EP2009369B1

EP2009369B1 - A heat pump air condition system, and the steam jet system and the control method thereof

Info

Publication number: EP2009369B1
Application number: EP07720698.5A
Authority: EP
Inventors: Yuhai Su; Guiping Liu; Changquan Sun
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2006-04-11
Filing date: 2007-04-06
Publication date: 2018-10-31
Anticipated expiration: 2027-04-06
Also published as: ES2705478T3; WO2007115494A1; TR201820044T4; RU2008143066A; EP2009369A1; PL2009369T3; EP2009369A4; CN1828186A; RU2426956C2; CN100386580C

Description

FIELD OF THE INVENTION

The present invention relates to the field of air source heat pump air conditioner, more particularly, to a heat pump air conditioning system which has good heating effect in working condition of outdoor ultra low temperature, and to a control method thereof.

BACKGROUND OF THE INVENTION

At present, common air source heat pump air conditioners sold in market have greatly decreased heat output or even cannot be started when working under outdoor ultra low temperature, therefore in the cold north area of China, air source heat pump air conditioners can only be used in transitional seasons, and once the cold winter comes, air source heat pump air conditioners can hardly meet basic heating requirements. It is well known that the traditional central heating supply in north area of China is mainly enabled by firing coal or gas, which can not satisfy the social development requirements in energy saving, environment protection and safety. Therefore, it is desired to develop a heat pump air conditioning system able to work under ultra low temperature so as to replace the traditional central heating supply in north area of China. Document JP2004183913 A discloses an air conditioner with a heat pump cycle having an intercooler whereby in heating operation the refrigerant flowing out of said intercooler is divided into two branches, one flow passing back through said intercooler to an intermediate gas inlet of a compressor.

SUMMARY OF THE INVENTION

The present invention aims at solving problems in prior art by providing a heat pump air conditioning system which has good heating effect in working condition of outdoor ultra low temperature, and a control method thereof.
The goal of the present invention is achieved by the subject-matter of claim 1.
A set of cooling coil pipes may be connected between said liquid reservoir and said outdoor unit heat exchanger.
Said sensors may be pressure sensors or temperature sensors.
A control method of the above mentioned heat pump air conditioning system according to claim 1 comprises a control method of the compressor steam jet system which comprises the following steps:

Step 1: detect the gas state at the first gas inlet, the second gas inlet and the gas outlet, which is correspondingly represented as Slower, S_jet and Supper;
Step 2: according to the gas state S_lower at the first gas inlet and the gas state Supper at the gas outlet, calculate out the gas state S_intermediate when said compressor is in operation;
Step 3: according to the relation between S_intermediate, S_jet and the predetermined target difference state S _target, control the opening degree of the second gas inlet.

Wherein the Step 1 further comprises: detect the gas pressures at the first gas inlet, the second gas inlet and the gas outlet of the compressor, which is correspondingly represented as P_lower, P_jet and P_upper, and calculate out the temperature T_jet corresponding to P_jet according to the relation between pressure and temperature;
the Step 2 further comprises: calculate out the intermediate pressure P_intermediate when said compressor is in operation with $P_{intermediate} = \sqrt{P_{lower} \times P_{upper}},$
and calculate out the corresponding temperature T_intermediate according to the relation between pressure and temperature;
the Step 3 further comprises:

Step 30: calculate out the temperature difference ΔT_actual which is corresponding to the actual pressure difference between the intermediate pressure of the compressor and the jet pressure from the second gas inlet of the compressor with ΔT_actual = T_jet -T_intermediate;
Step 31: calculate out the opening degree difference N of the second gas inlet according to the actual temperature difference ΔT_actual and the temperature difference ΔT_target corresponding to the predetermined target temperature difference with N =ΔT_target - ΔT_actual ;
Step 32: the actual opening degree of the second gas inlet is the sum of its original opening degree and the opening degree difference N.

