84results about How to "Reduce the amount of refrigerant" patented technology

The invention discloses a technology for separating low carbon olefin gases, for solving the problems that hydrogen, methane, ethane and propane and other products with high purity can not be acquired and dimethyl ether and oxygen and carbon monoxide in impurities are not removed efficiently, etc. in the prior art. The technology is characterized in that a step of removing carbon monoxide and oxygen is added, methanol-to-olefin gas streams processed by removing carbon monoxide and oxygen enter into a deethanizing column, deethanizing column overhead streams successively pass through an ethene hydrogenation reactor, six separation pots, a low pressure demethanizing column and an ethene rectification column, etc. to separate to obtain ethene and ethane products, and deethanizing column bottom streams successively pass through a propyne hydrogenation reactor, a methane stripper and a propylene rectification column, etc. to separate to obtain propylene and propane products. According to the invention, polymer grade ethene and propylene products can be obtained, and hydrogen, methane, ethane and propane products, etc. with high purity can be obtained.

A natural refrigerant low-pressure shell-type rotary compressor in which the amount of oil contained on the high-pressure side is reduced with sufficient lubrication and sealing performance at a sliding section secured. The compressor has a rotary refrigerant compression mechanism provided in a low-pressure enclosed container and having vanes, an oil separation element for separating lubricating oil from the refrigerant, and an oil supply passage for supplying the separated lubricating oil to a vane back pressure chamber of the compression mechanism, a crankshaft, a bearing, a cylinder, a piston, and oil supply spaces between the vanes. Vane skip is suppressed, and efficient lubrication and high sealing performance at the sliding section and a reduction in the amount of the oil contained on the high-pressure side are achieved at the same time. The compressor is highly reliable, is of low cost, has high performance, and uses a reduced amount of refrigerant.

Embodiments of the invention provide a method and a device for controlling a multi-split air-conditioning system, and the method and the device can improve heating capacity of the air-conditioning system. The method comprises: in a detection period of the multi-split air-conditioning system, determining and storing supercooling degree of a heat exchanger in the jth closed indoor unit in the ith period; according to the supercooling degree of the heat exchanger in the jth closed indoor unit in the ith period, obtaining a variation value of the opening of an electronic expansion valve of the jth closed indoor unit in the ith period; according to the variation value of the opening of an electronic expansion valve of the jth closed indoor unit in the ith period, and a pre-stored opening value of the electronic expansion valve of the jth closed indoor unit in the (i-1)th period, obtaining and storing a first opening value of the electronic expansion valve of the jth closed indoor unit in the ith period; and adjusting the opening of the electronic expansion valve of the jth closed indoor unit in the ith period to the first opening value. The invention is suitable to be used in the technical field of air-conditioning.

The invention discloses a low refrigerant charging amount heat pump device and a control method thereof. The device comprises a compressor, a compressor refrigerant gas outlet is sequentially connected with an indoor heat exchanger, a throttling device and an outdoor heat exchanger through a four-way reversing valve, an outlet of the outdoor heat exchanger is connected with an inlet of a liquid storage device through the four-way reversing valve, an outlet of the liquid storage device is connected with an inlet of the compressor, and the device further comprises a bypass pipeline; an inlet of the bypass pipeline is located between the compressor and the four-way reversing valve, an outlet of the bypass pipeline is located between the four-way reversing valve and the liquid storage device or located on the side or bottom of a shell of the liquid storage device, and a bypass electromagnetic valve is located on the bypass pipeline; under the heating condition, when the device stably runs, a refrigerant exhausted out of the compressor flows into the indoor heat exchanger through the four-way reversing valve and then flows back to the compressor through the throttling device, the outdoor heat exchanger, the four-way reversing valve and the liquid storage device, and a heating cycle is formed; and under the refrigerating condition, stable running is opposite to the heating cycle flow path. The control method of the device is further provided. In the cold starting process, the problem that a large number of refrigerants are gathered in the liquid storage device and the compressor, and consequently the pressure of an air inlet of the compressor is too low is solved.

