JP2019019997A - Compression type refrigerator - Google Patents

Abstract

To provide a compression type refrigerator which does not require a high-precision and expensive measuring apparatus such as temperature sensor or pressure sensor and is capable of using a general-purpose, inexpensive and simple measuring apparatus and securing an optimal refrigerant possession quantity corresponding to a refrigeration load or an operation point (a point determined from the refrigeration load and a differential pressure between an evaporator and a condenser) in the evaporator.SOLUTION: A compression type refrigerator comprises: first flow control means 6 which is installed in piping connecting an evaporator 3 with an economizer 4; second flow control means 7 which is installed in piping connecting the economizer 4 with a condenser 2; a control device 10 which performs opening/closing control of the first flow control means 6 and/or the second flow control means 7; and refrigeration load rate calculation means which calculates a refrigeration load rate during operation of the compression type refrigerator. The control device 10 compares a refrigeration load rate calculation value which is calculated by the refrigeration load rate calculation means, with a preset refrigeration load rate setting value and based on a comparison result, a refrigerant possession quantity of the evaporator 3 is controlled by the first flow control means 6 and/or the second flow control means 7.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a compression type refrigerator having an evaporator, a compressor, and a condenser, and in particular, a heat transfer tube group is arranged inside the shell, and cold water is passed through the heat transfer tube to fill the shell with liquid refrigerant. The present invention relates to a compression type refrigerator equipped with a full liquid evaporator.

2. Description of the Related Art Conventionally, a compression type refrigerator used for a refrigeration air conditioner or the like is composed of a closed system in which a refrigerant is enclosed, an evaporator that draws heat from cold water (cooled fluid) and evaporates the refrigerant to exert a refrigeration effect. A compressor that compresses the refrigerant gas evaporated in the evaporator into a high-pressure refrigerant gas, a condenser that cools and condenses the high-pressure refrigerant gas with cooling water (cooling fluid), and depressurizes the condensed refrigerant And an expansion valve (expansion mechanism) that is expanded by being connected by a refrigerant pipe.
In many cases, the above-mentioned compression refrigerator uses a full-liquid evaporator in which a heat transfer tube group is arranged inside a shell, cold water is passed through the heat transfer tube, and the shell fills with liquid refrigerant.
In the above-described full liquid evaporator, the efficiency of heat transfer affects the COP (coefficient of performance) of the refrigerator. Since the boiling heat transfer characteristics change depending on the height at which the heat transfer tube group is immersed in the refrigerant, conventionally, the efficiency of heat transfer in the evaporator has not been lowered by controlling the refrigerant liquid level of the evaporator.

  Regarding the control of the refrigerant liquid level of the evaporator, in JP-A-2014-85048 (Patent Document 1), the correlation between the evaporator LTD defined as the temperature difference between the chilled water outlet temperature and the evaporator refrigerant temperature and the refrigerating capacity. A technique has been proposed in which the flow rate of the refrigerant flowing into the evaporator is controlled by controlling a control valve installed in the refrigerant pipe to the evaporator using the above, thereby controlling the refrigerant liquid level of the evaporator.

JP 2014-85048 A

As proposed in Patent Document 1, when the flow rate of the refrigerant flowing into the evaporator is controlled using the correlation between the LTD of the evaporator and the refrigerating capacity (load), there are the following problems. .
(1) The difference in LTD between high load and low load is small, and precise control requires a highly accurate (expensive) temperature sensor or pressure sensor, which increases the product cost.
(2) When the fluctuation range of the refrigeration load or the cooling water temperature is large and the fluctuation frequency is high, it may be difficult to control the flow rate of the refrigerant due to the delay of the actual opening / closing operation of the control valve.
(3) In actual operation, when the heat transfer tube becomes dirty, it is difficult to bring it close to the target LTD.

  The present invention has been made in view of the above-described circumstances, and does not require a highly accurate and expensive measuring device such as a temperature sensor or a pressure sensor, and can use a general-purpose inexpensive and simple measuring device. It is an object of the present invention to provide a compression type refrigerator that can secure an optimum refrigerant holding amount according to a refrigeration load or an operating point (a point determined by a refrigeration load and a differential pressure between an evaporator and a condenser). To do.

  In order to achieve the above-mentioned object, in a compression refrigerator having an evaporator, a compressor, a condenser, and an economizer, a first flow rate control means installed in a pipe connecting the evaporator and the economizer, and the economizer And a second flow rate control means installed in a pipe connecting the condenser, a control device for controlling the opening and closing of the first flow rate control means and / or the second flow rate control means, and the operation of the compression refrigerator Refrigeration load factor calculation means for calculating a refrigeration load factor in the control unit, the control device compares the refrigeration load factor calculation value calculated by the refrigeration load factor calculation means with a preset refrigeration load factor setting value, The refrigerant holding amount of the evaporator is controlled by the first flow rate control means and / or the second flow rate control means based on the comparison result.

According to a preferred aspect of the present invention, as the refrigerant charging amount charged in the compression refrigerator at a predetermined rated cooling water inlet temperature, the first refrigerant charging amount at which the LTD of the evaporator becomes the smallest at the rated load factor, Two of the second refrigerant filling amounts that satisfy the allowable LTD of the evaporator at a predetermined low load factor are set, and the relationship between the refrigeration load factor and the LTD at the rated cooling water inlet temperature in the two refrigerant filling amounts is expressed. A graph is obtained, and the set value of the refrigeration load factor is a refrigeration load factor at an intersection of the graphs of the LTD of the evaporator from the low load factor of the evaporator to the rated load factor in the two refrigerant charging amounts. To do.
According to the present invention, it is possible to easily obtain the optimum LTD of the evaporator on each of the rated load side (high load side) and the low load side simply at one intersection point in the entire range from high load to low load. it can.

According to a preferred aspect of the present invention, the refrigeration load factor at the intersection of the LTD graphs from the low load factor of the evaporator to the rated load factor, or the graph, at the two refrigerant charging amounts at a predetermined low cooling water inlet temperature, When not intersecting, a predetermined rated refrigeration load factor (100%) in the second refrigerant charge amount is obtained as a low temperature side refrigeration load factor, and a predetermined rated cooling water inlet temperature and a predetermined low cooling in the second refrigerant charge amount are obtained. For each of the water inlet temperatures, a graph representing the relationship between the refrigeration load factor and the differential pressure between the evaporator and the condenser is obtained, and the refrigeration load factor set value on the graph obtained for the rated cooling water inlet temperature is obtained. A corresponding point A is determined, a point B corresponding to the low temperature side refrigeration load factor on the graph obtained for the low cooling water inlet temperature is determined, and a straight line connecting the point A and the point B is determined. Obtains a first set operating range and a second set operating range that are partitioned by an approximate curve that approximates the straight line, and an operating point determined by the calculated value of the refrigeration load factor and the differential pressure between the evaporator and the condenser is The refrigerant possession amount of the evaporator is controlled by the first flow rate control means and / or the second flow rate control means depending on whether it is in one set operation range or the second set operation range. And
ADVANTAGE OF THE INVENTION According to this invention, the optimal LTD of an evaporator can be obtained according to the said operating point in the driving | running | working range of high load to low load from predetermined rated cooling water temperature to low cooling water temperature.

