KR20040053696A - Refrigerating system using two stage refrigerating cycle - Google Patents

Abstract

PURPOSE: A cryogenic freezing system using a binary cooling cycle is provided to prevent overload of a compressor and a condenser, thereby realizing a normal operation of a cryogenic freezing system. CONSTITUTION: A high stage cycle part(100) includes a compressor(110) compressing a refrigerant, a condenser(120) condensing the compressed refrigerant, an expansion valve(130) reducing a pressure of the condensed refrigerant, and an evaporator(140) executing heat exchange by the refrigerant supplied from the capillary. A low stage cycle part(200) includes a condenser exchanging heat with the evaporator of the high stage cycle in an intermediate heat exchanger. A bypass line(150) is installed to connect a rear end of the condenser and a front end of the compressor. A pressure sensor is installed in the bypass line for measuring a pressure. An opening and shutting element(154) opens and shuts the bypass line based on the sensed pressure.

Description

Refrigerating system using two stage refrigerating cycle

The present invention relates to a refrigeration cycle, and more particularly to a deep-temperature refrigeration system using a binary refrigeration cycle configured to relieve the load of the compressor of the high temperature cycle while using a binary refrigeration cycle to achieve deep (cold) refrigeration. It is about.

The refrigerator which stores general food generally has a refrigerator compartment and a freezer compartment. The temperature of such a common freezing compartment and a refrigerating compartment is reduced to a temperature at which freezing storage of food is required.

However, since there are objects that should be stored at a very low temperature (ultra low temperature or deep temperature) in a hospital or a laboratory, not a general food, a temperature inside the high temperature can be maintained at a low temperature of -60 to -70 ° C or lower. There is a need for freezers.

According to this need, a deep-temperature refrigeration system has been proposed that can maintain a high internal temperature at a very low temperature by using a two-way refrigeration cycle composed of a high temperature cycle portion and a low temperature cycle portion, and FIG. 1 is a schematic diagram showing the principle thereof.

As shown, the binary refrigeration cycle is composed of a high temperature cycle portion 10 and a low temperature cycle portion 20. The high temperature cycle portion 10, the compressor 12 for compressing the refrigerant in the gas state, the condenser 14 for dissipating and condensing the heat of the refrigerant compressed in the compressor, the low-pressure pressure of the liquid refrigerant condensed in the condenser Expansion valve 16, and an evaporator 18 that generates cold air by evaporating the low-temperature low-pressure refrigerant while passing through the components. The high temperature cycle portion 10 has a temperature characteristic of a refrigerant almost similar to that of a general refrigeration cycle, and the evaporator 18 maintains a low temperature, but compared to the evaporator 28 of the low temperature cycle portion 20 described later. Has a relatively high temperature.

The low temperature cycle section 20 includes a compressor 22 for compressing a gaseous refrigerant, a condenser 24 for condensing the compressed refrigerant, an expansion valve 26 for lowering the condensed refrigerant, and a low temperature low pressure refrigerant. It includes an evaporator 28 for performing a heat exchange using. Here, the evaporator 28 of the low temperature cycle section 10 should be kept at a lower temperature than that to form the ultra low temperature (for example, low temperature of -60 ~ -70 ℃ or less) required in the freezing space. do.

The ultra-low temperature state of the low temperature cycle portion 20 can be maintained such that the evaporator 18 of the high temperature cycle portion 10 and the condenser 24 of the low temperature cycle portion 20 are an intermediate heat exchanger such as a cascade condenser. This is because sufficient heat exchange is performed inside the 30, so that the liquid refrigerant in a low temperature state can be generated and supplied to the condenser 24. Of course, the type of the coolant in the low temperature cycle portion 20 should also be selected to have a vaporization characteristic capable of sufficiently forming a low temperature.

In a deep-temperature refrigeration system using such a dual cycle, it is important to what extent the evaporator of the low-temperature cycle can be reduced. This is because lowering the temperature in the refrigerator to the low temperature described above is substantially influenced by the temperature of the evaporator of the low temperature cycle.

In the intermediate heat exchanger 30, the evaporator 18 of the high temperature cycle and the condenser 24 of the low temperature cycle 20 perform heat exchange, and the condenser 24 of the low temperature cycle is substantially in a high temperature state. to be. For example, since the temperature of the refrigerant leaving the low temperature cycle compressor is about 80 ° C, the condenser 24 is also at a very high temperature. The evaporator 18 of the high temperature cycle 10 performing heat exchange with the condenser 24 in such a high temperature state becomes substantially very high temperature state. That is, the temperature of the refrigerant exiting the evaporator 18 after heat exchange with the condenser 24 is much higher than the evaporator of the refrigeration cycle of the conventional refrigerator.