The invention discloses a printing and dyeing sludge pyrolysis treatment device which successively comprises a sludge chamber, a combustion chamber and a product collecting chamber from top to bottom, wherein a feed port is arranged on the sludge chamber, and a support plate with holes is arranged between the sludge chamber and the combustion chamber; the combustion chamber is connected with a combustion engine, and a pyrolysis cavity is arranged in the combustion chamber; and a dump valve is arranged between the combustion chamber product collecting chamber. The invention also discloses a printing and dyeing sludge treatment method. In the invention, by adopting the vertical arrangement from top to bottom, the automatic flowing nature of the substance is fully utilized, and the problems of high viscosity and hard feeding of printing and dyeing sludge are solved. Sludge drying, pyrolysis, pyrolysis gas recycling and control are integrated, and energy consumption is effectively reduced. Not only is the recycling of the printing and dyeing sludge realized, but also the harm to environment is greatly lowered. Therefore, the demands of industry development and environmental protection can be well adapted and satisfied.

The invention discloses a heat recovery external unit system and an air conditioner system. The heat recovery external unit system comprises a compressor (1), a high-pressure air pipe (2), a first branch (5), a second branch (6) and a third branch (7); the first branch (5), the second branch (6) and the third branch (7) are arranged in parallel; a first outdoor heat exchanger (8) is arranged on the first branch (5); a second outdoor heat exchanger (9) is arranged on the second branch (6); and when the air conditioner system is positioned in a low temperature refrigeration mode where the outdoor temperature is lower than a first preset temperature, or is positioned in a high temperature heating mode where the outdoor environment temperature is higher than a second preset temperature, one of the first branch (5) and the second branch (6) is connected and the other one is disconnected, and the third branch (7) communicates with the high-pressure air pipe (2), wherein the first preset temperature is lower than the second preset temperature. According to the heat recovery external unit system, a situation that rapid refrigeration is realized in a low temperature environment or rapid heating is realized in a high temperature environment can be ensured, and the use comfort of an air conditioner is improved.

The invention provides a fresh air conditioner and a control method thereof. The fresh air conditioner comprises an air conditioner main body, wherein a fresh air duct and an exhaust air duct are formed in the air conditioner main body; a heat exchange core body is arranged in the air conditioner main body; a fresh air flow duct and an exhaust air flow duct are formed on the heat exchange core body; the fresh air flow duct communicates with the fresh air duct; the exhaust air flow duct communicates with the exhaust air duct; a first heat exchanger is arranged in the fresh air duct; a heat recovery air duct is connected between the exhaust air duct and the exhaust air flow duct; and a second heat exchanger is arranged in the heat recovery air duct and connected with the first heat exchangerthrough a refrigerant pipeline. According to the fresh air conditioner, the heat and cold in airflow in the exhaust air duct are recovered by the heat exchange core body, and the other heat and coldin the exhaust air duct are recovered by the second heat exchanger in the heat recovery air duct, so that the heat recovery efficiency of the fresh air conditioner is improved, and the fresh air conditioner is more energy-saving.

The invention provides a continuous purification method for crude acetonitrile. A lateral line condenser is arranged at a third rectifying tower, so that the heat energy of an acetonitrile final product can be adequately recovered, the load of a reboiler at the bottom of the third rectifying tower and the refrigerant quantity of an acetonitrile final product cooler can be effectively reduced, the energy consumption can be saved, and 500-600MJ of energy can be saved for each ton of the acetonitrile product; and distillate is returned from the top of the third rectifying tower, so that the accumulation of oxazole in a system can be reduced, the yield of the acetonitrile can be guaranteed as well, and the problem that the operation load of a first rectifying tower can be obviously increased since all the distillate on the top of the third rectifying tower returns to the first rectifying tower in the prior art can be improved. Furthermore, a corresponding pipeline for adding a polymerization inhibitor is increased on the conventional three-tower and one-kettle refining technology, so that the problem that the exposed devices are easy to polymerize in the existing acetonitrile purification process in China can be solved, and the continuous purification method has the advantages of being high in industrial application value, and high in acetonitrile final product purity.

The invention discloses a separation method for preparing low-carbon olefin gas through methanol conversion, and aims to solve the problems that products with high purity such as hydrogen, methane, ethane and propane which cannot be obtained in the prior art and oxygen, carbon oxide and the like in dimethyl enther and gas impurities cannot be effectively removed. According to the method, a step of removing the carbon oxide and the oxygen is increased, a methanol prepared olefin gas material flow from which the carbon oxide and the oxygen are removed enters a deethanizing column; the material flow on the top of the deethanizing column flows through an acetylene hydrogenation reactor, six separation tanks, a demethanizing column, an ethylene rectifying column and the like in sequence to separate to obtain ethylene and ethane products; and the material flow at the bottom of the deethanizing column flows through a propyne hydrogenation reactor, a methane stripping column, a propylene rectifying column and the like in sequence to separate to obtain propene and propane products. By using the separation method, polymer grade ethylene and propene products can be obtained, and products with high purity such as hydrogen, methane, ethane and propane can also be obtained.

