KR101069159B1 - Frost-proof type refrigeration system - Google Patents

Abstract

Room temperature sensor for measuring the temperature in the freezer or refrigerating chamber, pressure sensor for measuring the pressure of the refrigerant discharged from the evaporator, hot gas three-way valve installed between the compressor and the condenser to control the hot gas from the compressor side to the evaporator and A non-imaging cooling system is disclosed that includes a control unit. The cooling system of the present invention controls the hot gas three-way valve when the room temperature is lower than or equal to the set value and sends hot gas of high temperature and high pressure to the evaporator to mix with the low temperature and low pressure refrigerant discharged from the expansion valve so as to prevent frosting. . Since the cooling system of the present invention does not occur the defrosting process, the defrosting process is unnecessary, so that the refrigeration cycle can be performed without interruption, and precise control of the room temperature is possible. Therefore, it can be suitably used in a company using a freezer and a freezer compartment of a pharmaceutical company, a clean room freezer and a freezer compartment for a special purpose, and always maintain the same temperature to keep the stored goods in an optimal state.

Description

Frost-Proof Type Refrigeration System

The present invention relates to a non-imaging type cooling system, and more particularly, to prevent frost from occurring in an evaporator by mixing hot gas of a refrigerant compressed by a compressor with a low temperature low pressure refrigerant liquid passed through an expansion valve in an evaporator. Therefore, the defrosting process is unnecessary, and thus, a refrigeration cycle can be performed without interruption, and a non-frosting type cooling system capable of maintaining a precise and constant temperature of a refrigerating or refrigerating room.

In general, the freezer compartment and the refrigerating compartment is a system in which the refrigerant temperature is lower than the outside air by using a refrigeration cycle in which the refrigerant circulates the compressor, the condenser, the expansion valve (expansion valve) and the evaporator. During the freezer / refrigerator operation, the cool refrigerant passing through the expansion valve passes through the evaporator and moisture in the chamber lands on the evaporator. This conception prevents the heat exchange in the evaporator smoothly, which is a factor that reduces the performance of the refrigerator compartment. Therefore, the defrosting process is often performed in the freezer / refrigerator compartment.

Defrosting methods include spraying defrosting method, electric heater defrosting method and hot gas defrosting method. Sprinkling defrosting method is to remove the frost formed by sending water heated to 25 ℃ or higher to the evaporator. Wet steam is formed only after the defrosting process is completed because dehumidification process forms a lot of moisture vapor in the chamber during defrosting. There is a problem. The electric heater defrosting method is a method of removing frost formed on an evaporator by heating with an electric heater. Although moisture vapor in the room is less than that of the sprinkling method, the electric charge and room temperature increase are provided. Hot gas defrosting method is a method of removing hot frost to the evaporator frosted, the refrigeration cycle of the freezer / refrigerator compartment is complicated, the equipment cost rises. In addition, during this defrosting process, the refrigeration cycle is stopped, so if the temperature in the chamber rises above the set point and the temperature drops below the set point during the operation of the freezer / refrigerator, the operation of the freezer / refrigerator stops, but the temperature in the chamber falls below the set point. There is also a problem. That is, the temperature deviation in a room becomes large. Such deviations in room temperature, especially temperature rises, may cause deterioration of stored foods, drugs, etc., which requires attention.

As a specific example, Japanese Patent Laid-Open No. 1999-0042360 (published June 15, 1999) discloses a defrosting system of a refrigerator using a high temperature refrigerant gas. In this system, the defrost process is performed when the frost is formed over the set thickness. The defrost process removes the frost quickly by supplying the hot refrigerant gas from the compressor to the evaporator immediately without passing through the condenser. Since the refrigeration cycle is not formed during the defrosting process, the temperature in the chamber increases.

Korean Patent Publication No. 10-0703128 (registered on March 28, 2007) discloses an automatic defrosting device for a refrigerator and a freezer. The device automatically performs cooling and defrosting functions as the coolant of low temperature or high temperature and high pressure flows according to the operation mode, and the cooling function is maintained even during the defrosting operation. The apparatus cannot perform the cooling function at the same time as the defrosting operation by the single cold air generating unit and the control unit, but when the plurality of cold air generating units and the control unit are used, the cooling function can be performed simultaneously with the defrosting operation. In this apparatus, a coolant of a hot gas is supplied to one cold air generating unit and a control unit according thereto, and a low temperature coolant is supplied from the other cold air generating unit and the control unit according to the cooling function while a defrost operation is performed. This device has the disadvantage of complicated operation and complicated structure to perform cooling function and defrost function at the same time.

