KR102180120B1 - Laboratory Refrigerator - Google Patents

Abstract

The present invention provides a laboratory refrigerator capable of precisely maintaining the temperature and minimizing frost generated in a refrigeration chamber. To this end, the present invention relates to the refrigerator having an inverter motor, a capillary tube, an evaporator, and a condenser. The laboratory refrigerator may include an inverter control unit that computes an expansion temperature difference which is a temperature difference between the external temperature of the refrigeration chamber and a refrigerant flowing in the capillary tube, and lowers the rotating speed of the inverter motor to lower the temperature of the refrigerant discharged from the capillary tube when the expansion temperature difference exceeds a preset reference value, thereby reducing the expansion temperature difference to restrain generation of the frost in the evaporator.

Description

Laboratory refrigerator {Laboratory Refrigerator}

The present invention relates to a method for defrosting frost in a laboratory refrigerator, and more particularly, by controlling the inverter motor to minimize the difference in expansion temperature, which is the temperature difference between the external temperature of the laboratory refrigerator and the refrigerant expanding while flowing through the capillary tube, in the evaporator of the laboratory refrigerator. It relates to a laboratory refrigerator that suppresses the generated frost.

The refrigerator includes a compressor, a condenser, an expander, and an evaporator driven by alternating current, and is configured to cool the refrigerating chamber using a cooling cycle of compression-condensation-expansion-evaporation.

The cooling cycle of a refrigerator is a compression cycle that compresses the refrigerant returned in a gaseous state to high temperature and high pressure, a condensation cycle that condenses and liquefies the compressed gas at high temperature and high pressure, an expansion cycle that reduces the pressure of the condensed gas, and reduces the pressure. It consists of an evaporation cycle in which the true refrigerant is vaporized to absorb heat from the refrigerating chamber to lower the temperature.

Here, the condenser is disposed outside the refrigerator to cool the high-temperature-high-pressure refrigerant, whereas the evaporator is installed inside the refrigerator because the temperature of the refrigerating chamber needs to be lowered. There is a problem that the heat absorbing ability of absorbing heat of the refrigerating chamber decreases. On the other hand, Korean Patent Application Publication No. 10-2012-0022315 has proposed a cooling system that determines whether frost is stuck in the refrigerating compartment using a frost detection device, and performs a defrost operation when frost is stuck in the refrigerating compartment. The cooling system of Korean Patent Application Laid-Open No. 10-2012-0022315 uses a heater or a blower fan to perform a defrost operation that removes frost whenever there is frost, and this defrost operation performs a defrost operation after frost in the refrigerator. As a result, the aspect of preventing sex from getting caught is insufficient.

In addition, in the case of a refrigerator that must maintain a constant temperature, for example, a medical refrigerator for storing blood or plasma, or a laboratory refrigerator for storing reagents and samples, it is difficult to arbitrarily heat the inside of the refrigerator compartment or drive a blower fan to defrost frost. have.

In response, the applicant of the present invention proposed a method for defrosting medical refrigerators and medical refrigerators that suppress frost by equalizing the pressure of the refrigerant discharged from the capillary tube by adjusting the driving time of the compressor driven by AC through registration number 10-1396693. have.

However, as a method of controlling the operating time of a compressor that operates at full power when power is applied, it is difficult to keep the temperature of the refrigerating chamber precisely and uniformly while suppressing frost at the same time. Basically, in order to prevent frost from occurring, the temperature of the evaporator stored in the refrigerator compartment must be raised, whereas the refrigerator compartment must be continuously cooled to maintain the target temperature. have.

Accordingly, the applicant of the present invention intends to achieve the goal of precisely maintaining the temperature of the refrigerating chamber and defrosting frost by finely controlling the rotation amount of the compressor only when necessary by improving the technology previously developed and applied to the product.

An object of the present invention is to finely adjust the rotational speed of the compressor at an appropriate time so that the difference between the expansion temperature, which is the difference between the external temperature of the refrigerating chamber and the refrigerant that expands and flows in the capillary tube, is minimized. It is to provide a laboratory refrigerator that suppresses frost.

Meanwhile, the technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems that are not mentioned are clearly to those of ordinary skill in the technical field to which the present invention belongs from the following description. It will be understandable.

