JP2019190827A - Freezing and refrigeration system - Google Patents

Abstract

To make a design for producing equal splitting of refrigerant to a plurality of circuits of a cooling coil at a unit cooler and perform an effective heat transfer action at a heat transfer surface of the unit cooler so as to improve an operation efficiency.SOLUTION: Refrigerant liquefied in a low receiver 110 is sent by a liquid transferring pump 130 to a distributor 140 through an expansion valve 132, the refrigerant is divided to flow and sent to each of cooling coils of a unit cooler 150. The distributor 140 is designed for performing a uniform distribution of refrigerant in view of its nozzle diameter, tube diameter and tube length. The refrigerant passed through the unit cooler 150 is merged by a confluent manifold 152, and after this operation, the refrigerant returns back to the low receiver 110. An overheat state of the refrigerant is calculated in reference to a pressure corresponding temperature got from the results of detection of a temperature sensor 154 and a pressure sensor 156 at the refrigerant outlet side of the unit cooler 150 and a flow rate of the refrigerant is controlled by an expansion valve 132 under an operation of an overheat state controller 158.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigeration system or a refrigeration system using a unit cooler (hereinafter collectively referred to as a “refrigeration / refrigeration system”), and more specifically, to a refrigeration / refrigeration in which refrigerant is divided into a plurality of circuits of a cooling coil in the unit cooler. It relates to the improvement of the system.

  In a secondary cooling system (Secondary Refrigeration System) that sends a refrigerant that has been cooled to a predetermined temperature to the heat exchanger in advance, or in a liquid pump type refrigeration system, a conventional manifold (liquid header) is used to By causing the refrigerant to flow into each circuit of the cooling coil, the refrigerant is evaporated inside the cooling coil, and heat exchange between the outside air of the cooling coil and the refrigerant is performed using the heat of vaporization.

  By the way, when the refrigerant flows into the unit cooler cooling coil composed of multiple circuits, a pressure loss for each circuit occurs due to evaporation (vaporization) that occurs at the same time. When the manifold is used, the pressure loss is different for each circuit, and it becomes difficult to flow a uniform amount of refrigerant into each circuit, and the heat transfer effect on the effective heat transfer surface is reduced.

  Specifically, among the circuits of the cooling coil, an unequal flow is generated such that the refrigerant liquid flows to the outlet in a certain circuit and the superheated gas passes to the outlet in a certain circuit. As a result, the heat transfer action on the heat transfer surface cannot be used effectively, and the operating efficiency of the refrigeration system is significantly reduced.

  In addition, when the unit cooler is disposed below the receiver tank (downstream of the refrigerant), there is a risk that unevaporated refrigerant liquid may stay in the suction pipe unless the refrigerant flow rate is properly controlled. The liquid refrigerant staying in the suction pipe is difficult to evaporate, becomes a resistance to the refrigerant gas continuously evaporated inside the unit cooler, and makes it difficult for the refrigerant to pass through the cooling coil. As a result, the pressure inside the unit cooler is increased, that is, the refrigerant temperature is increased, and the refrigerating capacity is decreased due to a decrease in temperature difference.

  In order to avoid the inconvenience, there is a method in which the refrigerant flow rate is adjusted by a needle valve or the like with reference to a circuit in which the refrigerant flows from several circuits in a multi-circuit without being evaporated. However, the flow rate adjustment by the needle valve or the manual expansion valve is not a means for ensuring the proper flow rate by detecting the dryness of the cooling coil outlet. In other words, the heat transfer rate changes due to the temperature difference with the air that passes when heat exchange is performed in the cooling coil, which does not guarantee an appropriate overheating region for the tube length of the cooling coil. The flow rate is only adjusted so as not to return the unevaporated refrigerant liquid at the outlet of the cooling coil.

  If a distributor (refrigerant diverter) can be used when the refrigerant flows into each circuit of the cooling coil of the unit cooler, the refrigerant should be evenly distributed to the refrigerant circuit and the refrigerant side heat transfer surface can be used effectively. And can greatly improve the efficiency of the system. As a background art using such a distributor, for example, there is a refrigeration system described in Patent Document 1 below. This is because the refrigerant flow passages in a plurality of cooling coil systems are arranged in consideration of the temperature distribution, so that the temperature unevenness of the outlet air is eliminated, the capacity reduction of the refrigerator is suppressed, and the energy saving operation is enabled. For this purpose, a distributor is connected to each refrigerant flow passage on the inlet side of the refrigerant flow passage of each cooling coil system.

