet pressure of the water. Select the head of the brine pump with respect to the rated flow rate and the resistance of the piping system, adjust the rated flow rate by restricting the valve installed at the brine outlet of the subcooler, and use the water inlet pressure to the subcooler. The method for producing supercooled water according to claim 4, wherein the outlet pressure of the brine is increased and heat exchange is performed in a countercurrent. Select the head of the brine pump with respect to the rated flow and the resistance of the piping system, adjust the rated flow by restricting the valve installed at the brine outlet of the subcooler, and adjust the outlet pressure of the brine to the subcooler. The supercooled water according to claim 5, wherein heat exchange is performed in parallel flow by making the pressure greater than the water outlet pressure and making the brine inlet pressure to the supercooler greater than the water inlet pressure. Manufacturing method. Position the supercooler from the supercooler so that the outlet pressure of the water to the supercooler is higher than the sum of the water-side loss pressure and the brine-side loss pressure of the supercooler. It is installed at a position lower than the water surface of the ice heat storage tank for storing ice produced by the method, and the water outlet pressure to the supercooler is made larger than the inlet pressure of the brine to exchange heat in countercurrent, The method for producing supercooled water according to claim 4. Position the supercooler from the supercooler so that the outlet pressure of the water to the supercooler is higher than the sum of the water-side loss pressure and the brine-side loss pressure of the supercooler. Installed at a position lower than the surface of the ice heat storage tank for storing ice produced by the water, the water outlet pressure to the supercooler is greater than the brine outlet pressure, and the water inlet pressure to the subcooler is set to the brine inlet The method for producing supercooled water according to claim 5, wherein heat exchange is performed in parallel flow at a pressure larger than the pressure.

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