CN115468327A - A Self-cascading Refrigeration System with Staged Partial Condenser - Google Patents

Abstract

The invention provides a self-cascading refrigeration system with a staged subcondenser, including a compressor, which adopts a staged compressor, has a primary suction port a, a secondary suction port b, and an exhaust port c; a condenser, which The inlet of the refrigerant channel is connected to the exhaust port c of the compressor, which is used to condense the high-temperature and high-pressure gaseous mixed refrigerant discharged from the compressor into a gas-liquid two-phase mixed refrigerant; the gas-liquid separator, the gas The inlet of the liquid separator is connected to the outlet of the refrigerant channel of the condenser, which is used for flash separation of the gas-liquid two-phase mixed refrigerant discharged from the condenser; The device assembly is used to rectify and purify the gaseous mixed refrigerant working medium after flash evaporation in the gas-liquid separator, which can effectively reduce the pressure ratio of the mixed working medium rich in high-composition branches undergoing the compression process, and realize low-temperature cooling capacity Cascade utilization can obtain lower refrigeration temperature; this scheme has simple structure, remarkable energy-saving effect, and reliable and stable operation.

Description

A Self-cascading Refrigeration System with Staged Partial Condenser

technical field

The invention belongs to the low-temperature throttling refrigeration technology of mixed working medium, and in particular relates to a self-cascading refrigeration system with a graded separator.

Background technique

The self-cascading refrigeration system is a refrigeration system that uses non-azeotropic mixed working fluid and realizes multi-stage cascade through a single compressor to obtain a low temperature below -60°C. The system has the advantages of simple structure, reliable operation, and low cost. , Widely used in various low-temperature refrigeration and other fields. Therefore, the self-cascading refrigeration system is of great significance for saving energy and protecting the environment. The traditional single-stage self-cascading refrigeration cycle adopts single-stage compression and has low-temperature performance requirements, so that the working fluid flowing out from the bottom of the gas-liquid separator rich in high-boiling point components has a high compression ratio, and the total energy consumption of the compressor is high. As a result, the refrigeration efficiency obtained by the traditional single-stage compression cycle is low and the refrigeration temperature is limited. The traditional self-cascade technology also has the problem of using a phase separator to separate the mixed refrigerant, and the separation efficiency is low. Non-azeotropic mixed working fluid can improve the purity of low boiling point components and achieve lower evaporation temperature, but its high pressure ratio makes the energy consumption of the system relatively high. On the other hand, a rectification device is used to improve the self-cascading refrigeration cycle Efficient separation of mixed working fluids, but there are problems such as poor rectification effect when the ambient temperature rises.

In the prior art, the refrigeration system with two compressors connected in series is taken as an example, so that the high-boiling-point working fluid absorbs heat in the low-temperature stage condenser and directly mixes with the outlet working medium of the first-stage compressor before entering the second-stage compressor. Reduce the suction temperature of the secondary compressor, thereby reducing the discharge temperature of the secondary compressor. However, because the system needs to be equipped with two compressors in series, the complexity and cost of the system increase, and the gas-liquid separator in the system is not equipped with an effective component separation device, so that the separation of high and low boiling point components in the partial condenser The efficiency is low, and the purity of low-boiling components cannot be effectively improved, resulting in a limited refrigeration temperature that the system can produce. In particular, the disadvantage of the refrigeration system using two series compressors in series is that the lubricating oil carried by the working medium rich in high boiling point components only enters the secondary compressor, while the low boiling point working medium entering the primary compressor passes through The gas-liquid separation effect does not carry lubricating oil, so that the internal moving parts of the first-stage compressor cannot be lubricated, and failures such as dry burning of the compressor and insufficient oil seal occur, which aggravate the damage of the first-stage compressor.

Contents of the invention

The purpose of the present invention is to solve the above-mentioned problems in the prior art, and provide a self-cascading refrigeration system with a fractional condenser, which is applied to low-temperature throttling refrigeration in specific places, and can realize high-efficiency separation of high and low boiling points and low-temperature refrigeration .