JP 2012-172919

  By the way, when using the distributor, in the case of the pressure drop type, depending on the thermodynamic characteristics of the refrigerant, for example, if a pressure drop of about 50 kPa at the nozzle and about 20 kPa is not obtained at the tube, the refrigerant is evenly divided. There is a restriction that cannot be done. In addition, when using a Venturi type distributor, a pressure restoration effect can be obtained after passing through the stream line, but because of its structure, the distributable range is limited to about 20 circuits, so it is limited to a small unit cooler. The In fact, as a result of performance tests of various types of venturi types, it was not possible to perform a diversion with the required accuracy.

  In addition, in the refrigeration system of the liquid pump system, the pressure of the liquid refrigerant sent by the liquid pump is low only by increasing the discharge pressure with respect to the saturation pressure of the refrigerant itself by about 150 kPa to 250 kPa, The temperature of the supplied liquid refrigerant is close to the evaporation temperature of the refrigerant that evaporates in the heat exchanger. For this reason, the expansion valve that automatically adjusts the flow rate or the refrigerant that passes through the distributor adds only the pressure of the pump discharge pressure and the pressure of the liquid column, or reduces the pressure only by subtracting the head from the pump discharge pressure. Since there is only a zone, it will pass through the expansion valve and the flow divider, respectively, while the liquid phase remains unchanged.

  At this time, expansion expansion does not occur in the expansion valve, gasification due to the dryness occurring before the nozzle cannot be expected in the distributor, and turbulent flow due to generation of the jet flow when passing through the nozzle does not occur. For this reason, it was impossible to cope with the design method based on the knowledge so far.

  The present invention pays attention to the above points, and an object of the present invention is to provide a distributor design method capable of evenly dividing the refrigerant into a plurality of circuits of the cooling coil in the unit cooler. The other purpose is to maximize the heat transfer surface of the unit cooler, effectively perform the heat transfer action, and improve the operation efficiency of the refrigeration / refrigeration system.

  The present invention relates to a refrigeration / refrigeration system that performs freezing or refrigeration using a unit cooler having a cooling coil composed of a plurality of circuits, and distributes the refrigerant to each circuit of the cooling coil of the unit cooler. The distributor includes a nozzle and a plurality of tubes that connect the cooling coil formed of a plurality of circuits of the unit cooler to the nozzle with the same length, and the distributor obtained by actual measurement is provided. From the relationship between the pressure drop amount of the nozzle and the tube and the refrigerating capacity of the unit cooler, the inner diameter of the nozzle, the length of the tube, and the distributor having the inner diameter are selected. Alternatively, a refrigeration / refrigeration system that performs refrigeration or refrigeration using a unit cooler having a cooling coil composed of a plurality of circuits, the pump means sending refrigerant to the unit cooler, and the pump means to the unit A flow rate adjusting means for adjusting a flow rate of the refrigerant sent to the cooler; and a distributor for diverting the refrigerant whose flow rate is adjusted by the flow rate adjusting means to each circuit of the cooling coil of the unit cooler. Is an expansion valve having an orifice for adjusting the flow rate of the refrigerant sent from the pump means to the unit cooler, and the refrigerant flow rate by the orifice of the expansion valve based on the degree of superheat of the refrigerant on the refrigerant outlet side of the unit cooler And a superheat degree controller for controlling the distribution. The compressor includes a nozzle and a plurality of tubes that connect the cooling coil composed of a plurality of circuits of the unit cooler to the nozzle with the same length, and the pressure of the nozzle and the tube of the distributor obtained from actual measurement From the relationship between the amount of descent and the refrigeration capacity of the unit cooler, the inner diameter of the nozzle and the length of the tube and the distributor having the inner diameter that can be diverted are selected, and the nozzle diameter of the orifice of the expansion valve is The nozzle diameter is larger than the nozzle diameter corresponding to the cross-sectional area obtained from the DD.Will formula based on the refrigeration / refrigeration capacity of the unit cooler and the type of refrigerant, and the nozzle diameter is adjustable in flow rate. .

