CN103105021A

CN103105021A - Refrigeration heat pump unit of carbon dioxide (CO2) transcritical cycle and control method thereof

Info

Publication number: CN103105021A
Application number: CN2013100229459A
Authority: CN
Inventors: 秦海涛
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-01-22
Filing date: 2013-01-22
Publication date: 2013-05-15
Anticipated expiration: 2033-01-22
Also published as: CN103105021B

Abstract

The invention belongs to the technical field of transcritical carbon dioxide (CO2) refrigeration heat pumps. A refrigeration heat pump unit of a CO2 transcritical cycle comprises a CO2 refrigerant compressor, a gas cooler, a regenerator, a throttle valve I, a gas-liquid separator, a throttle valve II, an evaporator, a controller, a pressure sensor, a temperature sensor and a superheat temperature sensor. All parts are connected through pipelines to form a closed system. The controller controls opening degrees of the throttle valve I and the throttle valve II according to detected refrigerant pressure in the gas cooler, detected refrigerant temperature of an outlet of the gas cooler, refrigerant superheat degree of an outlet of the evaporator and the highest cooling pressure Pg of system operation, and the unit is enabled to be operated under high cycling efficiency. The refrigeration heat pump unit of the CO2 transcritical cycle and a control method of the refrigeration heat pump unit of the CO2 transcritical cycle have the advantages that when environment temperature or environment temperature of a cooled department changes, the controller can adjust the unit and enable the unit to be operated under the high cycling efficiency, and the method is simple, easy to achieve, reliable and stable.

Description

CO 2refrigerating heat pump unit and control method thereof across critical cycle

Technical field

The invention belongs to across critical CO ₂the refrigerating heat pump technical field.

Background technology

Due to the material impact that CFCs warms for ozone layer and atmosphere, protection of the environment realizes that CFCs substitutes becomes the common problem of paying close attention in the whole world.HFCs class cold-producing medium substitutes as CFCs's, although do not damage the ozone layer, its obvious greenhouse effects, or environment is warmed and has a certain impact.So people start to advocate energetically the use natural refrigerant.CO ₂natural refrigerant is subject to again extensive concern, CO ₂the research of refrigerating heat pump device becomes again valued focus in the world with application.

Of the prior art across critical CO ₂refrigeration system mainly comprises compressor, cooler, regenerator, choke valve, gas-liquid separator, evaporimeter etc., prior art across critical CO ₂the deficiency of refrigeration system is: when the residing environment of system changes, the distribution of refrigerant in system can change, due to the HTHP CO in gas cooler ₂cold-producing medium can not liquefy, and causes the distribution of refrigerant in all parts larger on the impact of system pressure, and the high-low pressure of refrigeration system is regulated difficulty; Due to across critical CO ₂temperature and pressure be not corresponding one by one, supercritical CO ₂heat release in cooler, variations in temperature is very large, and larger cooler is imported and exported the temperature difference and is made to improve across critical cycle efficiency, different outlet temperatures, the cooling pressure of a corresponding optimum makes cycle efficieny the highest.So when environment temperature changes while causing that gas cooler exit temperature changes, can not make corresponding adjustment to cooling pressure, to guarantee that refrigeration system has the higher coefficient of performance, and different from subcritical cycle be, cooling pressure is not more low better, but, for different outlet temperatures, has an optimal value, therefore, regulate difficulty.

summary of the invention

The present invention proposes for addressing the above problem, and its purpose is to provide a kind of CO ₂across the refrigerating heat pump unit of critical cycle, reasonable, brief compactness that unit arranges; The present invention also provides CO in addition ₂across the control method of the refrigerating heat pump unit of critical cycle, by the control to system cools pressure, maintain the system optimization operation.

Technical scheme of the present invention is: CO ₂refrigerating heat pump unit across critical cycle, comprise CO ₂coolant compressor, gas cooler, regenerator, the choke valve I, gas-liquid separator, the choke valve II, evaporimeter and controller, it is characterized in that: unit also comprises pressure sensor, temperature sensor and overtemperature sensor, described each parts connect into a closed-system by pipeline: exhaust outlet of compressor is connected with the gas cooler import, the gas cooler outlet is connected with regenerator import I, regenerator outlet I is divided into two-way, one tunnel is connected with evaporator after the choke valve II, another road is connected with the gas-liquid separator air inlet pipe through the choke valve I, gas-liquid separator top escape pipe is communicated with the pipeline that the choke valve II is connected with evaporator, gas-liquid separator bottom drain pipe is communicated with the pipeline that the choke valve II is connected with evaporator, evaporator outlet is connected with regenerator import II, regenerator outlet II is connected with the compressor air suction mouth, pressure sensor is arranged on the pipeline that exhaust outlet of compressor is connected with the gas cooler import, temperature sensor is arranged on gas cooler and exports on the pipeline be connected with regenerator import I, the overtemperature sensor setting is on the pipeline of evaporator outlet, pressure sensor, the overtemperature sensor is connected with controller by holding wire with temperature sensor.