According to a preferred aspect of the present invention, a point A ′ and a point B ′ at which a straight line connecting the point A and the point B or a line obtained by extending an approximate curve intersects the entire allowable operating range are obtained, and the point The first set operation range and the second set operation range are corrected based on A ′ and point B ′.
According to a preferred aspect of the present invention, the liquid level detection means provided in the space capable of storing the refrigerant liquid provided upstream of the first flow rate control means and / or the second flow rate control means, and the liquid A predetermined upper liquid level and lower liquid level are set in the surface detection means, and when the refrigeration load factor calculation value calculated by the refrigeration load factor calculation means is larger than the refrigeration load factor setting value, The first flow rate control means and / or the second flow rate control means is controlled so that the liquid level of the refrigerant liquid becomes the upper liquid level, and the refrigeration load factor calculation value calculated by the refrigeration load factor calculation means is the refrigeration load factor. When the load factor is smaller than the set value, the first flow rate control means and / or the second flow rate control means are controlled so that the liquid level of the refrigerant liquid in the space becomes the lower liquid level. To do.

According to a preferred aspect of the present invention, the condenser has a space capable of storing a predetermined amount of refrigerant liquid capable of controlling a refrigerant holding amount of the evaporator at a lower portion, and the second flow rate control means. The refrigerant holding amount of the evaporator is controlled only by the above.
According to a preferred aspect of the present invention, the economizer has a space capable of storing a predetermined amount of refrigerant liquid capable of controlling a refrigerant holding amount of the evaporator at a lower portion, and includes only the first flow rate control means. The refrigerant holding amount of the evaporator is controlled by the above.

According to a preferred aspect of the present invention, a storage container capable of storing a predetermined amount of refrigerant liquid capable of controlling a refrigerant holding amount of the evaporator is provided in a pipe connecting the evaporator and the economizer, The refrigerant holding amount of the evaporator is controlled by one flow rate control means, or the storage container is provided in a pipe connecting the economizer and the condenser, and the refrigerant holding amount of the evaporator is set by the second flow rate control means. It is characterized by controlling.
According to a preferred aspect of the present invention, a subcooler capable of storing a predetermined amount of refrigerant liquid capable of controlling the amount of refrigerant retained in the evaporator is provided below the condenser, and only the second flow rate control means. The refrigerant holding amount of the evaporator is controlled by the above.

  According to a preferred aspect of the present invention, a plurality of storage spaces in a storage container provided in the condenser, the economizer, and a pipe connecting the evaporator and the economizer or a pipe connecting the economizer and the condenser are provided. A predetermined amount of refrigerant liquid capable of controlling the refrigerant holding amount of the evaporator is stored using a combination, and the refrigerant holding of the evaporator is stored by the first flow rate control unit and / or the second flow rate control unit. It is characterized by controlling the amount.

According to another aspect of the present invention, there is provided a compression type refrigerator having an evaporator, a compressor, and a condenser, a flow rate control unit installed in a pipe connecting the evaporator and the condenser, and the flow rate control unit. A control device that performs opening / closing control; and a refrigeration load factor calculation unit that calculates a refrigeration load factor during operation of the compression refrigerator, wherein the control device calculates the refrigeration load factor calculated by the refrigeration load factor calculation unit The value is compared with a preset refrigeration load factor set value, and the refrigerant holding amount of the evaporator is controlled by the flow rate control means based on the comparison result.
This aspect is applicable to a compression refrigerator that does not include an economizer.

  According to a preferred aspect of the present invention, the refrigeration load factor includes temperature measuring means for measuring an inlet temperature and an outlet temperature of the cold water flowing through the water chamber of the evaporator, and a flow rate measuring means for measuring the flow rate of the cold water. The calculating means calculates a refrigeration load factor based on measured values obtained by the temperature measuring means and the flow rate measuring means.

The present invention has the following effects.
(1) A high-precision and expensive measurement device such as a temperature sensor or a pressure sensor is not required, and a general-purpose simple measurement device can be used.
(2) Even when the fluctuation range of the refrigeration load or the cooling water temperature is large and the fluctuation frequency is high, an optimum refrigerant holding amount can be secured in the evaporator according to the refrigeration load.
(3) Regardless of the state of the heat transfer tube, the evaporator can ensure the optimum amount of refrigerant in accordance with the refrigeration load.

FIG. 1 is a schematic view showing an embodiment of a compression refrigerator according to the present invention. FIGS. 2A, 2B, 2C, and 2D are schematic views showing the relationship between the refrigeration load and the amount of refrigerant stored in the evaporator. FIG. 3 is a graph showing the test results, showing the relationship between the refrigeration load factor (%) and the evaporator LTD (° C.) defined as the temperature difference between the cold water outlet temperature and the evaporator refrigerant temperature. . FIG. 4 is a graph showing the test results, showing the relationship between the refrigeration load factor (%) and the evaporator LTD (° C.) defined as the temperature difference between the cold water outlet temperature and the evaporator refrigerant temperature. . FIG. 5 is a graph showing the relationship between the refrigeration load factor (%) and the differential pressure (kPa) between the evaporator and the condenser. FIG. 6 is a graph showing the relationship between the refrigerant amount (kg) and the evaporator LTD under rated operating conditions. FIG. 7 is a schematic diagram showing an embodiment in which a storage container for storing the entire difference in the refrigerant holding amount of the evaporator is provided. FIG. 8 is a schematic view showing an embodiment in which a storage container for storing a part of the difference in the refrigerant holding amount of the evaporator is provided. FIG. 9 is a schematic view showing another embodiment in which a storage container for storing a part of the difference in the refrigerant holding amount of the evaporator is provided. FIG. 10 is a schematic view showing another embodiment in which a storage container for storing a part of the difference in the refrigerant holding amount of the evaporator is provided in a compression refrigerator that does not include an economizer.

Hereinafter, an embodiment of a compression refrigerator according to the present invention will be described with reference to FIGS. 1 to 10. 1 to 10, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.
FIG. 1 is a schematic view showing an embodiment of a compression refrigerator according to the present invention. As shown in FIG. 1, the compression refrigerator includes a compressor 1 that compresses refrigerant, a condenser 2 that cools and compresses the compressed refrigerant gas with cooling water (cooling fluid), and cold water (cooled fluid). ), An evaporator 3 that evaporates the refrigerant and exerts a refrigeration effect, and an economizer 4 that is an intermediate cooler disposed between the condenser 2 and the evaporator 3. Are connected by a refrigerant pipe 5 that circulates.