  According to one of the main forms, the refrigeration / refrigeration system includes a primary cooling system and a secondary cooling system, and the pump means, the expansion valve, and the distributor are provided in the secondary cooling system. It is characterized by. According to another aspect, when the receiver for supplying the refrigerant is located on the lower side with respect to the unit cooler, the unit cooler and the receiver are reduced in the amount of pressure drop by the expansion valve and the distributor. The pressure capacity of the refrigerant in the pump means is set so that the pressure capacity corresponding to the height difference is applied, and the receiver for supplying the refrigerant is positioned above the unit cooler. The pressure of refrigerant in the pump means so that the pressure corresponding to the height difference between the unit cooler and the receiver is subtracted from the pressure drop by the expansion valve and the distributor. Is set.

  According to still another aspect, the degree of superheat of the refrigerant on the refrigerant outlet side of the unit cooler is detected from detection results of a temperature sensor and a pressure sensor provided on the refrigerant outlet side of the unit cooler. The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

  According to the present invention, the refrigerant is equally divided into each circuit of the cooling coil of the unit cooler based on the appropriate design of the diverting means, and the superheat degree control by the expansion valve is combined to improve the efficiency of the refrigeration / refrigeration system. Improvements can be made.

It is a figure which shows the structure of Example 1 of this invention. (A) is a general view, and (B) is a diagram showing the main part. It is a figure which shows the distributor in the said Example. (A) is a figure which shows a structure, (B) and (C) are graphs which show the relationship between refrigerating capacity and the amount of pressure drops. FIG. 3 is a diagram showing the state of the refrigerant in each circuit of the cooling coil. (A) shows the case of this embodiment, (B) shows the case without a nozzle, and (C) shows the case of the prior art. It is a figure which shows the relationship between the height position of the receiver 110 and the unit cooler 150, and a pump pressure. It is a figure which shows the structure of Example 2 of this invention.

  Hereinafter, the form for implementing this invention is demonstrated in detail based on an Example.

  A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention is applied to a liquid pump type refrigeration system. FIG. 1A shows the entire refrigeration system 100 of the present embodiment. In the figure, a refrigerator (compressor) 114-> condenser (condenser) 116-> receiver 118-> flow rate adjustment valve (needle valve) 120 are arranged in that order on the delivery side of the gasified refrigerant in the low receiver 110. A circulation circuit is connected so that the gasified refrigerant is liquefied and returned to the low receiver 110.

  On the other hand, on the delivery side of the liquefied refrigerant in the low receiver 110, a liquid feed pump 130 → an expansion valve 132 → a distributor 140 → a unit cooler 150 → a merging manifold 152 are connected in this order by pipes, and the gasified refrigerant Is returned to the low receiver 110 again.

  A temperature sensor 154 and a pressure sensor 156 are attached to the refrigerant outlet side of the unit cooler 150, and these are connected to the superheat degree controller 158. The control output side of the superheat degree controller 158 is connected to the expansion valve 132. The superheat degree controller 158 detects the difference from the actually measured value by the temperature sensor 154, that is, the degree of superheat, based on the detection result of the refrigerant pressure equivalent temperature by the pressure sensor 156, and based on the result, the opening degree of the expansion valve 132 is determined. To be controlled.

  Explaining the general operation of the refrigeration system configured as described above, the gasified refrigerant in the low receiver 110 is compressed by the refrigerator 114 and then condensed by the condenser 116, whereby the liquefied refrigerant is It is sent to the receiver 118. The refrigerant stored in the receiver 118 is squeezed and expanded by the flow rate adjustment valve 120 and is returned to the low receiver 110.

  The liquefied refrigerant in the low receiver 110 is sent to the distributor 140 via the expansion valve 132 by the liquid feed pump 130, whereby the refrigerant is divided and sent to each cooling coil of the unit cooler 150. The refrigerant that has passed through the unit cooler 150 is gasified, merged by the merge manifold 152, and then returned to the low receiver 110 again. A temperature sensor 154 and a pressure sensor 156 are provided on the refrigerant outlet side of the unit cooler 150, and detection results thereof are input to the superheat degree controller 158. The superheat degree controller 158 detects the superheat degree by subtracting the actually measured value read by the temperature sensor 154 from the pressure equivalent saturation temperature converted from the detection result of the pressure sensor 156. And according to this detected superheat degree, the refrigerant | coolant flow control is performed by the expansion valve 132, and also the superheat degree in the unit cooler 150 is controlled.