The above object is, according to the present invention, in a refrigerator having an inverter motor, a capillary tube, an evaporator and a condenser, calculating an expansion temperature difference, which is a temperature difference between an external temperature of a refrigerating chamber and a refrigerant flowing through the capillary tube, and the expansion temperature difference is preset. When exceeding the reference value, lowering the rotational speed of the inverter motor to lower the temperature of the refrigerant discharged from the capillary tube, thereby reducing the expansion temperature difference to suppress the generation of frost generated in the evaporator for laboratory further comprising an inverter controller Achieved by the refrigerator.

In addition, the refrigerating chamber further includes a circulation fan that prevents frost from forming in the evaporator when the expansion temperature difference exceeds the preset reference value, wherein the circulation fan lowers the rotation speed of the inverter motor. By operating at the same time, the expansion temperature difference may be further reduced.

In addition, at least a portion of the outer surface of the evaporator is additionally provided with a heat insulating material, the heat insulating material prevents contact between the evaporator and a refrigerant tube supplying the refrigerant to the evaporator, and a cooling phenomenon occurring on the outer surface of the evaporator By reducing, it is possible to suppress the generation of frost generated in the evaporator.

In addition, in order to prevent the expansion temperature difference from increasing when the casement cover of the refrigerator is open, an insulating means for preventing the frost from occurring by slowing the heat transfer rate between the evaporator and the refrigerating chamber may be additionally provided.

In addition, the heat insulating means may be made of expanded polystyrene in a sheet shape having a predetermined thickness, and the thickness of the heat insulating means may be changed in response to a change in temperature in a region in which the refrigerator is disposed.

In addition, the inverter controller may control the amount of rotation of the inverter motor so that the expansion temperature difference is 38°C to 64°C.

In addition, the refrigerant may have a temperature of the refrigerant directed from the capillary tube to the evaporator in the range of 38°C to 58°C when the expansion temperature difference is 38°C to 64°C.

In addition, the inverter controller may perform reduction control on the expansion temperature difference after the internal temperature of the refrigerating chamber reaches a target temperature.

In addition, the inverter control unit may vary the rotational speed of the inverter motor by changing a frequency of an AC applied to the inverter motor, and the frequency may be 10hz to 100hz.

According to the present invention, it is possible to maintain precise temperature while minimizing frost generated in the refrigerating chamber.

On the other hand, the effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those of ordinary skill in the art from the following description. I will be able to.

1 is a perspective view of a laboratory refrigerator according to an embodiment of the present invention.
2 shows a reference diagram for a cooling cycle and a defrost principle according to an embodiment of the present invention.
3 is a conceptual diagram illustrating an example of an inverter control unit.
4 is a perspective view illustrating an internal blower of a laboratory refrigerator according to an embodiment.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this case, it should be noted that the same components in the accompanying drawings are indicated by the same reference numerals as possible. In addition, detailed descriptions of known functions and configurations that may obscure the subject matter of the present invention will be omitted. For the same reason, some elements in the accompanying drawings are exaggerated, omitted, or schematically illustrated.

1 is a perspective view of a laboratory refrigerator according to an embodiment of the present invention, and FIG. 2 is a reference diagram for a cooling cycle and a defrost principle according to an embodiment of the present invention.

1 and 2, the laboratory refrigerator according to the embodiment includes a main body 103 and a refrigerating chamber 101, and the refrigerating chamber 101 contains test drugs, cell tissue samples, blood, and other medical drugs or instruments. It may be provided with a casement cover 102 with a transparent window to confirm.

A condenser 120 may be disposed below the laboratory refrigerator 100. The condenser 120 may be implemented in a form without a radiating fin so that ventilation is not blocked by dust or external contaminants in pharmaceutical companies, laboratories, hospitals, health centers, and other medical facilities in which the laboratory refrigerator 100 is installed. The condensation efficiency of the condenser 120 may be slightly lowered by the removal of the radiating fin, but when considering the storage stability of test drugs, medical drugs, blood, plasma, and instruments that need to be kept at a constant temperature at all times, the installation of a radiating fin Is not essential.

The condenser 120 may be disposed under the housing 103 of the laboratory refrigerator 100. This is due to the lowest temperature on the floor.

The present invention focuses on stably driving the laboratory refrigerator 100 to have efficient cooling performance, rather than focusing on it, and drives a separate heater for frost defrost, or a compressor (inverter motor) for frost defrost. The main focus is to ensure that the temperature stability is not impaired by driving the motor with full power.