  In the embodiment shown in FIG. 1, the compressor 1 is composed of a multistage turbo compressor. The multistage turbo compressor is connected to the economizer 4 by the refrigerant pipe 5, and the refrigerant gas separated by the economizer 4 is introduced into an intermediate portion of the multistage compression stage of the multistage turbo compressor.

As shown in FIG. 1, an electric control valve 6 is provided in the refrigerant pipe 5 that connects the evaporator 3 and the economizer 4. The control valve 6 constitutes a first flow rate control means for controlling the flow rate of the refrigerant flowing from the economizer 4 to the evaporator 3. The first flow rate control means may have a configuration in which an electric control valve and an orifice are combined in series or in parallel.
The refrigerant pipe 5 that connects the economizer 4 and the condenser 2 is provided with an electric control valve 7. The control valve 7 constitutes second flow rate control means for controlling the flow rate of the refrigerant flowing from the condenser 2 to the economizer 4. The second flow rate control means may have a configuration in which an electric control valve and an orifice are combined in series or in parallel.

  The economizer 4 is provided with a liquid level detecting means 8 comprising a liquid level gauge, a limit switch, a float switch or the like for detecting the liquid level of the refrigerant liquid stored in the economizer 4. Further, the condenser 2 is provided with a liquid level detecting means 9 comprising a liquid level gauge, a limit switch, a float switch or the like for detecting the liquid level of the refrigerant liquid stored in the condenser 2. The control valve 6, the control valve 7, the liquid level detection means 8 and the liquid level detection means 9 are each connected to the control device 10.

As shown in FIG. 1, the evaporator 3 is provided with a temperature sensor T1 for measuring the cold water inlet temperature and a temperature sensor T2 for measuring the cold water outlet temperature. That is, the temperature sensor T1 measures the inlet temperature of cold water that exchanges heat with the refrigerant in the evaporator 3, and the temperature sensor T2 measures the outlet temperature of cold water after heat exchange with the refrigerant in the evaporator 3. ing. The temperature sensor T1 and the temperature sensor T2 are connected to the control device 10, respectively. In addition, a flow rate sensor FE for measuring the cold water flow rate is installed at the cold water inlet or outlet pipe. The flow sensor FE is connected to the control device 10. The control device 10 is provided with a refrigeration load factor calculating means. The refrigeration load factor calculating means includes a temperature difference between the chilled water inlet temperature measured by the temperature sensor T1 and the chilled water outlet temperature measured by the temperature sensor T2, and a flow rate sensor FE. The refrigeration load factor is calculated from the measured cold water flow rate.
As shown in FIG. 1, a differential pressure gauge ΔPe is provided between the chilled water inlet pipe and the chilled water outlet pipe to measure the pressure difference at the chilled water inlet / outlet of the evaporator 3, and the refrigeration load factor calculating means calculates the pressure difference. The flow rate of cold water flowing through the evaporator 3 is estimated, and the refrigeration load factor may be calculated from the estimated cold water flow rate and the temperature difference between the cold water inlet temperature and the cold water outlet temperature.

  The control device 10 compares the refrigeration load factor calculation value calculated by the refrigeration load factor calculation means with a preset refrigeration load factor setting value (described later), and based on the comparison result, the first flow rate composed of the control valve 6. The refrigerant holding amount of the evaporator 3 is controlled by the second flow rate control means including the control means and / or the control valve 7. That is, the control device 10 is configured to control the refrigerant holding amount of the evaporator 3 based on the refrigeration load factor.

2A, 2 </ b> B, 2 </ b> C, and 2 </ b> D are schematic diagrams illustrating the relationship between the refrigeration load and the amount of refrigerant stored in the evaporator 3. 2A, 2B, 2C, and 2D, the substantially inverted trapezoidal solid line in the evaporator 3 indicates the heat transfer tube group 3a, and the dotted line indicates the average boiling liquid level AL.
2 (a) and 2 (b) are diagrams showing a comparison between a case where the refrigerant holding amount is small (FIG. 2 (a)) and a case where the refrigerant is large (FIG. 2 (b)) at low load.
As shown in FIG. 2A, when the refrigerant holding amount is small, the exposed heat transfer tubes increase, the heat transfer area decreases, and the LTD increases.
As shown in FIG. 2B, when the amount of refrigerant held is large, the exposed heat transfer tubes are reduced, the heat transfer area is increased, and the LTD is reduced.
As shown in FIGS. 2A and 2B, at a low load, the boiling state is gentle and the average boiling liquid level is low. The size of the heat transfer area that can contribute to heat transfer varies with LTD. If the amount of refrigerant continues to be added in order to reduce the LTD, the LTD will decrease to some extent, but if the amount of refrigerant is further increased, the effect of submerging (liquid head) from a certain point, as in the case of high load described below. As a result, the LTD increases.

2 (c) and 2 (d) are diagrams showing a comparison between a case where the refrigerant holding amount is small (FIG. 2 (c)) and a case where the refrigerant is large (FIG. 2 (d)) at high load. 2C and 2D, the alternate long and two short dashes line indicates the average boiling liquid level at low load with the same refrigerant holding amount.
As shown in FIGS. 2 (c) and 2 (d), when the load is high, the boiling state is intense, and with the same refrigerant content, the average boiling liquid level AL at high load is the average boiling liquid level at low load (two points). It is higher than that shown by the chain line. In this state, when the amount of refrigerant is further increased, the average boiling liquid level is further increased. From a certain point, the influence of submerging (liquid head) starts and the LTD tends to increase. Due to the increase in the average boiling liquid level, boiling at the bottom of the heat transfer tube group 3a is suppressed. On the contrary, if the amount of refrigerant is reduced, the LTD starts to increase from a certain point due to a lack of heat transfer area. That is, there exists an optimum liquid level according to the refrigeration load.

Next, a description will be given of test results performed by the compression refrigerator shown in FIG. 1 on the premise that an optimum liquid level exists according to the refrigeration load shown in FIG.
The test operation was performed with different refrigerant charge amounts of the first refrigerant charge amount W1 and the second refrigerant charge amount W2 as the total refrigerant charge amount charged in the refrigerator. The relationship between the first refrigerant charge amount W1 and the second refrigerant charge amount W2 is W1 <W2. Each test was performed by storing the minimum amount of refrigerant in the condenser 2 and the economizer 4. When the refrigerator is operated with the refrigerant charging amount W1 and the refrigerant charging amount W2, respectively, the difference in operation is the refrigerant holding amount (W2-W1) of the evaporator 3. That is, when the refrigerator is operated with the second refrigerant filling amount W2, the refrigerant holding amount of the evaporator 3 is increased by (W2-W1) than when the first refrigerant filling amount W1.