In order to achieve the above object, the present invention adopts the following technical scheme: a self-cascading refrigeration system with a step-by-step decondenser, including a compressor, with a primary suction port a, a secondary suction port b and an exhaust port c, A staged compressor is used; the condenser, the inlet of the refrigerant channel is connected to the exhaust port c of the compressor, and is used to condense the high-temperature and high-pressure gaseous mixed refrigerant discharged from the compressor into a gas-liquid two-phase mixed refrigerant working fluid; a gas-liquid separator, the inlet of which is connected to the outlet of the refrigerant working medium channel of the condenser, and is used for flash separation of the gas-liquid two-phase mixed refrigerant working medium discharged from the condenser; A fractional condenser assembly is arranged above the interior of the gas-liquid separator, which is used to rectify and purify the gaseous mixed refrigerant working medium after flashing inside the gas-liquid separator; The refrigerant working medium is mixed with a part of the liquid-phase refrigerant working medium discharged from the bottom outlet of the gas-liquid separator, and finally enters the first-stage suction port a of the compressor through the first refrigerant working medium pipeline of the fractional condenser assembly; the gas-liquid Another part of the liquid-phase refrigerant working medium discharged from the outlet at the bottom of the separator finally enters the secondary suction port b of the compressor through the second refrigerant working medium pipeline of the staged partial condenser assembly, thereby realizing staged compression.

As a preferred solution, the graded subcondenser assembly includes a first subcondenser and a second subcondenser, and the first subcondenser is located below the second subcondenser; the gas-phase refrigerant flowing out from the top of the gas-liquid separator After the working medium is mixed with a part of the liquid-phase refrigerant working medium discharged from the bottom outlet of the gas-liquid separator; after passing through the refrigerant working medium pipeline of the second sub-condenser, it enters the first-stage suction port a of the compressor; the gas Another part of the liquid-phase refrigerant working fluid discharged from the bottom of the liquid separator enters the secondary suction port b of the compressor through the refrigerant working medium pipeline of the first sub-condenser.

As a preferred solution, it also includes a first regenerator, which is used to superheat the refrigerant working fluid passing through the refrigerant working medium channel of the second sub-condenser, and finally enter the first-stage suction port a of the compressor.

As a preferred solution, the first regenerator includes a low-temperature side channel and a high-temperature side channel, the outlet of the refrigerant working medium channel of the second sub-condenser is connected to the inlet of the low-temperature side channel of the first regenerator, and the low-temperature side channel of the first regenerator The outlet of the side channel is connected to the first-stage suction port a of the compressor, so that the refrigerant working medium discharged from the second sub-condenser enters the first-stage suction port a of the compressor after being overheated by the first regenerator; The high temperature side channel inlet of the first regenerator is connected with the bottom outlet of the gas-liquid separator.

As a preferred solution, the outlet of the high-temperature side channel of the first regenerator is divided into two branches, wherein the refrigerant working fluid flowing out of the first branch enters the refrigerant working medium channel of the first sub-condenser, and the second branch The refrigerant working medium flowing out is mixed with the refrigerant working medium flowing out from the top outlet of the gas-liquid separator, and then enters the refrigerant working medium channel of the second sub-condenser.

As a preferred solution, a first throttling component and an evaporative condenser are sequentially arranged on the first branch, and the inlet of the first throttling component is connected to the outlet of the high-temperature side channel of the first regenerator, and the first throttling component The outlet of the flow component is connected with the low-temperature side channel inlet of the evaporative condenser, and the low-temperature side channel outlet of the evaporative condenser is connected with the refrigerant working medium channel inlet of the first sub-condenser.

As a preferred solution, the high temperature side channel inlet of the evaporative condenser is connected with the top outlet of the gas-liquid separator, the high temperature side channel outlet of the evaporative condenser is connected with the high temperature side channel inlet of the second regenerator, and the second circuit The outlet of the high-temperature side channel of the heater is connected with the inlet of the refrigerant working medium channel of the evaporator through the third throttling part, and the outlet of the refrigerant working medium channel of the evaporator is connected with the inlet of the low-temperature side channel of the second regenerator. The refrigerant working medium at the outlet of the low-temperature side channel of the heater and part of the liquid-phase refrigerant working medium discharged from the bottom outlet of the gas-liquid separator are throttled and mixed into the refrigerant working medium channel of the second sub-condenser.

As a preferred solution, the refrigerant working medium is a binary or higher non-azeotropic mixed refrigerant working medium composed of a mixture of a high-boiling point refrigerant working medium and a low-boiling point refrigerant working medium, and the low-boiling point refrigerant working medium The refrigerant is HC or HFC refrigerant, and the low boiling point refrigerant is one or more of R1150, R50 or R23; the high boiling point refrigerant is HC or HFC refrigerant. The boiling point refrigerant is one or more of R134a, R152a, R600, and R600a.

