CN113432325A

CN113432325A - Cascade compression refrigeration system and refrigeration equipment with same

Info

Publication number: CN113432325A
Application number: CN202010208879.4A
Authority: CN
Inventors: 赵向辉; 孙永升; 陶瑞涛; 刘煜森; 冯茹丹
Original assignee: Qingdao Haier Smart Technology R&D Co Ltd; Haier Smart Home Co Ltd
Current assignee: Qingdao Haier Smart Technology R&D Co Ltd; Haier Smart Home Co Ltd
Priority date: 2020-03-23
Filing date: 2020-03-23
Publication date: 2021-09-24

Abstract

The invention provides a cascade compression refrigeration system and a refrigeration device with the same, wherein the cascade compression refrigeration system comprises: a high-temperature-stage refrigeration cycle circuit in which a first refrigerant flows and an evaporation unit is provided; the low-temperature-stage refrigeration circulation loop is used for circulating a second refrigerant and is internally provided with a low-temperature-stage compressor, a condensing part, a low-temperature-stage evaporation tube and a heat exchange assembly; the heat exchange assembly comprises: a heat releasing part arranged between the low-temperature stage compressor discharge port and the condensing part; the heat absorption part is arranged between the low-temperature-stage evaporation pipe and a low-temperature-stage compressor suction inlet; the heat absorbing part is used for promoting the second refrigerant flowing through the heat absorbing part to absorb the heat of the second refrigerant flowing through the heat radiating part to increase the temperature, so that the suction temperature of the low-temperature stage compressor can be increased, and the heat load of the high-temperature stage refrigeration cycle can be reduced.

Description

Cascade compression refrigeration system and refrigeration equipment with same

Technical Field

The invention relates to the field of refrigeration, in particular to a cascade compression refrigeration system and refrigeration equipment with the same.

Background

A cascade compression refrigeration system generally includes two separate refrigeration cycles, which are called a high-temperature stage refrigeration cycle (referred to as a high-temperature portion) and a low-temperature stage refrigeration cycle (referred to as a low-temperature portion), respectively. The high temperature portion uses a first refrigerant having a relatively high normal boiling point, and the low temperature portion uses a second refrigerant having a relatively low normal boiling point. And the condensation evaporator is used for condensing the second refrigerant vapor discharged by the compressor of the low-temperature part by utilizing the cold energy prepared by the first refrigerant of the high-temperature part, and is an evaporator of the high-temperature part and a condenser of the low-temperature part.

In the prior art, in a low-temperature stage refrigeration cycle loop, the temperature of a second refrigerant flowing from a return pipe to a suction inlet of a low-temperature stage compressor is low, so that the suction temperature of the compressor at a low-temperature part is low, condensation or frost can be caused around the return pipe of the low-temperature stage compressor and the suction inlet of the low-temperature stage compressor, and the loss of cold energy is caused. For small domestic refrigeration appliances, a loss of tens of watts or even a few watts of cooling capacity results in a significant reduction in the efficiency of the refrigeration.

Therefore, how to increase the suction temperature of the compressor at the low temperature part becomes a technical problem to be solved by those skilled in the art.

Disclosure of Invention

An object of the present invention is to provide a cascade compression refrigeration system and a refrigeration apparatus having the same that at least partially solve the above problems.

It is a further object of the present invention to increase the suction temperature of the compressor in the low temperature stage refrigeration cycle of a cascade compression refrigeration system.

It is a further object of the present invention to improve the refrigeration efficiency of the storage compartment in a refrigeration appliance having a cascade compression refrigeration system.

A further object of the present invention is to reduce the thermal load applied to the high-temperature stage refrigeration cycle by the low-temperature stage refrigeration cycle, thereby improving the energy utilization efficiency of the entire cascade compression refrigeration system.

A further object of the present invention is to improve the efficiency of energy utilization in the low temperature stage refrigeration cycle of a cascade compression refrigeration system.

The invention provides a cascade compression refrigeration system and refrigeration equipment with the same, comprising: a high-temperature stage refrigeration cycle circuit, wherein an evaporation part is arranged in the high-temperature stage refrigeration cycle circuit and is used for circulating a first refrigerant; the low-temperature-stage refrigeration circulation loop is used for circulating a second refrigerant and is internally provided with a low-temperature-stage compressor, a condensing part, a low-temperature-stage evaporation pipe and a heat exchange assembly; the evaporation part is used for promoting the first refrigerant flowing through the evaporation part to absorb the heat of the second refrigerant flowing through the condensation part; the heat exchange assembly comprises: a heat releasing part arranged between the low-temperature stage compressor discharge port and the condensing part; the heat absorption part is arranged between the low-temperature-stage evaporation pipe and a low-temperature-stage compressor suction inlet; the heat absorbing portion is for causing the second refrigerant flowing therethrough to absorb heat of the second refrigerant flowing through the heat radiating portion.

Optionally, the low-temperature stage refrigeration cycle further comprises: the low-temperature-stage throttling device is arranged between the condensing part and the low-temperature-stage evaporating pipe; the heat absorption air return pipe section is arranged between the low-temperature-stage evaporation pipe and the low-temperature-stage compressor suction inlet; at least part of the heat absorption return pipe section is abutted against the low-temperature-level throttling device, so that the second refrigerant flowing through the heat absorption return pipe section absorbs the heat of the second refrigerant flowing through the low-temperature-level throttling device.

Optionally, the heat absorption portion is disposed between the heat absorption return air duct section and the compressor suction inlet.

Optionally, the high temperature stage refrigeration cycle comprises: a high temperature stage compressor; a high-temperature-stage condenser disposed between the discharge port of the high-temperature-stage compressor and the evaporation unit; the cooling system comprises a plurality of cooling branches which are mutually connected in parallel, wherein each cooling branch is internally provided with a branch throttling device; the plurality of cooling branches includes: the first cooling branch is internally provided with a first cooling evaporation pipe which is used for promoting a first refrigerant flowing through the first cooling evaporation pipe to absorb heat; the first cooling evaporation pipe and the low-temperature-level evaporation pipe are used for cooling the same storage compartment in the refrigeration equipment.

Optionally, the first cooling evaporating pipe and the low-temperature stage evaporating pipe are arranged on the same fin group in a penetrating mode.

Optionally, a check valve is further disposed in the first cooling branch, and the check valve is disposed downstream of the first cooling evaporation tube and is configured to allow only the first refrigerant from the first cooling evaporation tube to flow out in one direction.

Optionally, the high temperature stage refrigeration cycle further comprises: and the second cooling evaporator is arranged between the high-temperature-stage condenser and the suction inlet of the high-temperature-stage compressor and is used for promoting the first refrigerant from the plurality of cooling branches to pass through the suction inlet of the high-temperature-stage compressor.

Optionally, the evaporation part is arranged between the high-temperature-stage condenser and the second cooling evaporator; the plurality of cooling branches are arranged between the high-temperature-stage condenser and the evaporation part.

Optionally, the high temperature stage refrigeration cycle further comprises: and an electric switching valve having a plurality of valve ports for communicating with one cooling branch line, respectively, for adjusting a flow path of the first refrigerant therethrough by controllably opening or closing the valve ports.

According to another aspect of the present invention, there is also provided a refrigerating apparatus including: a box body; the cascade compression refrigeration system of any one of the above mentioned is arranged in the box body.

The invention discloses a cascade compression refrigeration system and refrigeration equipment with the same, wherein the cascade compression refrigeration system comprises a high-temperature-level refrigeration circulation loop and a low-temperature-level refrigeration circulation loop. The low-temperature stage refrigeration cycle loop comprises a heat exchange assembly, a heat radiation part and a heat absorption part, wherein the heat radiation part is arranged between a discharge port and a condensation part of the low-temperature stage compressor, and the heat absorption part is arranged between a low-temperature stage evaporation pipe and a suction port of the low-temperature stage compressor. The heat absorption part is used for promoting the second refrigerant flowing through the heat absorption part to absorb the heat of the second refrigerant flowing through the heat release part, so that the second refrigerant in the low-temperature stage refrigeration cycle loop is heated before flowing into the suction inlet of the compressor, the suction temperature of the low-temperature stage compressor can be increased, the cold loss caused by too low suction temperature can be reduced or avoided, the refrigeration efficiency is improved, the condensation or frosting problem around the suction inlet of the low-temperature stage compressor can be reduced or avoided, and the running performance of the cascade compression refrigeration system is improved.