Korean Patent Publication No. 10-0889907 (registered on March 13, 2009) discloses an energy saving hot gas defrosting apparatus and method for a large refrigeration and refrigeration system. This device sends the high temperature, high pressure hot gas refrigerant from the compressor to the evaporator through the bypass branch pipe without passing through the expansion valve to perform the defrosting process and does not send the refrigerant to the condenser. As a result, natural cooling is blocked and the pressure supplied to the evaporator is kept constant, thereby improving the defrosting efficiency.

On the other hand, Patent Publication No. 10-0674531 (registered January 19, 2007) discloses a non-implantation cooling system. This system forms an antifreeze circulation cycle separately from the refrigerant circulation cycle and heat exchanges between the refrigerant circulation cycle and the antifreeze circulation cycle to form a low temperature antifreeze. The outside air sucked by the operation of the fan is directly contacted with the low temperature antifreeze flowed by the wrinkle structure and heat exchanged so that the temperature is lowered and then supplied to the storage compartment such as a showcase. Because of this process, no frosting occurs and the cooling system can be operated continuously. However, this system is not recommended to be applied to refrigerators or showcases with clean foods due to the possibility of contamination by antifreeze during the inflow of external air. Since the capacity of the water remover should be installed on a summer basis and an electric heater or other heating medium is required to increase the temperature, there is a problem in that an increase in the capacity and the system are complicated, and the installation cost is high, thereby increasing the economic burden on the consumer.

The present invention has been made to solve the above problems of the prior art. Accordingly, an object of the present invention is to eliminate the frosting process is not generated in the evaporator by mixing the hot gas of the refrigerant compressed by the compressor with the low-temperature low-pressure refrigerant liquid passed through the expansion valve in the evaporator, so that the defrosting process is unnecessary, thereby freezing The cycle can be performed without interruption, and to provide a non-implanted cooling system that can maintain a precise and constant temperature inside the freezer compartment or the refrigerating compartment.

According to an aspect of the present invention, there is provided a non-imaging type cooling system that includes a compressor for compressing a refrigerant, a condenser for condensing the refrigerant discharged from the compressor, an expansion valve for expanding the refrigerant discharged from the condenser, and the expansion. And an evaporator for evaporating the refrigerant discharged from the valve. The cooling system includes an indoor temperature sensor measuring a temperature in a freezing compartment or a refrigerating chamber, a pressure sensor measuring a pressure of a refrigerant discharged from the evaporator, and a hot gas provided between the compressor and the condenser to transfer the hot gas from the compressor side to the evaporator. And a hot gas three-way valve and a control unit for controlling sending, wherein the control unit controls the hot gas three-way valve when the room temperature becomes lower than a set value, and sends the high temperature and high pressure hot gas to the evaporator to discharge the low temperature from the expansion valve. The cooling system is operated by mixing with a low pressure refrigerant so that no frosting occurs.

On the inlet side of the expansion valve is provided with a solenoid valve for adjusting the flow rate of the low-temperature low-pressure refrigerant entering the expansion valve, the control unit controls the solenoid valve when the room temperature is below the set value to enter the expansion valve It is desirable to reduce the flow rate of the refrigerant.

The amount of change of the inflow amount of the hot gas flowing into the evaporator is preferably controlled by the pressure of the refrigerant measured by the pressure sensor.

The inflow amount of the hot gas flowing into the evaporator is preferably adjusted according to the set value of the room temperature.

The set temperature of the room temperature of the cooling system is a temperature in the range of 2 ~ 8 ℃, the hot gas such that the difference between the evaporation temperature of the refrigerant and the room temperature in the evaporator is in the range of 3 ~ 4 ℃ when the room temperature is at the set value Inflow of may be controlled.