Beneficial effect

First, the present invention can achieve high-efficiency separation of high and low boiling points and low-temperature refrigeration, and is different from the common technical route in the prior art. This solution adopts a specific technical route and utilizes a staged compressor with two-stage suction ports, Most of the mixed working medium rich in high boiling point components from the bottom of the gas-liquid separator flows into the staged compressor through the medium-pressure suction port of the compressor to achieve a low compression ratio compression process, and all of it comes from the gas-liquid separator The mixed working medium rich in low boiling point components at the top and a small part of the mixed working medium rich in high boiling point components from the bottom of the gas-liquid separator only flow into the staged compressor through the low-pressure suction port of the compressor to achieve high compression ratio compression process, so as to realize the cascade compression process of the mixed working fluid, reduce the compression ratio of the compressor, and thus significantly reduce the total energy consumption of the compressor.

Second, this scheme adopts the structural design concept of the first sub-condenser and the second sub-condenser stacked high and low to realize the stepwise rectification and purification process of the low-boiling point components of the gaseous mixed working medium in the gas-liquid separator and The low-temperature cooling capacity at different temperature levels is used in stages to obtain lower cooling temperatures and improve cooling efficiency.

Third, this program also increases the subcooling degree of the liquid mixed working medium at the bottom outlet of the gas-liquid separator by setting the first regenerator at the bottom outlet of the gas-liquid separator, and ensures that the first suction gas entering the stage compressor The mixed working medium at the port is in a superheated or saturated vapor state, which plays a role in improving the refrigeration efficiency and ensuring the dry compression process of the compressor.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only For some embodiments of the invention, those skilled in the art can also obtain other drawings based on these drawings without creative effort.

Fig. 1 is the schematic diagram of the self-cascading refrigerating system of the present invention band fractional condenser;

Marks in the figure: 1. Compressor, 2. Condenser, 3. Gas-liquid separator, 4. First throttling part, 5. Evaporation condenser, 6. Second regenerator, 7. Third throttling part , 8, evaporator, 9, the second sub-condenser, 10, the first sub-condenser, 11, the first regenerator, 12, the second throttling part; a, the primary suction port, b, the secondary Suction port, c, exhaust port.

detailed description

The present invention will be specifically described through exemplary embodiments below. It should be understood, however, that elements, structures and characteristics of one embodiment may be beneficially incorporated in other embodiments without further recitation.

It should be noted that unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by those with ordinary skill in the field of the present invention. Words such as "a", "an" or "the" used in the specification and claims of the patent application of the present invention do not express a limitation on quantity, but mean that there is at least one. Words such as "comprises" or "comprises" and similar terms indicate that the elements or items preceded by "comprises" or "comprises" include the elements or items listed after "comprises" or "comprises" and their equivalents, but do not exclude other Components or objects with the same function.

This embodiment provides a self-cascading refrigeration system with a fractional condenser, including a compressor 1, a condenser 2, a gas-liquid separator 3, a first throttling component 4, an evaporative condenser 5, and a second regenerator 6. The third throttling component 7 , the evaporator 8 , the second sub-condenser 9 , the first sub-condenser 10 , the first regenerator 11 and the second throttling component 12 .

In this embodiment, the compressor 1 adopts a step-by-step compressor, which has a primary suction port a, a secondary suction port b, and a high-pressure exhaust port c; wherein the primary suction port a is a low-pressure suction port, and the secondary suction port a is a low-pressure suction port. Gas port b is a medium-pressure suction port. The first-stage suction port a and the second-stage suction port b provided by compressor 1 can realize the working fluid flowing out of the bottom and top of gas-liquid separator 3 into compressor 1 respectively. In the cascade compression process, the outlet c of the compressor 1 is connected to the inlet of the gas-liquid separator 3 through the condenser 2, the gas-liquid separator 3 is also provided with a top outlet and a bottom outlet, the top outlet of the gas-liquid separator 3, the evaporation The high-temperature side channel of the condenser 5, the high-temperature side channel of the second regenerator 6, the third throttle member 7, and the inlet of the evaporator 8 are connected in series in sequence, and the outlet of the evaporator 8 passes through the low-temperature side channel of the second regenerator 6 It is connected with the outlet pipe of the second throttling part 12; the bottom outlet of the gas-liquid separator 3 is connected with the inlet of the high-temperature side channel of the first regenerator 11, and the outlet of the high-temperature side channel of the first regenerator 11 is divided into two branches A branch is connected with the inlet of the first throttling part 4, and the outlet of the first throttling part 4 is connected with the inlet of the evaporative condenser 5 low-temperature side passage, and the outlet of the evaporative condenser 5 low-temperature side passage is connected with the first sub-condenser 10, the outlet of the first sub-condenser 10 is connected to the secondary suction port b of the compressor 1; the other branch of the high temperature side channel outlet of the first regenerator 11 is connected to the The inlet is connected, the outlet of the second throttling part 12 is connected with the inlet of the second sub-condenser 9, the outlet of the second sub-condenser 9 is connected with the low-temperature side channel inlet of the first regenerator 11, and the first regenerator 11 The outlet of the low-temperature side channel is connected to the primary suction port a of compressor 1. Wherein the outlet of the low-temperature channel of the second regenerator 6 is connected to the pipeline between the outlet of the second throttling component 12 and the inlet of the second sub-condenser 9 . The first throttling part 4 is arranged on the pipeline between the gas-liquid separator 3 and the evaporative condenser 5, and the second throttling part 12 is arranged on the pipeline between the gas-liquid separator 3 and the second sub-condenser 9 , the third throttling component 7 is arranged on the connecting pipe between the evaporator 8 and the high temperature side pipe of the second regenerator 6 .