  FIG. 1B shows an enlarged connection portion between the distributor 140 and the unit cooler 150, and the distributor 140 has a nozzle 142 and a tube 144. The distributor 140 and each cooling coil of the unit cooler 150 are connected by a tube 144 having the same length. In the illustrated example, the unit cooler 150 is provided with five cooling coils, and therefore, the number of tubes 144 is also five.

  The present inventor pays attention to the pressure of the liquid feed pump 130 for feeding the refrigerant cooled in the low receiver 110, and the pressure on the refrigerant inlet side of the unit cooler 150 is 100 kPa or more with respect to the saturation pressure of the refrigerant. A refrigerant distribution method has been proposed in which the liquid pressure is ensured so that the refrigerant can be distributed satisfactorily by the pressure drop type distributor 140, and the distributor when “R-404A” is used as the refrigerant is proposed. It is reported that even if the pressure drop at 140 is 65 kPa, even diversion is possible (for example, Japan Society of Refrigeration and Air Conditioning, “Freezing” October 2007, Vol. 82, No. 960, P817-P824, “Environment See "What is a refrigeration system that supports an easy-to-use cold chain?"). In general, in order for the distributor 140 to equally distribute the refrigerant to the cooling coils, a certain pressure drop or more is required on the nozzle 142 side and the tube 144 side.

  The pressure drop in the distributor 140 is mainly related to the diameter (inner diameter) Dn of the nozzle 142 and the length Lt and diameter (inner diameter) Dt of the tube 144 as shown in FIG. FIG. 5B shows an example of the relationship between the pressure drop amount of the nozzle 142 and the refrigerating capacity or cooling capacity (including the case of refrigeration). This graph is an example in the case of the inner diameter Dn = 4.5 mm. When the pressure drop amount is 35 kPa or less, the refrigerant cannot be divided evenly regardless of the refrigerating capacity. FIG. 3C shows an example of the relationship between the pressure drop amount of the tube 144 and the refrigerating capacity. This graph shows an example in which the inner diameter Dt = 3.25 mm (outer diameter is 3/16 inch) and the length Lt = 1500 mm. When the pressure drop is 15 kPa or less, the refrigerant is evenly distributed regardless of the refrigerating capacity. This is not possible.

Next, a design method will be described based on a specific example. For example, it is assumed that carbon dioxide (R-744) is used as the refrigerant, and the unit cooler 150 having the specifications shown in Table 1 below is used. In this example, as indicated by an arrow, TD (difference between the refrigerant evaporation temperature in the evaporator and the internal temperature) = 10 ° C., a refrigerating capacity of about 30 kw can be obtained, and the temperature difference of the passing air is About 4 ° C.

Next, calculation examples of the orifice of the expansion valve 132 are as shown in Tables 2 to 4 below. Table 2 shows various conditions and DDWILL equation, and Table 3 shows the relationship between the nozzle diameter, the cross-sectional area, and the mass flow rate of the orifice of the expansion valve 132. Table 4 shows the relationship between the nozzle diameter and the refrigerating capacity. The coefficient “5020” of the DDWILL equation in Table 2 is a numerical value obtained by the inventor Nakayama from an experiment. Generally, “3880” when the refrigerant is ammonia, “5470” when R22 is used, and “4660” when methyl chloride is used. In these tables, for example, in the case of the above-described refrigeration capacity of 30 kw, the nozzle diameter of the orifice is 3 mm from Table 4. Since the flow rate is adjusted centering on this, the nozzle diameter of the orifice may be 4 to 4.5 mm if a margin is taken into account. The difference between the inlet side pressure P1 and the outlet side pressure P2 in the expansion valve 132 is 125 kPa. Thus, even if a general expansion valve is used, the necessary mass flow rate of the refrigerant can be ensured even with a very small differential pressure of about 100 kPa by deriving the orifice diameter from the DDWILL type. Under this condition, the refrigerant liquid passes through the expansion valve 132 in a state where there is no change in the liquid phase / gas phase or the change in dryness.