Further, the cascade compression refrigeration system and the refrigeration equipment with the cascade compression refrigeration system are provided, wherein the first cold supply evaporation pipe and the low-temperature evaporation pipe in the high-temperature refrigeration circulation loop penetrate through the same fin group, and the first cold supply evaporation pipe and the low-temperature evaporation pipe are used for supplying cold to the same storage compartment, so that the refrigeration efficiency of the storage compartment can be improved, and the storage compartment can be rapidly cooled.

Further, the cascade compression refrigeration system and the refrigeration equipment with the cascade compression refrigeration system have the advantages that the heat release part of the heat exchange assembly is arranged between the discharge port of the low-temperature stage compressor and the condensation part, so that the heat load provided by the low-temperature stage refrigeration circulation loop to the high-temperature stage refrigeration circulation loop is reduced, and the energy utilization efficiency of the whole cascade compression refrigeration system is improved.

Further, the cascade compression refrigeration system and the refrigeration equipment with the cascade compression refrigeration system are provided with a low-temperature stage throttling device and a heat absorption air return pipe section in the low-temperature stage refrigeration cycle loop, wherein the low-temperature stage throttling device is arranged between the condensation part and the low-temperature stage evaporation pipe, the heat absorption air return pipe section is arranged between the low-temperature stage evaporation pipe and the heat absorption part, and at least part of the heat absorption air return pipe section is attached to the low-temperature stage throttling device, so that the second refrigerant flowing through the heat absorption air return pipe section absorbs the heat of the second refrigerant flowing through the low-temperature stage throttling device, the energy utilization efficiency in the low-temperature stage refrigeration cycle loop is improved, and the energy utilization efficiency of the whole refrigeration equipment is further improved.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Some specific embodiments of the invention will be described in detail hereinafter, by way of illustration and not limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

FIG. 1 is a schematic diagram of a refrigeration appliance having a cascade compression refrigeration system according to one embodiment of the present invention;

FIG. 2 is a schematic diagram of a cascade compression refrigeration system according to one embodiment of the present invention;

figure 3 is a pressure-enthalpy diagram corresponding to the operation of the low temperature stage refrigeration cycle in the cascade compression refrigeration system of figure 2;

figure 4 is a schematic diagram of a cascade compression refrigeration system according to another embodiment of the present invention.

Detailed Description

Figure 1 is a schematic diagram of a refrigeration appliance 10 having a cascade compression refrigeration system according to one embodiment of the present invention.

The refrigeration device 10 may be a small household refrigeration device for storing food, medicine, or other items, and may be, for example, a refrigerator, or freezer.

Although the cascade compression refrigeration system is already involved in large-scale refrigeration equipment, the operation noise and the energy consumption of the existing cascade compression refrigeration system are too high, so that the cascade compression refrigeration system in the prior art cannot be applied to small-scale household refrigeration equipment.

The cascade compression refrigeration system of the present embodiment is particularly suitable for use in small household refrigeration appliances 10, such as refrigerators.

The refrigeration apparatus 10 in the present embodiment is exemplified by a refrigerator. The refrigeration appliance 10 having the cascade compression refrigeration system may be a refrigerator.

The refrigeration appliance 10 may generally include: a cabinet 110 and a cascade compression refrigeration system provided in the cabinet 110. Wherein, a storage compartment 111 for storing articles is further formed in the case body 110. In this embodiment, the storage compartment 111 may be a plurality of compartments, and may include, for example, a refrigeration compartment, a freezing compartment (which is a normal freezing compartment), a variable temperature compartment, and/or a cryogenic compartment. In other alternative embodiments, the storage compartment 111 may be one, for example, a cryogenic compartment or a temperature-changing compartment. A plurality of evaporator installation cavities for installing evaporators may be further formed in the cabinet 110, and the evaporator installation cavities may be disposed at the back, side, top, or bottom of the storage compartment 111.

Figure 2 is a schematic diagram of a cascade compression refrigeration system according to one embodiment of the present invention.

The cascade compression refrigeration system may be a two-stage cascade circulation system, a three-stage cascade circulation system, or a four-stage cascade circulation system, where the cascade stage is not specifically limited. The present embodiment is merely exemplary of a cascade compression refrigeration system having a two-stage cascade cycle system, and those skilled in the art should be fully capable of extension in this regard.

The cascade compression refrigeration system may include: the high-temperature-stage refrigeration cycle circuit and the low-temperature-stage refrigeration cycle circuit may further include: a radiator fan 280 and a blower fan 290. The high-temperature refrigeration circulation loop forms a high-temperature refrigeration circulation system, and the low-temperature refrigeration circulation loop forms a low-temperature refrigeration circulation system.

And a high-temperature stage refrigeration cycle circuit for circulating the first refrigerant, and in which a high-temperature stage compressor 211 and an evaporation unit 231 are provided. And a low-temperature stage refrigeration cycle circuit for circulating the second refrigerant, and having a low-temperature stage compressor 251, a condensing part 232, a low-temperature stage evaporating pipe 256, and a heat exchange assembly disposed therein. The low-temperature-stage evaporation tube 256 is used to promote the second refrigerant flowing through the low-temperature-stage evaporation tube to absorb heat in the storage compartment 111, so that the storage compartment 111 is cooled.

The evaporation portion 231 serves to cause the first refrigerant flowing therethrough to absorb heat of the second refrigerant flowing through the condensation portion 232. Condensing portion 232 may be located between the discharge of low temperature stage compressor 251 and low temperature stage evaporator tube 256. The evaporation portion 231 and the condensation portion 232 may be thermally connected so that the first refrigerant flowing through the evaporation portion 231 may absorb heat released from the second refrigerant flowing through the condensation portion 232. For example, the evaporation portion 231 and the condensation portion 232 may be integrally formed to form a condensation evaporator.

The high-temperature stage refrigeration cycle circuit further includes: and a high-temperature-stage condenser 212 provided between the discharge port of the high-temperature-stage compressor 211 and the evaporator 231.

That is, the high-temperature stage refrigeration cycle may include: a high-temperature stage compressor 211, a high-temperature stage condenser 212, and an evaporator 231.

The refrigerant, also called refrigerant, usually completes energy conversion by phase change, and is a working substance that circulates in a refrigeration system of the refrigeration equipment 10, and its working principle is: the refrigerant absorbs heat of a substance to be cooled in the evaporator to evaporate, transfers the absorbed heat to ambient air or water in the condenser to be cooled into liquid, and circulates back and forth to achieve the refrigeration effect by means of state change. The refrigerants can be roughly classified into the following three categories, according to the magnitude of the condensation pressure at normal temperature and the magnitude of the evaporation temperature at atmospheric pressure: a high temperature refrigerant, a medium temperature refrigerant, and a low temperature refrigerant. The "high temperature" and the "low temperature" in the "high temperature stage refrigeration cycle circuit" and the "low temperature stage refrigeration cycle circuit" are relative, and the evaporation temperature of the first refrigerant flowing through the high temperature stage refrigeration cycle circuit is higher than the evaporation temperature of the second refrigerant flowing through the low temperature stage refrigeration cycle circuit.

The refrigerant can be classified into the following three groups according to its composition: pure working medium refrigerant, azeotropic refrigerant and non-azeotropic refrigerant. Pure working medium refrigerant, also called single refrigerant, refers to a refrigerant formed by a single component substance. The azeotropic refrigerant is a refrigerant prepared by mixing two or more mutually soluble single-component substances according to a certain mass ratio or volume ratio at normal temperature, the properties of the azeotropic refrigerant are the same as those of a single refrigerant, the azeotropic refrigerant has a constant evaporation temperature under a constant pressure, and the components of a gas phase and a liquid phase are the same. The non-azeotropic refrigerant is a mixed solution of two or more single refrigerants which do not form azeotropic solution, when the solution is heated, the evaporation proportion of the volatile component is large, the evaporation proportion of the non-volatile component is small, the gas-liquid two-phase composition is different, and the temperature of the refrigerant is changed in the evaporation process, and the refrigerant has similar characteristics in the condensation process.

The first refrigerant of the present embodiment may be a medium-temperature refrigerant, and the second refrigerant may be a low-temperature refrigerant.

The absolute pressure range of the high pressure side of the low-temperature stage refrigeration circulation loop in a stable operation state is configured to be 2-11 bar, and the absolute pressure range of the low pressure side of the low-temperature stage refrigeration circulation loop in the stable operation state is configured to be 0.2-1.1 bar.

