CN113776220B

CN113776220B - Room air conditioner and control method thereof

Info

Publication number: CN113776220B
Application number: CN202110977237.5A
Authority: CN
Inventors: 石文星; 于天蝉; 王文涛; 王正华; 蒋海华; 史发斌; 王宝龙; 于佳丘
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2021-08-24
Filing date: 2021-08-24
Publication date: 2022-09-09
Anticipated expiration: 2041-08-24
Also published as: CN113776220A

Abstract

The invention provides a room air conditioner and a control method thereof, wherein the room air conditioner comprises a first circulation loop, a second circulation loop, an indoor fan and an outdoor fan, wherein working media of the first circulation loop and the second circulation loop exchange heat through a heat exchanger; the first circulation loop comprises a first compressor, a first four-way reversing valve, a first indoor heat exchanger, a first electronic expansion valve, a first passage of the heat exchanger, a second electronic expansion valve and a first outdoor heat exchanger which are connected; the second circulation loop comprises a second compressor, a second four-way reversing valve, a second indoor heat exchanger, a third electronic expansion valve, a second passage of the heat exchanger, a fourth electronic expansion valve and a second outdoor heat exchanger which are connected; the first electronic expansion valve, the second electronic expansion valve, the third electronic expansion valve and the fourth electronic expansion valve can be fully opened or throttled respectively. The mode of cooling and dehumidifying, step heating, heating and dehumidifying and outdoor heat exchanger defrosting can be operated, condensation supercooling or condensation heat recovery is realized, and the high-efficiency, energy-saving and comfortable operation is realized.

Description

Room air conditioner and control method thereof

Technical Field

The invention relates to the technical field of air conditioners, in particular to a room air conditioner and a control method thereof.

Background

The air conditioning system can improve the comfort of living and working environments, and is an important choice for improving the comfort requirement of people at present.

In order to further improve the comfort of the indoor environment, the indoor air needs to be dehumidified, and particularly, for hot-summer and warm-winter areas, there is a need for indoor dehumidification in summer, transition seasons and winter. For small and medium-sized buildings for residence and office, due to space limitation, a large-scale temperature and humidity independent control air conditioning system based on a chilled water or solution dehumidification technology is difficult to use, and usually, only a room air conditioner can be adopted to meet the indoor temperature and humidity regulation and control requirements. The existing room air conditioner is a direct expansion type room air conditioner, a condensation dehumidification heat and humidity coupling processing method is adopted, indoor sensible heat and latent heat load are simultaneously removed by utilizing a low-temperature cold source lower than dew point temperature, however, when the air conditioner needs to operate a dehumidification mode in transition seasons or winter, excessive refrigeration occurs indoors, and indoor comfort is reduced.

In the patent of 'a double-temperature room air conditioner' with Chinese patent application number 202010124780.6, a room air conditioner with double evaporation temperatures is provided, the system divides refrigerant after condensation to adjust the opening degree of throttle valves on different branches, so that a refrigeration cycle has double evaporation temperatures, and independent temperature and humidity regulation is realized.

In a refrigeration cycle in which air passages of cooling and dehumidifying and reheating heat exchangers are connected in series, which is proposed in "cold サイクル and control at と" (hot and hot pines and wiry. cold サイクル and hot pines and wiry. と and control at-6. cold ,2003,78(911):52-58 "), in an indoor unit, a double electronic expansion valve and a reheater are used in series, and when dehumidification is performed, a part of high-pressure gas-liquid refrigerant is introduced into a reheater in the indoor unit, and air passes through the evaporator and then the reheater to perform reheating after air dehumidification, thereby avoiding an increase in energy consumption for reheating the reheater; however, when heating in winter, if the method is adopted for dehumidification and heating, the heating quantity is smaller due to the fact that the heat absorption of the evaporator is offset with the partial condensation heat, and the energy efficiency ratio is lower; and if a four-way valve reversing heating mode is adopted, the evaporator is switched to be a condenser, and the evaporator can not play a role in evaporating and absorbing heat, so that the dehumidification function is lost.

Although the technology can partially meet the dehumidification requirement, the energy efficiency ratio is low during refrigeration or heating, and the functions of summer dehumidification and winter dehumidification and reheating are difficult to realize simultaneously, so that the requirement of indoor dehumidification for a long time all year around cannot be met effectively and energy-effectively.

Therefore, how to solve the problem that the existing air conditioner can not effectively and energy-saving meet the long-term indoor dehumidification requirement all the year around is an important subject to be solved in the industry at present.

Disclosure of Invention

The invention provides a room air conditioner and a control method thereof, which are used for solving the defect that the air conditioner in the prior art cannot effectively save energy and meet the requirement of indoor dehumidification for a long time all year round, a first circulation loop and a second circulation loop are adjusted to be a refrigerating cycle or a heating cycle by reversing two four-way valves, and the operation modes of step cooling dehumidification, step heating, heating dehumidification and defrosting can be freely switched by adjusting the opening and closing states of a first electronic expansion valve, a second electronic expansion valve, a third electronic expansion valve and a fourth electronic expansion valve, so that working media of the first circulation loop and the second circulation loop can exchange heat at a heat exchanger to realize condensation supercooling or condensation heat recovery, the room air conditioner can efficiently, save energy and comfortably operate, and the various requirements of heating, cooling, dehumidifying and dehumidifying of the air conditioner are met.

The invention provides a room air conditioner, which comprises a first circulation loop, a second circulation loop, an indoor fan and an outdoor fan, wherein a working medium of the first circulation loop and a working medium of the second circulation loop exchange heat through a heat exchanger;

the first circulation loop comprises a first compressor, a first four-way reversing valve, a first indoor heat exchanger, a first electronic expansion valve, a first passage of the heat exchanger, a second electronic expansion valve and a first outdoor heat exchanger which are sequentially connected;

a first interface of a first four-way reversing valve is connected with an exhaust port of the first compressor, a second interface of the first four-way reversing valve is connected with the first indoor heat exchanger, a third interface of the first four-way reversing valve is connected with the first outdoor heat exchanger, a fourth interface of the first four-way reversing valve is connected with an air inlet of the first compressor, and the first interface of the first four-way reversing valve, the second interface of the first four-way reversing valve, the third interface of the first four-way reversing valve and the fourth interface of the first four-way reversing valve can be switched on;

the second circulation loop comprises a second compressor, a second four-way reversing valve, a second indoor heat exchanger, a third electronic expansion valve, a second passage of the heat exchanger, a fourth electronic expansion valve and a second outdoor heat exchanger which are connected in sequence;

a first interface of a second four-way reversing valve is connected with an exhaust port of the second compressor, a second interface of the second four-way reversing valve is connected with the second indoor heat exchanger, a third interface of the second four-way reversing valve is connected with the second outdoor heat exchanger, a fourth interface of the second four-way reversing valve is connected with an air inlet of the second compressor, and the first interface of the second four-way reversing valve, the second interface of the second four-way reversing valve, the third interface of the second four-way reversing valve and the fourth interface of the second four-way reversing valve can be communicated in a reversing way;

the first electronic expansion valve, the second electronic expansion valve, the third electronic expansion valve and the fourth electronic expansion valve can be switched between a full-open state and a throttling state respectively;

the indoor fan is used for driving indoor air to sequentially flow through the second indoor heat exchanger and the first indoor heat exchanger;

and the outdoor fan is used for driving outdoor air to sequentially flow through the first outdoor heat exchanger and the second outdoor heat exchanger.