Referring to FIG. 2, the laboratory refrigerator according to the embodiment may include an inverter motor 110, a condenser 120, a capillary tube 130, an evaporator 140, and an inverter controller 150. The inverter motor 110 operates by alternating current, and is driven by an alternating current that is adjusted and applied by the inverter control unit 150.

The inverter motor 110 compresses the low-temperature-low pressure refrigerant applied through the evaporator 140 and applies the high-temperature-high pressure to the condenser 120.

The inverter motor 110 may increase the temperature of the refrigerant and apply it to the condenser 120 so that the gaseous refrigerant applied from the evaporator 140 can be easily converted into a liquid state through refrigerant compression. At this time, the refrigerant at point B is in a high temperature-high pressure state.

The gaseous refrigerant compressed in the high-temperature-high pressure state by the inverter motor 110 is cooled in the condenser 120 installed outside the laboratory refrigerator 100, so the refrigerant loses heat at point C and transitions to the low-temperature-high pressure state. .

The liquid refrigerant cooled in the condenser 120 is applied to the capillary tube 130, and the capillary tube 130 has a narrower tube diameter compared to the pipes at points A, B, and C, so from the condenser 120 to the capillary tube 130. The applied refrigerant is resisted by the flow of the refrigerant and the pressure decreases. Accordingly, at point D, the refrigerant enters a low-temperature-low pressure state and is applied to the evaporator 140.

The evaporator 140 receives a refrigerant in a low-temperature-low-pressure state by reducing the pressure in the capillary tube 130 and guides it to the refrigerating chamber 101, and the refrigerant in the low-temperature-low pressure state in the refrigerating chamber 101 absorbs the latent heat required for evaporation. Then, by evaporation, the refrigerant is converted into a gaseous state in a low temperature-low pressure state. Accordingly, the temperature of the refrigerating chamber 101 is lowered, and the refrigerant passing through the evaporator 140 is applied to the inverter motor 110 and compressed while absorbing heat in the refrigerating chamber 101.

On the other hand, in the cooling cycle of compression-condensation-expansion-evaporation each proceeding in the inverter motor 110, the condenser 120, the capillary tube 130, and the evaporator 140, the refrigerating chamber 101 absorbs heat from the refrigerating chamber 101. ) The surface temperature of the evaporator 140 that cools the interior is relatively low compared to the air temperature inside the refrigerating chamber 101, and thus, moisture condensed from the air in the interior space that is relatively high and humid on the surface of the evaporator 140 This can stick and cause frost. The thickness of the castle generated on the surface of the evaporator 140 gradually increases over time, and as a result, the flow of air passing through the evaporator 140 is gradually weakened and the heat exchange capacity of the evaporator 140 decreases. I can.

Conventionally, the heater was operated to defrost frost growing in the evaporator 140, but the operation of the heater can rapidly increase the temperature of the refrigerating chamber 101, as well as the temperature uniformity inside the refrigerating chamber 101. Can hurt.

On the other hand, in the case of performing the pressure control of the capillary tube by driving the compressor with full power according to Korean Registration No. 10-1396693, which the applicant previously applied and applied to the product, the refrigerating chamber ( 101) Although the temperature is stable, there is a disadvantage that the pressure fluctuates within the set value range due to the characteristic that the compressor driven by AC is driven by full power.

Accordingly, the applicant of the present invention devised a method of suppressing frost generated in the evaporator 140 by increasing or decreasing the rotation amount of the inverter motor 110 so as to minimize the temperature difference between the inside and the outside of the refrigerating chamber 101, that is, the expansion temperature difference.

To this end, in the laboratory refrigerator 100 according to the embodiment, one temperature sensor may be provided on the outer side of the refrigerating chamber 101 and in the capillary tube 130, respectively, and a refrigerating chamber using a temperature measured by each of a pair of temperature sensors. By minimizing the temperature difference between the inside and outside of (101), the occurrence of frost is suppressed.

Typically, a refrigerator (or freezer) has the refrigerant applied from the capillary tube 130 to the evaporator 140 to reach -80°C, but in this embodiment, the temperature of the refrigerant applied from the capillary tube 130 to the evaporator 140 Is set to reach -40°C to -60°C, thereby reducing the deviation from the air temperature outside the refrigerating chamber 101. This temperature difference is defined as a "expansion temperature difference" in this specification, and the expansion temperature difference may mean a temperature difference between the temperature of the refrigerant expanded in the capillary tube 130 and the temperature outside the refrigerating chamber 101.