Wherein, the high pressure side in the low-temperature stage refrigeration cycle is that: in the flow direction of the second refrigerant, a portion between the discharge port of the low-temperature-stage compressor 251 and the upstream of the suction port of the low-temperature-stage throttling device 255 in the low-temperature-stage refrigeration cycle circuit. The low-pressure side in the low-temperature stage refrigeration cycle is as follows: in the flow direction of the second refrigerant, a portion between the discharge port downstream of the low-temperature-stage throttling device 255 and the suction port of the low-temperature-stage compressor 251 in the low-temperature-stage refrigeration cycle circuit. In general, the high-side absolute pressure of the low-temperature stage refrigeration cycle may be detected at a preset position near the downstream of the discharge port of the low-temperature stage compressor 251, and the low-side absolute pressure of the low-temperature stage refrigeration cycle may be detected at a preset position near the upstream of the suction port of the low-temperature stage compressor 251. In some alternative embodiments, if the low temperature stage compressor 251 is provided with a process port for direct communication with a low pressure cavity inside the low temperature stage compressor 251, the low pressure side absolute pressure can be detected at the process port.

The low-temperature stage refrigeration cycle loop can enter a stable operation state after being started for a certain time. In the embodiment, whether the low-temperature-stage refrigeration circulation circuit is in a stable operation state is judged according to the low-pressure-side absolute pressure of the low-temperature-stage refrigeration circulation circuit. After the low-temperature refrigeration circulation loop is started, the absolute pressure of the low-pressure side of the low-temperature refrigeration circulation loop can be continuously acquired. If the ratio of the highest value of the absolute pressure of the low-pressure side of the low-temperature stage refrigeration circulation loop to the average value of the absolute pressure of the low-pressure side of the low-temperature stage refrigeration circulation loop is smaller than a first preset ratio and the ratio of the lowest value of the absolute pressure of the low-pressure side of the low-temperature stage refrigeration circulation loop to the average value of the absolute pressure of the low-pressure side of the low-temperature stage refrigeration circulation loop is larger than a second preset ratio within a first set time, it is indicated that the low-temperature stage refrigeration circulation loop within the first set time is in a stable operation state. The average value of the low-pressure-side absolute pressure of the low-temperature-stage refrigeration cycle circuit is an arithmetic average value of the highest value of the low-pressure-side absolute pressure of the low-temperature-stage refrigeration cycle circuit and the lowest value of the low-pressure-side absolute pressure of the low-temperature-stage refrigeration cycle circuit within a first set time. The first set time may be any time within a range of 0.25 to 1 hour, for example, 0.25 hour, 0.5 hour, or 1 hour, and preferably, 0.25 hour or 0.5 hour. The first predetermined ratio may be any value in the range of 1 to 1.2, for example, 1, 1.1, or 1.2, preferably 1.1, and the second predetermined ratio may be any value in the range of 0.85 to 0.95, for example, 0.85, 0.9, or 0.95, preferably 0.9. In this embodiment, the absolute pressure of the low-pressure side of the low-temperature refrigeration cycle loop can be acquired after a test pack (GB/T8059) is put into the storage compartment 111 of the refrigeration apparatus 10, so as to monitor the stable operation state of the low-temperature refrigeration cycle loop.

Because the exhaust pressure of the low-temperature stage compressor 251 is set corresponding to the high-pressure side absolute pressure of the low-temperature stage refrigeration cycle, the suction pressure of the low-temperature stage compressor 251 is set corresponding to the low-pressure side absolute pressure of the low-temperature stage refrigeration cycle, and when the low-temperature stage refrigeration cycle runs, the low-temperature stage compressor 251 has lower suction pressure and lower exhaust pressure, which can effectively reduce the noise generated during running, and can also reduce the energy consumption during running, and can be suitable for the household small refrigeration equipment 10.

The absolute pressure range of the high-pressure side of the low-temperature refrigeration cycle loop in a stable operation state can be configured to be 2-9 bar or 2-10 bar. The absolute pressure of the high-pressure side of the low-temperature stage refrigeration cycle in a stable operation state can be any value within 2-11 bar, for example, 2bar, 3bar, 4bar, 5bar, 6bar, 7bar, 8bar, 9bar, 10bar or 11 bar.

The lowest absolute pressure range of the low-pressure side of the low-temperature stage refrigeration cycle loop in a stable operation state can be configured to be 0.2-0.8 bar, or 0.2-0.6 bar, or 0.2-0.5 bar, or 0.2-0.4 bar.

In some optional embodiments, the lower limit of the absolute pressure at the low-pressure side of the low-temperature stage refrigeration cycle loop in the stable operation state may be configured to be 0.2 to 0.8bar, or 0.2 to 0.6bar, or 0.2 to 0.5bar, or 0.2 to 0.4 bar.

The low temperature stage refrigeration cycle loop may be pre-set with multiple refrigeration temperatures, for example, but not limited to, refrigeration temperatures of 5 ℃, -5 ℃, -18 ℃, -40 ℃, -60 ℃ or-80 ℃. The low-temperature refrigeration circulation loop can reach respective stable operation state when operating according to different refrigeration temperatures. The refrigeration temperatures are different, and the absolute pressures of the low-pressure sides of the low-temperature refrigeration circulation loops in the stable operation state can be different. The low-pressure side absolute pressure of the low-temperature stage refrigeration circulation loop in a stable operation state reaches a lower limit value in a set time period before the low-temperature stage refrigeration circulation loop is shut down. The refrigeration temperatures are different, the lower limit value of the absolute pressure of the low-pressure side of the low-temperature stage refrigeration circulation loop in the stable operation state can be different, but the lower limit value of the absolute pressure can be in the range of 0.2-0.8 bar, or 0.2-0.6 bar, or 0.2-0.5 bar, or 0.2-0.4 bar.

The lowest absolute pressure of the low-pressure side of the low-temperature stage refrigeration cycle in a stable operation state can be any value in the range of 0.2-0.8 bar, for example, 0.2bar, 0.3bar, 0.4bar, 0.5bar, 0.6bar, 0.7bar, or 0.8 bar.

The evaporation temperature range of the second refrigerant on the low-pressure side of the low-temperature stage refrigeration cycle circuit in a steady operation state may be configured to be-111 to-35 ℃. The evaporation temperature of the second refrigerant in the low-pressure side of the low-temperature stage refrigeration cycle circuit may refer to the evaporation temperature of the second refrigerant in the low-temperature stage evaporation tube 256. The evaporation temperature of the second refrigerant in the low-temperature-stage evaporation pipe 256 can reach below-60 ℃, or even below-80 ℃, and the second refrigerant can be used for creating a low temperature of about-60 ℃ or even-80 ℃ for the storage compartment 111 in the household small refrigeration equipment 10, so that the fresh-keeping capacity of the household small refrigeration equipment 10 is improved.

In the present embodiment, the evaporation temperature range of the second refrigerant on the low-pressure side of the low-temperature stage refrigeration cycle in the steady operation state may be configured to be-80 to-35 ℃ or-75 to-40 ℃.

The second refrigerant can be pure working medium refrigerant or azeotropic refrigerant, and the standard boiling point range of the second refrigerant can be configured to be-60 to-30 ℃, or-55 to-35 ℃, or-50 to-35 ℃. For example, the second refrigerant may be an R22 refrigerant (normal boiling point may be-40.8 ℃), or may be an R290 refrigerant (normal boiling point may be-42.2 ℃), or may be an R404A refrigerant (normal boiling point may be-46.1 ℃), or may be an R1270 (normal boiling point may be-47.7 ℃), or may be an R410A refrigerant (normal boiling point may be-51.4 ℃), or may be an R32 (normal boiling point may be-51.7 ℃).

The low temperature stage compressor 251 may be an R600a compressor. When the existing R600a compressor is applied to a low-temperature stage refrigeration cycle loop, the low-temperature lubricating oil can be replaced in the R600a compressor, the process is simple, and the cost is low. Since the R600a compressor has low operation noise and high energy efficiency, the noise of the low-temperature stage refrigeration cycle can be reduced and the energy-saving effect can be improved by combining the R600a compressor with the R290 refrigerant.

The type of the low-temperature stage compressor 251 is not limited thereto, and the low-temperature stage compressor 251 may be used as long as the above-described operation performance is provided.