In this solution, the exhaust port c of the compressor 1 is connected to the inlet of the gas-liquid separator 3 through the condenser 2, so that the high-temperature and high-pressure gaseous mixed refrigerant working medium coming out of the exhaust port c of the compressor 1 is condensed by the condenser 2 Release heat into a higher temperature and high pressure gas-liquid two-phase mixed refrigerant and enter the gas-liquid separator 3 for flash separation. The secondary suction port b of the compressor 1 passes through the first sub-condenser 10 and the evaporation condenser 5. The low-temperature side channel is connected, so that part of the liquid mixed refrigerant working medium flowing out from the bottom of the gas-liquid separator 3 and the gaseous mixed refrigerant working medium flowing out from the top of the gas-liquid separator 3 are heat-exchanged by the evaporative condenser 5, and finally compressed The secondary suction port b of the machine 1 flows into the compressor 1 to complete the compression process with a low compression ratio, and the primary suction port a of the compressor 1 is connected with the second sub-condenser 9 through the first regenerator 11, so that the After the gaseous refrigerant working medium in the second regenerator 6 is mixed with the liquid refrigerant working medium throttled by the second throttling part 12, it passes through the second sub-condenser 9 and finally enters the primary suction port a of the compressor 1 The high compression ratio compression process is completed, so that the staged compression is finally completed in the compressor 1 . Condenser 2, the inlet of the refrigerant channel is connected to the exhaust port c of compressor 1, and is used to condense the high-temperature and high-pressure gaseous mixed refrigerant discharged from compressor 1 into a gas-liquid two-phase mixed refrigerant .

In this scheme, the compressor 1 utilizes the characteristic that the non-azeotropic mixed working fluid is flashed and separated into a gas phase and a liquid phase mixed working medium in the gas-liquid separator 3, and the evaporation temperature of the working medium rich in high boiling point components in the branch is throttled. High, its evaporation pressure is also high, so that the gas-phase mixed working medium entering the secondary suction port b of compressor 1 has higher purity, and the working medium rich in low boiling point components in the branch circuit has a low evaporation temperature after throttling, and its evaporation The pressure is also low, so that it only flows into the primary suction port a of the compressor 1, so that the two branch working fluids are compressed in stages in the compressor 1, reducing the energy consumption of the compressor and producing a lower refrigeration temperature.

The function of the gas-liquid separator 3 is to separate the high-temperature and high-pressure gas-liquid two-phase mixed working fluid from the condenser 2 into a gas-phase mixed working medium rich in low-boiling point components flowing out from the outlet of the top working medium and enriched in high-boiling point components. The separated liquid-phase mixed working medium flows out from the outlet of the working medium at the bottom, and the gas-liquid separator 3 is equipped with a condensing structure, and the condensing structure is the fractional condensing device assembly that separates the rich liquid from the gas-liquid separator 3. The gas-phase working medium containing low-boiling point components is partially condensed, thereby obtaining a saturated gas-phase refrigerant working medium rich in higher-purity low-boiling point components flowing out from the top of the gas-liquid separator 3, wherein the condensed liquid refrigerant working medium flows back to the bottom of the gas-liquid separator 3, and flow out from the bottom of the gas-liquid separator 3 together with the liquid-phase refrigerant working medium rich in high boiling point components separated by flash evaporation.