The smaller the difference in expansion temperature, the less the refrigerant passing through the evaporator 140 absorbs heat from the refrigerating chamber 101, and the heat absorbing ability decreases. It is not a problem compared to the purpose of the laboratory refrigerator that should be performed, and by suppressing the occurrence of frost, the function of the laboratory refrigerator for stably operating samples, drugs, blood or cells stored in the refrigerator compartment 101 for a long time can be faithful.

In order to lower the expansion temperature difference, the applicant may change the frequency of the AC power applied from the inverter control unit 150 to the inverter motor. The inverter control unit 150 may have a structure as shown in FIG. 3.

The inverter control unit 150 will be described with reference to FIG. 3.

Referring also to FIG. 3, the inverter control unit 150 may include a rectifying unit 151, a coil unit 152, a feedback unit 153, a control unit (MCU) 154, and a switching unit 155.

The rectifying unit 151 rectifies commercial alternating current (AC) to generate direct current. The generated direct current is applied to the primary coil (marked by ?) of the transformer 152 and is energized through the switching unit 155 that is turned on and off by the pulse control signal CTRL generated by the control unit 154. When the switching unit 155 is controlled on-off by the control unit 154, the direct current generated by the rectifying unit 151 alternates between the flow and blocking of the current in the primary coil of the transformer 152, and at this time, the transformer ( Induction electromotive force is generated in the secondary coil of 152). At this time, the period of the induced electromotive force induced to the secondary coil of the transformer 152 is determined according to the period in which the control unit 154 controls the switching unit 155 on and off. For example, if the control unit 154 shortens the intermittent period for interrupting the switching unit 155, the frequency value of AC induced from the secondary coil of the transformer 152 increases, and vice versa.

The feedback unit 153 may include a resistor or a capacitor, and may lower the voltage of the output terminal AC OUT and provide it to the control unit 154. The control unit 154 determines whether the frequency and voltage of the AC output from the output terminal AC OUT is appropriate by referring to the voltage or frequency value provided from the feedback unit 153, and corrects the pulse control signal CTLR by referring to this. Thus, the intermittent period of the switching unit 155 can be controlled.

According to the intermittent period of the switching unit 155, the frequency range of the AC applied to the inverter motor 110 is varied. Usually, a motor driven by commercial AC is driven according to an AC frequency of 60hz, and it is very difficult to control the speed or rotation amount of the motor. In most cases, when the AC voltage applied to the motor is lowered, the torque required to drive the motor is insufficient and the operation of the motor is stopped. However, the inverter controller 150 according to the embodiment may increase or decrease the rotation amount of the motor by changing the frequency of the AC applied to the motor. For example, the inverter control unit 150 may vary the intermittent period of the switching unit 155 so that the frequency of the AC output from the output terminal AC OUT has a frequency range of 10 hz to 100 hz.

If the frequency of AC output from the output terminal (AC OUT) is 10hz, the inverter motor 110 can rotate with 1/6 rotational amount compared to 60hz of normal commercial AC (AC), and output from the output terminal (AC OUT). If the frequency of AC is 100hz, it is possible to obtain a rotation amount of 1.67 times. In the laboratory refrigerator 100 according to the embodiment, the inverter motor rotates only by a required amount of rotation to compress the refrigerant returned from the evaporator 140. If high compression is not required for the refrigerant returned from the evaporator 140, The frequency of the AC output from the output terminal (AC OUT) can be lowered (eg 30hz). Unlike the method in which the conventional compressor rotates at a rotational speed of 60hz and compresses the refrigerant as full-power, when the compressed refrigerant is returned through the condenser 120, the capillary tube 130 and the evaporator 140 , As the temperature change of the refrigerating chamber 101 is very small, precise temperature control for the inside of the refrigerating chamber 101 becomes possible.

The control unit 154 may be connected to the first sensor 10 for measuring the temperature outside the refrigerating chamber (room temperature) and the second sensor 20 for measuring the temperature of the refrigerant discharged from the capillary tube 130.