  Next, assuming that the distributor 140 shown in FIG. 2 is used, when the refrigeration capacity is 30 kW, the pressure drop of the nozzle 142 is 49 kPa (see FIG. 2B), and the pressure drop of the tube 144 is Is 26 kPa (see FIG. 2 (C)). In any case, the flow can be separated beyond the region where the flow cannot be separated, and good uniform flow of the refrigerant can be performed. In other words, a distributor having a nozzle diameter Dn, a tube diameter Dt, and a tube length Lt is selected so as to provide a pressure drop amount in a divertable region in the refrigerating capacity. Under this condition, when the refrigerant liquid passes through the nozzle 142 and the tube 144 of the distributor 140, an appropriate pressure drop can be obtained even with a saturated liquid without gas due to the dryness of the refrigerant.

  FIG. 3 shows this state. FIG. 6A shows the case of the present embodiment, which uses the expansion valve 132 and the distributor 140 having the above-described conditions. According to this, the refrigerant supplied to the distributor 140 at −30 ° C. is equally divided into each cooling coil of the unit cooler 150 and gasified near the outlet of each cooling coil, and its temperature is around −29 ° C. It has become. The air temperature on the inlet side of the unit cooler 150 is −20.3 ° C., whereas the temperature on the outlet side is −24.6 ° C., and the temperature difference is 4.3 ° C. Since the unit cooler 150 shown in Table 1 has a refrigeration capacity of 30 kW and an air temperature difference of about 4 ° C., the capacity of the unit cooler 150 is substantially achieved by designing as in this embodiment. And very efficient operation.

  The distributor 141 in FIG. 3 (B) shows an example in the case where the nozzle 142 is not provided. In each cooling coil of the unit cooler 150, overrun occurs in the circuit in the coil due to the uneven flow of the refrigerant. For this reason, there is variation in the temperature on the outlet side of each cooling coil. Further, since the vaporized refrigerant does not have the ability to cool the air, an ineffective region of the heat transfer surface of the unit cooler 150 is generated, and the cooling capacity of the air is lowered as a whole. It can only be cooled to 9 ° C.

  FIG. 3 (C) shows an example of a conventional manifold system. In the manifold 151, the refrigerant is not equally divided as in the case of FIG. 3 (B). In this example, air at −20.3 ° C. is cooled only to −23.3 ° C., and the performance of each cooling coil of the unit cooler 150 is not fully utilized.

  As described above, according to the present embodiment, the heat exchange (heat transfer action) in the unit cooler 150 is effectively achieved by designing the distributor 140 so that the refrigerant is equally divided into the cooling coils of the unit cooler 150. As a result, the operating efficiency of the refrigeration system can be improved.

  In addition, the flow rate control based on the degree of superheat is accurately performed by the expansion valve 132, so that the refrigeration system can fully demonstrate the refrigerating capacity of the unit cooler in the liquid pump system with a standard and simple control system of the direct expansion system. The system efficiency can be significantly improved. Further, since the liquid pump type automatic operation is performed, it is possible to perform the operation with the optimum dryness by the cooling coil constituted by a plurality of circuits of the unit cooler 150 while performing the superheat degree control.

  Furthermore, since the distribution of the refrigerant is equally distributed to each cooling coil of the unit cooler 150 by the distributor 140 and the superheat degree control by the expansion valve 132 is combined, the ineffective region of the heat transfer surface due to the uneven flow is eliminated. As a whole, an appropriate refrigeration system with high efficiency can be provided. That is, as shown in FIG. 3A, since the refrigerant is in a gas-liquid two-phase state over almost the entire length of each circuit of the cooling coil of the unit cooler 150, heat exchange is performed in the entire unit cooler 150. As a result, efficient operation is performed.