According to the room air conditioner provided by the invention, the first compressor and the second compressor are arranged in the same shell, and the first compressor and the second compressor are driven by the same motor.

According to the room air conditioner provided by the invention, the heat exchanger is any one of a plate heat exchanger with an insulating layer arranged outside and a double-pipe heat exchanger with an insulating layer arranged outside.

The room air conditioner provided by the invention further comprises a three-medium heat exchanger for performing heat exchange on the working medium of the first circulation loop, the working medium of the second circulation loop and outdoor air in a pairwise independent manner, wherein the first outdoor heat exchanger and the second outdoor heat exchanger are two heat exchange pipelines of the three-medium heat exchanger.

The invention also provides a control method of the room air conditioner, which is based on any one of the room air conditioner and comprises the following steps:

when the first circulation loop and the second circulation loop are both refrigeration circulation, controlling the first electronic expansion valve to be in a throttling state, controlling the second electronic expansion valve to be in a fully-opened state, controlling the third electronic expansion valve to be in a fully-opened state, controlling the fourth electronic expansion valve to be in a throttling state, and controlling both the indoor fan and the outdoor fan to be opened so as to enable the room air conditioner to operate a step cooling and dehumidifying mode;

when the first circulation loop is a heating circulation loop and the second circulation loop is a refrigerating circulation loop, controlling the first electronic expansion valve to be in a throttling state, controlling the second electronic expansion valve to be in a fully-opened state, controlling the third electronic expansion valve to be in a throttling state, controlling the fourth electronic expansion valve to be in a fully-opened state, and controlling both the indoor fan and the outdoor fan to be opened so as to enable the room air conditioner to operate in a dehumidification and reheating mode; wherein the content of the first and second substances,

when the first circulation loop is in a refrigeration cycle, controlling the first interface of the first four-way reversing valve to be communicated with the third interface of the first four-way reversing valve, the second interface of the first four-way reversing valve and the fourth interface of the first four-way reversing valve;

when the second circulation loop is in a refrigeration cycle, controlling the first interface of the second four-way reversing valve to be communicated with the third interface of the second four-way reversing valve, the second interface of the second four-way reversing valve and the fourth interface of the second four-way reversing valve;

and when the first circulation loop is a heating circulation loop, controlling the conduction of a first interface of the first four-way reversing valve, a second interface of the first four-way reversing valve, a third interface of the first four-way reversing valve and a fourth interface of the first four-way reversing valve.

The control method of the room air conditioner provided by the invention further comprises the following steps:

when the first circulation loop and the second circulation loop are both heating loops, controlling the first electronic expansion valve to be in a fully-opened state, the second electronic expansion valve to be in a throttling state, the third electronic expansion valve to be in a throttling state, and the fourth electronic expansion valve to be in a fully-opened state, and controlling both the indoor fan and the outdoor fan to be opened so as to enable the room air conditioner to operate a step heating mode; wherein the content of the first and second substances,

and when the second circulation loop is a heating circulation loop, controlling the conduction of the first interface of the second four-way reversing valve and the second interface of the second four-way reversing valve, and the conduction of the third interface of the second four-way reversing valve and the fourth interface of the second four-way reversing valve.

when the first circulation loop is a refrigeration cycle and the second circulation loop is a heating cycle, controlling the first electronic expansion valve to be in a full-open state, the second electronic expansion valve to be in a throttling state, the third electronic expansion valve to be in a full-open state, the fourth electronic expansion valve to be in a throttling state, controlling the indoor fan to be opened, and controlling the outdoor fan to be closed, so that the room air conditioner operates in a first outdoor heat exchanger defrosting mode; wherein the content of the first and second substances,

and when the second circulation loop is a heating loop, controlling the conduction of a first interface of the second four-way reversing valve, a second interface of the second four-way reversing valve, a third interface of the second four-way reversing valve and a fourth interface of the second four-way reversing valve.

when the first circulation loop is a heating circulation loop and the second circulation loop is a refrigerating circulation loop, the first electronic expansion valve is controlled to be in a full-open state, the second electronic expansion valve is in a throttling state, the third electronic expansion valve is in a full-open state, the fourth electronic expansion valve is in a throttling state, the indoor fan is controlled to be started, and the outdoor fan is closed so that the room air conditioner operates in a second outdoor heat exchanger defrosting mode.

According to the control method of the room air conditioner provided by the invention, when the room air conditioner operates in a step cooling and dehumidifying mode, the evaporation temperature and the condensation temperature of the working medium of the first circulation loop are respectively lower than the evaporation temperature and the condensation temperature of the working medium of the second circulation loop.

According to the control method of the room air conditioner, when the room air conditioner operates in the step heating mode, the evaporation temperature and the condensation temperature of the working medium of the first circulation loop are respectively higher than the evaporation temperature and the condensation temperature of the working medium of the second circulation loop.

The room air conditioner and the control method thereof provided by the invention have the advantages that the first circulation loop and the second circulation loop are adjusted to be heating circulation or refrigerating circulation by reversing the two four-way valves, the first electronic expansion valve, the second electronic expansion valve, the third electronic expansion valve and the fourth electronic expansion valve can be respectively switched in a fully open state or a throttling state, so that working media of the first circulation loop and the second circulation loop can exchange heat at a heat exchanger, condensation supercooling or condensation heat recovery is realized, the room air conditioner can run a mode of step cooling and dehumidification, step heating, dehumidification and defrosting, and the cooling capacity grade is improved while the whole refrigerating capacity and the power consumption of a system are not changed; the total heating capacity can be ensured to be unchanged, the evaporation temperature of the working medium of the low-temperature circulation loop is increased, and when the outdoor temperature is low, the problems of performance reduction, frosting and the like caused by the fact that the low-temperature circulation loop takes a large amount of heat from the outdoor are avoided; the electric heating reheating with low energy efficiency is not needed, the dehumidification effect is ensured, meanwhile, the offset of cold and heat is reduced, and the energy consumption of the air conditioner is reduced; the room air conditioner can run efficiently, energy-saving and comfortably, and meets various requirements on heating, cooling, dehumidifying and defrosting of the air conditioner.