In this embodiment, the refrigerant working medium inlet of the gas-liquid separator 3 is connected to the exhaust port c of the compressor 1 through the condenser 2, so that the high-temperature and high-pressure gas-liquid two-phase mixed refrigerant working medium from the condenser 2 is separated from the gas-liquid The flash separation in the device 3 is divided into a liquid-phase mixed refrigerant working medium rich in high-boiling components and a gas-phase mixed refrigerant rich in low-boiling components, and a fractional condenser is arranged above the interior of the gas-liquid separator 3 The component is used for rectifying and purifying the gaseous mixed refrigerant working medium flashed in the gas-liquid separator 3 . The gas-phase refrigerant working medium rich in low-boiling point components flashed and separated by the gas-liquid separator 3 is partially condensed under the action of the fractional condenser assembly, and the gas-phase refrigerant working medium with higher purity low-boiling point components is obtained. The substance flows out from the top outlet of the gas-liquid separator 3; the liquid refrigerant working fluid condensed by the sub-condenser assembly returns to the bottom of the gas-liquid separator 3 and is separated by the flash evaporation of the gas-liquid separator 3. The separated liquid-phase refrigerant is mixed and discharged through the bottom outlet of the gas-liquid separator 3.

In this solution, the graded subcondenser assembly includes a first subcondenser 10 and a second subcondenser 9 , and the first subcondenser 10 is located below the second subcondenser 9 . The function of the second sub-condenser 9 is: the gas-phase mixed working medium rich in low-boiling components flowing out from the gas-liquid separator 3 top working medium outlet can be passed through the second regenerator 6 for superheating and then continue to pass through the second The sub-condenser 9 is superheated to obtain low-pressure superheated steam entering the first-stage suction port a of the compressor 1. The function of the first sub-condenser 10 is to make the high-boiling-point group rich in the working medium outlet flow out from the bottom of the gas-liquid separator 3 The divided liquid mixed working fluid is evaporated on the evaporation side of the evaporative condenser 5 and continues to be overheated after evaporating and absorbing heat, and then the medium-pressure superheated steam obtained enters the secondary suction port b of the compressor 1, thereby realizing the staged compression of the two branched working fluids process, thereby reducing the energy consumption of the compressor 1.

In a specific embodiment: the first subcondenser 10 and the second subcondenser 9 are both arranged in the upper space of the gas-liquid separator 3, and the working medium vapor of the gas-liquid separator 3 is from bottom to top First flow through the outside of the first sub-condenser 10 to experience the first-stage rectification and purification process, and then flow through the outside of the second sub-condenser 9 to experience the second-stage rectification and purification process; The sub-condenser 10 and the second sub-condenser 9 realize the cascade rectification and purification of the low-boiling point components of the gaseous mixed working medium in the gas-liquid separator 3, and realize the cascade utilization of low-temperature cooling capacity at different temperature positions.

In this embodiment, the first regenerator 11 is arranged between the gas-liquid separator 3 and the second throttling part 12, so that the liquid mixed refrigerant working medium rich in high boiling point components from the bottom of the gas-liquid separator 3 passes through the second After the high temperature side of the first regenerator 11 is subcooled, part of it flows into the second throttling component 12 and mixes with the refrigerant rich in low boiling point components superheated by the second regenerator 6, and then flows into the second sub-condenser 9, Thereby realizing the rectification requirement of the second sub-condenser 9, the first regenerator 11 is arranged between the second sub-condenser 9 and the compressor 1, and the purpose of setting the first regenerator 11 is: for recovering the second sub-condenser The low-temperature cooling capacity of the mixed refrigerant working medium at the outlet of the condenser 9, while ensuring that the mixed refrigerant working medium before entering the suction port a of the compressor 1 is in a saturated vapor state or a superheated state, so as to avoid the existence of the compression process in the compressor 1 Wet compression process. Make the gaseous refrigerant working medium rich in low boiling point components from the top outlet of the gas-liquid separator 3 pass through the second sub-condenser 9 to absorb heat and cool down, and at the same time ensure that the refrigerant working medium in the second sub-condenser 9 is superheated, Thus, the dryness requirement of the compression process of the compressor 1 is ensured.