The control unit 154 calculates the "expansion temperature difference" by referring to the measured values of the first sensor 10 and the second sensor 20, and the expansion temperature difference increases the frost of the refrigerator compartment 101 while maintaining the temperature of the refrigerator compartment 101. The switching unit 155 may be controlled to suppress generation.

The control unit 154 may control the switching unit 155 so that the expansion temperature difference has a range of 38°C to 64°C. In general, the temperature of the refrigerant discharged from the capillary tube 130 in a refrigerator or freezer is maintained at -70°C to -80°C. Existing refrigerators and freezers are being developed in a way that increases the cooling rate of the refrigerating chamber in a short time.

If the temperature of the refrigerant discharged from the capillary tube 130 to the evaporator 140 is in the line of -70°C to -80°C, and the temperature outside the refrigerating chamber 101 is the temperature of the image (eg 3°C), the temperature of the refrigerant and room temperature The expansion temperature difference with respect to (e.g. 3°C) reaches 73°C to 83°C, and this temperature difference is advantageous for rapidly cooling the refrigerating chamber 101, while frost is generated in the evaporator 140 installed inside the refrigerating chamber 101. May cause lamination.

Instead of slightly lowering the cooling rate of the refrigerating chamber 101, the present applicant focused on ensuring that valuables to be stored in the refrigerating chamber 101, that is, various items sensitive to temperature changes, including reagents, drugs, blood, and cellular tissues, can be safely stored have. Since the storage temperature of drugs (and others) in a laboratory refrigerator or a medical refrigerator is in the range of 2°C to 8°C, it is characterized in that it suppresses the occurrence of frost and maintains a stable temperature rather than rapid cooling of the refrigerator compartment 101.

The control unit 154 controls the switching unit 155 so that the expansion temperature difference ranges from 38°C to 64°C, and when the expansion temperature difference is 38°C to 64°C, the capillary tube 130 in the laboratory refrigerator under development by the applicant In the temperature of the refrigerant directed to the evaporator 140 has a range of -38 ℃ to -58 ℃. When the temperature of the refrigerant discharged from the capillary tube 130 is in the range of -38°C to -58°C, the applicant determines that the effect of suppressing frost stacked on the evaporator 140 is the highest. It is planned to apply this temperature range.

Meanwhile, the control unit 154 may perform refrigeration and frost control according to each of the following items.

1) It is determined whether the internal temperature of the refrigerator compartment 101 has reached the target temperature,

2) After the internal temperature of the refrigerating chamber 101 reaches the target temperature, reduction control is performed so that the expansion temperature difference value becomes the lowest,

3) During the reduction control, when the temperature of the inside of the refrigerator compartment 101 deviates from the target temperature, the reduction control is stopped, and the temperature control is performed so that the temperature inside the refrigerator compartment 101 becomes the target temperature.

That is, the reduction control is performed after the temperature control, and thereafter, temperature control and reduction control may be selectively performed according to the internal temperature of the refrigerating chamber 101.

In the refrigerator compartment of the laboratory refrigerator 100 according to the embodiment described with reference to FIGS. 1 to 3, a blower shown in FIG. 4 is installed so that the temperature of the refrigerator compartment 101 is uniform in the interior of the refrigerator compartment 101 without distinction between upper and lower left and right. May be.

This will be described with reference to FIG. 4.

4 shows an example of the blower 160 shown in FIG. 1. Referring to FIG. 4 together, the blower 160 according to the embodiment is provided with an inclined guide 160a between the blowing fan 161, the blowing fan 161 and the refrigerating chamber wall surface S1, and the inclined guide 160a is provided. The wind direction of the blowing fan 161 can be set by using. The blowing direction of the blowing fan 161 may be directed toward the front of the refrigerating compartment 101, that is, the door direction, which causes the air discharged from the blowing fan 161 to be refracted from the door and directed toward the inside of the refrigerating compartment. It follows to cause convection in the refrigerator compartment 101. If the internal volume of the refrigerating chamber 101 is very large, the blowing fan 161 may be disposed vertically toward the lower side of the refrigerating chamber 101 by the inclined guide 160a, or may face the side wall of the refrigerating chamber 101. . However, it is not limited.

Meanwhile, when the expansion temperature difference exceeds a preset reference value, the refrigerating compartment 101 may additionally include and drive an ice-making compartment circulation fan so that frost does not accumulate on the evaporator 140.