Drawings

In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a room air conditioner provided by the present invention;

FIG. 2 is a schematic diagram of the room air conditioner of the present invention in a step cooling and dehumidifying mode;

FIG. 3 is a schematic view of the room air conditioner in accordance with the present invention operating in a step heating mode;

FIG. 4 is a schematic diagram of the room air conditioner according to the present invention in a dehumidification and reheat mode;

FIG. 5 is a schematic view of the room air conditioner provided by the present invention operating in a first outdoor heat exchanger defrost mode;

fig. 6 is a schematic view illustrating the operation of the second outdoor heat exchanger defrosting mode of the room air conditioner according to the present invention.

Reference numerals:

11: a first compressor; 21: a second compressor; 12: a first indoor heat exchanger;

13: a first outdoor heat exchanger; 14: a first electronic expansion valve; 15: a second electronic expansion valve;

16: a first four-way reversing valve; 16 d: first four-way selector valve 16 e: first four-way reversing valve

The first interface of (1); the second interface of (1);

16 c: first four-way selector valve 16 s: first four-way selector valve 22: a second indoor heat exchanger;

the third interface of (1); the fourth interface of (2);

23: a second outdoor heat exchanger; 24: a third electronic expansion valve; 25: a fourth electronic expansion valve;

26: a second four-way reversing valve; 26 d: second four-way selector valve 26 e: second four-way change valve

The first interface of (1); the second interface of (1);

26 c: second four-way selector valve 26 s: second four-way selector valve 3: a heat exchanger;

the third interface of (1); the fourth interface of (1);

4: an indoor fan; 5: an outdoor fan; a: an outdoor unit;

b: an indoor unit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The room air conditioner of the present invention is described below with reference to fig. 1 to 6, and includes a first circulation loop and a second circulation loop, wherein the working medium of the first circulation loop and the working medium of the second circulation loop exchange heat through a heat exchanger, so as to achieve condensation supercooling or condensation heat recovery.

The first circulation loop comprises a first compressor 11, a first four-way reversing valve 16, a first indoor heat exchanger 12, a first electronic expansion valve 14, a first passage of the heat exchanger 3, a second electronic expansion valve 15 and a first outdoor heat exchanger 13 which are connected in sequence.

The first port 16d of the first four-way reversing valve is connected with the exhaust port of the first compressor 11, the second port 16e of the first four-way reversing valve is connected with the first indoor heat exchanger 12, the third port 16c of the first four-way reversing valve is connected with the first outdoor heat exchanger 13, the fourth port 16s of the first four-way reversing valve is connected with the air inlet of the first compressor 11, and the first port 16d of the first four-way reversing valve, the second port 16e of the first four-way reversing valve, the third port 16c of the first four-way reversing valve and the fourth port 16s of the first four-way reversing valve can be communicated in a reversing mode.

When the first interface 16d of the first four-way reversing valve is communicated with the second interface 16e of the first four-way reversing valve and the third interface 16c of the first four-way reversing valve is communicated with the fourth interface 16s of the first four-way reversing valve, the first circulation loop is a heating circulation loop.

When the first port 16d of the first four-way reversing valve is communicated with the third port 16c of the first four-way reversing valve and the second port 16e of the first four-way reversing valve is communicated with the fourth port 16s of the first four-way reversing valve, the first circulation loop is a refrigeration cycle.

The second circulation loop comprises a second compressor 21, a second four-way reversing valve 26, a second indoor heat exchanger 22, a third electronic expansion valve 24, a second passage of the heat exchanger 3, a fourth electronic expansion valve 25 and a second outdoor heat exchanger 23 which are connected in sequence.

The first port 26d of the second four-way reversing valve is connected with the exhaust port of the second compressor 21, the second port 26e of the second four-way reversing valve is connected with the second indoor heat exchanger 22, the third port 26c of the second four-way reversing valve is connected with the second outdoor heat exchanger 23, the fourth port 26s of the second four-way reversing valve is connected with the air inlet of the second compressor 21, and the first port 26d of the second four-way reversing valve, the second port 26e of the second four-way reversing valve, the third port 26c of the second four-way reversing valve and the fourth port 26s of the second four-way reversing valve can be communicated in a reversing manner.

When the first port 26d of the second four-way reversing valve is communicated with the second port 26e of the second four-way reversing valve, and the third port 26c of the second four-way reversing valve is communicated with the fourth port 26s of the second four-way reversing valve, the second circulation loop is a heating cycle.

When the first port 26d of the second four-way reversing valve is communicated with the third port 26c of the second four-way reversing valve, and the second port 26e of the second four-way reversing valve is communicated with the fourth port 26s of the second four-way reversing valve, the second circulation loop is a refrigeration cycle.

The first electronic expansion valve 14, the second electronic expansion valve 15, the third electronic expansion valve 24, and the fourth electronic expansion valve 25 can be switched between a fully open state and a throttled state. Here, the throttle state refers to a state in which the electronic expansion valve is not fully opened.

Specifically, when the first circulation loop and the second circulation loop are both refrigeration cycles, the first electronic expansion valve 14 is in a throttling state, the second electronic expansion valve 15 is in a full-open state, the third electronic expansion valve 24 is in a full-open state, the fourth electronic expansion valve 25 is in a throttling state, the working medium in the second circulation loop is subjected to the throttling action of the fourth electronic expansion valve 25 to reduce the pressure and the temperature, and enters the heat exchanger 3 to be partially evaporated and absorbed, so that the working medium in the first circulation loop is condensed and released heat at the heat exchanger 3, the condensation supercooling is realized, the cold quantity of the working medium in the first circulation loop at the first indoor heat exchanger 12 is improved, and the cold quantity is used for indoor dehumidification; part of cold energy of the second circulation loop is used for condensing and supercooling working medium of the first circulation loop, and the rest of cold energy is used for indoor cooling, so that the room air conditioner operates in a cooling and dehumidifying mode to realize indoor dehumidification in summer, and the cold energy grade is improved while the whole refrigerating capacity and power consumption of the system are not changed.