For example, the high-side absolute pressure of the low-temperature stage refrigeration cycle may be 3.022bar and the low-side absolute pressure may be 0.368bar in a steady state operation. The second refrigerant may be R290 refrigerant. The condensation temperature of the second refrigerant at the high-pressure side in the low-temperature-level refrigeration cycle loop can be-12.1 ℃, and the evaporation temperature at the low-pressure side can be-62.8 ℃, so that the low-temperature environment of about-55 ℃ can be created for the storage chamber 111 when the low-temperature-level refrigeration cycle loop operates. The absolute pressure of the low-pressure side of the low-temperature-stage refrigeration circulation circuit in a stable operation state can also be 0.287bar, and the evaporation temperature of the second refrigerant at the low-pressure side in the low-temperature-stage refrigeration circulation circuit can be-67.2 ℃ at the moment, so that a low-temperature environment of about-60 ℃ can be created for the storage chamber 111 during operation of the low-temperature-stage refrigeration circulation circuit.

In some alternative embodiments, the high-side absolute pressure of the low-temperature stage refrigeration cycle may be 3.507bar and the low-side absolute pressure may be 0.287bar at steady state operation. The second refrigerant may be R1270 refrigerant.

The condensing temperature of the second refrigerant on the high-pressure side in the low-temperature stage refrigeration cycle loop can be-16 ℃, and the evaporating temperature on the low-pressure side can be-72 ℃, so that a low-temperature environment of about-65 ℃ can be created for the storage compartment 111 when the low-temperature stage refrigeration cycle loop operates.

In other alternative embodiments, the evaporation temperature range of the second refrigerant at the low-pressure side of the low-temperature stage refrigeration cycle in the steady operation state may be further configured to be-111 to-50 ℃.

The second refrigerant may be a non-azeotropic refrigerant, wherein the second refrigerant may include the first component. The standard boiling point range of the first component can be set to-60-0 ℃, or-50-0 ℃, or-45-0 ℃, or-15-0 ℃. The mass fraction of the first component in the second refrigerant may be set to 20% to 80%.

For example, the second refrigerant may include R600a refrigerant and R170 refrigerant, wherein the first component may be R600a refrigerant, and the mass fraction of the R600a refrigerant in the second refrigerant may be in the range of 30% to 80%, or 40% to 60%. Or the second refrigerant may include R600 refrigerant and R170 refrigerant, wherein the first component may be R600 refrigerant, and the R600 refrigerant may account for 40% to 80% of the mass fraction of the second refrigerant. Or the second refrigerant may include R600a refrigerant and R1150 refrigerant, wherein the first component may be R600a refrigerant, and the R600a refrigerant may account for a mass fraction in the second refrigerant ranging from 40% to 80%. Or the second refrigerant may include R600 refrigerant and R1150 refrigerant, wherein the first component may be R600 refrigerant, and the R600 refrigerant may account for 50% to 80% of the mass fraction of the second refrigerant. Or the second refrigerant can comprise R290 refrigerant and R170 refrigerant, wherein the first component can be R290 refrigerant, and the mass fraction of the R290 refrigerant in the second refrigerant can be 50-70%. Or the second refrigerant can comprise R290 refrigerant and R1150 refrigerant, wherein the first component can be R290 refrigerant, and the mass fraction of the R290 refrigerant in the second refrigerant can be 70-80%. Or the second refrigerant may include R1270 refrigerant and R170 refrigerant, wherein the first component may be R1270 refrigerant, and the mass fraction of R1270 refrigerant in the second refrigerant may be in the range of 60% to 80%. Or the second refrigerant may include R1270 refrigerant and R1150 refrigerant, wherein the first component may be R1270 refrigerant, and the mass fraction of R1270 refrigerant in the second refrigerant may be in a range of 70% to 80%.

An ODP (Ozone Depletion Potential) value of the second refrigerant may be configured to be 0, and a GWP of the second refrigerant may be configured to be 0₁₀₀(GWP was calculated based on 100 years and is reported as GWP₁₀₀Wherein GWP, which is an abbreviation of Global Warming Potential, for representing Global Warming Potential) value may be configured to be 200 or less.

The evaporation temperature range of the first refrigerant at the low-pressure side of the high-temperature refrigeration cycle loop in a stable operation state can be configured to be-40 ℃ to 0 ℃, or-35 ℃ to-10 ℃, or-30 ℃ to-15 ℃. The condensing temperature of the second refrigerant at the high pressure side in the low temperature stage refrigeration cycle circuit is higher than the evaporating temperature of the first refrigerant flowing through the low pressure side in the high temperature stage refrigeration cycle circuit, for example, the condensing temperature of the second refrigerant at the high pressure side in the low temperature stage refrigeration cycle circuit may range from-25 ℃ to-5 ℃.

The first refrigerant in the high-temperature-stage refrigeration cycle circuit absorbs heat of the second refrigerant in the low-temperature-stage refrigeration cycle circuit flowing through the condensation portion 232 when flowing through the evaporation portion, so that the second refrigerant in the condensation portion 232 is cooled and condensed into a liquid state. That is, the high-temperature-stage refrigeration cycle circuit can provide a pre-cooling function for the low-temperature-stage refrigeration cycle circuit by using the first refrigerant, so that the second refrigerant in the low-temperature-stage refrigeration cycle circuit can be converted from a gaseous state to a liquid state. The second refrigerant is evaporated in the low-temperature stage evaporating pipe 256 by heat absorption, and can absorb a large amount of heat, thereby realizing an effective refrigeration function at a lower temperature.

For example, the first refrigerant may be R600a refrigerant and the high temperature stage compressor 211 may be R600a compressor. In the high-temperature-stage refrigeration cycle, the condensation temperature of the first refrigerant on the high-pressure side is higher than the ambient temperature, and the first refrigerant releases heat on the high-pressure side. The first refrigerant flowing through the evaporation part (low pressure side) of the high temperature stage refrigeration cycle circuit may absorb heat of the second refrigerant flowing through the condensation part 232 (high pressure side) of the low temperature stage refrigeration cycle circuit, so that the second refrigerant flowing through the condensation part 232 is condensed.

In the low-temperature stage refrigeration cycle loop, when the ambient temperature is set to be a common indoor temperature, the common indoor temperature can be any value within a range of 7-40 ℃, the exhaust temperature of the low-temperature stage compressor 251 can be set to be less than or equal to 110 ℃ and the shell temperature of the low-temperature stage compressor 251 can be set to be less than or equal to 110 ℃ under the conditions that the suction temperature of the low-temperature stage compressor 251 is 10-38 ℃ and the suction superheat degree of the low-temperature stage compressor 251 is 80-95K (K is a thermodynamic temperature unit). In other alternative embodiments, in the case where the suction temperature of the low-temperature stage compressor 251 is in the range of 15 to 35 ℃, and the suction superheat degree of the low-temperature stage compressor 251 is 80 to 85K (K is a thermodynamic temperature unit), the discharge temperature of the low-temperature stage compressor 251 may be set to 100 ℃ or less, and the shell temperature of the low-temperature stage compressor 251251 may be set to 100 ℃ or less.

The cylinder volume of the low temperature stage compressor 251 can be configured to be less than or equal to 20ml, for example, the cylinder volume of the low temperature stage compressor 251 can be configured to be 4-20 ml, or 5-15 ml, or 8.5-13.5 ml. Wherein, the low temperature stage compressor 251 may be a piston type.

The low-temperature stage refrigeration cycle circuit is not provided with a jet cooling circuit.

The low temperature stage refrigeration cycle circuit may further include: a heat exchange assembly including a heat emitting part 241 and a heat absorbing part 242. And a heat radiating unit 241 disposed between the discharge port of the low-temperature stage compressor 251 and the condensing unit. Heat absorbing unit 242 is provided between low-temperature-stage evaporator 256 and the suction port of low-temperature-stage compressor 251. The heat radiating portion 241 and the heat absorbing portion 242 may be fitted or attached to each other such that the second refrigerant flowing through the heat radiating portion 241 may exchange heat with the second refrigerant flowing through the heat absorbing portion 242. The heat absorbing part 242 functions to cause the second refrigerant flowing therethrough to absorb heat of the second refrigerant flowing through the heat radiating part 241.

The heat exchange assembly of this embodiment may be a double pipe heat exchanger. The sleeve heat exchanger is a concentric sleeve formed by mutually sleeving and connecting two standard pipes with different sizes, wherein the outer passage is called a shell pass, and the inner passage is called a pipe pass. The two different media can flow in the shell side and the tube side in the opposite directions (or in the same direction) to achieve the effect of heat exchange. The heat absorbing part 242 may be a shell side, and the heat radiating part 241 may be a tube side. In other alternative embodiments, the heat absorbing portion 242 may be tube-side and the heat releasing portion 241 may be shell-side.