In this scheme, in a specific embodiment, the liquid working medium rich in high boiling point components flowing out of the first regenerator 11 is divided into two branches: the liquid working medium in the first branch passes through the first throttling Part 4 enters the evaporative condenser 5 after throttling and cooling down, absorbs the condensation heat of the gaseous refrigerant working medium rich in low-boiling components from the gas-liquid separator 3, and then enters the first sub-condenser 10 to realize the gas-liquid separator After the first-stage rectification and purification of the gaseous mixed refrigerant in 3, it enters the second-stage suction port b of compressor 1 to complete the compression process with a low compression ratio; the liquid refrigerant in the second branch passes through the second throttling After the component 12 is throttled and lowered in temperature and pressure, it mixes with the refrigerant working medium from the second regenerator 6 and enters the second sub-condenser 9 to realize the second-stage rectification and purification of the gaseous mixed working medium in the gas-liquid separator 3 , and then through the first regenerator 11 to absorb heat, and finally flow into the compressor 1 through the primary suction port a of the compressor 1 to complete the high compression ratio compression process.

In this embodiment, the gas-phase mixed refrigerant working medium rich in low-boiling components flowing out from the outlet of the working medium at the top of the gas-liquid separator 3 is condensed by the evaporative condenser 5 and then enters the high-temperature side of the second regenerator 6 for subcooling and second regenerator 6. After throttling by the three-throttling part 7, the low-pressure two-phase refrigerant working fluid flows into the evaporator 8 to evaporate and absorb heat, and the saturated gas refrigerant working fluid enters the low-temperature side of the second regenerator 6 and is superheated and then mixed with the refrigerant from the second section. The working medium after throttling and depressurization of the flow part 12 is mixed, and the mixed gas-liquid two-phase refrigerant working medium enters the second sub-condenser 9 for overheating and the low-temperature side of the first regenerator 11 for overheating, and then enters the compressor 1 stage At the suction port a, the liquid-phase mixed refrigerant refrigerant rich in high-boiling components flowing out of the outlet of the refrigerant refrigerant at the bottom of the gas-liquid separator 3 is divided into two branches after being supercooled by the high-temperature side of the first regenerator 11, of which One branch flows into the first throttling part 4 to obtain a medium-pressure two-phase refrigerant working medium, and then enters the evaporative condenser 5 to evaporate and absorb heat, and after the first sub-condenser 10 is overheated, the obtained medium-pressure superheated steam enters the compression The secondary suction port b of the engine 1 is compressed into high temperature and high pressure gas. At the same time, another branch flowing out from the first regenerator 11 flows into the second throttling component 12 and is throttled and depressurized with the gas from the first After the superheated steam from the two recuperators 6 is mixed, it enters the second sub-condenser 9 and is sucked into the primary suction port a of the compressor 1 after being overheated. Compared with the prior art, the adoption of the staged compressor and the flow direction of the refrigerant working medium can ensure that the compressor is sufficiently lubricated. (In the prior art, for a refrigeration system with two series-connected compressors, during the operation of the system, the lubricating oil in the system is often carried by the refrigerant and discharged from the compressor, and is brought back to the compressor by the refrigerant after circulation. There are two phases in the circulation process, that is, liquid refrigerant and vapor refrigerant, and the lubricating oil is basically in a liquid state. When the refrigerant changes from liquid to vapor in the gas-liquid separator, the lubricating oil will be separated from the vapor refrigerant, and no longer Flowing with the vapor refrigerant, if the lubricating oil carried by the separated liquid refrigerant only enters the secondary compressor and does not enter the primary compressor, the internal moving parts of the primary compressor will be insufficiently lubricated during use. Faults such as compressor dry burning and insufficient oil seal will aggravate the damage of the primary compressor.)

The working principle of this scheme is as follows: the superheated steam flowing out from the exhaust port c of the compressor 1 is partially condensed by the condenser 2, and then enters the gas-liquid separator 3 with a double-stage partial condenser structure for flash separation and purification, and enters The refrigerant working medium vapor of the gas-liquid separator 3 first flows through the outside of the first sub-condenser 10 from bottom to top to undergo the first-stage rectification and purification process, and then flows through the outside of the second sub-condenser 9 to undergo the second-stage purification process. Distillation and purification process, so that the saturated gas-phase refrigerant working medium rich in higher purity low-boiling point components flows out from the top of the gas-liquid separator 3, and the condensed liquid refrigerant working medium flows back to the bottom of the gas-liquid separator 3, It flows out from the bottom of the gas-liquid separator 3 together with the liquid working medium rich in high boiling point components separated by flash evaporation. Thus, the mixed refrigerant working fluid is divided into two branches, one of which flows to: the saturated gaseous refrigerant working fluid rich in higher-purity low-boiling point components flowing out from the top of the gas-liquid separator 3, the gaseous refrigerant The working medium first enters the high-temperature side channel of the condensing evaporator 5 and is partially condensed into a gas-liquid two-phase working medium, then enters the high-temperature side channel of the second regenerator 6 for supercooling, and then enters the third throttling part 7 to throttle and reduce pressure After the low-pressure two-phase refrigerant working medium is obtained, it enters the evaporator 8 to evaporate and absorb heat to realize low-temperature refrigeration. The saturated gaseous refrigerant working medium flowing out of the evaporator 8 is overheated through the low-temperature side channel of the second regenerator 6, and is combined with the The liquid working medium throttled by the second throttling part 12 is mixed, and then enters the second sub-condenser 9 for overheating and the first regenerator 11 low-temperature side channel for overheating, and the low-pressure gaseous refrigerant flowing out of the first regenerator 11 works The mass is sucked into the first suction port a of the compressor 1 to complete the compression process with a high compression ratio.