It should be noted that the working medium in the first circulation loop is condensed at the heat exchanger 3 to release heat, so that the temperature of the working medium entering the first circulation loop of the first electronic expansion valve 14 can be reduced, the flash gas generated during or after throttling can be reduced, and the refrigeration efficiency of the first circulation loop can be improved.

When the first circulation loop is a heating circulation loop and the second circulation loop is a refrigerating circulation loop, the first electronic expansion valve 14 is in a throttling state, the second electronic expansion valve 15 is in a fully-opened state, the third electronic expansion valve 24 is in a throttling state, the fourth electronic expansion valve 25 is in a fully-opened state, a working medium in the first circulation loop is subjected to the throttling action of the first electronic expansion valve 14 to reduce the pressure and the temperature, enters the heat exchanger 3 to be partially evaporated and absorbed, so that the working medium in the second circulation loop is condensed and released in the heat exchanger 3 to realize the condensation and supercooling of the working medium in the second circulation loop, and part of condensation heat of the second circulation loop is used for absorbing heat of an evaporator of the first circulation loop, thereby realizing the recovery of the condensation heat, and the second indoor heat exchanger 22 is an evaporator of the second circulation loop and is used for absorbing dehumidification latent heat of indoor air; the first indoor heat exchanger 12 is a condenser of the first circulation loop, and is used for releasing heat to indoor air, and can heat the indoor air passing through the second indoor heat exchanger 22, so that the room air conditioner operates in a dehumidification reheating mode, indoor dehumidification in winter can be realized, and the heat and cold compensation is reduced while dehumidification is ensured, and the energy consumption of the air conditioner is reduced.

According to the arrangement, the room air conditioner adjusts the first circulation loop and the second circulation loop into refrigeration cycle or heating cycle by reversing the two four-way valves, and can freely switch the operation modes of cooling and dehumidification, step heating, heating and dehumidification and defrosting by adjusting the opening and closing states of the first electronic expansion valve 14, the second electronic expansion valve 15, the third electronic expansion valve 24 and the fourth electronic expansion valve 25, so that the room air conditioner can efficiently, energy-saving and comfortably operate, and meet various requirements on heating, cooling, dehumidification and defrosting of the air conditioner; compared with the existing air conditioner, the room air conditioner realizes refrigeration and dehumidification of indoor air in summer and winter respectively, realizes dehumidification and reheating through condensation heat recovery in transition seasons and winter with higher humidity, obviously improves indoor comfort in regions with high humidity, summer heat and winter all the year round, and greatly reduces operation energy consumption of the air conditioner.

In this embodiment, the room air conditioner further comprises an indoor fan 4 and an outdoor fan 5, wherein the indoor fan 4 is used for driving indoor air to sequentially flow through the second indoor heat exchanger 22 and the first indoor heat exchanger 12; the outdoor fan 5 serves to drive outdoor air to flow through the first outdoor heat exchanger 13 and the second outdoor heat exchanger 23 in this order. Thus, the step cooling and the step heating are convenient to realize.

Specifically, the first indoor heat exchanger 12 and the second indoor heat exchanger 22 are arranged side by side, the indoor fan 4 is located outside the first indoor heat exchanger 12, that is, the first indoor heat exchanger 12 is located between the indoor fan 4 and the second indoor heat exchanger 22, and thus, when the indoor fan 4 is started, indoor air is sucked by the indoor fan 4, passes through the second indoor heat exchanger 22, enters the indoor fan 4 after passing through the first indoor heat exchanger 12, and is discharged by the indoor fan 4.

The first outdoor heat exchanger 13 and the second outdoor heat exchanger 23 are arranged side by side, the outdoor fan 5 is located outside the second outdoor heat exchanger 23, that is, the second outdoor heat exchanger 23 is located between the outdoor fan 5 and the second outdoor heat exchanger 23, so that when the outdoor fan 5 is started, outdoor air firstly passes through the first outdoor heat exchanger 13 under the suction effect of the outdoor fan 5, then passes through the second outdoor heat exchanger 23, enters the outdoor fan 5, and is discharged by the outdoor fan 5.

In this embodiment, the first compressor 11 and the second compressor 21 are disposed in the same housing, and the first compressor 11 and the second compressor 21 are driven by the same motor, so as to reduce the volume of the room air conditioner and reduce the energy efficiency.

In this embodiment, the heat exchanger 3 may be a plate heat exchanger having an insulating layer disposed outside, or may be a double pipe heat exchanger having an insulating layer disposed outside, so that the first circulation loop and the second circulation loop exchange heat at the heat exchanger 3, and thereby condensation supercooling or condensation heat recovery may be achieved.

In this embodiment, the room air conditioner may include a three-medium heat exchanger, the first outdoor heat exchanger 13 and the second outdoor heat exchanger 23 may be two heat exchange pipelines of the three-medium heat exchanger, and the three-medium heat exchanger may enable the working medium of the first circulation loop, the working medium of the second circulation loop, and the outdoor air to exchange heat independently in pairs.

In other embodiments, the first outdoor heat exchanger 13 and the second outdoor heat exchanger 23 may be common heat exchangers.

Here, the structures of the first outdoor heat exchanger 13 and the second outdoor heat exchanger 14 are not particularly limited, and only two independent heat exchanges of the working medium of the first circulation circuit, the working medium of the second circulation circuit, and the outdoor air can be realized.

In this embodiment, the first indoor heat exchanger 12, the second indoor heat exchanger 22, and the indoor fan 4 constitute an indoor unit B, the first compressor 11, the second compressor 21, the heat exchanger, the first four-way selector valve 16, the second four-way selector valve 26, the first electronic expansion valve 14, the second electronic expansion valve 15, the third electronic expansion valve 24, the fourth electronic expansion valve 25, the first outdoor heat exchanger 13, and the second outdoor heat exchanger 23 constitute an outdoor unit a, and the outdoor unit a and the indoor unit B are connected by a liquid pipe and a gas pipe to form a room air conditioner.

The present embodiment provides a method for controlling a room air conditioner, where the room air conditioner according to any of the above embodiments includes:

when the first circulation loop and the second circulation loop are both refrigeration circulation, controlling the first electronic expansion valve 14 to be in a throttling state, controlling the second electronic expansion valve 15 to be in a fully-opened state, controlling the third electronic expansion valve 24 to be in a fully-opened state, controlling the fourth electronic expansion valve 25 to be in a throttling state, and controlling the indoor fan 4 and the outdoor fan 5 to be both opened, so that the room air conditioner operates in a step cooling and dehumidifying mode;

when the first circulation loop is a heating circulation and the second circulation loop is a refrigerating circulation, the first electronic expansion valve 14 is controlled to be in a throttling state, the second electronic expansion valve 15 is in a full-open state, the third electronic expansion valve 24 is in a throttling state, the fourth electronic expansion valve 25 is in a full-open state, and the indoor fan 4 and the outdoor fan 5 are controlled to be both opened, so that the room air conditioner operates in a dehumidification and reheating mode.