Described choke valve I (4) is electric control valve, and choke valve II (6) is electric control valve or mechanical type control valve.

CO of the present invention ₂control method across the refrigerating heat pump unit of critical cycle, it is characterized in that described control method is: the Refrigerant Superheat at Evaporator Outlet that the gas cooler inner refrigerant pressure P k that controller detects according to pressure sensor, the gas cooler that temperature sensor detects outlet refrigerant temperature tk, overtemperature sensor detect and the highest cooling pressure Pg of system operation, the aperture of control choke valve I and choke valve II; The concrete control of choke valve I is; The setting optimum pressure is Pz, Pz=-0.71471+0.27243tk, and controller compares Pk, Pg, tri-parameters of Pz: as Pz≤Pg, during and Pk>Pz, controller output signal is controlled choke valve I valve port opening and is opened greatly, makes Pk=Pz; As Pz≤Pg, during and Pk<Pz, controller output signal is controlled choke valve I valve port opening and is turned down, and makes Pk=Pz; As Pz>Pg, during and Pk>Pg, controller output signal is controlled choke valve I valve port opening and is opened greatly, makes Pk=Pg; As Pz>Pg, during and Pk<Pg, controller output signal is controlled choke valve I valve port opening and is turned down, and makes Pk=Pg; The concrete control of choke valve II is; Refrigerant superheat degree setting value is tz, when the degree of superheat, during higher than setting value tz, opens large choke valve II, makes refrigerant superheat degree convergence setting value tz, when the degree of superheat, during lower than setting value tz, turns down the choke valve II, makes refrigerant superheat degree convergence setting value tz.

Process of refrigerastion of the present invention is:

CO ₂compressor sucks refrigerant gas, discharges high temperature and high pressure gas after compression and enters in gas cooler, after the gas cooler cooling, enter in regenerator again cooling, cooled CO ₂cold-producing medium is respectively by two choke valves in parallel: choke valve I and the throttling of choke valve II, through the choke valve II, throttling becomes gas-liquid two-phase CO to cold-producing medium ₂enter into evaporimeter heat absorption vaporization, through the choke valve I, throttling becomes gas-liquid two-phase CO on another road ₂enter into gas-liquid separator, entering into evaporimeter respectively after the top and bottom interface pipeline of gas-liquid separator and the refrigerant mixed after the choke valve II is again freezed, the rear cold-producing medium of refrigeration becomes the low-temp low-pressure gas-liquid mixture and enters into evaporimeter, enter into regenerator after heat absorption becomes overheated gas through evaporimeter, in regenerator with gas cooler cold-producing medium heat exchange out, temperature enters into compressor suction after raising, so circulation.The present invention carrys out the regulating system distribution of refrigerant by the two-way throttling, thereby regulating system pressure remains on the optimal design operating mode.The choke valve II major control evaporator outlet degree of superheat, prevent that overfeeding from causing compressor hydraulic compression or degree of superheat heat exchange efficiency bigger than normal to descend, and functional equivalent is in the choke valve of conventional refrigeration system; Choke valve I mainly carrys out the distribution of cold-producing medium in regulating system according to cooling pressure, too high when cooling pressure, choke valve leaves greatly, cold-producing medium discharge in cooler is increased, and be stored in gas-liquid separator with liquid state after throttling; When cooling pressure is too low, choke valve I turns down, and in cooler, the cold-producing medium discharge reduces, but compressor is constantly air-breathing, the liquid refrigerant of storing in gas-liquid separator progressively supplements cooling pressure is improved, and gas-liquid separator is equivalent to the cushion space of cold-producing medium storage.

By the present invention, when evaporimeter environment of living in or gas cooler environment of living in change, the refrigerating heat pump unit can be according to the exit refrigerant superheat degree of evaporimeter, high side pressure and the gas cooler exit temperature of system, system is controlled to stable operation under best evaporating temperature and high-pressure, thereby improve the cooling effectiveness of system, can effectively prevent that high side pressure from increasing extremely simultaneously.