In the low-temperature-stage refrigeration cycle circuit, the second refrigerant temperature in a section between the low-temperature-stage evaporation tube 256 and the suction port of the low-temperature-stage compressor 251 is low, and the second refrigerant temperature in a section between the discharge port of the low-temperature-stage compressor 251 and the condensing portion 232 is relatively high and higher than the second refrigerant temperature flowing through the heat absorbing portion 242.

By arranging the heat exchange component, the second refrigerant flowing through the heat absorption part 242 absorbs the heat of the second refrigerant flowing through the heat release part 241, and the second refrigerant in the low-temperature stage refrigeration cycle loop is heated before flowing into the compressor suction inlet, so that the suction temperature of the low-temperature stage compressor 251 can be increased, the cold loss caused by too low suction temperature can be reduced or avoided, the refrigeration efficiency is increased, the problems of condensation or frost formation around the suction inlet of the low-temperature stage compressor 251 can be reduced or avoided, the series problems of wet stroke, liquid impact, oil shortage of the low-temperature stage compressor 251 and the like caused by too low suction superheat can be reduced or avoided, and the operation performance of the cascade compression refrigeration system is improved. Compared with the scheme that the heat insulation cotton is arranged on the pipe section at the upstream of the suction inlet of the low-temperature stage compressor 251, the consistency of the product performance of the household small refrigeration equipment 10 during batch production is improved.

The heat radiating portion 241 is disposed between the low-temperature-stage compressor 251 and the condensing portion 232, and the second refrigerant flowing through the heat radiating portion 241 transfers heat to the second refrigerant flowing through the heat absorbing portion 242 to heat the second refrigerant, thereby making full use of energy in the low-temperature-stage refrigeration cycle, improving energy utilization efficiency of the low-temperature-stage refrigeration cycle, and further improving energy utilization efficiency of the entire refrigeration apparatus 10.

In the cascade compression refrigeration system and the refrigeration equipment 10 having the same of the present embodiment, the heat radiating portion 241 of the heat exchange component is disposed between the discharge port of the low-temperature stage compressor 251 and the condensing portion 232, so that the heat load provided by the low-temperature stage refrigeration cycle to the high-temperature stage refrigeration cycle is reduced, and the energy utilization efficiency of the entire cascade compression refrigeration system is improved.

The first refrigerant in the high-temperature-stage refrigeration cycle circuit absorbs heat of the second refrigerant in the low-temperature-stage refrigeration cycle circuit flowing through the condensation portion 232 while flowing through the evaporation portion 231, so that the second refrigerant in the condensation portion 232 is cooled and condensed into a liquid state. That is, the high-temperature-stage refrigeration cycle circuit can provide a pre-cooling function for the low-temperature-stage refrigeration cycle circuit by using the first refrigerant, so that the second refrigerant in the low-temperature-stage refrigeration cycle circuit can be converted from a gaseous state to a liquid state. The second refrigerant is evaporated in the low-temperature stage evaporating pipe 256 by heat absorption, and can absorb a large amount of heat, thereby realizing an effective refrigeration function at a lower temperature.

In some alternative embodiments, the first refrigerant is changed into a high-temperature and high-pressure gaseous first refrigerant by the high-temperature stage compressor 211, and then enters the high-temperature stage condenser 212, and is condensed into a high-pressure liquid first refrigerant, and the first refrigerant flowing out of the high-temperature stage condenser 212 may flow through the bypass throttle 218, and is converted into a low-pressure gas-liquid two-phase first refrigerant, and then enters the evaporation portion 231 to absorb heat and evaporate into a low-pressure gaseous first refrigerant, and finally flows into the suction port of the high-temperature stage compressor 211, so as to form a complete high-temperature stage refrigeration cycle.

The low temperature stage refrigeration cycle circuit may further include: a low temperature stage heat sink 252, a low temperature stage desiccant filter 254, a low temperature stage throttling device 255, a low temperature stage reservoir 257, and a heat absorption return air pipe segment 258.

The low-temperature-stage throttling device 255 is provided between the condensing unit 232 and the low-temperature-stage evaporating pipe 256. The low-temperature stage throttling device 255 may also be a capillary tube or an expansion valve.

And a heat absorption return pipe section 258 disposed between the low-temperature stage evaporator 256 and the suction port of the low-temperature stage compressor 251. At least part of the heat absorption return air pipe section 258 can be arranged in a manner of being attached to the low-temperature-stage throttling device 255, so that the second refrigerant flowing through the heat absorption return air pipe section 258 absorbs heat of the second refrigerant flowing through the low-temperature-stage throttling device 255, the energy utilization efficiency in the low-temperature-stage refrigeration cycle loop is improved, the energy utilization efficiency of the whole refrigeration equipment 10 is further improved, the temperature of the second refrigerant flowing to the suction port of the low-temperature-stage compressor 251 is favorably improved, and the suction temperature of the low-temperature-stage compressor 251 is further improved.

The heat absorption return pipe section 258 and the heat absorption part 242 are arranged on the flow path between the low-temperature stage evaporation pipe 256 and the low-temperature stage compressor 251, namely, the flow path between the low-temperature stage evaporation pipe 256 and the low-temperature stage compressor 251 is divided into two different pipe sections, the relative positions of the different pipe sections can be flexibly arranged, the two different pipe sections can respectively exchange heat with different positions in the low-temperature stage refrigeration circulation loop, the suction temperature of the low-temperature stage compressor 251 is improved, and the energy utilization efficiency of the whole cascade type compression refrigeration system is improved.

The heat absorbing return pipe section 258 may be disposed between the low-temperature stage evaporation pipe 256 and the heat absorbing part 242, that is, the heat radiating part 241 is disposed between the heat absorbing return pipe section 258 and the compressor suction port.

The heat absorption return gas pipe section 258 may form a double pipe heat exchanger with the low temperature stage throttling device 255, the low temperature stage throttling device 255 may be a pipe pass, and the heat absorption return gas pipe section 258 may be a shell pass. In other alternative embodiments, the heat absorbing return air pipe 258 and the low-temperature-stage throttling device 255 may be two copper pipes abutting against each other, wherein one copper pipe is the heat absorbing return air pipe 258, and the other copper pipe is the low-temperature-stage throttling device 255. The two copper pipes are arranged in a mutual attaching mode. The contact part between the two copper pipes can be fixed by tin soldering to strengthen the heat transfer. The two copper pipes can be wrapped with aluminum foils.

In some alternative embodiments, the condensing evaporator may also be a double pipe heat exchanger. The evaporation portion 231 may be a tube side, and the condensation portion 232 may be a shell side. In other alternative embodiments, the condensing evaporator may also be two copper tubes abutting against each other, wherein one copper tube is the evaporation portion 231 and the other copper tube is the condensation portion 232. The two copper pipes are arranged in a mutual attaching mode. The contact part between the two copper pipes can be fixed by tin soldering to strengthen the heat transfer. The two copper pipes can be wrapped with aluminum foils.

And a low-temperature stage filter drier 254 disposed between the condensing unit 232 and the low-temperature stage throttling device 255, and functioning to filter impurities in the second refrigerant and prevent ice blockage.

The low-temperature-stage radiator 252 is provided between the discharge port of the low-temperature-stage compressor 251 and the condensing unit 232, and may be provided between the low-temperature-stage compressor 251 and the heat radiating unit 241, for example. The low-temperature-stage radiator 252 pre-cools the second refrigerant in the low-temperature-stage refrigeration cycle before flowing to the condensing portion 232, so that the second refrigerant can be sufficiently condensed when flowing through the condensing portion 232.

And the low-temperature-stage liquid storage bag 257 is arranged at the downstream of the low-temperature-stage evaporating pipe 256 and is positioned between the low-temperature-stage evaporating pipe 256 and the heat absorption gas return pipe section 258. The low-temperature-stage liquid storage bag 257 can prevent the second refrigerant flowing to the suction port of the low-temperature-stage compressor 251 from carrying liquid second refrigerant, can also adjust the amount of the second refrigerant required by other components in the low-temperature-stage refrigeration cycle circuit, and can prevent the second refrigerant at the low-temperature-stage evaporation tube 256 from slowly migrating to the suction port of the low-temperature-stage compressor 251 when the low-temperature-stage refrigeration cycle system is stopped.