The low temperature and low pressure refrigerant passing through the expansion valve is introduced into the evaporator coil through a liquid pipe distributor connected to a plurality of liquid pipes connected to the plurality of evaporator coils, and the hot gas of the high temperature and high pressure is connected to the plurality of evaporator coils. The hot gas pipe is connected to the evaporator coil through a hot gas distributor connected to the low temperature low pressure refrigerant and the high temperature high pressure hot gas, or the low temperature low pressure refrigerant and the high temperature high pressure hot gas are mixed using a mixer.

It is preferable that the circulation of air is generated by the fin filter unit and the air duct provided in the chamber of the cooling system so that the distribution of the interior temperature is kept constant.

The cooling system comprises at least two compressors, and the compressors are preferably operated alternately without stopping.

Since the non-imaging type cooling system of the present invention enables precise control of the room temperature of the freezer compartment or the refrigerator compartment, it can always be suitably used in a company using a freezer and refrigerator compartment of a pharmaceutical company, a clean room freezer compartment and a refrigerator of a special purpose. Maintaining the same temperature keeps the goods in optimal condition.

1 is a view showing a schematic configuration of a non-implantation type cooling system according to an embodiment of the present invention.
2 is a view showing a configuration for forming an air circulation in the refrigerating chamber of the cooling system of the present invention.
3 is a view showing a distribution configuration of refrigerant liquid and hot gas for a plurality of evaporator coils in the cooling system of the present invention.
4 is a view illustrating a configuration in which a refrigerant liquid and hot gas are mixed in a cooling system of the present invention and then distributed to a plurality of evaporator coils.
5 is a T (temperature) -S (entropy) diagram showing a refrigeration cycle operating in the cooling system of the present invention.

Hereinafter, the present invention will be described with reference to the drawings.

As shown in Fig. 1, the non-landing type cooling system of the present invention includes a compressor 1, a condenser 2, an expansion valve 8 and an evaporator 3, like a conventional cooling system. As shown in FIG. 5, the refrigerant entering the compressor 1 may be a low temperature low pressure saturated steam (state 1). The low temperature low pressure refrigerant saturated steam (state 1) is compressed by a compressor to form high temperature high pressure refrigerant vapor (state 2). The refrigerant vapor then enters the condenser 2 to heat transfer around and turn into a saturated liquid (state of 3). Normally the pressure is maintained at this point. As the refrigerant of the saturated liquid passes through the expansion valve (8), the temperature and the pressure decrease, and the saturated liquid and the saturated steam are mixed (a state of 4). Thereafter, the refrigerant passes through the evaporator (3), takes heat away from the surroundings, evaporates, and is converted back into saturated steam (state 1). This refrigeration cycle is repeated. Here, the low temperature low pressure refrigerant means the state of the refrigerant from the 4 state to the 1 state in FIG. 5, and the high temperature high pressure refrigerant means the state of the refrigerant from the 2 state to the 3 state. In an ideal refrigeration cycle, the temperature and pressure are kept constant.

In FIG. 1, the liquid separator 5 is used to separate the refrigerant gas and the refrigerant liquid, and the oil separator 6 is used to separate the refrigerant and the refrigerant oil. The receiver 4 is a means for storing the saturated liquid 3 (state of 3), and the dryer 11 is for removing moisture contained in the refrigerant. The saturated liquid from which moisture is removed is supplied to the expansion valve 8 through the liquid pipe 17 via the sight glass 12. At this time, the valve 13 and the solenoid valve 7 is installed to block or adjust the amount of the refrigerant supplied to the expansion valve (8).

Now, the features of the present invention will be described. The non-imaging cooling system of the present invention includes an indoor temperature sensor 16a for measuring a temperature in a freezer compartment or a refrigerating compartment, a pressure sensor 16b for measuring the pressure of a refrigerant discharged from the evaporator 3, a compressor 1, and a condenser ( 2) a hot gas three-way valve 9 and a control unit 14 installed between the two to regulate the sending of the hot gas refrigerant from the compressor 1 side to the evaporator 3. The control unit 14 typically consists of a programmable logic controller (PLC).