FIG. 3 and FIG. 4 are graphs showing the test results, showing the relationship between the refrigeration load factor (%) and the evaporator LTD (° C.) defined as the temperature difference between the chilled water outlet temperature and the evaporator refrigerant temperature. It is a graph. In FIG. 3, the cooling water inlet temperature of the condenser 2 is 32 ° C., and in FIG. 4, the cooling water inlet temperature of the condenser 2 is 12 ° C.
From the test results shown in FIG. 3, at a certain intermediate refrigeration capacity (refrigeration load factor A point), a graph of the first refrigerant charge amount W1 (shown by a thick solid line) and a graph of the second refrigerant charge amount W2 (shown by a thick broken line) ) Appeared. The LTD in the case of the first refrigerant charge amount W1 on the rated load factor side larger than the refrigeration load factor A point is smaller than the LTD in the case of the second refrigerant charge amount W2 and is lower on the low load factor side than the refrigeration load factor A point. The LTD in the case of the two refrigerant filling amounts W2 is smaller than the LTD in the case of the first refrigerant filling amount W1. In other words, the LTD of the evaporator is the smallest when the first refrigerant charging amount W1 is larger than the refrigeration load factor A, and the second refrigerant charging is smaller than the refrigeration load factor A. In the case of the quantity W2, the LTD of the evaporator is small.
In the test results shown in FIG. 4, the graph of the first refrigerant charge amount W1 (shown by a thick solid line) and the graph of the second refrigerant charge amount W2 (shown by a thick broken line) are 100% load factor (refrigeration load factor B point). ) Were closest to each other but did not intersect.

As can be seen from FIG. 3 in which a phenomenon in which the graph of the first refrigerant charge amount W1 and the graph of the second refrigerant charge amount W2 intersect each other appears, the refrigerator is charged with the refrigerant of the second refrigerant charge amount W2, and the refrigeration at the intersection A Using the load factor as a branch point, as shown in (1) and (2) below, the optimum liquid level is ensured according to the refrigeration load by setting the amount of refrigerant in the evaporator 3 so that the evaporator LTD becomes as small as possible. It is possible to improve the heat transfer performance of the evaporator.
(1) When the refrigeration load factor during operation of the refrigerator is larger than the refrigeration load factor at the intersection A, the condenser 2 and the refrigerant 2 so that the amount of refrigerant retained in the evaporator 3 at the above-described first refrigerant charge amount W1 is obtained. / Or (e.g., the amount of refrigerant (W2-W1)) is temporarily stored in the economizer 4. When a storage container is separately installed (described later), the refrigerant amount (W2-W1) may be temporarily stored in at least one of the condenser 2, the economizer 4, and the storage container.
(2) When the refrigeration load factor during operation of the refrigerator is equal to or less than the refrigeration load factor at the intersection A, the condenser 2 is set so as to have the refrigerant holding amount of the evaporator 3 when the second refrigerant charging amount W2 is described above. The refrigerant amount temporarily stored in the economizer 4 is sent to the evaporator 3. When a storage container is separately installed, the amount of refrigerant temporarily stored in at least one of the condenser 2, the economizer 4, and the storage container is sent to the evaporator 3.
In FIG. 3, the thin line is a control line CL that summarizes the controls (1) and (2), and the thin line is displayed overlapping the graph of the first refrigerant filling amount W1 or the second refrigerant filling amount W2. Although it should be, for convenience of illustration, it is displayed slightly below the graph of the first refrigerant charge amount W1 or the graph of the second refrigerant charge amount W2.

If the cooling water inlet temperature 32 ° C. is generalized from the test results shown in FIG. 3 and expressed as “predetermined rated cooling water inlet temperature”, the refrigeration load factor setting value preset in the control device 10 is as follows: Can be defined.
The refrigerant charge amount that fills the compression refrigerator at a predetermined rated cooling water inlet temperature is a first refrigerant charge amount W1 that minimizes the LTD of the evaporator 3 at the rated load factor, and evaporates at a predetermined low load factor. A graph representing the relationship between the refrigeration load factor and the LTD at the rated cooling water inlet temperature in the two refrigerant filling amounts W1 and W2 is set for the two refrigerant filling amounts W2 that satisfy the allowable LTD of the vessel 3 The refrigeration load factor setting value is obtained by calculating the intersection of the graphs of the LTD 3 of the evaporator 3 from the low load factor of the evaporator 3 to the rated load factor at the two refrigerant charging amounts W1 and W2 (that is, the intersection shown in FIG. 3). It is the refrigeration load factor in A).

  In the above description, the method of controlling the refrigerant holding amount of the evaporator 3 with the intersection A as a branch point has been described. However, the waveform of the graph of FIG. 3 obtained by a test for one or a plurality of refrigerant charging amounts. Depending on the characteristics, the LTD of the evaporator 3 from the low load factor to the rated load factor is generally reduced, or any one point where a certain effect is obtained is determined as the refrigeration load factor set value, and the refrigerator is in operation. May be compared with the refrigeration load factor set value, and the refrigerant holding amount of the evaporator 3 may be controlled based on the comparison result.

FIG. 5 is a graph showing the relationship between the refrigeration load factor (%) and the differential pressure (kPa) between the evaporator 3 and the condenser 2. The refrigerant | coolant with the 2nd refrigerant | coolant filling amount W2 is filled into a refrigerator, and the correlation graph of FIG. 5 is calculated | required from the refrigerating load factor (%) and the differential pressure between an evaporator and a condenser during refrigerator operation.
FIG. 6 is a graph showing the relationship between the refrigerant amount (kg) and the evaporator LTD under rated operating conditions.