In the low-temperature stage refrigeration cycle circuit, the second refrigerant may sequentially flow through a discharge port of the low-temperature stage compressor 251, the low-temperature stage radiator 252, the heat radiation portion 241, the condensation portion 232, the low-temperature stage filter drier 254, the low-temperature stage throttling device 255, the low-temperature stage evaporation tube 256, the low-temperature stage liquid storage bag 257, the heat absorption return pipe 258, the heat absorption portion 242, and a suction port of the low-temperature stage compressor 251 to form a complete cycle.

Fig. 3 is a pressure-enthalpy diagram corresponding to the operation state of the low-temperature stage refrigeration cycle in the cascade compression refrigeration system shown in fig. 2. The ordinate of the diagram represents absolute pressure and the abscissa represents specific enthalpy.

The low-temperature stage compressor 251 sucks the second refrigerant (corresponding to point 1 in fig. 2 and 3) at normal temperature and low pressure, and the second refrigerant is changed into a gaseous second refrigerant at high temperature and high pressure by the low-temperature stage compressor 251. The second refrigerant (corresponding to point 2 in fig. 2 and 3) flowing out of the discharge port of the low temperature stage compressor 251 may flow through the low temperature stage radiator 252. After the second refrigerant flows through the low-temperature stage heat sink 252 to dissipate heat (corresponding to point 3 in fig. 2 and 3), the temperature may be close to the ambient temperature but still be a superheated gas, i.e., the superheat of the second refrigerant may be reduced during the flow through the low-temperature stage heat sink 252. The second refrigerant flowing out of the discharge port of the low-temperature-stage radiator 252 may flow through the heat radiating portion 241 of the heat exchange assembly, and transfer a part of the heat in the heat radiating portion 241 to the second refrigerant in the heat absorbing portion 242, thereby raising the temperature of the second refrigerant in the heat absorbing portion 242. After the second refrigerant flows through the heat radiating portion 241 to radiate heat (corresponding to point 4 in fig. 2 and 3), the temperature may be close to the ambient temperature but still be superheated gas, and the degree of superheat of the second refrigerant may be reduced during the flow through the heat radiating portion 241. The second refrigerant flowing out of the heat radiating portion 241 may enter the condensing portion 232, be condensed into a high-pressure liquid-containing second refrigerant (corresponding to point 5 in fig. 2 and 3), flow through the low-temperature stage throttling device 255, be converted into a low-pressure gas-liquid two-phase second refrigerant (corresponding to point 6 in fig. 2 and 3), and then enter the low-temperature stage evaporating tube 256 to absorb heat and evaporate into a low-pressure gaseous second refrigerant. It should be noted that "gaseous" herein means that most of the second refrigerant is in a gaseous state, and does not mean that all of the second refrigerant is in a gaseous state, that is, the second refrigerant after flowing through the low-temperature stage evaporation tube 256 may carry liquid second refrigerant. If the second refrigerant after flowing through the low-temperature-stage evaporating tube 256 carries the liquid second refrigerant, the low-temperature-stage refrigeration cycle is configured to enhance the heat exchange efficiency between the low-temperature-stage throttling device 255 and the heat-absorbing return-air tube 258 (i.e., enhance heat regeneration). After the second refrigerant (corresponding to point 7 in fig. 2 and 3) output from the low-temperature stage evaporating pipe 256 enters the heat absorbing return pipe 258 and absorbs the heat of the second refrigerant flowing through the low-temperature stage throttling device 255 (corresponding to point 8 in fig. 2 and 3), the temperature can be increased but the superheat degree is low. After the second refrigerant enters the heat absorption portion 242 of the heat exchange assembly, the temperature may be raised to approximately ambient temperature, with a corresponding increase in superheat. The second refrigerant from the heat absorption part 242 may flow into a suction port of the low temperature stage compressor 251 to form a complete low temperature stage refrigeration cycle.

The high-temperature stage refrigeration cycle circuit may further include: an electric switching valve 217, at least one cooling branch, a second cooling evaporator 222, a dew prevention pipe 215, and a high temperature stage reservoir. Wherein, the number of the cooling branch can be one or more. The cooling branch circuits of the present embodiment may be plural and arranged in parallel with each other.

And an electric switching valve 217 having a plurality of valve ports for communicating with one cooling branch line, respectively, the electric switching valve 217 for adjusting a flow path of the first refrigerant therethrough by controllably opening or closing the valve ports. The electrically-operated switching valve 217 serves to switch the flow direction of the first refrigerant so that the first refrigerant flowing therethrough is controllably flowed to the one or more cooling branches. The electrically-operated switching valve 217 may be disposed upstream of the plurality of cooling branches and downstream of the high-temperature stage condenser 212.

A plurality of cooling branches are arranged in parallel, and a branch throttling device 218 is arranged in each cooling branch. The number of cooling branches may be two, three, four or five, or any other number. In this embodiment, the number of the cooling branches may be three, including a first cooling branch, a second cooling branch and a third cooling branch. The bypass restriction 218 may be a capillary tube or an expansion valve, and the arrangement of the restriction is well known to those skilled in the art and will not be described herein.

Wherein, the first cooling branch is provided with a first cooling evaporating pipe 219 and a one-way valve 220 therein. The first refrigerant-cooling evaporation tube 219 serves to promote the first refrigerant flowing therethrough to absorb heat. The first cooling evaporator 219 and the low-temperature-stage evaporator 256 are used to cool the same storage compartment 111 in the refrigeration apparatus 10. For example, first cooling evaporator pipe 219 may be used with low temperature stage evaporator pipe 256 for being disposed in an evaporator installation cavity corresponding to a cryogenic compartment and for cooling the cryogenic compartment. The first cold-supplying evaporating pipe 219 and the low-temperature stage evaporating pipe 256 are arranged on the same fin group in a penetrating manner. The first cold-supplying evaporator tube 219 can form a double-tube evaporator with the low-temperature stage evaporator tube 256 and the fin set through which the two pass. That is, the dual-tube evaporator has the first cooling evaporator 219 and the low-temperature stage evaporator 256, and has two sets of evaporators. The first cooling evaporator 219 and the low-temperature stage evaporator 256 may be disposed adjacent to each other, or may be disposed by winding each other, but is not limited thereto.

The first cooling evaporation tube 219 and the low-temperature-stage evaporation tube 256 are disposed in the same evaporator installation cavity corresponding to the same storage compartment 111, and are used for cooling the same storage compartment 111, so that the cooling efficiency of the storage compartment 111 can be improved, and the storage compartment 111 can be cooled rapidly.

The first cold supply evaporating pipe 219 and the low temperature stage evaporating pipe 256 form a double-pipe evaporator, which is not only beneficial to improving the refrigerating efficiency of the double-pipe evaporator, but also beneficial to miniaturizing the structure of the double-pipe evaporator, simplifying the overall structure of the refrigerating equipment 10 with the cascade compression refrigerating system and reducing the manufacturing cost.

When the cascade compression refrigeration system is started to operate, the cooling process of the deep cooling chamber can be divided into an initial stage and a later stage, and the two stages are total. The initial stage can be a process of reducing the temperature of the deep cooling chamber from the ambient temperature to a first preset temperature, and the later stage can be a process of reducing the temperature of the deep cooling chamber from the first preset temperature to a second preset temperature, wherein the first preset temperature is higher than the second preset temperature. The first predetermined temperature may be any value between-10 and-28 deg.C, for example-18 deg.C, and the second predetermined temperature may be any value between-40 and-80 deg.C, for example-55 deg.C. The first cold stage evaporator 219 may be used to provide cold for the early stage and the low temperature stage evaporator 256 may be used to provide cold for the later stage.

Generally, whether the evaporator is providing cooling is determined by whether the refrigerant circulates therein. For example, whether the first refrigerant flows through the first cooling evaporation pipe 219 or not may be controlled by controlling the electric switching valve 217 (described in detail below), so as to control whether the first cooling evaporation pipe 219 supplies cooling, and whether the second refrigerant flows through the low temperature stage evaporation pipe 256 or not may be controlled by controlling whether the low temperature stage compressor 251 is turned on, so as to control whether the low temperature stage evaporation pipe 256 supplies cooling.

In some alternative embodiments, the first cooling evaporator 219 and the low temperature stage evaporator 256 can also be used to be disposed in the evaporator installation cavity corresponding to the temperature changing compartment and to supply cooling to the temperature changing compartment. The variable-temperature chamber can selectively control the first cooling evaporation pipe 219 or the low-temperature-stage evaporation pipe 256 to supply cooling independently according to actual needs, or control the first cooling evaporation pipe 219 and the low-temperature-stage evaporation pipe 256 to supply cooling together, so that the variable-temperature chamber can obtain different refrigeration effects to meet different refrigeration requirements.