The control unit 14 controls the hot gas three-way valve 9 when the room temperature reaches or lower than the set value, and sends the hot gas of high temperature and high pressure to the evaporator 3 through the hot gas pipe 19 to be discharged from the expansion valve 8. The cooling system is operated by mixing with the low temperature and low pressure refrigerant which does not occur. The amount of hot gas supplied can be appropriately adjusted according to the conditions, as described below. At this time, in addition to the low-temperature low-pressure refrigerant from the expansion valve (8) to control the hot gas three-way valve (9) to supply hot gas to the evaporator (3), the low-temperature low-pressure refrigerant from the expansion valve (8) By adjusting the amount, more precise control is possible. That is, the controller 14 may reduce the flow rate of the low-temperature low-pressure refrigerant entering the expansion valve 8 by controlling the solenoid valve 7 installed at the inlet side of the expansion valve 8 when the room temperature becomes a set value or less. have.

For pharmaceutical companies to store drugs or ingredients, or to keep fresh food, the room temperature should be around 2-8 ° C. The temperature in this range can set the setpoint of the room temperature. In order to maintain the room temperature at this setpoint, the evaporator temperature in the evaporator of the cooling system is lower than this, and heat exchange between the evaporator and the air in the room must be made. However, if the difference between the evaporation temperature and the room temperature is too large, heat exchange between them rapidly causes the room temperature to be much lower than the set point, and such rapid cooling causes frost on the evaporator surface. That is, it is difficult to perform precise control of the room temperature. Conventional cooling systems are operated in this way, when the cooling occurs due to rapid cooling, the refrigeration cycle is stopped and the defrosting process is executed. On the other hand, if the difference between the evaporation temperature and the room temperature is too small, since the cooling proceeds too slowly, it cannot be practically used because it is difficult to obtain a substantial cooling effect.

The non-imaging type cooling system of the present invention achieves precise control of the room temperature without occurrence of frost by cooling rapidly when the room temperature is high and slow cooling when the room temperature reaches a set value.

To this end, the operation of the cooling system of the present invention is performed by the controller 14 as follows. If the temperature in the room is higher than the set point, it is operated along the path of a conventional refrigeration cycle, that is, the path 1-> 2-> 3-> 4-> 1 in FIG. At this time, the hot gas three-way valve 9 is open only to the condenser 2 on the compressor 1 side and closed to the evaporator 3 so that no hot gas is supplied to the evaporator. When the room temperature reaches the set value by such cooling, the control unit 14 controls the hot gas three-way valve 9 to supply hot gas to the evaporator, and also controls the solenoid valve 7 to be discharged from the expansion valve 8. The amount of low-temperature low-pressure refrigerant supplied to the evaporator 3 is reduced.

According to this operation, the temperature and pressure of the refrigerant flowing into the evaporator 3 increase. This causes a decrease in the performance of cooling the indoor air, so rapid cooling of the indoor air is prevented. At this time, if the evaporation temperature and the pressure in the evaporator 3 is properly adjusted, the temperature of the room can be maintained almost at the set point. If the difference between the room temperature and the evaporator temperature, that is, the evaporation temperature of the refrigerant, is about 3-4 ° C., the room temperature does not drop significantly even if it is maintained or cooled at that temperature. The heat exchange between the evaporator and the indoor air is slow if the insulation is slow, but ultimately the temperature of the indoor air is cooled down to the temperature of the evaporator. A small temperature difference does not cause a substantial drop in room temperature. That is, the heat exchange due to such a small temperature difference is only to compensate for the heat loss.

In the non-imaging type cooling system of the present invention, when the room temperature reaches a set value, the amount of hot gas supplied to the evaporator 3 and its change amount and the low temperature low pressure refrigerant discharged from the expansion valve 8 into the evaporator The inflow rate is controlled by the pressure of the refrigerant measured by the pressure sensor 16b and the set value of the room temperature.