The present invention relates to an air conditioner system, in which an air-cooled condenser mounted on a refrigerant circulation line between a water-cooled condenser and an expansion valve and a blower fan for blowing air to the air-cooled condenser are arranged at one side of the water-cooled condenser in a state of being disposed in a row in the air flow direction and are arranged within the width of the one side of the water-cooled condenser, thereby enabling the enhancement of installability and assemblability inside an engine room by simplifying and reducing the package, reducing noise of the blower fan and securing adequate cooling performance because of the blower fan disposed between two air-cooled heat exchangers even when inflowing air is insufficient, such as in an idling condition.

The invention relates to an anti-condensation device and method for a refrigerant heat dissipation main control board and an air conditioner unit, wherein the anti-condensation device for a refrigerant heat dissipation main control board includes: a detection mechanism and a control mechanism, and the detection mechanism is used to detect whether the refrigerant heat dissipation main control When condensation occurs, the regulating mechanism is used to reduce the amount of refrigerant flowing into the refrigerant heat dissipation main control board from the refrigerant inflow end of the refrigerant heat dissipation main control board when the detection mechanism detects condensation on the refrigerant heat dissipation main control board in the heating mode, to eliminate condensation. By reducing the amount of refrigerant flowing into the refrigerant heat dissipation main control board at the refrigerant inflow end from the refrigerant heat dissipation main control board, the present invention is compared with the existing adjustment method of controlling the amount of refrigerant flowing through the refrigerant cooling heat dissipation plate from the outflow end. On the end, the amount of refrigerant flowing into the refrigerant cooling plate is reduced, and the amount of refrigerant per unit capacity in the refrigerant cooling plate is reduced, which avoids the retention of refrigerant in the refrigerant cooling plate, makes the adjustment faster, and has a significant anti-condensation effect.

The invention relates to the technical field of refrigerators, in particular to a control method for a refrigerator. The control method for the refrigerator comprises the steps that different control modes are operated according to different environment temperatures, refrigeration of a refrigerating chamber is conducted preferably when the environment temperature is smaller than a set environment temperature value as well as when the environment temperature is not smaller than the set environment temperature value and the temperature in a freezing chamber is smaller than a set freezing temperature value, and refrigeration of a temperature-variable chamber is conducted after refrigeration of the refrigerating chamber is completed; and whether refrigeration of the refrigerating chamber is needed or not is monitored while refrigeration of the temperature-variable chamber is conducted, and a throttling mechanism of the freezing chamber is controlled to be connected with a freezing refrigeration circuit when both refrigeration of the refrigerating chamber and refrigeration of the temperature-variable chamber are not needed, so that independent refrigeration of the freezing chamber is conducted. When the environment temperature is larger than the set environment temperature value and the temperature in the freezing chamber is not smaller than the set freezing temperature value, refrigeration of the refrigerating chamber is conducted after the refrigerator operates in the initial operating mode. According to the control method for the refrigerator, a compressor operates under a small load condition, so that damage caused by liquid impact is avoided, the refrigerating speeds of all the chambers are guaranteed, and the system stability is improved.

The embodiment of the invention provides a water chiller-heater unit and a control method of the water chiller-heater unit and relates to the field of air conditioners. The water chiller-heater unit solves the problem that in the prior art, when a water chiller-heater unit conducts refrigeration, because a balance tank cannot store a refrigerant and the outdoor environment temperature is too high or the indoor load is too low, the water chiller-heater unit gives a high pressure alarm. According to the water chiller-heater unit, a first electromagnetic valve, a second electromagnetic valve, a balance tank connected with an electronic expansion valve in parallel and a controller are additionally arranged in a traditional unit; and the first electromagnetic valve controls the flow direction of a refrigerant in a communicating pipe between the balance tank and a shell and tube heat exchanger, the second electromagnetic valve controls the flow direction of the refrigerant in the communicating pipe between the balance tank and a finned heat exchanger, and the controller controls the first electromagnetic valve to be opened and the second electromagnetic valve to be closed or controls the first electromagnetic valve to be closed and the second electromagnetic valve to be opened according to the operation mode of the water chiller-heater unit and the exhaust pressure of a compressor in a compression assembly. The water chiller-heater unit and the control method are used for production and control of water chiller-heater units.