At the same time, the saturated liquid working medium rich in high boiling point components flowing out from the bottom of the gas-liquid separator 3 flows into the high temperature side channel of the first regenerator 11 and after supercooling, the obtained high boiling point The liquid working medium of the components is divided into two branches, one of which flows to the first throttling part 4 to throttle and reduce pressure, and the outflowing medium-pressure two-phase refrigerant working medium passes through the evaporative condenser 5 after heat exchange in the low-temperature side channel , the medium-pressure superheated steam obtained after heat exchange in the first sub-condenser 10 enters the secondary suction port b of the compressor 1, and at the same time, the liquid refrigerant working medium in another branch flows to the second throttling part 12 knots After the temperature and pressure drop of the stream, it is mixed with the gaseous refrigerant working medium from the second regenerator 6 and enters the second sub-condenser 9 to realize the second-stage rectification and purification of the gaseous mixed working medium in the gas-liquid separator 3. After absorbing heat through the low-temperature side channel of the first regenerator 11, it flows into the primary suction port a of the compressor 1 to complete the high compression ratio compression process, thereby realizing the step compression process in the compressor 1, thus completing a cycle. The above-mentioned refrigeration cycle system can effectively reduce the compressor pressure ratio of the mixed working medium rich in high-composition branches undergoing the compression process.

This scheme realizes the cascade compression of the working fluid through a staged compressor, reduces the compression ratio of the compressor, reduces the energy consumption of the compressor and the exhaust temperature; realizes the cascade rectification and purification of the gaseous mixed working medium by setting a two-stage condenser, and realizes low temperature The cascade utilization of cooling capacity improves the purity of low boiling point components and obtains lower refrigeration temperature; by setting the first regenerator 11, the subcooling degree of the mixed working medium is increased and the wet compression process of the mixed working medium is avoided. The system is simple in structure, remarkable in energy-saving effect, reliable and stable in operation, and has broad application prospects.

In this scheme, the working fluid used is a binary or higher non-azeotropic mixed working fluid composed of a mixture of high boiling point working medium and low boiling point working medium, and the low boiling point working medium is HC or HFC such as R1150, R50, R23, etc. Working fluid, high boiling point working fluid is R134a, R152a, R600, R600a and other HC or HFC working fluid.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, may use the technical content disclosed above to make some changes or modify them into equivalent embodiments with equivalent changes, but as long as they do not depart from the technical solution of the present invention, the Technical Essence Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solution of the present invention.

Claims (8)