The relationship between FIG. 5 and FIG. 6 will be further described in consideration of the relationship between FIG. 3 and FIG.
First, from FIG. 6, the relationship between the refrigerant amount (kg) and the LTD of the evaporator 3 under the rated operating condition shown in FIG. 6 is that the cooling water inlet temperature of the condenser 2 is 32 ° C. and the refrigeration load factor is 100%. It is obtained with the rated load factor.
(1) As shown in FIG. 6, the amount of the refrigerant with the smallest LTD of the evaporator is 350 kg. Therefore, the first refrigerant charging amount W1 is set to 350 kg.
(2) Similar to (1) above, evaporation occurs at a rated cooling water temperature (for example, 32 ° C.) or a low cooling water temperature (for example, 12 ° C.) at a low refrigeration capacity (for example, a refrigeration load factor of 20%). The smallest refrigerant charge amount is determined such that the LTD of the vessel is equal to or less than the allowable LTD. It is inexpensive because it has the smallest amount of refrigerant. In FIG. 6, the relationship between the refrigerant amount and the LTD of the evaporator 3 under the rated operating condition (refrigeration load factor 100%) is illustrated, but the graph at the time of low refrigeration capacity (for example, refrigeration load factor 20%) is illustrated. Although not shown in the figure because it is the same as 6, the smallest filling amount at which the LTD of the evaporator 3 is equal to or less than the allowable LTD is 400 kg. Therefore, the second refrigerant charging amount W2 is set to 400 kg. This second refrigerant charging amount W2 = 400 kg is the refrigerant charging amount actually charged in the refrigerator.
When determining both the charging amounts of (1) and (2) above, the economizer 4 and the condenser 2 or the storage container store the same minimum required amount of refrigerant that can be operated or a certain amount of refrigerant. Store the amount.
When the first refrigerant charging amount W1 = 350 kg and the second refrigerant charging amount W2 = 400 kg, the refrigerant amount stored in the evaporator 3 has a difference of (400 kg−350 kg) = 50 kg under the same operating conditions.

(3) As shown in FIG. 3, from the rated refrigeration capacity (example: load factor 100%) at the rated cooling water temperature (example: 32 ° C.) with both filling amounts (1) and (2) above. A performance test of partial refrigeration capacity up to a low refrigeration capacity (eg, load factor 20%) is performed, and a correlation with LTD in each refrigeration capacity is obtained. That is, the change tendency of LTD due to the difference in the amount of refrigerant of 50 kg stored in the evaporator 3 at the rated cooling water temperature is confirmed.
(4) As shown in FIG. 4, as in (3) above, the rated refrigeration capacity (eg, load factor 100%) to the low refrigeration capacity (eg, load factor) at a low cooling water temperature (eg, 12 ° C.). The performance test of partial refrigeration capacity up to 20%) is performed, and the correlation with LTD in each refrigeration capacity is obtained. That is, the LTD change tendency due to the difference in the amount of refrigerant of 50 kg stored in the evaporator 3 at the time of the low cooling water temperature is confirmed.
The rated / low cooling water temperature and rated / low refrigeration capacity in (3) and (4) above are the operating range (1) such as the specification conditions of the cooling water temperature and refrigeration capacity specified by the customer or the customer. (Operation range (1) is shown in FIG. 5).
During the tests (3) and (4) above, the economizer 4 and the condenser 2 or the storage container store the same minimum required amount of refrigerant that can be operated, or store a certain amount of refrigerant. .

(5) As shown in FIG. 5, the above-mentioned (at the rated cooling water temperature (example: 32 ° C.) and the low cooling water temperature (12 ° C.) in the filling amount (eg, W2 = 400 kg) actually filled ( From the test results of 3) and (4), a curve or a straight line graph 1 and a graph 2 representing the relationship between the refrigerating capacity and the pressure difference between the evaporator and the condenser are prepared. That is, in FIG. 5, the upper dotted line is the graph 1, and the lower dotted line is the graph 2. In FIG. 3, the refrigeration capacity at the intersection (point A) of the 350 kg (W1) and 400 kg (W2) graphs is obtained, and the corresponding point A on the graph 1 in FIG. 5 is obtained. Similarly, in FIG. 4, in the result of this experiment, no intersection appears up to the rated refrigeration capacity, so the point of the rated refrigeration capacity at 400 kg (example: load factor 100%) on the graph 2 in FIG. Let it be a point. In FIG. 4, when the graphs of 350 kg (W1) and 400 kg (W2) intersect, the intersection of the 350 kg and 400 kg graphs is designated as point B, the refrigeration capacity at that time is obtained, and the corresponding points on graph 2 of FIG. Let it be point B. The refrigeration load factor at the point B determined in this way is defined as a low temperature side refrigeration load factor.
(6) Further, in FIG. 5, a graph of the refrigeration capacity range and the differential pressure range that can be actually operated as a refrigerator is created. In FIG. 5, the upper solid line is the graph 3, and the lower solid line is the graph 4. These graphs 3 and 4 may be appropriately determined in consideration of the surging line of the refrigerator, the protective operation, the failure avoiding operation, the limiting operation, and the like.
By connecting both ends of Graph 3 and Graph 4 with a straight line or a curved line (when there are many cooling water temperature patterns), the operation surrounded by two solid lines and two thin lines is possible. The operation range (2) as a whole region is determined. That is, since the refrigerator cannot be operated outside the operating range (2), the evaporator refrigerant holding amount control is possible even when the heat transfer tube is dirty.

(7) Next, in FIG. 5, points A and B are connected by a straight line (when the cooling water temperature is 2 points) or an approximate curve (when testing is performed at multiple cooling water temperatures), and B → A The intersection of the extension line and the graph 3 is obtained from the graph 3, and the point is set as A ′. The point A ′ may be determined within a setting allowable range centered on the intersection of the extension line B → A and the graph 3. Similarly, the intersection of the extension line of A → B and the graph 4 is obtained from the graph 4, and the point is set as B ′. The point B ′ may be determined within a setting allowable range centered on the intersection of the extension line B → A and the graph 4. The operation range (2) is divided into a first set operation range I and a second set operation range II from the B′-BAA ′ line thus obtained. By doing so, FIG. 5 is completed, and the data of FIG. 5 is stored in the memory of the control device 10. The branch line [B'-BAA '] is prepared in case of frequent swinging left and right around the branch line [B'-BAA'] due to load fluctuation, cooling water temperature fluctuation, etc. On the other hand, dead zones (0 to several percent) are provided on the left and right sides, or the control of the amount of refrigerant in the evaporator 3 is not performed within a certain time, thereby preventing hunting of the control valve.
(8) As an example, when the operating point (determined from the calculated value of the refrigeration load factor and the differential pressure between the evaporator 3 and the condenser 2) enters the region of the first set operating range I in FIG. A refrigerant amount of 350 kg = 50 kg is temporarily stored in one or a plurality of combinations of the economizer 4, the condenser 2, or the storage container. Further, when the operating point enters the second set operating range II, the refrigerant temporarily stored in one or a combination of the economizer 4, the condenser 2, or the storage container [400 kg−350 kg = 50 kg]. ] Is returned to the evaporator 3.