Wherein the Step 1 further comprises: detect the gas temperatures at the first gas inlet, the second gas inlet and the gas outlet of the compressor, which is correspondingly represented as T_lower, T_jet and T_upper, and calculate out the pressures P_lower and P_upper corresponding to Tiower and T_upper according to the relation between pressure and temperature;
the Step 2 further comprises: calculate out the intermediate pressure P_intermediate when said compressor is in operation with
$P_{int ernediate} = \sqrt{P_{lower} \times P_{upper}},$
and calculate out the corresponding temperature T_intermediate according to the relation between pressure and temperature;
the Step 3 further comprises:

Step 30: calculate out the temperature difference ΔT_actual which is corresponding to the actual pressure difference between the intermediate pressure of the compressor and the jet pressure from the second gas inlet of the compressor with ΔT_actual = T_jet -T_intermediate;
Step 31: calculate out the opening degree difference N of the second gas inlet according to the actual temperature difference ΔT_actual and the temperature difference ΔT_target corresponding to the predetermined target temperature difference with N =ΔT_target - ΔT_actual;
Step 32: the actual opening degree of the second gas inlet is the sum of its original opening degree and the opening degree difference N.

Compared with prior art technology, the present invention employs the steam jet system to jet intermediate pressure refrigerant steam to the compressor and controls the pressure at the jet mouth (that is the second gas inlet of the compressor) in order to keep the refrigerant jet amount to the compressor at the optimum value. In normal working condition, the present invention works as common heat pump air conditioning unit in cooling and heating operations; when the outdoor temperature greatly decreases and the heat output is reduced, the steam jet system in the system will work and jet intermediate pressure saturated refrigerant gas to the compressor, thereby double compression is enabled inside the compressor which increases the heat output and the energy efficiency ratio when the system is working under low temperature outdoor, and the defrosting frequency and defrosting time are greatly decreased.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic view illustrating the principle of the heat pump air conditioning system according to the first embodiment of the present invention;
Figure 2 is a pressure-enthalpy chart during heating operation of the heat pump air conditioning system;
Figure 3 is a schematic view illustrating the principle of a heat pump air conditioning system which is not part of the present invention.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further features and advantages of the present invention will become apparent from the following detailed description, in combination with the appended drawings.

First Embodiment

Figure 1 is a schematic view illustrating the principle of the heat pump air conditioning system according to the first embodiment of the present invention, wherein the solid lines with arrowheads represent the flow direction of the refrigerant when the heat pump air conditioning system is in heating operation. As illustrated in Figure 1, the heat pump air conditioning system comprises an indoor throttle device 20, an indoor unit heat exchanger 19, a four-way valve 13, an outdoor unit heat exchanger 14, an outdoor throttle device 15, a set of cooling coil pipes 16 and a liquid reservoir 17, wherein these components are connected in series by means of copper pipes to form a cooling and heating loop. The outdoor throttle device 15 consists of a check valve and an electronic expansion valve which are connected in parallel. Said heat pump air conditioning system further comprises a compressor steam jet system, and said compressor steam jet system comprises a compressor 11 which comprises a first gas inlet 111, a second gas inlet 112 and a gas outlet 113, said gas outlet 113 is connected with said four-way valve 13, said first gas inlet 111 is connected with said four-way valve 13 through a gas-liquid separator, and said second gas inlet 112 is connected to between said indoor throttle device 20 and said liquid reservoir 17 by means of the bypass pipe on which an electronic expansion valve 21 is disposed, that is to connect with the outflow end of the indoor throttle device 20. An absorption coil pipe 18 is disposed on said bypass pipe, and the absorption coil pipe 18 is disposed inside the liquid reservoir 17, so that the refrigerant which is supplemented to the second gas inlet of the compressor is able to make sufficient heat exchange in the liquid reservoir 17 which ensures all the supplementaries in the compressor is gas without any liquid, thereby the compressor is ensured with good reliability. Wherein the compressor 11 can be an Enhanced Vapor Injection digital scroll compressor, and the indoor throttle device 20 can be an electronic expansion valve.
The heat pump air conditioning system further comprises a steam jet control device, and said steam jet control device comprises three sensors and said electronic expansion valve 21. In one embodiment, the three sensors are respectively a low pressure sensor 201, a high pressure sensor 202 and a jet pressure sensor 203. The high pressure sensor 202 is disposed at the gas outlet 113 of the compressor 11, the low pressure sensor 201 is disposed at the first gas inlet 111 of the compressor 11, the jet pressure sensor 203 is disposed at the second gas inlet 112 of the compressor 11, and the electronic expansion valve 21 is disposed on said bypass pipe. When the heat pump air conditioning system is in heating operation under low temperature, the refrigerant flowing out of the indoor unit heat exchanger 19 is divided into two branches; one flow of refrigerant passes the electronic expansion valve 21 which is disposed on said bypass pipe and the coil pipe 18 which is disposed inside the liquid reservoir 17, and then is absorbed into the second gas inlet 112 of the compressor 11; the other flow of refrigerant goes directly into the liquid reservoir and passes the cooling coil pipe 16 of the outdoor unit and the auxiliary throttle device 15 then into the outdoor unit heat exchanger 14.
The working principle of the steam jet control device is that: the pressures of gas in and out of the compressor is detected by sensors which are disposed at the gas inlets and gas outlet of the compressor, then according to the changes of pressure of gas in and out of the compressor to control the opening degree of the second gas inlet so as to control the steam jet amount, which comprises the following steps:

(1) detect the gas pressures respectively at the first gas inlet, the second gas inlet and the gas outlet of the compressor by sensors, wherein the pressure is correspondingly represented as P_lower, P_jet and P_upper;
(2) calculate out the temperature T_jet corresponding to P_jet according to the relation between pressure and temperature;
(3) calculate out the intermediate pressure P_intermediate when said compressor is in operation with $P_{int ermediate} = \sqrt{P_{lower} \times P_{upper}},$
and calculate out the corresponding temperature T_intermediate according to the relation between pressure and temperature;
(4) calculate out the temperature difference ΔT_actual which is corresponding to the actual pressure difference between the intermediate pressure of the compressor and the jet pressure from the second gas inlet of the compressor with ΔT_actual = T_jet - T_intermediate;
(5) calculate out the opening degree difference N of the second gas inlet with N =ΔT_target - ΔT_actual, wherein ΔT_target is the temperature difference corresponding to the predetermined target temperature difference;
(6) the actual opening degree of the second gas inlet is the sum of its original opening degree and the opening degree difference N.

In this embodiment, the opening degree of the second gas inlet is controlled by adjusting the opening degree of the electronic expansion valve 21. In this situation, in the step (5), the opening degree difference of the electronic expansion valve 21 is N = ΔT_target - ΔT_actual; in the step (6), the actual opening degree of the electronic expansion valve 21 is the sum of its original opening degree and the opening degree difference N.
The working process of the heat pump air conditioning system will be described in combination with the Figure 2. When the system is in heating operation under outdoor low temperature, the low-temperature and low-pressure refrigerant gas (state point 1) steamed from the outdoor unit heat exchanger 14 is compressed by the compressor 11 to reach the state point 2 of the intermediate pressure and then mixed in the scroll coil of the compressor 11 to the state point 10 with the intermediate pressure gas (state point 9) which is absorbed from the second gas inlet 112 of compressor, then continuously compressed by the compressor 11 to be the high-temperature and high-pressure gas (state point 3); the high-temperature and high-pressure refrigerant gas in the indoor unit heat exchanger 19 is cooled and condensed to be high-temperature and high-pressure refrigerant liquid (state point 4), then the high pressure liquid is throttled and pressure-reduced to be gas liquid mixture (state point 5) by the indoor throttle device 20 such as the electronic expansion valve; at this time, the refrigerant is flowing into two branches, one flow of refrigerant passes the electronic expansion valve 21 to be throttled to intermediate pressure refrigerant of gas liquid mixture (state point 8) and enters the absorption coil pipe 18 of the liquid reservoir 17, becomes intermediate pressure saturate steam (state point 9) after absorbing the heat energy, then the intermediate pressure saturate steam is absorbed by the second gas inlet 112 of the compressor 11; the other flow of refrigerant goes directly into the container formed between the case of the liquid reservoir 17 and the absorption coil pipe 18, making heat exchange with the refrigerant which is in the absorption coil pipe 18 so as to release heat energy, and passes the outdoor unit cooling coil pipe 16 and gets condensed to super-cooled liquid (state point 6); the super-cooled liquid is throttled to reach the state point 7 by the outdoor throttle device 15 such as the electronic expansion valve and then enters the outdoor unit heat exchanger 14 to be steamed to reach the state point 1 and then to be absorbed by the gas inlet 111 of the compressor, thus a heating loop is completed.
The working principle of the whole heat pump air conditioning system is that: in normal working condition, the present invention works as common heat pump air conditioning unit in cooling and heating operations; when the outdoor temperature decreases and the heat output is reduced, the steam jet control device in the system will work and jet intermediate pressure saturated refrigerant gas to the compressor, thereby double compression is enabled inside the compressor which increases the heat output and the energy efficiency ratio when the system is working under low temperature outdoor. In addition, the compress ratio of the compressor and the gas exhaust temperature of the system are within logical range, and the system is proved to be operated with good stability and reliability from a large number of experiments; the system employs intelligent defrosting mode to make the system to run or not run defrosting by high-pressure control, which enables "defrosting when needed, stop defrosting when no needed".