Specifically, when the room air conditioner operates in the step cooling and dehumidifying mode, in the first circulation loop, the exhaust gas of the first compressor 11 sequentially passes through the first interface 16d of the first four-way reversing valve and the third interface 16c of the first four-way reversing valve and then enters the first outdoor heat exchanger 13 for condensation and heat release, after condensation and heat release, the exhaust gas passes through the fully-opened second electronic expansion valve 15 and enters the heat exchanger 3 for absorbing the evaporation cold of the working medium of the second circulation loop for supercooling, then enters the first electronic expansion valve 14 for throttling, the throttled working medium enters the first indoor heat exchanger 12 for absorbing indoor heat, and then passes through the second interface 16e of the first four-way reversing valve and the fourth interface 16s of the first four-way reversing valve as the suction gas and enters the first compressor 11; in the second circulation loop, the exhaust gas of the second compressor 21 sequentially passes through the first interface 26d of the second four-way reversing valve and the third interface 26c of the second four-way reversing valve, enters the second outdoor heat exchanger 23, exchanges heat with the condensed working medium in the first circulation loop to absorb the heat of the working medium in the first circulation loop, then passes through the fully-opened third electronic expansion valve 24, enters the second indoor heat exchanger 22 to absorb indoor heat, and then passes through the second interface 26e of the second four-way reversing valve and the fourth interface 26s of the second four-way reversing valve to enter the second compressor 21 as the suction gas. In this way, the first circulation loop is a refrigeration cycle with condensing and supercooling, and the cold energy of the first circulation loop is used for indoor dehumidification; the second circulation loop is a refrigeration cycle, part of cold energy of the second circulation loop is used for condensing and supercooling the working medium of the first circulation loop, and the rest of cold energy is used for indoor cooling, so that the room air conditioner operates in a step cooling and dehumidifying mode.

It should be noted that the fourth electronic expansion valve 25 throttles, so that the working medium in the second circulation loop can become a low-temperature and low-pressure liquid, and the heat of the working medium in the first circulation loop is absorbed in the heat exchanger 3 to be partially evaporated, so that the working medium in the first circulation loop is condensed and subcooled.

When the indoor fan 4 is turned on, the indoor air is cooled by the second indoor heat exchanger 22 and dehumidified by the first indoor heat exchanger 12; when the outdoor fan 5 is started, outdoor air passes through the first outdoor heat exchanger 13 with lower condensation temperature and then passes through the second outdoor heat exchanger 23 with higher condensation temperature, evaporation cold provided by the first circulation loop is used for processing latent heat load, and evaporation cold provided by the second circulation loop is used for processing sensible heat load, so that the heat exchange efficiency is improved, and the sensible heat load and the latent heat load are independently processed.

And in the step cooling and dehumidifying mode, the evaporation temperature and the condensation temperature of the working medium in the first circulation loop are respectively lower than those of the working medium in the second circulation loop. Therefore, the first circulation loop is in low-temperature circulation, the second circulation loop is in high-temperature circulation, the indoor air needs to be cooled by the second indoor heat exchanger 22 with high evaporation temperature firstly and then dehumidified by the first indoor heat exchanger 12 with low evaporation temperature, and the indoor air can be ensured to be subjected to stepped cooling and dehumidifying treatment.

When the room air conditioner operates in a dehumidification and reheating mode, in a first circulation loop, exhaust of a first compressor 11 sequentially passes through a first interface 16d of a first four-way reversing valve and a second interface 16e of the first four-way reversing valve and then enters a first indoor heat exchanger 12 for condensation and heat release, after the condensation and heat release, the exhaust is throttled by a first electronic expansion valve 14 and then enters a heat exchanger 3 for absorbing condensation heat of working media of a second circulation loop, and then the exhaust passes through a second electronic expansion valve 15 and a first outdoor heat exchanger 13 which are fully opened, and then passes through a third interface 16c of the first four-way reversing valve and a fourth interface 16s of the first four-way reversing valve and then enters the first compressor 11 as suction air; in the second circulation loop, the exhaust gas of the second compressor 21 sequentially passes through the first interface 26d of the second four-way reversing valve and the third interface 26c of the second four-way reversing valve, is condensed by the second outdoor heat exchanger 23 to release heat, then passes through the fully-opened fourth electronic expansion valve 25, enters the heat exchanger 3, releases the condensation heat to the first circulation loop, enters the third electronic expansion valve 24 to be throttled, and the throttled working medium enters the second indoor heat exchanger 22 to absorb heat, and then passes through the second interface 26e of the second four-way reversing valve and the fourth interface 26s of the second four-way reversing valve to enter the second compressor 21 as the suction gas. Thus, the first circulation loop is a heating loop, the heat exchanger 3 is used as an evaporator of the first circulation loop, heat absorbed by the evaporation of the working medium of the first circulation loop is derived from condensation heat of outdoor air and the working medium of the second circulation loop, and the condensation heat of the working medium of the first circulation loop is used for reheating dehumidified indoor air; the second circulation circuit is a refrigeration cycle, the heat exchanger 3 is used as a condenser of the second circulation circuit, part of condensation heat of the second circulation circuit is used for absorbing heat of an evaporator of the first circulation circuit, and the second indoor heat exchanger 22 is used for absorbing latent heat of dehumidification of indoor air, so that the room air conditioner operates in a dehumidification and reheating mode.

It should be noted that, the first electronic expansion valve 14 throttles, so that the working medium in the first circulation loop can become a low-temperature and low-pressure liquid, and the heat absorbed by the working medium in the second circulation loop in the heat exchanger 3 is partially evaporated, so that the working medium in the second circulation loop is condensed to release heat.

When the indoor fan 4 is turned on, the indoor air is dehumidified by the second indoor heat exchanger 22, and is reheated and heated by the first indoor heat exchanger 12; when the outdoor fan 5 is turned on, the heat exchange amount of the first outdoor heat exchanger 13 and the second outdoor heat exchanger 23 can be adjusted by adjusting the air speed of the outdoor fan 5, so as to adjust the recovered condensation heat; the heat exchanger 3 serves as an evaporator of the first circulation circuit and a condenser of the second circulation circuit, respectively, and recovers the dehumidified condensation heat for reheating, and the amount of heat absorbed by evaporation in the first circulation circuit is not necessarily equal to the amount of heat absorbed by condensation in the second circulation circuit, so that the surplus heat is absorbed or discharged by the first outdoor heat exchanger 13 and the second outdoor heat exchanger 23.