More specifically, referring to FIG. 5, when hot gas of high temperature and high pressure is mixed in the evaporator 3 in addition to the low temperature low pressure refrigerant 4 discharged from the expansion valve 8, the evaporator temperature and pressure of the refrigerant in the evaporator 3. Rises. As an example, the state of the refrigerant in FIG. 5 becomes a state of five. When the hot gas of high temperature and high pressure is mixed more, the evaporation temperature and pressure of the refrigerant are further increased, that is, the state of 5 ". The process of mixing the low temperature and low pressure refrigerant and the hot gas of high temperature and high pressure is a spontaneous process that increases entropy. The higher the evaporator temperature and pressure in the evaporator, the lower the heat exchange performance of the evaporator, because the evaporator reduces heat exchange with the indoor air, preventing rapid cooling and keeping the room temperature almost constant when the evaporator is at the proper evaporation temperature. If the flow rate of the low temperature low pressure refrigerant discharged from the expansion valve 8 is reduced and the high temperature high pressure hot gas is introduced to the same temperature and pressure as the state of 5, the ratio of the hot gas in the refrigerant of the evaporator is larger than the state of 5 The entropy is further increased, i.e., at 5 '. This means that the rate of saturated steam in the air is high, which means that the heat exchange performance of the evaporator refrigerant is low, so that when the room temperature is at or below the set point, the refrigeration cycle is 4-> 5 or 5 '-> 1'-> 2 '-> 3-> 4 or 4-> 5 "-> 1"-> 2 "-> 3-> 4 path. When the refrigerator door is opened and the room temperature is higher than the set point, it is operated again in the normal refrigeration cycle, that is, 4-> 1-> 2-> 3-> 4.

When the set value of the room temperature to be kept constant is determined, it is possible to determine the condition of the evaporator refrigerant to the extent that the room temperature does not decrease while performing heat exchange with the room air, that is, to compensate for the heat loss during the heat exchange. This may be determined by the amount of heat exchanged refrigerant, evaporation temperature and entropy, and the evaporation temperature and entropy may be determined by inflow of hot gas and inflow of refrigerant at low temperature and low pressure. Whether the determined evaporation temperature and pressure has been reached can be confirmed by comparing with the measured value of the pressure sensor 16b, and the ultimate room temperature control can be performed by comparing the measured value of the indoor temperature sensor 16a with the set value. If the room temperature is lower than the set point, increasing the absolute or relative inflow of hot gas can increase the room temperature by lowering the heat exchange performance of the evaporator. For example, if the evaporation temperature is set to 3-4 ° C. below the room temperature, the evaporation pressure is determined accordingly. Whether this evaporation pressure has been reached is checked by comparison with the measured value of the pressure sensor 16b. The amount of energy that the refrigerant heat exchanges in the evaporator can then be calculated and the amount of refrigerant in the evaporator, the amount of hot gas and the amount of refrigerant entering the low temperature low pressure can be determined according to the amount of energy. Theoretically, hot gas inflow can be determined by calculating the amount of heat exchanged energy, but in actual control, more precise control can be achieved by adjusting the rate of change of hot gas inflow based on the room temperature measurement and the pressure sensor. have. For example, when the room temperature reaches the set value, the control may be performed by increasing the rate of change of the hot gas inflow and decreasing the rate of change of the hot gas inflow closer to the expected evaporation pressure.

On the other hand, when hot gas is added to the evaporator, the evaporation pressure is increased. If the evaporation pressure is too high, the compressor may be overwhelmed and cause damage to the compressor. Therefore, it is desirable to raise the evaporation pressure only if possible to a pressure within the limits allowed by the compressor. To this end, it is to reduce the inflow of refrigerant at low temperature and low pressure with the input of hot gas. However, in some cases, the suction pressure adjusting valve 10 is installed on the suction pipe 18 connecting the evaporator 3 and the liquid separator 5 in case the pressure of the evaporator must be increased beyond the limit permitted by the compressor. It is desirable to. This means that if the evaporation pressure is too high, some of the saturated steam of the refrigerant from the evaporator is branched and only the refrigerant corresponding to the pressure allowed by the compressor is sent to the liquid separator 5.

In winter, the pressure of the refrigerant does not rise well, so the blower controller (FSC) 15 controls the blower to form a high pressure of 15-18 kg / cm ² to maintain a high pressure when the hot gas is introduced into the evaporator (3). To compensate for the temperature.

In the evaporator of a conventional refrigerating chamber, one distributor is installed, but in the case of the refrigerating chamber of the non-implantation type cooling system according to the present invention, as shown in FIG. 3, a liquid pipe distributor 3-2 and hot gas connected to a plurality of distribution pipes are shown. The distributor 3-3 is installed together and such distribution tubes are connected to the evaporator coils 3-1, respectively, so that the low pressure refrigerant and the high pressure hot gas are uniformly mixed, or as shown in FIG. 3-6) and the check valve 3-7 are used to mix the low pressure refrigerant and the high pressure hot gas, and the room temperature is kept uniform without variation. 3 and 4 omit the connection of the distribution tubes to the middle of the evaporator coils 3-1.