From the correlation graph shown in FIG. 5, the cooling water inlet temperature 12 ° C. is generalized to be expressed as “predetermined low cooling water inlet temperature”, and the cooling water inlet temperature 32 ° C. is generalized to “predetermined rated cooling water inlet temperature”. In other words, the control by the control device 10 can be defined as follows.
When the cooling load rate at the intersection of the graphs of the LTD from the low load factor of the evaporator 3 to the rated load factor at the two refrigerant charging amounts W1 and W2 at a predetermined low cooling water inlet temperature, or when the graph does not intersect, A predetermined rated refrigeration load factor (100%) at the second refrigerant charge amount W2 is obtained as a low temperature side refrigeration load factor (refrigeration load factor at point B in FIG. 4), and a predetermined rated cooling at the second refrigerant charge amount W2 is obtained. For each of the water inlet temperature and the predetermined low cooling water inlet temperature, graphs 1 and 2 representing the relationship between the refrigeration load factor and the differential pressure between the evaporator 3 and the condenser 2 are obtained. A point A (see FIG. 5) corresponding to the refrigeration load factor set value on the obtained graph 1 is determined, and the low temperature side refrigeration load factor on the graph 2 obtained for the low cooling water inlet temperature is determined. Point B ( 5), a first set operating range I and a second set operating range II divided by a straight line connecting the point A and the point B or an approximate curve approximating the straight line are obtained, and the refrigeration load factor is determined. Depending on whether the operating point determined by the calculated value and the differential pressure between the evaporator 3 and the condenser 2 is in the first set operating range I or the second set operating range II, a second control valve 6 is provided. The refrigerant holding amount of the evaporator 3 is controlled by the second flow rate control means including the 1 flow rate control means and / or the control valve 7.
When the point A and the point B are connected by a straight line, the control can be easily performed. When the point A and the point B are connected by an approximate curve, the low load factor at each cooling water temperature is used. A more accurate setting operation range can be obtained by acquiring a plurality of pressure differential relationships between the evaporator and the condenser up to the rated load factor, and performing a linear approximation between the point A and the point B to create a curve. it can. Further, a point A ′ and a point B ′ where a straight line connecting point A and point B or a line obtained by extending an approximate curve intersects the entire allowable operating range (shown by a solid line) with respect to the rated setting operating range of the dotted line. And the first set operation range I and the second set operation range II may be corrected based on the points A ′ and B ′.

Next, a method for controlling refrigerant storage, that is, a method for controlling the amount of refrigerant retained in the evaporator will be described.
The part of the evaporator 3 that temporarily stores the difference between the two refrigerant holding amounts is provided with liquid level detection means capable of detecting the lower liquid level and the upper liquid level to be controlled, and downstream of the storage part. Is provided with a flow rate control means to control the liquid level of the storage portion. The upper liquid level position and the lower liquid level position are previously determined by design and experiment so that the difference between the upper liquid level and the lower liquid level to be controlled becomes the difference between the two kinds of refrigerant holding amounts of the evaporator 3. Set it up.
i) Part to be stored: condenser 2 or economizer 4 or storage container.
ii) Liquid level detection means: liquid level gauge, limit switch, float switch, etc.
iii) Flow rate control means: an electric valve or a combination of an electric valve and an orifice.
When controlling the refrigerant holding amount of the evaporator 3 only at the point A shown in FIG. 3, the control is performed as follows.
When the refrigeration load factor during operation> the refrigeration load factor at point A, the flow rate control is performed by the flow rate control means on the downstream side of the storage portion so that the liquid level of the storage portion becomes the upper liquid level position.
When the refrigeration load factor during operation is refrigeration load factor of point A, the flow rate control is performed by the flow rate control means on the downstream side of the storage portion so that the liquid level of the storage portion is at the lower liquid level position.
In addition, the following method etc. can be considered as a countermeasure when the liquid surface to be controlled is frequently switched between the upper level and the lower level due to a continuous load fluctuation or the like near point A.
i) Control method by a predetermined time: The control target liquid level is not switched within a certain time after the control target liquid level is switched.
ii) Control method by dead zone: Control is performed by providing a dead zone above and below the refrigeration load factor at point A.

When the control method of the refrigerant storage, that is, the control method of the refrigerant holding amount of the evaporator is arranged, it can be defined as follows.
The liquid level detection means provided in the space capable of storing the refrigerant liquid provided upstream of the first flow rate control means and / or the second flow rate control means, and the liquid level detection means include a predetermined upper liquid level. When the refrigeration load factor calculation value calculated by the refrigeration load factor calculation means is larger than the refrigeration load factor setting value (refrigeration load factor at point A shown in FIG. 3), The refrigeration load factor calculation value calculated by the refrigeration load factor calculation means by controlling the first flow rate control means and / or the second flow rate control means so that the liquid level of the refrigerant liquid in the space becomes the upper liquid level. Is smaller than the set value of the refrigeration load factor, the first flow rate control means and / or the second flow rate control means are controlled so that the liquid level of the refrigerant liquid in the space becomes the lower liquid level.

Next, an embodiment in which a storage container that stores the entire difference in the refrigerant holding amount of the evaporator or a part of the difference is provided will be described with reference to FIGS.
FIG. 7 is a schematic diagram showing an embodiment in which a storage container for storing the entire difference in the refrigerant holding amount of the evaporator is provided. As shown in FIG. 7, the first storage container 11 is installed between the economizer 4 and the evaporator 3, and the second storage container 12 is installed between the condenser 2 and the economizer 4. The refrigerant pipe 5 that connects the first storage container 11 and the evaporator 3 is provided with a control valve 6 that constitutes a first flow rate control means. The refrigerant pipe 5 that connects the second storage container 12 and the economizer 4 is provided with a control valve 7 that constitutes a second flow rate control means.

  The first storage container 11 is provided with a liquid level detection means 13 including a liquid level gauge, a limit switch, a float switch, or the like that detects the liquid level of the refrigerant liquid stored in the first storage container 11. Further, the second storage container 12 is provided with a liquid level detection means 14 including a liquid level gauge, a limit switch, a float switch, or the like that detects the liquid level of the refrigerant liquid stored in the second storage container 12. . The control valve 6, the control valve 7, the liquid level detection means 13 and the liquid level detection means 14 are each connected to the control device 10.

  According to the compression refrigerator configured as shown in FIG. 7, the entire amount of the difference in the refrigerant holding amount of the evaporator 3 is stored in the first storage container 11 and the second storage container 12, thereby condensing with the economizer 4. The container 2 can be made compact. A part of the difference in the refrigerant holding amount of the evaporator 3 can be stored in the first storage container 11 and the second storage container 12, and the remainder can be stored in the condenser 2 or the economizer 4.

FIG. 8 is a schematic view showing an embodiment in which a storage container for storing a part of the difference in the refrigerant holding amount of the evaporator is provided. As shown in FIG. 8, a storage container 15 is installed between the condenser 2 and the economizer 4. The refrigerant pipe 5 that connects the economizer 4 and the evaporator 3 is provided with a control valve 6 that constitutes a first flow rate control means. The refrigerant pipe 5 that connects the storage container 15 and the economizer 4 is provided with a control valve 7 that constitutes a second flow rate control means.
The storage container 15 is provided with a liquid level detection means 16 including a liquid level gauge, a limit switch, a float switch, or the like that detects the liquid level of the refrigerant liquid stored in the storage container 15. The control valve 6, the control valve 7, and the liquid level detection means 16 are each connected to the control device 10.