  If there is a difference in height between the low receiver 110 and the unit cooler 150, it is necessary to determine the capacity of the liquid feed pump 130 in consideration of this. In the example of FIG. 4A, the low receiver 110 is positioned below the unit cooler 150, and the height difference is ha. Therefore, in addition to the pressure drop amount by the expansion valve 132 and the distributor 140, the liquid feeding pump 130 is required to have a pressurizing capacity corresponding to the height difference ha. For example, assuming that the refrigerant pressure before the expansion valve of the unit cooler 150 is 200 kPa, a pressurizing capacity equivalent to 200 + ha, which is obtained by adding the height difference ha to this, is required at a minimum. In the example of FIG. 4B, the low receiver 110 is positioned above the unit cooler 150, and the height difference is hb. In this case, since the pressure of the liquid column is added to the discharge pressure of the liquid feed pump 130, if the pressure of the liquid column is subtracted from the discharge pressure of the liquid feed pump 130 and the refrigerant pressure before the expansion valve of the unit cooler 150 becomes 200 kPa, Good.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. In addition, the same code | symbol is used for the component which is the same as that of Example 1, or is common. The refrigeration system 200 according to the second embodiment includes a primary cooling system 202 and a secondary cooling system 204, and a heat exchanger 210 is provided between them. The primary cooling system 202 includes a refrigerator 114, a condenser 116, a receiver 118, an expansion valve 232, a temperature sensor 254, a pressure sensor 256, a superheat degree controller 258, and a primary side of the heat exchanger 210. The secondary cooling system 204 includes a secondary refrigerant receiver 111, a liquid feed pump 130, an expansion valve 132, a distributor 140, a unit cooler 150, a merge manifold 152, a temperature sensor 154, a pressure sensor 156, a superheat degree controller 158, and a heat exchanger 210. It is constituted by the secondary side.

  The gasified secondary refrigerant in the secondary refrigerant receiver 111 of the secondary cooling system 204 is cooled and liquefied in the heat exchanger 210 by the primary refrigeration system supplied from the receiver 118 of the primary cooling system 202. The refrigerant returns to the secondary refrigerant receiver 110. On the other hand, the primary refrigerant gasified by the heat exchanger 210 is liquefied again by the refrigerator 114 and the condenser 116 and returns to the receiver 118. The operations of the expansion valve 232, the temperature sensor 254, the pressure sensor 256, and the superheat degree controller 258 in the primary cooling system 202 are the same as those of the expansion valve 132, the temperature sensor 154, the pressure sensor 156, and the superheat degree controller 158 in the secondary cooling system 204. The detection results of the temperature sensor 254 and the pressure sensor 256 at the primary outlet of the heat exchanger 210 are input to the superheat degree controller 158, and the degree of superheat is detected. The refrigerant flow rate is controlled by the expansion valve 232 in accordance with the detected degree of superheat. As the primary refrigerant, for example, HFC refrigerant such as ammonia or R410A is used. As the secondary refrigerant, for example, an HFC refrigerant such as carbon dioxide or ammonia is used.

  Even in such a secondary cooling system, the same effect can be obtained by designing the expansion valve 132 and the distributor 140 of the secondary cooling system 204 in the same manner as in the above embodiment.

In addition, this invention is not limited to the Example mentioned above, A various change can be added in the range which does not deviate from the summary of this invention. For example, the following are also included.
(1) The above embodiment is an example in which the present invention is mainly applied to a refrigeration system, but can be similarly applied to a refrigeration system or a freezing system. For example, the present invention can be applied to various systems that require the refrigerant to be evenly distributed over multiple circuits, such as a plate-type ice making machine that uses flow dividers for a plurality of plates.
(2) The system configuration shown in the above embodiment is an example, and the present invention can be applied to various known configurations. For example, in the said Example, although the case where there was one unit cooler was shown, you may increase / decrease the number of installation as needed. The same applies to the number of distribution cooling coils of the distributor.
(3) The numerical values shown in the above embodiments are also examples, and may be changed as appropriate.

  According to the present invention, the refrigerant is equally divided into each circuit of the cooling coil of the unit cooler based on the appropriate design of the flow divider, and the superheat control by the expansion valve is combined. It is suitable for a refrigeration / refrigeration system that evenly distributes refrigerant.

100: Refrigeration system 110: Low receiver 111: Secondary refrigerant receiver 114: Refrigerator 116: Condenser 118: Receiver 120: Flow rate adjusting valve 130: Liquid feed pump 132: Expansion valve 140, 141: Distributor 142: Nozzle 144: Tube 150 : Unit cooler 151: Manifold 152: Merge manifold 156: Pressure sensor 154: Temperature sensor 158: Superheat controller 200: Refrigeration system 202: Primary cooling system 204: Secondary cooling system 210: Heat exchanger Dn: Nozzle inner diameter Dt: Tube inner diameter Lt: Tube length

The present invention pays attention to the above points, and an object thereof is to evenly distribute the refrigerant to a plurality of circuits of the cooling coil in the unit cooler . Another object is to improve the operation efficiency of the refrigeration / refrigeration system by making the best use of the heat transfer surface in the unit cooler, effectively performing the heat transfer action.