Here, the driving of the ice-making compartment circulation fan is for lowering an expansion temperature difference, which is a temperature difference between a temperature outside the refrigerator compartment and a refrigerant flowing through the capillary tube, and may be performed together with an operation of lowering the rotation speed of the inverter motor.

In addition, an insulating material may be additionally attached to the outer side edge of the evaporator 140.

Here, the heat insulating material attached to the edge of the evaporator 140 prevents direct contact between the evaporator 140 and the refrigerant tube of the evaporator 140, and reduces the supercooling phenomenon at the edge of the evaporator 140 to reduce the phenomenon of frost formation. There is an effect.

In addition, in order to prevent the expansion temperature difference in the open state of the casement cover 102, in the present invention, an insulating means may be additionally provided to prevent frost by slowing the heat transfer rate between the evaporator 140 and the refrigerating chamber 101. have.

Here, the insulating means may be a sheet-shaped expanded polystyrene having a certain thickness, and the expanded polystyrene is interposed only between the evaporator 140 and the refrigerating chamber 101, but adhesives are applied to the upper and lower surfaces of the insulating means, respectively. It may be applied and fixed to be in close contact with the upper surfaces of the evaporator 140 and the refrigerating chamber 101.

In addition, as the insulating means, not only the foamed polystyrene, but also a material having a low heat transfer coefficient may be variously applied, and the thickness of the insulating means is preferably determined according to the data of the temperature performance test result.

On the other hand, the embodiments of the present invention disclosed in the present specification and drawings are merely provided specific examples to facilitate the description of the present invention and to aid understanding of the present invention, and are not intended to limit the scope of the present invention. It is obvious to those of ordinary skill in the art that other modifications based on the technical idea of the present invention may be implemented in addition to the embodiments disclosed herein.

100: laboratory refrigerator 101: refrigerator compartment
110: inverter motor 120: condenser
130: capillary tube 140: evaporator
150: inverter control unit

Claims (9)

In a refrigerator having an inverter motor, a capillary tube, an evaporator, a condenser, and a refrigerator compartment,
An expansion temperature difference, which is a temperature difference between the external temperature of the refrigerating chamber and the refrigerant flowing through the capillary, is calculated,
When the expansion temperature difference exceeds a preset reference value, the rotation speed of the inverter motor is lowered to lower the temperature of the refrigerant discharged from the capillary tube,
In response to a decrease in the temperature of the refrigerant, an inverter control unit for suppressing the generation of frost generated in the evaporator by reducing the expansion temperature difference; further comprising,

The refrigerating chamber further includes a circulation fan that prevents frost from forming in the evaporator when the expansion temperature difference exceeds the preset reference value,
The circulation fan further reduces the expansion temperature difference by operating at the same time as lowering the rotation speed of the inverter motor,

Insulation is additionally provided on at least a part of the outer surface of the evaporator,
The heat insulator prevents contact between the evaporator and a refrigerant tube supplying the refrigerant to the evaporator, reduces a cooling phenomenon occurring on the outer surface of the evaporator, and suppresses the generation of frost generated in the evaporator,

In order to prevent the expansion temperature difference from increasing when the casement cover of the refrigerator is open, heat insulation means for preventing the frost from occurring by slowing the heat transfer speed between the evaporator and the refrigerating chamber is additionally provided, and

The heat insulating means is composed of expanded polystyrene in the shape of a sheet having a predetermined thickness,
The thickness of the heat insulating means can be changed in response to a temperature change amount of a region in which the refrigerator is disposed,

The inverter control unit,
After the internal temperature of the refrigerating chamber reaches a target temperature, reduction control for the expansion temperature difference is performed,

The inverter control unit,
Changing the frequency of the AC applied to the inverter motor to change the rotation speed of the inverter motor,
The frequency is a laboratory refrigerator, characterized in that 10hz to 100hz.
delete delete delete delete The method of claim 1,
The inverter control unit,
The laboratory refrigerator, characterized in that controlling the rotation amount of the inverter motor so that the expansion temperature difference is 38 ℃ to 64 ℃.
The method of claim 6,
The refrigerant is
When the expansion temperature difference is 38 ℃ to 64 ℃, the temperature of the refrigerant from the capillary to the evaporator is 38 ℃ to 58 ℃ laboratory refrigerator, characterized in that.
delete delete

Images