  According to the compression type refrigerator configured as shown in FIG. 8, the condenser 2 can be made compact by dividing and storing the difference in the refrigerant holding amount of the evaporator 3 into the storage container 15 and the economizer 4. it can. In this case, the liquid level control of the economizer 4 is necessary, and the economizer 4 is provided with a liquid level detecting means (illustrated by a dotted line). Further, in the configuration shown in FIG. 8, the difference in the refrigerant holding amount of the evaporator 3 can be stored only in the storage container 15. In that case, the economizer 4 need not be provided with a liquid level detecting means.

FIG. 9 is a schematic view showing another embodiment in which a storage container for storing a part of the difference in the refrigerant holding amount of the evaporator is provided. As shown in FIG. 9, a storage container 17 is installed between the economizer 4 and the evaporator 3. The refrigerant pipe 5 that connects the storage container 17 and the evaporator 3 is provided with a control valve 6 that constitutes a first flow rate control means. The refrigerant pipe 5 that connects the condenser 2 and the economizer 4 is provided with a control valve 7 that constitutes a second flow rate control means.
The storage container 17 is provided with a liquid level detection means 18 including a liquid level gauge, a limit switch, a float switch, or the like that detects the liquid level of the refrigerant liquid stored in the storage container 17. The control valve 6, the control valve 7, and the liquid level detection means 18 are each connected to the control device 10.

  According to the compression refrigerator configured as shown in FIG. 9, the economizer 4 can be made compact by dividing and storing the difference in the refrigerant holding amount of the evaporator 3 between the storage container 17 and the condenser 2. it can. In this case, it is necessary to control the liquid level of the condenser 2, and the condenser 2 is provided with liquid level detection means (illustrated by a dotted line). Further, in the configuration shown in FIG. 9, the difference in the refrigerant holding amount of the evaporator 3 can be stored only in the storage container 17. In that case, the condenser 2 may not be provided with a liquid level detecting means.

FIG. 10 is a schematic diagram showing another embodiment in which a storage container for storing a difference in the amount of refrigerant stored in the evaporator is provided in a compression refrigerator that does not include an economizer. As shown in FIG. 10, a storage container 20 is installed between the condenser 2 and the evaporator 3. The refrigerant pipe 5 that connects the storage container 20 and the evaporator 3 is provided with a control valve 21 that constitutes a third flow rate control means.
The storage container 20 is provided with a liquid level detection means 22 including a liquid level gauge, a limit switch, a float switch, or the like that detects the liquid level of the refrigerant liquid stored in the storage container 20. The control valve 21 and the liquid level detection means 22 are each connected to the control device 10.

According to the compression type refrigerator configured as shown in FIG. 10, the condenser 2 can be made compact by storing in the storage container 20 the entire difference in the refrigerant holding amount of the evaporator 3. Moreover, the storage container 20 can be deleted from the configuration shown in FIG. 10, and the difference in the refrigerant holding amount of the evaporator 3 can be stored only in the condenser 2. In that case, the condenser 2 needs to be provided with a liquid level detecting means.
In the present embodiment, the method of controlling the refrigerant holding amount of the evaporator 3 by the third flow rate control means in the compression refrigerator that does not include the economizer has been described. However, in the compression refrigerator that includes the economizer described above, In this embodiment, when it takes time to transfer the refrigerant by the first flow rate control means and / or the second flow rate control means, the third flow rate control means transfers the refrigerant in a short time without going through an economizer. It is also possible to use.

The control method of the refrigerant holding amount of the evaporator 3 in the compression refrigerator of each embodiment configured as shown in FIGS. 1 and 7 to 10 is summarized as follows.
1) The condenser 2 has a space capable of storing a predetermined amount of refrigerant liquid capable of controlling the amount of refrigerant retained in the evaporator 3 at the lower portion, and the refrigerant retained in the evaporator 3 only by the second flow rate control means. The amount is controlled (the embodiment shown in FIG. 1).
2) The economizer 4 has a space capable of storing a predetermined amount of refrigerant liquid capable of controlling the refrigerant holding amount of the evaporator 3 at the lower portion, and the refrigerant holding amount of the evaporator 3 only by the first flow rate control means. Is controlled (the embodiment shown in FIG. 1).
3) A storage container 17 capable of storing a predetermined amount of refrigerant liquid capable of controlling the amount of refrigerant stored in the evaporator 3 is provided in a pipe connecting the evaporator 3 and the economizer 4, and the evaporator is controlled by the first flow rate control means. 3 is controlled (the embodiment shown in FIG. 9), or a storage container 15 is provided in a pipe connecting the economizer 4 and the condenser 2, and the refrigerant flow rate of the evaporator 3 is controlled by the second flow rate control means. Control (the embodiment shown in FIG. 8).
4) A subcooler capable of storing a predetermined amount of refrigerant liquid capable of controlling the refrigerant holding amount of the evaporator 3 is provided below the condenser 2, and the refrigerant holding amount of the evaporator 3 only by the second flow rate control means. (In the embodiment shown in FIG. 1, an embodiment (not shown) in which a subcooler is provided below the condenser 2).
5) In the condenser 2, the economizer 4, and the first storage container 11 provided in the pipe connecting the evaporator 3 and the economizer 4 or the second storage container 12 provided in the pipe connecting the economizer 4 and the condenser 2. A predetermined amount of refrigerant liquid capable of controlling the amount of refrigerant retained in the evaporator 3 is stored using a combination of a plurality of storage spaces, and the evaporator 3 is stored by the first flow rate control means and / or the second flow rate control means. Is controlled (the embodiment shown in FIG. 7).
6) The refrigerant | coolant liquid of the difference of the refrigerant | coolant holding amount of the evaporator 3 is stored in the condenser 2 or the storage container 20 separately provided in the downstream of the condenser 2, and the storage part in any one of the condenser 2 and the storage container 20 The third flow rate control means is provided in the pipe directly connected to the evaporator 3, and when the stored liquid is sent to the evaporator 3, it is sent directly by the third flow rate control means (the embodiment shown in FIG. 10).