The invention discloses a multiple-on-line system and a liquid return prevention control method thereof, wherein the method comprises the following steps of: controlling the multiple-on-line system to switch to a defrosting mode to operate to defrost when the multiple-on-line system is in heating operation and if an outdoor unit receives a defrosting instruction; detecting gas exhaust pressure, gas return pressure and a gas exhaust temperature of a compressor in real time; after defrosting is completed, sending a defrosting completion signal to a flow-splitting device by the outdoor unit, controlling the compressor to reduce frequency and a plurality of electric-control valves to open, and controlling any one of the electric-control valves to open and the rest of the electric-control valves to close during reversing of a four-way valve, thereby reducing amount of a refrigerant returned to a low-pressure gas-liquid separator; and regulating number of the open electric-control valves according to the gas exhaust pressure, the gas return pressure and the gas exhaust temperature. According to the method disclosed by the invention, liquid return risk of the compressor after defrosting is completed can be avoided, and the safety reliability of the system is greatly improved.

The invention provides a freezing apparatus. When the high pressure side is up to a critical pressure, a compression mechanism can be prevented from being influenced by the high pressure, and the freezing capacity of the freezing apparatus can be prevented from being influenced by outside air temperature. The freezing apparatus comprises an electric expansion valve (33) that is connected to the downstream side of an air cooler (28) and the upstream side of an electric expansion valve (39); a casing (36) that is connected to the downstream side of the freezing apparatus and the upstream side of an electric expansion valve (39); a separating heat exchanger (29) that is set at the downstream side of the freezing apparatus and the upstream side of an electric expansion valve (39); an auxiliary circuit (48) that helps a refrigerant in the casing flows from electric expansion valves (43,47) into the separating heat exchanger, and then into the middle compression part of a compressor (11); and a main circuit (38) that helps the refrigerant flows from the lower part of the casing into the separating heat exchanger , and flows into the electric expansion valve (39) after heat exchange with the refrigerant flows in the first path; and a control apparatus (57) adjusts the pressure in the high pressure side of the refrigerant loop at the upstream side through the electric expansion valve (33).

The invention provides a cooling device which is provided with a separation recycling device with a supercritical pressure formed at a high-pressure side, can provide hot water by using waste heat, and enables high-efficient operation of a refrigeration cycle. The cooling device (R) of the invention is provided with a separation recycling device with a supercritical pressure formed at the high-pressure side; the cooling device (R) is provided with a waste heat recovery heat exchanger (70), and the waste heat recovery heat exchanger (70) is provided with a waste heat recovery medium flow path (70B) and a refrigerant flow path (70A); and the cooling device (R) allows the second refrigerant flow (main refrigerant flow towards an evaporator) which flows out from a gas cooler (46) and has not flowed into an intermediate heat exchanger (80) forming the separation recycling device to flow into the refrigerant flow path (70A) of the waste heat recovery heat exchanger (70).

The invention discloses a compressor. The compressor comprises a motor, a crankshaft, a compressing mechanism and a noise reduction cover, wherein the motor comprises a stator and a rotor, the stator is arranged on the rotor in a sleeving manner, an exhaust channel is arranged on the rotor, a balancing block is arranged on the upper end surface of the rotor and provided with a first end surface and a second end surface which are oppositely arranged, the first end surface is suitable for being connected with the rotor, the two ends in the extending direction of the balancing block are a windward end part and a leeward end part respectively, the windward end part is connected between the first end surface and the second end surface, and in the direction from the first end surface to the second end surface, the windward end part is inclined toward the leeward end part; the upper end of the crankshaft is connected with the rotor, and the exhaust channel is close to the crankshaft; the compressing mechanism is connected with the lower end of the crankshaft; and the crankshaft penetrates the noise reduction cover which is arranged on the upper end surface of the compressing mechanism in a covering manner, and a vent hole is formed in the noise reduction cover and is opposite to the exhaust channel. According to the compressor provided by the invention, the problem of oil accumulation and discharge is solved.

The invention discloses a refrigeration device. Between an outdoor unit (20) having a lower stage side compressor (21) and an indoor unit (40), an option unit (30) having a higher stage side compressor (31) and a gas / liquid separator (33) is provided. During a defrost operation, an outdoor heat exchanger (22) is defrosted by refrigerant delivered from the lower stage side compressor (21) and refrigerant of the gas / liquid separator (33) is sucked into the higher stage side compressor (31) and delivered to the suction side of the lower stage side compressor (21). The option unit (30) is provided with an injection pipe (36) for returning a part of refrigerant delivered from the higher stage side compressor (31) to the suction side of the higher stage side compressor (31). Consequently, refrigerant flowing from the gas / liquid separator (33) to the higher stage side compressor (31) is gasified by high temperature delivery refrigerant.