The present invention relates to a refrigeration / refrigeration system that performs freezing or refrigeration using a unit cooler having a cooling coil composed of a plurality of circuits, and distributes the refrigerant to each circuit of the cooling coil of the unit cooler. The distributor includes a nozzle and a plurality of tubes that connect the cooling coil composed of a plurality of circuits of the unit cooler to the nozzle with the same length, and obtained from an actual measurement , From the relationship between the pressure drop amount of the nozzle and tube of the distributor and the refrigeration capacity of the unit cooler, and the relationship between the shuntable area and the non-shrinkable area in this relationship, the refrigerating capacity of the unit cooler to be used, and di having an internal diameter and length as well as the inner diameter thereof of the tube of the nozzle to be diverted can range Characterized in that selects the Toribyuta. Alternatively, the pump means for sending the refrigerant to the unit cooler, the flow rate adjusting means for adjusting the flow rate of the refrigerant sent from the pump means to the unit cooler, and the refrigerant whose flow rate is adjusted by the flow rate adjusting means is used as the unit cooler. A distributor for diverting to each circuit of the cooling coil, and the flow rate adjusting means includes an expansion valve having an orifice for adjusting the flow rate of the refrigerant sent from the pump means to the unit cooler, and the refrigerant of the unit cooler A superheat degree controller that controls the flow rate of the refrigerant through the orifice of the expansion valve based on the superheat degree of the refrigerant on the outlet side, and the distributor includes a nozzle and a plurality of circuits of the unit cooler Multiple channels connecting the cooling coil to the nozzle with the same length. And a chromatography blanking, was obtained from the measured, the pressure drop of the distributor nozzles and tubes and the relationship between the refrigerating capacity of the unit cooler, and the relationship of the flow can range and shunt impossible range in this connection And selecting the distributor having the inner diameter of the nozzle and the length of the tube and the inner diameter of the unit cooler, which is the refrigeration capacity of the unit cooler to be used, and the nozzle diameter of the orifice of the expansion valve is The nozzle diameter is larger than the nozzle diameter corresponding to the cross-sectional area obtained from the DD.Will formula based on the refrigeration / refrigeration capacity of the unit cooler and the type of refrigerant, and the nozzle diameter is adjustable in flow rate. .

According to the present invention, the refrigerant is equally divided into each circuit of the cooling coil of the unit cooler by an appropriate design of the distributor , and the efficiency of the refrigeration / refrigeration system is improved by combining superheat degree control with an expansion valve. Can be planned.

Next, calculation examples of the orifice of the expansion valve 132 are as shown in Tables 2 and 3 below. Table 2 shows various conditions and DDWILL formula, and Table 3 (A) shows the relationship between the nozzle diameter, cross-sectional area, and mass flow rate of the orifice of the expansion valve 132. Table 3 (B) shows the relationship between nozzle diameter and capacity. The coefficient “5020” of the DDWILL equation in Table 2 is a numerical value obtained by the inventor Nakayama from an experiment. Generally, “3880” when the refrigerant is ammonia, “5470” when R22 is used, and “4660” when methyl chloride is used. In these tables, for example, in the case of the above-described refrigeration capacity of 30 kw, the nozzle diameter of the orifice is 3 mm from Table 3 (B) . Since the flow rate is adjusted centering on this, the nozzle diameter of the orifice may be 4 to 4.5 mm if a margin is taken into account. The difference between the inlet side pressure P1 and the outlet side pressure P2 in the expansion valve 132 is 125 kPa. Thus, even if a general expansion valve is used, the necessary mass flow rate of the refrigerant can be ensured even with a very small differential pressure of about 100 kPa by deriving the orifice diameter from the DDWILL type. Under this condition, the refrigerant liquid passes through the expansion valve 132 in a state where there is no change in the liquid phase / gas phase or the change in dryness.