  Although the embodiment of the present invention has been described so far, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention may be implemented in various different forms within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Evaporator 4 Economizer 5 Refrigerant piping 6, 7, 21 Control valve 8, 9, 13, 14, 16, 18, 22 Liquid level detection means 10 Control apparatus 11 1st storage container 12 2nd storage Container 15, 17, 20 Storage container FE Flow rate sensor T1, T2 Temperature sensor W1 First refrigerant filling amount W2 Second refrigerant filling amount

Claims (12)

In a compression refrigerator equipped with an evaporator, compressor, condenser, and economizer,
First flow rate control means installed in a pipe connecting the evaporator and the economizer;
A second flow rate control means installed in a pipe connecting the economizer and the condenser;
A control device that controls opening and closing of the first flow rate control means and / or the second flow rate control means;
Refrigeration load factor calculating means for calculating a refrigeration load factor during operation of the compression refrigerator,
The control device compares the refrigeration load factor calculation value calculated by the refrigeration load factor calculation means with a preset refrigeration load factor setting value, and based on the comparison result, the first flow rate control means and / or the second refrigeration load factor calculation value. A compression type refrigerator that controls the amount of refrigerant in the evaporator by means of flow rate control means. As the refrigerant charge amount that fills the compression refrigerator at a predetermined rated cooling water inlet temperature, the first refrigerant charge amount that minimizes the LTD of the evaporator at the rated load factor, and the evaporator charge amount at the predetermined low load factor. Two of the second refrigerant charge amounts satisfying the allowable LTD are set, and a graph representing the relationship between the refrigeration load factor and the LTD at the rated cooling water inlet temperature in the two refrigerant charge amounts is obtained.
2. The refrigeration load factor set value is a refrigeration load factor at an intersection of an evaporator LTD graph from a low load factor of an evaporator to a rated load factor in the two refrigerant charging amounts. The compression refrigerator as described. The refrigeration load factor at the intersection of the LTD graphs from the low load factor of the evaporator to the rated load factor at the two refrigerant charging amounts at a predetermined low cooling water inlet temperature, or when the graph does not intersect, the second refrigerant The predetermined rated refrigeration load factor (100%) in the filling amount is obtained as the low temperature side refrigeration load factor,
For each of the predetermined rated cooling water inlet temperature and the predetermined low cooling water inlet temperature in the second refrigerant charge amount, obtain a graph representing the relationship between the refrigeration load factor and the differential pressure between the evaporator and the condenser,
Determining a point A corresponding to the refrigeration load factor set value on the graph obtained for the rated cooling water inlet temperature;
Determining a point B corresponding to the low temperature side refrigeration load factor on the graph obtained for the low cooling water inlet temperature;
A first set operation range and a second set operation range that are partitioned by a straight line connecting the points A and B or an approximate curve that approximates the straight line are obtained, and the refrigeration load factor calculated value, the evaporator, and the condensation are obtained. The first flow rate control means and / or the second flow rate control means according to whether the operating point determined by the pressure difference between the vessels is in the first set operating range or the second set operating range. The compression type refrigerator according to claim 2, wherein the refrigerant holding amount of the evaporator is controlled.   A point A ′ and a point B ′ where a straight line connecting the point A and the point B or a line obtained by extending an approximate curve intersects the entire allowable operating range are obtained, and based on the points A ′ and B ′. The compression refrigerator according to claim 3, wherein the first set operation range and the second set operation range are corrected. A liquid level detection means provided in a space capable of storing a refrigerant liquid provided upstream of the first flow rate control means and / or the second flow rate control means;
In the liquid level detection means, a predetermined upper liquid level and a lower liquid level are set,
When the refrigeration load factor calculation value calculated by the refrigeration load factor calculation means is larger than the refrigeration load factor setting value, the first flow rate control means so that the liquid level of the refrigerant liquid in the space becomes the upper liquid level. And / or controlling the second flow rate control means,
When the refrigeration load factor calculation value calculated by the refrigeration load factor calculation means is smaller than the refrigeration load factor setting value, the first flow rate control is performed so that the liquid level of the refrigerant liquid in the space becomes the lower liquid level. 2. The compression refrigerator according to claim 1, wherein the compressor and / or the second flow rate control means are controlled.   The condenser has a space in a lower part capable of storing a predetermined amount of refrigerant liquid capable of controlling the amount of refrigerant stored in the evaporator, and the amount of refrigerant stored in the evaporator only by the second flow rate control means. The compression type refrigerator according to any one of claims 1 to 4, wherein the compressor is controlled.   The economizer has a space in the lower part capable of storing a predetermined amount of refrigerant liquid capable of controlling the amount of refrigerant stored in the evaporator, and the amount of refrigerant stored in the evaporator can be reduced only by the first flow rate control means. It controls, The compression type refrigerator as described in any one of Claims 1 thru | or 4 characterized by the above-mentioned.   A storage container capable of storing a predetermined amount of refrigerant liquid capable of controlling the amount of refrigerant stored in the evaporator is provided in a pipe connecting the evaporator and the economizer, and the evaporator is controlled by the first flow rate control means. The refrigerant holding amount is controlled, or the storage container is provided in a pipe connecting the economizer and the condenser, and the refrigerant holding amount of the evaporator is controlled by the second flow rate control means. The compression type refrigerator as described in any one of 1 thru | or 4.   A subcooler capable of storing a predetermined amount of refrigerant liquid capable of controlling the amount of refrigerant retained in the evaporator is provided below the condenser, and the amount of refrigerant retained in the evaporator is reduced only by the second flow rate control means. It controls, The compression type refrigerator as described in any one of Claims 1 thru | or 4 characterized by the above-mentioned.   The condenser, the economizer, and a pipe connecting the evaporator and the economizer or a combination of a plurality of storage spaces in a storage container provided in the pipe connecting the economizer and the condenser A predetermined amount of refrigerant liquid capable of controlling the refrigerant holding amount is stored, and the refrigerant holding amount of the evaporator is controlled by the first flow rate control means and / or the second flow rate control means. The compression type refrigerator according to any one of claims 1 to 4. In a compression refrigerator equipped with an evaporator, a compressor and a condenser,
Flow rate control means installed in a pipe connecting the evaporator and the condenser;
A control device for controlling opening and closing of the flow rate control means;
Refrigeration load factor calculating means for calculating a refrigeration load factor during operation of the compression refrigerator,
The control device compares the refrigeration load factor calculation value calculated by the refrigeration load factor calculation means with a preset refrigeration load factor setting value, and the refrigerant control amount of the evaporator by the flow rate control means based on the comparison result Compressive refrigerator characterized by controlling. Temperature measuring means for measuring an inlet temperature and an outlet temperature of cold water flowing through the water chamber of the evaporator;
Flow rate measuring means for measuring the flow rate of the cold water,
The said refrigeration load factor calculation means calculates a refrigeration load factor based on the measured value obtained by the said temperature measurement means and the said flow rate measurement means, The Claim 1 thru | or 11 characterized by the above-mentioned. Compression refrigerator.

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