The invention discloses an air conditioner and a control method thereof, and belongs to the technical scheme of defrosting of air conditioners. The air conditioner comprises a first pipeline and a second pipeline. A first end of the first pipeline communicates with an exhaust port of a compressor. A second end of the first pipeline communicates with a first end port, connected with an indoor heat exchanger, of an outdoor heat exchanger. A first end of the second pipeline communicates with the exhaust port of the compressor. A second end of the second pipeline communicates with an air return port of the compressor. The first pipeline and the second pipeline are additionally arranged in the air conditioner pipeline, wherein the first pipeline can be used for guiding high-temperature refrigerants exhausted by the compressor into the outdoor heat exchanger so as to enable frost condensed on the outdoor heat exchanger to be melted for defrosting and melting ice; and the second pipeline can be used for guiding the high-temperature refrigerants exhausted by the compressor into the air return port of the compressor so as to heat and vaporize the liquid-state refrigerants flowing back to the compressor, reduce the amount of the refrigerants condensed into liquid when flowing through the outdoor heat exchanger and ensure the overall safe and effective operation of the compressor and the air conditioner.

The invention provides a freezing apparatus. When the high pressure side is up to a critical pressure, a steady freezing capacity can be guaranteed. The freezing apparatus comprises an electric expansion valve (33) that is connected to the downstream side of an air cooler (28) and the upstream side of an electric expansion valve (39); a liquid storing device (36) that is connected to the downstream side of the electric expansion valve (33) and the upstream side of an electric expansion valve (39); a heat exchanger (29) that is set at the downstream side of the air cooler and the upstream side of an electric expansion valve (33); an auxiliary circuit (48) that helps a refrigerant in the liquid storing device flows from electric expansion valves (43,47) into a first path (29A), and then back to a compressor (11); and a main circuit (38) that helps the refrigerant flows from the air cooler into a second path (29B) , and flows into the electric expansion valve (33) after heat exchange with the refrigerant flows in the first path, and makes the refrigerant flows from the lower part of the liquid storing device into the electric expansion valve (39); and electromagnetic valves (66,67) that are switched selectively, and make the refrigerant flows out of the first path back into the middle pressure part of the compressor or back to a low pressure part.

The invention discloses a multi-unit system and a control method of a heating indoor unit thereof. The method comprises the following steps: a shunt device obtains the target opening and the target duration of a throttling element in an indoor unit according to a preset opening and duration table if the indoor unit which is not started or at a refrigeration mode receives heating mode commands when the multi-unit system is at a pure refrigeration mode or a main refrigeration mode, controls the throttling element in the indoor unit to be opened to the target opening to adjust the pressure in front and rear of the throttling element, and adjusts the opening of the throttling element to the maximum opening when the target opening is operated for the target duration; a refrigeration control valve corresponding to the indoor unit is controlled to be closed after time is delayed by a first preset time; a corresponding heating control valve is controlled to be opened after time is delayed by a second preset time. The method avoids scouring noise produced when refrigerant flows rapidly and the influence on the refrigeration capacity of other indoor units by performing pressure equalizing on the indoor unit receiving the heating mode commands.

The invention provides a fresh-air conditioner and a control method of the fresh-air conditioner. The fresh-air conditioner comprises a conditioner main body, a fresh-air duct, an air exhaust duct, aheat exchanger core body, a fresh-air heat exchanger and an air exhaust heat exchanger, wherein the fresh-air duct and the air exhaust duct are arranged inside the conditioner main body, the heat exchanger core body is arranged inside the conditioner main body, and the fresh-air duct and air exhaust duct respectively pass through the heat exchanger core body, and change heat through the heat exchanger core body; the fresh-air heat exchanger is arranged on the fresh-air duct and is located at the downstream of the heat exchanger core body on the fresh-air duct; and the air exhaust heat exchanger is arranged on the air exhaust duct and is located at the downstream of the heat exchanger core body on the air exhaust duct. The invention reduces the external energy dissipation of the building, and in a green energy-saving building, can not only reduce the indoor cooling / heat production demands, but also reduce the cost of the air conditioner by reducing the volume of two devices and refrigerant quantity, thus solving the technical problem of high power consumption of the fresh-air conditioner in the prior art.