The gasified secondary refrigerant in the secondary refrigerant receiver 111 of the secondary cooling system 204 is cooled and liquefied in the heat exchanger 210 by the primary refrigeration system supplied from the receiver 118 of the primary cooling system 202. The refrigerant returns to the secondary refrigerant receiver 110. On the other hand, the primary refrigerant gasified by the heat exchanger 210 is liquefied again by the refrigerator 114 and the condenser 116 and returns to the receiver 118. The operations of the expansion valve 232, the temperature sensor 254, the pressure sensor 256, and the superheat degree controller 258 in the primary cooling system 202 are the same as those of the expansion valve 132, the temperature sensor 154, the pressure sensor 156, and the superheat degree controller 158 in the secondary cooling system 204. The detection results of the temperature sensor 254 and the pressure sensor 256 at the primary outlet of the heat exchanger 210 are input to the superheat degree controller 158, and the degree of superheat is detected. The refrigerant flow rate is controlled by the expansion valve 232 in accordance with the detected degree of superheat. As the primary refrigerant, for example, HFC refrigerant such as ammonia or R410A is used. As the secondary refrigerant, for example, a natural refrigerant such as carbon dioxide or ammonia is used.

According to the present invention, the refrigerant is equally divided into each circuit of the cooling coil of the unit cooler by an appropriate design of the distributor , and superheat degree control by the expansion valve is combined. It is suitable for a refrigeration / refrigeration system that evenly distributes food.

Claims (5)

A freezing / refrigeration system that performs freezing or refrigeration using a unit cooler having a cooling coil composed of a plurality of circuits,
A distributor for diverting the refrigerant to each circuit of the cooling coil of the unit cooler;
The distributor includes a nozzle and a plurality of tubes that connect the cooling coil configured by a plurality of circuits of the unit cooler to the nozzle with the same length,
From the relationship between the pressure drop amount of the nozzle and tube of the distributor obtained from the actual measurement and the refrigeration capacity of the unit cooler, the inner diameter of the nozzle and the length of the tube and the inner diameter of the tube that can be divided were selected. Refrigeration / refrigeration system characterized by this. A freezing / refrigeration system that performs freezing or refrigeration using a unit cooler having a cooling coil composed of a plurality of circuits,
Pump means for sending refrigerant to the unit cooler;
Flow rate adjusting means for adjusting the flow rate of refrigerant sent from the pump means to the unit cooler;
A distributor for diverting the refrigerant whose flow rate is adjusted by the flow rate adjusting means to each circuit of the cooling coil of the unit cooler;
With
The flow rate adjusting means includes an expansion valve having an orifice for adjusting the flow rate of the refrigerant sent from the pump means to the unit cooler, and the expansion valve based on the degree of superheat of the refrigerant on the refrigerant outlet side of the unit cooler. A superheat degree controller that controls the flow rate of refrigerant through the orifice,
The distributor includes a nozzle and a plurality of tubes that connect the cooling coil composed of a plurality of circuits of the unit cooler to the nozzle with the same length,
Based on the relationship between the pressure drop amount of the nozzle and tube of the distributor obtained from the actual measurement and the refrigeration capacity of the unit cooler, the inner diameter of the nozzle and the length of the tube that can be divided and the distributor having the inner diameter are selected. ,
The nozzle diameter of the orifice of the expansion valve is a nozzle diameter larger than the nozzle diameter corresponding to the cross-sectional area obtained from the DD.Will formula based on the refrigeration / refrigeration capacity of the unit cooler and the type of refrigerant, and the flow rate adjustment A freezing and refrigeration system characterized by a possible nozzle diameter. The refrigeration / refrigeration system includes a primary cooling system and a secondary cooling system,
The refrigeration / refrigeration system according to claim 2, wherein the pump means, the expansion valve, and the distributor are provided in the secondary cooling system. When the receiver for supplying the refrigerant to the unit cooler is positioned on the lower side, the pressure corresponding to the height difference between the unit cooler and the receiver is reduced in the pressure drop by the expansion valve and the distributor. To set the pressurizing capacity of the refrigerant in the pump means so that the pressurizing capacity is added,
When the receiver for supplying the refrigerant is positioned on the upper side of the unit cooler, the pressure corresponding to the height difference between the unit cooler and the receiver is calculated from the pressure drop by the expansion valve and the distributor. 4. The refrigeration / refrigeration system according to claim 2, wherein the refrigerant pressurizing capacity in the pump means is set so as to obtain a subtracted pressurizing capacity.   The degree of superheat of the refrigerant on the refrigerant outlet side of the unit cooler is detected from detection results of a temperature sensor and a pressure sensor provided on the refrigerant outlet side of the unit cooler. Refrigeration / refrigeration system described in 1.

Images