Therefore, the refrigerant exiting the evaporator 18 has a high temperature and a high pressure. In this state, the refrigerant passes through the compressor 12 and the condenser 14 sequentially. As such, when the refrigerant flowing into the compressor 12 in the high temperature cycle becomes too high, the compressor may exceed the capacity of the compressor, thereby making it difficult to operate normally. Of course, although the compressor 12 may operate within a certain operating time, due to the evaporation pressure in the evaporator and the condensation pressure in the condenser, the compressor 12 may not be operated normally, and thus the deep freezer itself is substantially free. The operation reliability of may be a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a deep-temperature refrigeration system that enables a normal operation of a compressor despite the high pressure state of the refrigerant from the evaporator.

1 is a schematic diagram of a refrigeration cycle using a conventional two-way cycle.

Figure 2 is a schematic diagram of a high temperature cycle according to the present invention.

Explanation of symbols on the main parts of the drawings

100 ..... High Temperature Cycle 110 ..... Compressor

120 ..... Condenser 130 ..... Expansion valve

140 ..... evaporator 150 ..... bypass line

152 ..... reservoir `154 ..... solenoid valve

156 ..... Pressure switch

The deep-temperature refrigeration system using a binary refrigeration cycle according to the present invention for achieving the above object, the compressor for compressing the refrigerant, a condenser to condense the compressed refrigerant, expansion valve for reducing the condensed refrigerant, supply from the expansion valve A high temperature cycle including an evaporator for performing heat exchange by the refrigerant; And a low temperature cycle portion including an evaporator of the high temperature cycle and a condenser that heat exchanges inside the intermediate heat exchanger; A bypass line is provided to connect the rear end of the condenser and the front end of the compressor, and the bypass line opens and closes the bypass line based on a pressure measuring means for measuring pressure and a pressure value detected by the pressure measuring means. Characterized in that the opening and closing means.

And according to the embodiment of the pressure measuring means, it is composed of a pressure switch having a pressure sensor therein.

And according to the embodiment of the opening and closing means, it is composed of a solenoid valve opened and closed by an electrical signal from the pressure switch.

Next, the present invention will be described in more detail with reference to the embodiments shown in the drawings.

Figure 2 is a schematic diagram showing only the high temperature cycle according to the present invention. The evaporator 140 of the high temperature cycle according to the present invention is installed inside the intermediate heat exchanger 200 to perform heat exchange with the condenser 14 of the low temperature cycle.

Here, the configuration of the intermediate heat exchanger 200 and the condenser 14 is substantially the same as the conventional. In addition, the configuration of the low temperature cycle itself including the condenser 14 is also substantially the same as in the prior art, and detailed description thereof will be omitted in order to avoid duplication of the same part.

The high temperature refrigerant evaporated in the evaporator 140 flows into the compressor 110. The refrigerant compressed in the compressor 110 will be liquefied while condensing in the condenser 120. The liquid refrigerant from the condenser 120 is reduced in pressure while passing through the expansion valve 130, and then flows back into the evaporator 140.

According to the present invention, a bypass line 150 is formed between the rear end (downstream side) of the condenser 120 and the front end (upstream side) of the compressor 110. The bypass line 150 is installed to allow the refrigerant to pass when the compressor 110 is overloaded.

The bypass line 150 has an inlet between the condenser 120 and the expansion valve 130, and is connected to the front end of the compressor 110 to the outlet, in the direction of the arrow as shown The refrigerant can flow. That is, the refrigerant passing through the bypass line 150 in the direction of the arrow flows into the reservoir 152 installed at the rear end side of the bypass line 150, and the refrigerant in the low pressure state exiting the reservoir 152 is It can be introduced back into the compressor (110).

In addition, the inlet side of the bypass line 150 is provided with a pressure switch 156 with a built-in pressure sensor for sensing the pressure. A valve 154 operated by the pressure switch 156 is installed at the rear end thereof, and the valve 154 may use a solenoid valve operated by an electrical signal. That is, when the pressure value detected by the pressure switch 156 exceeds the set value (pressure value set to operate the compressor normally), the pressure switch 156 sends a predetermined signal to the valve 154. Valve 154 can be opened.

A reservoir 152 is provided at the rear end of the valve 154. The reservoir 152 stores a predetermined amount of refrigerant, and stores the refrigerant supplied to the compressor again, and has a function of a buffer. The inside of the reservoir 152 may accommodate a certain amount of refrigerant, thereby maintaining the refrigerant in a relatively low pressure state. In addition, the reservoir 152 introduces the refrigerant in the low pressure state into the compressor 110 according to the amount of the refrigerant introduced therein.