An object is to provide a high inner pressure type multistage compression rotary compressor capable of avoiding beforehand generation of vane fly of a second rotary compression element and realizing a stabilized operation, the rotary compressor includes a communication path which connects an intermediate pressure region to a region having a low pressure as a suction pressure of a first rotary compression element; and a valve device which opens or closes this communication path, the rotary compressor applies a high pressure as a back pressure of an upper vane, and this valve device opens the communication path in a case where a pressure difference between the intermediate pressure and the low pressure increases a predetermined upper limit value before the intermediate pressure reaches the high pressure.

The invention discloses an air conditioner system and a control method thereof. The air conditioner system comprises at least one heat exchanger and at least one control mechanism. Each control mechanism is connected with one of at least one heat exchanger and used for controlling the corresponding heat exchanger to be switched between a first work state and a second work state. When the heat exchangers are in the first work state, liquid discharging is conducted, and when the heat exchangers are in the second work state, liquid storage is conducted. The air conditioner system and the controlmethod thereof solve the technical problem that under the situation that excessive refrigerants exist in an air conditioner system in the prior art, running reliability is low.

The invention discloses an air conditioner control method, an air conditioner and a storage medium. The method comprises the steps of receiving a preset signal during the operation of the air conditioner, and closing a first electromagnetic valve according to the preset signal; and closing a second electromagnetic valve after the first electromagnetic valve is closed for a first preset duration, wherein the first electromagnetic valve is used for changing the on-off state of a pipeline through which a refrigerant moves from an outdoor unit of the air conditioner to an indoor unit of the air conditioner, and the second electromagnetic valve is used for changing the on-off state of a pipeline through which the refrigerant moves from the indoor unit to the outdoor unit. According to the air conditioner control method, the first electromagnetic valve is closed firstly, so that the pipeline of the refrigerant from the outdoor unit to the indoor unit is blocked, the refrigerant cannot flow from the outdoor unit to the indoor unit at the moment, the refrigerant in the indoor unit can move to the outdoor unit through the pipeline from the indoor unit to the outdoor unit, and the second electromagnetic valve is closed after a certain period of time; and therefore, the pipeline of the refrigerant from the indoor unit to the outdoor unit is blocked, the refrigerant amount of the indoor unit is small, and the use safety of the air conditioner is improved.

The invention relates to an air conditioner automatic liquid recycling control method, an air conditioner automatic liquid recycling control system and an air conditioner. The air conditioner automatic liquid recycling control method comprises the following steps: when receiving a liquid recycling command, judging whether the operation mode of the air conditioner is the refrigerating mode; if yes,closing a liquid connecting pipe, and detecting and judging whether the pressure in the liquid connecting pipe is greater than the first preset pressure value and lasts for the first preset time t1;if yes, judging whether the pressure in a gas connecting pipe is less than the second preset pressure value, if yes, giving out an automatic liquid recycling command for automatic liquid recycling, wherein the first preset pressure value is greater than the second preset pressure value. According to the air conditioner automatic liquid recycling control method, through comparing the size relationship of the liquid connecting pipe, the gas connecting pipe and the preset pressure values, whether automatic liquid recycling is carried out is judged, so that the situation that automatic liquid recycling is started caused by misjudgment of the air conditioner under other operating environments is prevented, judgement of starting the liquid recycling moment manually is not needed, and automatic direction and judgement of liquid recycling are realized to prevent a compressor from being damaged.

The invention relates to the technical field of intelligent household appliances, and discloses a control method for a multi-split air conditioner, the multi-split air conditioner comprises a plurality of indoor units, and each indoor unit comprises a throttling device, an indoor heat exchanger and a refrigerant block valve which are connected in sequence; the control method comprises the steps that under the condition that a shutdown instruction is received, the operation mode of the indoor unit is obtained; according to the operation mode of the indoor unit, a target control scheme of a throttling device and a refrigerant block valve of the indoor unit is determined; and the indoor unit is controlled to execute the target control scheme. According to the method, the indoor unit is shut down in different operation modes, and the throttling device and the refrigerant cut-off valve are controlled to execute different control schemes, so that cut-off of refrigerants in different flow directions is achieved. In this way, the refrigerant amount in the shut-down indoor unit is reduced, and the energy-saving performance of the system is also improved. The invention further discloses a control device for the multi-split air conditioner, the multi-split air conditioner and a storage medium.