When the first circulation loop is a refrigeration cycle, the first interface 16d of the first four-way reversing valve and the third interface 16c of the first four-way reversing valve are controlled to be communicated, and the second interface 16e of the first four-way reversing valve and the fourth interface 16s of the first four-way reversing valve are controlled to be communicated.

When the first circulation loop is a heating circulation loop, the first interface 16d of the first four-way reversing valve is controlled to be communicated with the second interface 16e of the first four-way reversing valve, and the third interface 16c of the first four-way reversing valve is controlled to be communicated with the fourth interface 16s of the first four-way reversing valve.

When the second circulation loop is a refrigeration cycle, the first interface 26d of the second four-way reversing valve is controlled to be communicated with the third interface 26c of the second four-way reversing valve, and the second interface 26e of the second four-way reversing valve is controlled to be communicated with the fourth interface 26s of the second four-way reversing valve.

When the second circulation loop is a heating loop, the first port 26d of the second four-way reversing valve and the second port 26e of the second four-way reversing valve are controlled to be communicated, and the third port 26c of the second four-way reversing valve and the fourth port 26s of the second four-way reversing valve are controlled to be communicated.

In this embodiment, the method for controlling a room air conditioner further includes: when the first circulation loop and the second circulation loop are in heating circulation, the first electronic expansion valve 14 is controlled to be in a full-open state, the second electronic expansion valve 15 is controlled to be in a throttling state, the third electronic expansion valve 24 is controlled to be in a throttling state, the fourth electronic expansion valve 25 is controlled to be in a full-open state, and the indoor fan 4 and the outdoor fan 5 are controlled to be opened, so that the room air conditioner operates in a step heating mode.

In the first circulation loop, exhaust gas of the first compressor 11 sequentially passes through a first interface 16d of a first four-way reversing valve and a second interface 16e of the first four-way reversing valve and then enters the first indoor heat exchanger 12 for condensation and heat release, a working medium after condensation and heat release passes through a fully-opened first electronic expansion valve 14 and then enters the heat exchanger 3, partial heat is released to the working medium of the second circulation loop and then throttled by a second electronic expansion valve 15, the throttled working medium enters the first outdoor heat exchanger 13 to absorb heat, and then the working medium passes through a third interface 16c of the first four-way reversing valve and a fourth interface 16s of the first four-way reversing valve and then enters the first compressor 11 as suction gas; in the second circulation loop, the exhaust gas of the second compressor 21 enters the second indoor heat exchanger 22 for condensation and heat release after passing through the first interface 26d of the second four-way reversing valve and the second interface 26e of the second four-way reversing valve, the working medium after condensation and heat release enters the heat exchanger 3 after being throttled by the third electronic expansion valve 24, partial condensation heat of the working medium of the first circulation loop is absorbed to be taken as heat of an evaporator of the heat pump cycle, the working medium passes through the fully-opened fourth electronic expansion valve 25, then enters the second outdoor heat exchanger 23 for heat absorption, and then enters the second compressor 21 as suction gas after passing through the third interface 26c of the second four-way reversing valve and the fourth interface 26s of the second four-way reversing valve. Thus, the first circulation loop is a heating loop, heat absorbed by evaporation of the working medium of the first circulation loop is from outdoor air, one part of condensation heat of the working medium of the first circulation loop is used for indoor heat supply, and the other part of condensation heat is used for evaporation heat extraction of the working medium of the second circulation loop; the second circulation loop is a heating loop, one part of heat absorbed by the second circulation loop is from outdoor air, one part of heat is from working medium condensation heat of the first circulation loop, and the condensation heat of the second circulation loop is all used for indoor heat supply, so that the room air conditioner operates in a heating mode.

It should be noted that the third electronic expansion valve 24 throttles, so that the working medium in the second circulation loop can become a low-temperature and low-pressure liquid, and the heat absorbed by the working medium in the first circulation loop in the heat exchanger 3 is partially evaporated, so that the working medium in the first circulation loop is condensed to release heat.

When the indoor fan 4 is turned on, the indoor air is heated by the second indoor heat exchanger 22 and then heated by the first indoor heat exchanger 12 for the second time, so that the cascade heating is realized; when the outdoor fan 5 is started, outdoor air passes through the first outdoor heat exchanger 13 with higher evaporation temperature and then passes through the second outdoor heat exchanger 23 with lower evaporation temperature, so that the total heating capacity is unchanged, the heat absorption capacity of low evaporation temperature circulation (second circulation loop) from the environment is reduced, and the efficiency is improved.

And in the cascade heating mode, the evaporation temperature and the condensation temperature of the working medium of the first circulation loop are respectively higher than the evaporation temperature and the condensation temperature of the working medium of the second circulation loop. Therefore, the first circulation loop is in high-temperature circulation, the second circulation loop is in low-temperature circulation, and the indoor air can be subjected to step heating treatment.

In this embodiment, the method for controlling a room air conditioner further includes: when the first circulation loop is a refrigeration cycle and the second circulation loop is a heating cycle, the first electronic expansion valve 14 is controlled to be in a full-open state, the second electronic expansion valve 15 is in a throttling state, the third electronic expansion valve 24 is in a full-open state, the fourth electronic expansion valve 25 is in a throttling state, the indoor fan 4 is controlled to be opened, the outdoor fan 5 is controlled to be closed, and the room air conditioner is enabled to operate in a first outdoor heat exchanger defrosting mode.