In order to keep the room temperature constant and to form a good air distribution and a clean room in the room, as shown in FIG. 2, the shock filter unit 20 is installed in the room and the shock filter unit 20 is provided with a duct 21. ) Is connected. Thus, the air from the side enters the fan filter unit 20 through the duct 21 and the clean air passing through the fan filter unit is formed into a clean room by the air circulation into the room, and the air distribution is good in the room. And a uniform temperature distribution. In order to maintain a uniform temperature distribution, the number of shock filter units should be estimated in consideration of the sufficient number of ventilations.

A spare compressor is added to avoid one compressor running for a long time and these two compressors can be operated to run alternately for a period of time, for example 6-8 hours. As a result, the compressor can be prevented from being burned out for a long time.

1: compressor 2: condenser
3: evaporator 3-1: evaporator coil
3-2: liquid pipe distributor 3-3: hot gas distributor
3-4: refrigerant liquid inlet 3-5: hot gas inlet
3-6: Mixer 3-7: Check Valve
4: receiver 5: liquid separator
6: oil separator 7: solenoid valve (electromagnetic valve)
8: Expansion valve (expansion valve) 9: Hot gas three-way valve (three-way valve)
10: suction pressure adjusting side 11: dryer
12: site glass 13: valve
14: PLC 15: Blower controller
16a: room temperature sensor 16b: pressure sensor
17: liquid pipe 18: suction pipe
19: hot gas pipe 20: shock filter unit
21: air duct

Claims (8)

A cooling system comprising a compressor for compressing a refrigerant, a condenser for condensing the refrigerant discharged from the compressor, an expansion valve for expanding the refrigerant discharged from the condenser, and an evaporator for evaporating the refrigerant discharged from the expansion valve. ,
The cooling system includes an indoor temperature sensor measuring a temperature in a freezing compartment or a refrigerating chamber, a pressure sensor measuring a pressure of a refrigerant discharged from the evaporator, and a hot gas provided between the compressor and the condenser to transfer the hot gas from the compressor side to the evaporator. And a hot gas three-way valve and a control unit for controlling sending, wherein the control unit controls the hot gas three-way valve when the room temperature becomes lower than a set value, and sends the high temperature and high pressure hot gas to the evaporator to discharge the low temperature from the expansion valve. The cooling system is operated by mixing with a low-pressure refrigerant to prevent frosting, and the change amount of the inflow amount of the hot gas flowing into the evaporator is controlled by the pressure of the refrigerant measured by the pressure sensor. Implantation cooling system. The method of claim 1,
On the inlet side of the expansion valve is provided with a solenoid valve for adjusting the flow rate of the low-temperature low-pressure refrigerant entering the expansion valve, the control unit controls the solenoid valve when the room temperature is below the set value to enter the expansion valve Non-imaging cooling system, characterized in that to reduce the amount of refrigerant flow. delete The method of claim 1,
Non-implantation type cooling system, characterized in that the inflow of the hot gas flowing into the evaporator is adjusted according to the set value of the room temperature. The method of claim 1,
The set temperature of the room temperature of the cooling system is a temperature in the range of 2 ~ 8 ℃, the hot gas such that the difference between the evaporation temperature of the refrigerant and the room temperature in the evaporator is in the range of 3 ~ 4 ℃ when the room temperature is at the set value Non-imaging type cooling system, characterized in that the inflow of the is controlled. The method of claim 1,
The low temperature and low pressure refrigerant passing through the expansion valve is introduced into the evaporator coil through a liquid pipe distributor connected to a plurality of liquid pipes connected to the plurality of evaporator coils, and the hot gas of the high temperature and high pressure is connected to the plurality of evaporator coils. The hot gas pipe is connected to the evaporator coil through a hot gas distributor connected to the low-temperature low-pressure refrigerant and high-temperature high-pressure hot gas, or a low-temperature low-pressure refrigerant and high-temperature high-pressure hot gas is mixed using a mixer Non implantation cooling system. The method of claim 1,
Non-imaging type cooling system, characterized in that the circulation of the air is generated by the fin filter unit and the air duct provided in the room of the cooling system to maintain a constant distribution of room temperature. The method of claim 1,
And said cooling system comprises at least two said compressors, said compressors being operated alternately without interruption.

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