And a check valve 220 disposed downstream of the first cooling evaporation pipe 219, for allowing only the first refrigerant from the first cooling evaporation pipe 219 to flow out in one direction. That is, in the first cooling branch, the check valve 220 serves only to allow the first refrigerant from the upstream thereof to pass therethrough in one direction, and the check valve 220 can function to prevent the first refrigerant downstream of the check valve 220 from passing therethrough in the reverse direction.

When the low-temperature stage compressor 251 is operated, the temperature of the low-temperature stage evaporating pipe 256 is low. Due to the close distance between the low-temperature stage evaporator tube 256 and the first cooling evaporator tube 219, the first cooling evaporator tube 219 also has a relatively low line temperature, and even a significantly lower temperature than the other cooling evaporators in the high-temperature stage refrigeration cycle circuit located downstream of the first cooling evaporator tube 219. The one-way valve 220 arranged at the downstream of the first cooling evaporation pipe 219 is arranged in the first cooling branch, so that the first refrigerant in other cooling evaporators at the downstream of the first cooling evaporation pipe 219 can be prevented from flowing into the first cooling evaporation pipe 219 from the discharge port of the first cooling evaporation pipe 219, the first refrigerant in the high-temperature-stage refrigeration circulation loop can be prevented from flowing reversely, the effective circulation amount of the first refrigerant is ensured, and the overall refrigeration efficiency is improved.

A cooling evaporator for cooling the storage compartment 111 may not be provided in the second cooling branch.

A third cooling evaporator 221 may be disposed in the third cooling branch, and the third cooling evaporator 221 may be configured to be disposed in an evaporator installation cavity corresponding to the refrigerating compartment and configured to supply cooling to the refrigerating compartment.

And a second cooling evaporator 222 disposed between the high-temperature-stage condenser 212 and the suction port of the high-temperature-stage compressor 211, for causing the first refrigerant from the plurality of cooling branches to pass to the suction port of the high-temperature-stage compressor 211. The second cooling evaporator 222 is also used for promoting the first refrigerant flowing through the second cooling evaporator to absorb heat, so that the storage compartment 111 where the second cooling evaporator 222 is located is cooled. The second cooling evaporator 222 may be adapted to be disposed in an evaporator installation cavity corresponding to the freezing compartment and to supply cooling to the freezing compartment.

The evaporation portion 231 may be disposed between the high-temperature-stage condenser 212 and the second cooling evaporator 222, and the plurality of cooling branches may be disposed between the high-temperature-stage condenser 212 and the evaporation portion 231. That is, the plurality of cooling branches may be located downstream of the high temperature stage condenser 212 and upstream of the evaporation portion 231, and the second cooling evaporator 222 may be located downstream of the evaporation portion 231 and upstream of the suction port of the high temperature stage compressor 211.

The first cooling evaporator 219 and the third cooling evaporator are disposed between the high-temperature-stage condenser 212 and the evaporation portion 231, the second cooling evaporator is disposed between the evaporation portion 231 and the suction port of the high-temperature-stage compressor 211, and each evaporator or evaporator tube causes the first refrigerant flowing through the evaporator or evaporator tube to evaporate and absorb heat and supply cooling to the storage compartment 111, so that the cooling capacity generated in the high-temperature-stage cooling circulation loop is fully utilized, the energy utilization efficiency of the high-temperature-stage cooling circulation loop is improved, and further the energy utilization efficiency of the whole cooling device 10 is improved.

And a dew condensation preventing pipe 215 disposed between the high temperature stage condenser 212 and the cooling branch for inducing heat release of the first refrigerant flowing therethrough. The dew condensation preventing pipe 215 may be used to be disposed at an edge portion around the door body of the refrigeration apparatus 10. When the cascade compression refrigeration system operates, the first refrigerant discharges heat when flowing through the anti-dew pipe 215, so that the anti-dew pipe 215 heats up and generates heat, the phenomenon of dew formation at the edge of the door body of the refrigeration equipment 10 can be reduced or avoided, the edge of the door body of the refrigeration equipment 10 is kept dry, and the problems that the box body 110 is not tightly sealed due to rusting at the edge of the door body and the like can be avoided.

The high temperature stage reservoir may include a high temperature stage first reservoir and a high temperature stage second reservoir 223. The high-temperature-stage first receiver is disposed between the high-temperature-stage condenser 212 and the dew condensation preventing pipe 215, and is configured to adjust an amount of the first refrigerant required by other components (e.g., the high-temperature-stage condenser 212, the evaporation portion 231, or an evaporation pipe or an evaporator for cooling) in the high-temperature-stage refrigeration cycle. The flow rate of the first refrigerant required by each component in the high-temperature stage refrigeration cycle circuit can be different under different working conditions. The high temperature stage first receiver can be controlled to increase the liquid level when the first refrigerant flow required by other components in the high temperature stage refrigeration cycle is reduced. The high temperature stage first receiver may also be controllably adjusted down in liquid level as the first refrigerant flow required by other components within the high temperature stage refrigeration cycle circuit increases. The high-temperature first liquid storage bag is a high-pressure liquid storage bag. When the high-temperature-stage refrigeration cycle system stably operates, the first refrigerant entering the high-temperature-stage first liquid storage bag is usually in a saturated liquid state.

And a high-temperature-stage second reservoir 223 provided between the second cooling evaporator 222 and the suction port of the high-temperature-stage compressor 211. The high-temperature-stage second liquid storage bag 223 can prevent the first refrigerant flowing to the suction port of the high-temperature-stage compressor 211 from carrying the liquid first refrigerant, can also adjust the flow rate of the first refrigerant required by other components in the high-temperature-stage refrigeration cycle circuit, and can also prevent the first refrigerant at the second cooling evaporator 222 from slowly migrating to the suction port of the high-temperature-stage compressor 211 when the high-temperature-stage refrigeration cycle system is stopped.

The high-temperature stage refrigeration cycle circuit may further include: and a high-temperature stage dry filter 216 disposed between the dew condensation preventing pipe 215 and the electric switching valve 217. The high-temperature stage filter drier 216 functions to filter impurities in the first refrigerant and prevent ice blockage.

In this embodiment, in the high-temperature-stage refrigeration cycle loop, the first refrigerant may sequentially flow through the discharge port of the high-temperature-stage compressor 211, the high-temperature-stage condenser 212, the high-temperature-stage first reservoir, the dew prevention pipe 215, the high-temperature-stage drying filter 216, the electric switching valve 217, the plurality of cooling branches (including the branch throttle device 218, the first cooling evaporator, the check valve 220, and the third cooling evaporator 221), the evaporation portion 231, the second cooling evaporator 222, the high-temperature-stage second reservoir 223, and the suction port of the high-temperature-stage compressor 211, so as to form a complete cycle.

Fig. 4 is a schematic view of a cascade compression refrigeration system according to another embodiment of the present invention, in which the direction of the arrows show the direction of heat transfer.

In alternative embodiments, the heat exchange assembly may be structurally modified. For example, the heat exchange component may be two copper pipes abutting against each other, wherein one copper pipe is the heat absorbing portion 242, and the other copper pipe is the heat radiating portion 241. The two copper pipes are arranged in a mutual attaching mode. The contact part between the two copper pipes can be fixed by tin soldering to strengthen the heat transfer. The two copper pipes can be wrapped with aluminum foils.

In other alternative embodiments, the position of the evaporation portion 231 may be changed. A plurality of cooling branches may also be disposed between the high temperature stage condenser 212 and the second cooling evaporator 222, for example, the electric switching valve 217 and the cooling branch may be disposed between the dry filter 216 and the second cooling evaporator 222, and the evaporation portion 231 may be disposed within the second cooling branch.

As for the throttling device, fig. 2 to 4 are only illustrated by a capillary tube, but the throttling device in the above embodiment should not be construed as being limited to the capillary tube.