1. A self-cascading refrigeration system with a graded subcondenser, characterized in that: comprising The compressor adopts a staged compressor and has a primary suction port a, a secondary suction port b and an exhaust port c; a condenser, the inlet of the refrigerant channel is connected to the exhaust port c of the compressor, and is used to condense the high-temperature and high-pressure gaseous mixed refrigerant discharged from the compressor into a gas-liquid two-phase mixed refrigerant; A gas-liquid separator, the inlet of which is connected to the outlet of the refrigerant working medium channel of the condenser, and is used for flash separation of the gas-liquid two-phase mixed refrigerant working medium discharged from the condenser; inside the gas-liquid separator The upper part is equipped with a fractional condenser assembly, which is used to rectify and purify the gaseous mixed refrigerant after flashing inside the gas-liquid separator; The rectified and purified gas-phase refrigerant working medium flowing out from the top of the gas-liquid separator is mixed with a part of the liquid-phase refrigerant working medium discharged from the bottom outlet of the gas-liquid separator, and finally passes through the first refrigerant working medium of the fractional condenser assembly. The refrigerant pipeline enters the first-stage suction port a of the compressor; another part of the liquid-phase refrigerant working fluid discharged from the outlet at the bottom of the gas-liquid separator finally enters the second refrigerant working fluid pipeline of the compressor through the second refrigerant working fluid pipeline of the fractional condenser assembly. stage suction port b to achieve staged compression. 2. A self-cascading refrigeration system with a fractional condenser as claimed in claim 1, wherein the fractional condenser assembly comprises a first fractional condenser and a second fractional condenser, and the first fractional condenser The condenser is located below the second sub-condenser; the gas-phase refrigerant working fluid flowing out from the top of the gas-liquid separator is mixed with a part of the liquid-phase refrigerant working fluid discharged from the outlet at the bottom of the gas-liquid separator; the refrigerant working fluid passes through the second The refrigerant working medium pipeline of the sub-condenser enters the first-stage suction port a of the compressor; another part of the liquid-phase refrigerant working medium discharged from the bottom of the gas-liquid separator passes through the refrigerant of the first sub-condenser The working fluid pipeline enters the secondary suction port b of the compressor. 3. A kind of self-cascading refrigeration system with staged subcondenser as claimed in claim 2, is characterized in that: also comprise the first regenerator, be used for the refrigerant working medium that passes through the second subcondenser refrigerant working medium channel After the mass is overheated, it finally enters the primary suction port a of the compressor. 4. As claimed in claim 3, a self-cascading refrigeration system with staged partial condensers, characterized in that: the first regenerator includes a low-temperature side channel and a high-temperature side channel, and the refrigerant working medium of the second partial condenser The outlet of the channel is connected to the inlet of the low-temperature side channel of the first regenerator, and the outlet of the low-temperature side channel of the first regenerator is connected to the primary suction port a of the compressor, so that the refrigerant discharged from the second sub-condenser passes through After the first regenerator is overheated, it enters the primary suction port a of the compressor; the inlet of the high temperature side channel of the first regenerator is connected with the bottom outlet of the gas-liquid separator. 5. As claimed in claim 4, a self-cascading refrigeration system with a fractional condenser, characterized in that: the outlet of the high-temperature side channel of the first regenerator is divided into two branches, wherein the first branch flows out The refrigerant working medium enters the refrigerant working medium channel of the first sub-condenser, and the refrigerant working medium flowing out of the second branch is mixed with the refrigerant working medium flowing out from the top outlet of the gas-liquid separator and then enters the cooling chamber of the second sub-condenser. Agent channel. 6. As claimed in claim 5, a self-cascading refrigeration system with a fractional condenser, characterized in that: a first throttling component and an evaporative condenser are sequentially arranged on the first branch, and the first throttling component The inlet of the evaporative condenser is connected with the high temperature side channel outlet of the first regenerator, the outlet of the first throttling component is connected with the low temperature side channel inlet of the evaporative condenser, and the low temperature side channel outlet of the evaporative condenser is connected with the The refrigerant working medium channel inlet of the first sub-condenser is connected to each other. 7. As claimed in claim 6, a self-cascading refrigeration system with a fractional condenser, wherein: the high-temperature side channel inlet of the evaporative condenser is connected to the top outlet of the gas-liquid separator, and the evaporative condenser The outlet of the high-temperature side channel is connected with the inlet of the high-temperature side channel of the second regenerator, and the outlet of the high-temperature side channel of the second regenerator is connected with the inlet of the refrigerant working medium channel of the evaporator through the third throttling component, and the refrigerant of the evaporator The outlet of the working medium channel is connected to the inlet of the low-temperature side channel of the second regenerator, and the refrigerant working medium at the outlet of the low-temperature side channel of the second regenerator and part of the liquid-phase refrigerant discharged from the bottom outlet of the gas-liquid separator After the flow, it is mixed into the refrigerant working medium channel of the second sub-condenser. 8. The self-cascading refrigeration system with staged decondenser as claimed in any one of claims 1-7, wherein the refrigerant working fluid is a high boiling point refrigerant working fluid and a low boiling point refrigerant working fluid A non-azeotropic mixed refrigerant working fluid composed of binary or more than binary components. The low boiling point refrigerant working fluid adopts HC or HFC refrigerant working fluid, and the low boiling point refrigerant working medium is R1150, R50 or R23 One or more of them; the high boiling point refrigerant is HC or HFC refrigerant, and the high boiling point refrigerant is one or more of R134a, R152a, R600, R600a.

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