In the first circulation loop, the exhaust gas of the first compressor 11 sequentially passes through a first interface 16d of the first four-way reversing valve and a third interface 16c of the first four-way reversing valve and then enters the first outdoor heat exchanger 13 for condensation and heat release, the working medium after condensation and heat release enters the heat exchanger 3 after being throttled by the second electronic expansion valve 15, absorbs part of condensation heat of the second circulation loop, passes through the fully-opened first electronic expansion valve 14, enters the first indoor heat exchanger 12 for heat absorption, and then passes through a second interface 16e of the first four-way reversing valve and a fourth interface 16s of the first four-way reversing valve and then enters the first compressor 11 as suction gas; in the second circulation loop, the exhaust gas of the second compressor 21 sequentially passes through the first interface 26d of the second four-way reversing valve and the second interface 26e of the second four-way reversing valve and then enters the second indoor heat exchanger 22 for condensation and heat release, the working medium after condensation and heat release enters the heat exchanger 3 after passing through the fully-opened third electronic expansion valve 24, is subcooled by the first circulation loop, then passes through the fourth electronic expansion valve 25 for throttling, then enters the second outdoor heat exchanger 23 for evaporation and heat absorption, and then passes through the third interface 26c of the second four-way reversing valve and the fourth interface 26s of the second four-way reversing valve and then enters the second compressor 21 as the suction gas. Thus, the condensation heat of the first circulation loop is used for defrosting, part of the absorbed heat of the first circulation loop comes from the indoor space, and part of the absorbed heat comes from the condensation heat of the second circulation loop, so that the heat which is extracted from the indoor space by the first circulation loop is reduced; and the second circulation loop is a heating loop, the heat absorbed by the evaporation of the second circulation loop comes from outdoor air, one part of the heat generated by condensation is used as the heat absorbed by the evaporation of the first circulation loop, and the other part of the heat is used for indoor heat supply, so that the indoor uninterrupted heat supply is ensured, and the room air conditioner operates in a defrosting mode of the first outdoor heat exchanger.

When the indoor fan 4 is started, the indoor air is heated by the second indoor heat exchanger 22 and then passes through the first indoor heat exchanger 12, so that uninterrupted indoor heat supply is ensured; the outdoor fan 5 is turned off so that the first outdoor heat exchanger 13 does not exchange heat with the outside air, and thus the condensation heat of the first outdoor heat exchanger 13 can be used for quick defrosting.

In this embodiment, the room air conditioner further comprises: when the first circulation loop is a heating circulation and the second circulation loop is a refrigerating circulation, the first electronic expansion valve 14 is controlled to be in a full-open state, the second electronic expansion valve 15 is in a throttling state, the third electronic expansion valve 24 is in a full-open state, the fourth electronic expansion valve 25 is in a throttling state, the indoor fan 4 is controlled to be opened, the outdoor fan 5 is controlled to be closed, and the room air conditioner is enabled to operate in a second outdoor heat exchanger defrosting mode.

In the first circulation loop, the exhaust gas of the first compressor 11 sequentially passes through a first interface 16d of a first four-way reversing valve and a second interface 16e of the first four-way reversing valve, then enters a first indoor heat exchanger 12 for condensation and heat release, the working medium after condensation and heat release enters a heat exchanger 3 after passing through a fully-opened first electronic expansion valve 14, is subcooled by a second circulation loop, then is throttled by a second electronic expansion valve 15, then enters a first outdoor heat exchanger 13 for heat absorption, and then passes through a third interface 16c of the first four-way reversing valve and a fourth interface 16s of the first four-way reversing valve to enter the first compressor 11 as suction gas; in the second circulation loop, the exhaust gas of the second compressor 21 sequentially passes through the first interface 26d of the second four-way reversing valve and the third interface 26c of the second four-way reversing valve, enters the second outdoor heat exchanger 23 for condensation and heat release, the working medium after condensation and heat release is throttled by the fourth electronic expansion valve 25 and enters the heat exchanger 3, absorbs part of condensation heat of the first circulation loop, passes through the fully-opened third electronic expansion valve 24, enters the second indoor heat exchanger 22 for heat absorption, and then passes through the second interface 26e of the second four-way reversing valve and the fourth interface 26s of the second four-way reversing valve and enters the second compressor 21 as suction gas. In this way, the condensation heat of the second circulation loop is used for defrosting, part of the absorbed heat of the second circulation loop comes from the indoor space, and part of the absorbed heat comes from the condensation heat of the first circulation loop, so that the heat absorbed by the second circulation loop from the indoor space is reduced; and the first circulation loop is a heating loop, the heat absorbed by the evaporation of the first circulation loop comes from outdoor air, one part of the heat generated by condensation is used as the heat absorbed by the evaporation of the second circulation loop, and the other part of the heat is used for indoor heat supply, so that the indoor uninterrupted heat supply can be ensured, and the room air conditioner can operate in a defrosting mode of the second outdoor heat exchanger.

When the indoor fan 4 is started, the indoor air is cooled through the second indoor heat exchanger 22 and then heated through the first indoor heat exchanger 12, so that uninterrupted indoor heat supply is guaranteed; the outdoor fan 5 is turned off so that the second outdoor heat exchanger 23 does not exchange heat with the outside air, and thus the condensation heat of the second outdoor heat exchanger 23 can be used for quick defrosting.

According to the room air conditioner, under the step cooling and dehumidifying mode, the evaporation side provides double evaporation temperature cold sources, the high-temperature cold source is used for treating sensible heat load, the low-temperature cold source is mainly used for treating latent heat load, and compared with the traditional heat and humidity coupling air treatment mode, the room air conditioner has the advantages that the dehumidifying effect is guaranteed, meanwhile, a part of high-grade cold sources are saved, and the energy efficiency ratio of the air conditioner is improved; the heat exchanger is used for recovering the high-temperature evaporation cold energy for low-temperature circulating condensation supercooling, so that the cold energy grade is improved while the integral refrigerating capacity and power consumption of the system are not changed; the evaporation temperature of the two refrigeration circulation loops is regulated and controlled to adapt to the change of the indoor heat-humidity ratio, so that the cascade heat exchange is realized, and the overall performance coefficient of the system is improved; under the step heating mode, the double condensation temperature heat sources at the condensation side realize step heating, so that the heat exchange efficiency is improved, and the air supply comfort level is ensured; the heat exchanger 3 enables the low-temperature stage circulation to take part of condensation heat from the high-temperature stage circulation as evaporation heat absorption, can improve the overall evaporation temperature of the low-temperature stage circulation, and avoids the problems of performance reduction, frosting and the like caused by the large quantity of heat taken by the low-temperature stage circulation from the outdoor when the outdoor temperature is low; in the dehumidification and reheating mode, the two indoor heat exchangers are respectively used as an evaporator and a condenser of two cycles, so that the dehumidification and heating functions are realized, the heat exchanger 3 is used for recovering condensation heat for reheating, low-energy-efficiency electric heating reheating is not required, the dehumidification effect is ensured, the cold and heat quantity offset is reduced, and the energy consumption of the air conditioner is reduced; in the defrosting mode, the two outdoor heat exchangers are respectively used as an evaporator and a condenser of two cycles, and indoor uninterrupted heating is realized in the defrosting process, so that indoor thermal comfort is improved in the defrosting period; the air conditioner can freely switch four operation modes of step cooling and dehumidification, step heating, heating and dehumidification and uninterrupted heat supply and defrosting by utilizing the reversing of the two four-way valves, can efficiently, energy-saving and comfortably operate, and meets the various requirements of heating, cooling, dehumidification and defrosting of an outdoor heat exchanger in summer, hot and winter areas of China all year round.