Second Embodiment

The second embodiment is different from the first embodiment in that the sensors in the steam jet control device according to the second embodiment are temperature sensors, the working principle of the steam jet control device with temperature sensors is that: the temperatures of gas in and out of the compressor is detected by sensors which are disposed at the gas inlets and gas outlet of the compressor, then according to the changes of temperature of gas in and out of the compressor to control the opening degree of the second gas inlet so as to control the steam jet amount. In this embodiment, the opening degree of the second gas inlet is controlled by adjusting the opening degree of the electronic expansion valve 21, which comprises the following steps:

(1) detect the gas temperatures respectively at the first gas inlet, the second gas inlet and the gas outlet of the compressor by temperature sensors, wherein the temperature is correspondingly represented as T_lower, T_jet and T_upper;
(2) calculate out the pressures P_lower and P_upper corresponding to T_lower and T_upper according to the relation between pressure and temperature;
(3) calculate out the intermediate pressure P_intermediate when said compressor is in operation with $P_{middle} = \sqrt{P_{lower} \times P_{upper}},$
and calculate out the corresponding temperature T_intermediate according to the relation between pressure and temperature;
(4) calculate out the temperature difference ΔT_actual which is corresponding to the actual pressure difference between the intermediate pressure of the compressor and the jet pressure from the second gas inlet of the compressor with ΔT_actual = T_jet - T_intermediate;
(5) calculate out the opening degree difference N of the second gas inlet with N =ΔT_target - ΔT_actual, wherein ΔT_target is the temperature difference corresponding to the predetermined target temperature difference;
(6) the actual opening degree of the second gas inlet is the sum of its original opening degree and the opening degree difference N.

The system of Figure 3 which is not part of the present invention is different from the first embodiment in that no cooling coil pipe 16 and liquid reservoir 17 are disposed in the heat pump system according to the third embodiment, and no coil pipe 18 is disposed on the bypass pipe either. Besides, said bypass pipe can be directly led out of the outlet of the indoor unit heat exchanger.
The above descriptions and illustrations should not be construed as limiting the scope of the present invention, which is defined by the appended claims.