Naturally, the compressor 110 has a set allowable pressure. When the pressure exceeding the allowable pressure is applied, the overload state becomes impossible and the normal operation is impossible. The pressure switch 156 installed in the bypass line 150 detects the pressure of the refrigerant at the rear end of the condenser 120 using a built-in pressure sensor. Substantially, the pressure value detected by the pressure switch 156 becomes the same pressure value as the pressure discharged from the condenser 120.

In addition, the high pressure value detected by the pressure switch 156 has the same meaning as the high pressure value applied to the compressor 110, so that the compressor 110 is substantially overloaded when the binary refrigeration system is operated. It means that there is. As such, when the compressor is overloaded, the normal operation of the compressor 110 is substantially impossible.

Therefore, when the pressure value detected in this way exceeds the set value, the valve 154 is opened by the signal from the pressure switch 156. When the valve is opened, a portion of the refrigerant exiting the condenser 120 flows in the direction of the arrow along the bypass line 150.

Then, it flows into the reservoir 152 installed downstream of the bypass line 150 or through the front end (upstream side) of the compressor 110 according to the amount of the refrigerant inside the reservoir 152. It is introduced into the compressor 110.

In the high temperature cycle, the front end, that is, the upstream side of the compressor 110, is relatively low pressure. That is, the refrigerant passing through the compressor 110 is in a high pressure state because it is compressed. Therefore, from the rear end of the compressor 110, the refrigerant flowing before the expansion valve 130 is substantially a high pressure state. And the refrigerant in the line before the compressor 110 is relatively low compared to the refrigerant in this portion.

According to the present invention, as the high-pressure refrigerant is bypassed through the bypass line 150 to the front end of the reservoir 152 and / or the compressor 110, the pressure is substantially expanded after the compressor 110. The high pressure state of the refrigerant in front of the valve 130 can be solved. By the bypass line 150 of the present invention, by bypassing the refrigerant in the high pressure state (from the rear end of the compressor to the front end of the expansion valve), it will be possible to reduce the refrigerant pressure of the portion.

When the high pressure refrigerant is bypassed through the bypass line 150 as described above, the pressure of the portion is substantially lowered. In this case, the pressure of the refrigerant sensed by the pressure switch 156 becomes low compared with the previous state. When the pressure sensed by the pressure switch 156 is low, the pressure switch 156 will be closed by controlling the valve 154 again. When the valve 154 is closed, the high temperature cycle of the present invention will operate as before. That is, the refrigerant exiting the evaporator 140 passes through the compressor 110, the condenser 120, and the expansion valve 130 to become a liquid refrigerant at a low temperature and low pressure, and then returns to the evaporator 140. Therefore, the deep-temperature refrigeration system using the binary cycle of the present invention will be able to operate normally.

As described above, the present invention forms a bypass line 150 between the rear end of the condenser 120 and the front end of the compressor 110, the high pressure is formed there is a risk of overloading the compressor 110 and It can be seen that the technical subject is to reduce the pressure through the pass line 150.

Within the scope of the basic technical idea of the present invention, many other modifications will be possible to those skilled in the art, and the present invention should be interpreted based on the appended claims.

According to the present invention as described above, it can be seen that it is possible to prevent the compressor and the condenser from being overloaded by the bypass line described above. Therefore, it is possible to expect the effect of enabling the normal operation of the deep-temperature refrigeration system using the binary refrigeration cycle, which can substantially increase the reliability of the product.

Claims (4)

A compressor 110 for compressing the refrigerant, a condenser 120 for condensing the compressed refrigerant, an expansion valve 130 for lowering the condensed refrigerant, and an evaporator 140 for performing heat exchange by the refrigerant supplied from the expansion valve. A high temperature cycle including; A low temperature cycle including an evaporator of the high temperature cycle and a condenser 14 for heat exchange in the intermediate heat exchanger; A bypass line 150 is provided to connect the rear end of the condenser and the front end of the compressor, and the bypass line includes a pressure measuring means for measuring pressure and a bypass line based on a pressure value detected by the pressure measuring means. Deep cooling system using a binary refrigeration cycle, characterized in that for installing the opening and closing means for opening and closing. The deep-temperature refrigeration system according to claim 1, wherein the pressure measuring means comprises a pressure switch having a pressure sensor therein. The deep-temperature refrigeration system according to claim 2, wherein the opening and closing means comprises a solenoid valve that is opened and closed by an electrical signal from the pressure switch. The deep-temperature refrigeration system according to any one of claims 1 to 3, further comprising a reservoir provided on the bypass line downstream of said opening and closing means for storing a refrigerant.