A heat dissipation fan 280 for inducing the formation of an airflow passing through the high temperature stage condenser 212 and then through the low temperature stage radiator 252, or for inducing the formation of an airflow passing through the low temperature stage radiator 252 and then through the high temperature stage condenser 212, or for inducing the formation of airflows passing through the low temperature stage radiator 252 and the high temperature stage condenser 212, respectively. The low temperature stage radiator 252 may be disposed adjacent to the high temperature stage condenser 212, and the radiator fan 280 may be disposed at one side of the low temperature stage radiator 252 and the high temperature stage condenser 212. The cooling fan 280 can increase the wind speed and the wind volume flowing through the low-temperature-stage radiator 252 and the high-temperature-stage condenser 212, so as to promote the low-temperature-stage radiator 252 and the high-temperature-stage radiator to quickly dissipate heat, thereby enhancing the heat dissipation effect, and enabling the cascade compression refrigeration system and the refrigeration device 10 with the cascade compression refrigeration system to continuously work within a normal temperature range.

The temperature of the low temperature stage radiator 252 is lower than the temperature of the high temperature stage condenser 212. The low-temperature-stage radiator 252 and the high-temperature-stage condenser 212 are arranged adjacent to each other, and the same heat dissipation fan 280 can promote the formation of air flow which firstly flows through the low-temperature-stage radiator 252 and then flows through the high-temperature-stage condenser 212, so that the heat dissipation effects of the low-temperature-stage radiator 252 and the high-temperature-stage condenser 212 are ensured, the arrangement number of the heat dissipation fans 280 is simplified, the structure miniaturization is facilitated, and the cascade compression refrigeration system of the embodiment can be applied to the household small refrigeration equipment 10.

The air supply blower 290, which may be plural, is respectively disposed corresponding to one evaporator installation cavity and each storage compartment 111, and is configured to blow cool air to each storage compartment 111. The plurality of air supply fans may include a first air supply fan, may be disposed corresponding to the evaporator installation cavity in which the first cooling evaporation pipe 219 and the low-temperature stage evaporation pipe 256 are disposed, for example, may be disposed at one side of the first cooling evaporation pipe 219 and the low-temperature stage evaporation pipe 256, and serve to guide the air flow passing through the first cooling evaporation pipe 219 and the low-temperature stage evaporation pipe 256 to the storage compartment 111. That is, the air supply blower 290 functions to induce the formation of an air flow passing through the first cooling evaporation pipe 219 and the low-temperature stage evaporation pipe 256 and passing through the storage compartment 111.

In other alternative embodiments, the cascade compression refrigeration system may further comprise a heat exchange device disposed within the low temperature stage refrigeration cycle loop. A heat exchange device, comprising: a heat emitting member and a heat absorbing member. The heat sink is disposed between the condensing unit 232 and the low-temperature-stage throttling device 255. The heat absorbing member is arranged between the low-temperature-stage evaporation pipe 256 and the suction inlet of the low-temperature-stage compressor 251, and is configured to enable the second refrigerant flowing through the heat absorbing member to absorb heat of the second refrigerant flowing through the heat releasing member, so that the second refrigerant is condensed in multiple sections and evaporated in multiple sections, and the second refrigerant flowing out of the condensing part 232 can be continuously condensed in the heat releasing member, so that the second refrigerant flowing out of the heat releasing member can be fully condensed, and the second refrigerant flowing out of the low-temperature-stage evaporation pipe 256 can be continuously evaporated in the heat absorbing member, thereby reducing the compression ratio of the low-temperature-stage compressor 251 to a certain extent, reducing or avoiding cold loss caused by too low suction temperature, improving the refrigeration efficiency, and avoiding condensation or frost formation near the suction inlet of the low-temperature-stage compressor 251.

The cascade compression refrigeration system of the present embodiment and the refrigeration equipment 10 having the same, wherein the cascade compression refrigeration system includes a high-temperature stage refrigeration cycle loop and a low-temperature stage refrigeration cycle loop. The low-temperature-stage refrigeration cycle circuit includes a heat exchange assembly having a heat radiating portion 241 disposed between a discharge port of the low-temperature-stage compressor 251 and the condensing portion 232, and a heat absorbing portion 242 disposed between a low-temperature-stage evaporating pipe 256 and a suction port of the low-temperature-stage compressor 251. The heat absorbing part 242 is configured to cause the second refrigerant flowing through the heat absorbing part 241 to absorb heat of the second refrigerant flowing through the heat releasing part 241, so that the temperature of the second refrigerant in the low-temperature stage refrigeration cycle circuit is raised before the second refrigerant flows into the compressor suction inlet, thereby increasing the suction temperature of the low-temperature stage compressor 251, reducing or avoiding cold loss caused by too low suction temperature, increasing refrigeration efficiency, reducing or avoiding the problem of condensation or frost formation around the suction inlet of the low-temperature stage compressor 251, and reducing the heat load of the high-temperature stage refrigeration cycle circuit. Compared with the scheme that the heat insulation cotton is arranged on the pipe section at the upstream of the suction inlet of the low-temperature stage compressor 251, the consistency of the product performance of the household small refrigeration equipment 10 during batch production is improved.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.

Claims

1. A cascade compression refrigeration system comprising:

a high-temperature-stage refrigeration cycle circuit in which a first refrigerant flows and an evaporation unit is provided;

the low-temperature-stage refrigeration circulation loop is used for circulating a second refrigerant and is internally provided with a low-temperature-stage compressor, a condensing part, a low-temperature-stage evaporation tube and a heat exchange assembly; the evaporation portion for causing the first refrigerant flowing therethrough to absorb heat of the second refrigerant flowing through the condensation portion;

the heat exchange assembly comprises:

a heat radiating part arranged between the low-temperature stage compressor discharge port and the condensing part;

the heat absorption part is arranged between the low-temperature-stage evaporation pipe and a suction inlet of the low-temperature-stage compressor;

the heat absorbing portion is for causing the second refrigerant flowing therethrough to absorb heat of the second refrigerant flowing through the heat radiating portion.

2. The cascade compression refrigeration system of claim 1 wherein the low temperature stage refrigeration cycle further comprises:

the low-temperature-stage throttling device is arranged between the condensing part and the low-temperature-stage evaporation pipe;

the heat absorption air return pipe section is arranged between the low-temperature-stage evaporation pipe and the low-temperature-stage compressor suction inlet; at least part of the heat absorption return pipe section is abutted against the low-temperature-stage throttling device, so that the second refrigerant flowing through the heat absorption return pipe section absorbs the heat of the second refrigerant flowing through the low-temperature-stage throttling device.

3. The cascade compression refrigeration system of claim 2 wherein

The heat absorption part is arranged between the heat absorption gas return pipe section and the low-temperature stage compressor suction inlet.

4. The cascade compression refrigeration system of claim 1 wherein the high temperature stage refrigeration cycle comprises:

the cooling system comprises a plurality of cooling branches which are mutually connected in parallel, wherein each cooling branch is internally provided with a branch throttling device; the plurality of cooling branches includes:

a first cooling branch provided with a first cooling evaporation pipe therein, the first cooling evaporation pipe being used for promoting the first refrigerant flowing through the first cooling branch to absorb heat; the first cooling evaporation pipe and the low-temperature-level evaporation pipe are used for cooling the same storage compartment in the refrigeration equipment.

5. The cascade compression refrigeration system of claim 4 wherein

The first cold supply evaporating pipe and the low-temperature-stage evaporating pipe are arranged on the same fin group in a penetrating mode.

6. The cascade compression refrigeration system of claim 4 wherein

And a one-way valve is further arranged in the first cooling branch and is arranged at the downstream of the first cooling evaporation pipe and used for only allowing the first refrigerant from the first cooling evaporation pipe to flow out in a one-way mode.

7. The cascade compression refrigeration system of claim 4 wherein the high temperature stage refrigeration cycle further comprises:

a high temperature stage compressor;

a high-temperature-stage condenser disposed between the high-temperature-stage compressor discharge port and the evaporation unit;

a second cooling evaporator disposed between the high-temperature-stage condenser and the high-temperature-stage compressor suction port, for causing the first refrigerant from the plurality of cooling branches to pass to the high-temperature-stage compressor suction port.

8. The cascade compression refrigeration system of claim 7 wherein

The evaporation part is arranged between the high-temperature-stage condenser and the second cooling evaporator;

the plurality of cooling branches are arranged between the high-temperature-stage condenser and the evaporation part.

9. The cascade compression refrigeration system of claim 4 wherein the high temperature stage refrigeration cycle further comprises:

and an electric switching valve having a plurality of valve ports for communicating with one of the cooling branches, respectively, for adjusting a flow path of the first refrigerant therethrough by controllably opening or closing the valve ports.

10. A refrigeration appliance comprising:

a box body;

the cascade compression refrigeration system according to any one of claims 1 to 9 disposed within the tank.