Claims

A heat pump air conditioning system, comprising a four-way valve (13), an indoor unit heat exchanger (19), an indoor throttle device (20), an outdoor throttle device (15) and an outdoor unit heat exchanger (14) which are connected in series to form a loop, whereby said heat pump air conditioning system further comprises a compressor steam jet system, and said compressor steam jet system comprises a compressor (11) which comprises a first gas inlet (111), a second gas inlet (112) and a gas outlet (113), wherein said first gas inlet (111) is connected with said four-way valve (13) through a gas-liquid separator (12), and said second gas inlet (112) is connected to between said indoor throttle device (20) and said outdoor throttle device (15) by means of the bypass pipe on which an electronic expansion valve (21) is disposed, and said gas outlet (113) is connected with said four-way valve (13); said compressor steam jet system further comprises a first sensor (201) disposed at the first gas inlet (111), a second sensor (202) disposed at the second gas inlet (112), and a third sensor (203) disposed at the gas outlet (113; wherein said indoor throttle device (20) is serially connected to said outdoor throttle device (15) via a liquid reservoir (17), and said bypass pipe is connected between said indoor throttle device (20) and said liquid reservoir (17); wherein on said bypass pipe is disposed a coil pipe (18) which is disposed inside said liquid reservoir (17); when the heat pump air conditioning system is in heating operation under low temperature, the refrigerant flowing out of the indoor unit heat exchanger (19) is divided into two branches; one flow of refrigerant passes the electronic expansion valve (21) which is disposed on said bypass pipe and the coil pipe (18) which is disposed inside the liquid reservoir (17), and then is absorbed into the second gas inlet (112) of the compressor (11); the other flow of refrigerant goes directly into the liquid reservoir and passes a cooling coil pipe (16) of the outdoor unit and the auxiliary throttle device (15) then into the outdoor unit heat exchanger (14).
The heat pump air conditioning system according to claim 1, characterized in that, a set of cooling coil pipes (16) is connected between said liquid reservoir (17) and said outdoor unit heat exchanger (15).
The heat pump air conditioning system according to claim 1 or 2, characterized in that, said sensors are pressure sensors.
The heat pump air conditioning system according to claim 1 or claim 2, characterized in that, said sensors are temperature sensors.
A control method of the heat pump air conditioning system according to claim 1, comprising a control method of the compressor steam jet system which comprises the following steps:
Step 1: detect the gas state at the first gas inlet, the second gas inlet and the gas outlet, which is correspondingly represented as S_lower, S_jet and S_upper;

Step 2: according to the gas state S_lower at the first gas inlet and the gas state Supper at the gas outlet, calculate out the gas state S_intermediate when said compressor is in operation;

Step 3: according to the relation between S_intermediate, S_jet and the predetermined target difference state S _target, control the opening degree of the second gas inlet.
The control method of the heat pump air conditioning system according to the claim 5, characterized in that,
the Step 1 further comprises: detect the gas pressures at the first gas inlet, the second gas inlet and the gas outlet of the compressor, which is correspondingly represented as P_lower, P_jet and P_upper, and calculate out the temperature T_jet corresponding to P_jet according to the relation between pressure and temperature;
the Step 2 further comprises: calculate out the intermediate pressure P_intermediate when said compressor is in operation with $P_{int ermediate} = \sqrt{P_{lower} \times P_{upper}},$
and calculate out the corresponding temperature T_intermediate according to the relation between pressure and temperature;
the Step 3 further comprises:
Step 30: calculate out the temperature difference ΔT_actual which is corresponding to the actual pressure difference between the intermediate pressure of the compressor and the jet pressure from the second gas inlet of the compressor with ΔT_actual = T_jet -T_intermediate;

Step 31: calculate out the opening degree difference N of the second gas inlet according to the actual temperature difference ΔT_actual and the temperature difference ΔT_target corresponding to the predetermined target temperature difference with N =ΔT_target - ΔT_actual;

Step 32: the actual opening degree of the second gas inlet is the sum of its original opening degree and the opening degree difference N.
The control method of the heat pump air conditioning system according to the claim 6, characterized in that,
the Step 1 further comprises: detect the gas temperatures at the first gas inlet, the second gas inlet and the gas outlet of the compressor, which is correspondingly represented as corresponding T_lower, T_jet and T_upper, and calculate out the pressures P_lower and P_upper corresponding to T_lower and T_upper according to the relation between pressure and temperature;
the Step 2 further comprises: calculate out the intermediate pressure P_intermediate when said compressor is in operation with $P_{middle} = \sqrt{P_{lower} \times P_{upper}},$
and calculate out the corresponding temperature T_intermediate according to the relation between pressure and temperature;
the Step 3 further comprises:
Step 30: calculate out the temperature difference ΔT_actual which is corresponding to the actual pressure difference between the intermediate pressure of the compressor and the jet pressure from the second gas inlet of the compressor with ΔT_actual = T_jet -T_intermediate;

Step 31: calculate out the opening degree difference N of the second gas inlet according to the actual temperature difference ΔT_actual and the temperature difference ΔT_target corresponding to the predetermined target temperature difference with N =ΔT_target - ΔT_actual;

Step 32: the actual opening degree of the second gas inlet is the sum of its original opening degree and the opening degree difference N.