The invention has the beneficial effects as follows: when environment temperature or an environment temperature that is cooled change, controller can judge and regulate unit in the detected temperature of the outlet temperature sensor of gas cooler with at the detected pressure of the pressure sensor of gas cooler import department according to cold-producing medium moves unit under high cycle efficieny: method is simple, be easy to realize, and reliable, stable.

The accompanying drawing explanation

Fig. 1 is refrigerating heat pump machine set system schematic diagram of the present invention.

In accompanying drawing:

The 1-compressor; The 2-gas cooler; The 3-regenerator; 4-choke valve I; The 5-gas-liquid separator; 6-

The choke valve II; The 7-drain pipe; The 8-air inlet pipe; The 9-escape pipe; The 10-evaporimeter; The 11-pressure sensor; The 12-controller; The 13-temperature sensor; 14-overtemperature sensor.

The specific embodiment

Below, with reference to drawings and Examples to the detailed description of the invention.

Across critical CO ₂cold-producing medium refrigerating heat pump unit comprises CO ₂coolant compressor 1, gas cooler 2, regenerator 3, choke valve I 4, gas-liquid separator 5, choke valve II 6, evaporimeter 10, controller 12, pressure sensor 11, temperature sensor 13 and overtemperature sensor 14, each parts connect into a closed-system by pipeline: compressor 1 exhaust outlet is connected with gas cooler 2 imports, gas cooler 2 outlets are connected with regenerator 3 import I, regenerator 3 outlet I are divided into two-way, one tunnel is connected with evaporator after choke valve II 6, another road is connected with gas-liquid separator 5 entrances through choke valve I 4, gas-liquid separator 5 top escape pipes are communicated with the pipeline that choke valve II 6 is connected with evaporator, gas-liquid separator bottom drain pipe is communicated with the pipeline that choke valve II 6 is connected with evaporator, evaporimeter 10 outlets are connected with regenerator 3 import II, regenerator 3 outlet II are connected with compressor 1 air entry, pressure sensor 11 is connected on the pipeline that compressor 1 exhaust outlet is connected with gas cooler 2 imports, temperature sensor 13 is arranged on gas cooler 2 and exports on the pipeline be connected with regenerator 3 import I, overtemperature sensor 14 is connected on the pipeline of evaporimeter 10 outlets, pressure sensor 11, overtemperature sensor 14 is connected with controller by holding wire with temperature sensor 13.

The high temperature and high pressure gas of discharging from the high-pressure side blast pipe of compressor 1 enters into gas cooler 2, quilt

Be cooled to supercritical fluid, gas cooler 2 supercritical fluid out enters into 3 li of regenerators, with from evaporimeter 10, cold-producing medium out carries out heat exchange, the cold-producing medium after temperature reduces is divided into two-way, and wherein through the choke valve II, 6 throttlings become saturated gas-liquid two-phase CO on a road ₂cold-producing medium enters into evaporimeter 10 and carries out sweat cooling, and through the choke valve I, 4 throttlings become saturated gas-liquid two-phase CO on another road ₂enter into gas-liquid separator 5, cold-producing medium carries out sweat cooling by after gas-liquid separator 5 bottom drain pipes 7 and its top escape pipe 9 and choke valve II 6 exit refrigerant mixed, entering into evaporimeter 10.

When refrigerating heat pump device environment of living in changes, cause that cold-producing medium changes at the state of systemic circulation, the evaporimeter 10 outlet refrigerant superheat degree that the gas cooler 2 inner refrigerant pressure P k that controller 12 detects according to pressure sensor 11, the gas cooler that temperature sensor 13 detects 2 outlet refrigerant temperature tk, overtemperature sensor 14 detect and the highest cooling pressure Pg of system operation, the aperture of control choke valve I 4 and choke valve II 6; The concrete control of choke valve I 4 is; The setting optimum pressure is Pz, Pz=-0.71471+0.27243tk, and controller 12 compares Pk, Pg, tri-parameters of Pz: as Pz≤Pg, during and Pk>Pz, controller 12 output signals are controlled choke valve I 4 valve port opening and are opened greatly, make Pk=Pz; As Pz≤Pg, during and Pk<Pz, controller 12 output signals are controlled choke valve I 4 valve port opening and are turned down, and make Pk=Pz; As Pz>Pg, during and Pk>Pg, controller 12 output signals are controlled choke valve I 4 valve port opening and are opened greatly, make Pk=Pg; As Pz>Pg, during and Pk<Pg, controller 12 output signals are controlled choke valve I 4 valve port opening and are turned down, and make Pk=Pg; The concrete control of choke valve II 6 is; Refrigerant superheat degree setting value is tz, when the degree of superheat, during higher than setting value tz, opens large choke valve II 6, makes refrigerant superheat degree convergence setting value tz, when the degree of superheat, during lower than setting value tz, turns down choke valve II 6, makes refrigerant superheat degree convergence setting value tz.