The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment may be implemented by software plus a necessary general hardware platform, and may also be implemented by hardware. With this in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods according to the various embodiments or some portions of the embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A room air conditioner is characterized by comprising a first circulation loop, a second circulation loop, an indoor fan and an outdoor fan, wherein a working medium of the first circulation loop and a working medium of the second circulation loop exchange heat through a heat exchanger;

a first interface of a second four-way reversing valve is connected with an exhaust port of the second compressor, a second interface of the second four-way reversing valve is connected with the second indoor heat exchanger, a third interface of the second four-way reversing valve is connected with the second outdoor heat exchanger, a fourth interface of the second four-way reversing valve is connected with an air inlet of the second compressor, and the first interface of the second four-way reversing valve, the second interface of the second four-way reversing valve, the third interface of the second four-way reversing valve and the fourth interface of the second four-way reversing valve can be switched on;

the outdoor fan is used for driving outdoor air to sequentially flow through the first outdoor heat exchanger and the second outdoor heat exchanger;

when a first interface of the first four-way reversing valve is communicated with a second interface of the first four-way reversing valve, and a third interface of the first four-way reversing valve is communicated with a fourth interface of the first four-way reversing valve, the first circulation loop is a heating circulation loop;

when a first interface of the first four-way reversing valve is communicated with a third interface of the first four-way reversing valve and a second interface of the first four-way reversing valve is communicated with a fourth interface of the first four-way reversing valve, the first circulation loop is a refrigeration cycle;

when a first interface of the second four-way reversing valve is communicated with a second interface of the second four-way reversing valve, and a third interface of the second four-way reversing valve is communicated with a fourth interface of the second four-way reversing valve, the second circulation loop is a heating circulation loop;

the first interface of the second four-way reversing valve is communicated with the third interface of the second four-way reversing valve, and the second interface of the second four-way reversing valve is communicated with the third interface of the second four-way reversing valveFirst, theWhen the four interfaces are conducted, the second circulation loop is a refrigeration cycle;

when the first circulation loop and the second circulation loop are both refrigeration cycles, the first electronic expansion valve is in a throttling state, the second electronic expansion valve is in a fully-opened state, the third electronic expansion valve is in a fully-opened state, and the fourth electronic expansion valve is in a throttling state; the cold energy of the first circulation loop is used for indoor dehumidification; part of cold energy of the second circulation loop is used for condensing and supercooling the first circulation loop, and the rest of cold energy is used for cooling indoors;and isThe evaporation temperature and the condensation temperature of the working medium in the first circulation loop are respectively lower than the evaporation temperature and the condensation temperature of the working medium in the second circulation loop;

the first circulation loop is a heating circulation, and when the second circulation loop is a refrigerating circulation, the first electronic expansion valve is in a throttling state, the second electronic expansion valve is in a fully-opened state, the third electronic expansion valve is in a throttling state, and the fourth electronic expansion valve is in a fully-opened state; the second indoor heat exchanger is an evaporator of the second circulation loop and is used for absorbing the latent heat of dehumidification of indoor air; the first indoor heat exchanger is a condenser of the first circulation loop and used for reheating the dehumidified indoor air.

2. A room air conditioner as recited in claim 1 wherein said first compressor and said second compressor are disposed within the same housing and said first compressor and said second compressor are driven by the same motor.

3. A room air conditioner as set forth in claim 1 wherein said heat exchanger is any one of a plate type heat exchanger externally provided with an insulating layer and a double pipe type heat exchanger externally provided with an insulating layer.

4. The room air conditioner of claim 1 further comprising a three-medium heat exchanger for exchanging heat between the working medium of the first circulation loop, the working medium of the second circulation loop, and the outdoor air in pairs, wherein the first outdoor heat exchanger and the second outdoor heat exchanger are two heat exchange lines of the three-medium heat exchanger.

5. A room air conditioner control method, based on any one of claims 1-4, comprising:

when the first circulation loop and the second circulation loop are both refrigeration cycles, controlling the first electronic expansion valve to be in a throttling state, controlling the second electronic expansion valve to be in a fully-opened state, controlling the third electronic expansion valve to be in a fully-opened state, controlling the fourth electronic expansion valve to be in a throttling state, and controlling both the indoor fan and the outdoor fan to be opened so as to enable the room air conditioner to operate a step cooling and dehumidifying mode;

and when the first circulation loop is a heating circulation loop, controlling the conduction of the first interface of the first four-way reversing valve and the second interface of the first four-way reversing valve, and the conduction of the third interface of the first four-way reversing valve and the fourth interface of the first four-way reversing valve.

6. A control method of a room air conditioner according to claim 5, further comprising:

when the first circulation loop and the second circulation loop are both heating loops, controlling the first electronic expansion valve to be in a full-open state, the second electronic expansion valve to be in a throttling state, the third electronic expansion valve to be in a throttling state, and the fourth electronic expansion valve to be in a full-open state, and controlling both the indoor fan and the outdoor fan to be opened so as to enable the room air conditioner to operate a step heating mode; wherein, the first and the second end of the pipe are connected with each other,

7. A control method of a room air conditioner according to claim 5, further comprising:

8. A control method of a room air conditioner according to claim 5, further comprising:

when the first circulation loop is a heating circulation loop and the second circulation loop is a refrigerating circulation loop, the first electronic expansion valve is controlled to be in a full-open state, the second electronic expansion valve is in a throttling state, the third electronic expansion valve is in a full-open state, the fourth electronic expansion valve is in a throttling state, the indoor fan is controlled to be opened, and the outdoor fan is controlled to be closed, so that the room air conditioner operates a second outdoor heat exchanger defrosting mode.

9. A control method as claimed in claim 5, wherein when the room air conditioner operates in the step cooling and dehumidifying mode, the evaporating temperature and the condensing temperature of the working medium in the first circulation loop are lower than those of the working medium in the second circulation loop, respectively.

10. A control method as claimed in claim 6, wherein when the room air conditioner operates in the step heating mode, the evaporating temperature and the condensing temperature of the working medium in the first circulation loop are respectively higher than the evaporating temperature and the condensing temperature of the working medium in the second circulation loop.