Be more than an embodiment of the invention, the present invention is not limited only to this.For example, in the present embodiment, compressor (1) can single machine two-stage, can be also the unit single-stage; Choke valve II (6) can be electrodynamic type, can be also mechanical type; The form of gas cooler (2) and evaporimeter (10) can be the various forms such as air-source formula, water source type, and the pipe arrangement formation in above-mentioned embodiment etc. is not limited to this.

Claims

1.CO ₂refrigerating heat pump unit across critical cycle, comprise CO ₂coolant compressor (1), gas cooler (2), regenerator (3), choke valve I (4), gas-liquid separator (5), choke valve II (6), drain pipe (7), steam inlet pipe (8), escape pipe (9), evaporimeter (10) and controller (12), is characterized in that described across critical CO ₂cold-producing medium refrigerating heat pump unit also comprises pressure sensor (11), temperature sensor (13) and overtemperature sensor, described each parts connect into a closed-system by pipeline: compressor (1) exhaust outlet is connected with gas cooler (2) import, gas cooler (2) outlet is connected with regenerator (3) import I, regenerator (3) outlet I is divided into two-way, one tunnel is connected with evaporator after choke valve II (6), another road is connected with gas-liquid separator air inlet pipe (8) through choke valve I (4), gas-liquid separator (5) top escape pipe (9) is communicated with the pipeline that choke valve II (6) is connected with evaporator, gas-liquid separator (5) bottom drain pipe (7) is communicated with the pipeline that choke valve II (6) is connected with evaporator, evaporimeter (10) outlet is connected with regenerator (3) import II, regenerator (3) outlet II is connected with compressor (1) air entry, pressure sensor (11) is arranged on the pipeline that compressor (1) exhaust outlet is connected with gas cooler (2) import, temperature sensor (13) is arranged on gas cooler (2) and exports on the pipeline be connected with regenerator (3) import I, overtemperature sensor (14) is arranged on the pipeline of evaporimeter (10) outlet, pressure sensor (11), overtemperature sensor (14) is connected with controller by holding wire with temperature sensor (13).

2. CO according to claim 1 ₂across the refrigerating heat pump unit of critical cycle, it is characterized in that described choke valve I (4) is for electric control valve, choke valve II (6) is electric control valve or mechanical type control valve.

3. the described CO of claim 1 ₂control method across the refrigerating heat pump unit of critical cycle, it is characterized in that described control method is: evaporimeter (10) the outlet refrigerant superheat degree that gas cooler (2) the inner refrigerant pressure P k that controller (12) detects according to pressure sensor (11), the gas cooler (2) that temperature sensor (13) detects outlet refrigerant temperature tk, overtemperature sensor (14) detect and the highest cooling pressure Pg of system operation, the aperture of control choke valve I (4) and choke valve II (6); The concrete control of choke valve I (4) is; The setting optimum pressure is Pz, Pz=-0.71471+0.27243tk, controller (12) compares Pk, Pg, tri-parameters of Pz: as Pz≤Pg, during and Pk>Pz, controller (12) output signal is controlled choke valve I (4) valve port opening and is opened greatly, makes Pk=Pz; As Pz≤Pg, during and Pk<Pz, controller (12) output signal is controlled choke valve I (4) valve port opening and is turned down, and makes Pk=Pz; As Pz>Pg, during and Pk>Pg, controller (12) output signal is controlled choke valve I (4) valve port opening and is opened greatly, makes Pk=Pg; As Pz>Pg, during and Pk<Pg, controller (12) output signal is controlled choke valve I (4) valve port opening and is turned down, and makes Pk=Pg; The concrete control of choke valve II (6) is; Refrigerant superheat degree setting value is tz, when the degree of superheat, during higher than setting value tz, opens large choke valve II (6), make refrigerant superheat degree convergence setting value tz, when the degree of superheat during tz, turns down choke valve II (6) lower than setting value, make refrigerant superheat degree convergence setting value tz.