Refrigeration Heat Pump Unit

This application claims benefit of Chinese Patent Application No. 202410390137.6, filed Apr. 1, 2024, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in their entirety are herein incorporated by reference.

This application relates to the technical field of refrigeration heat pumps, in particular to a refrigeration heat pump unit with a centrifugal compressor.

This application aims to provide a refrigeration heat pump unit to at least solve or alleviate some of the problems existing in the prior art.

This application provides a refrigeration heat pump unit, wherein the refrigeration heat pump unit comprises a refrigerant circuit formed by a centrifugal compressor, a condenser, a throttling device, and an evaporator, wherein the centrifugal compressor includes a housing; a first motor disposed inside the housing; a second motor disposed inside the housing and disposed opposite to the first motor; and the refrigeration heat pump unit further comprises a controller, the controller being configured to turn on the first motor and turn off the second motor in response to a first working condition, turn off the first motor and turn on the second motor in response to a second working condition, and turn on the first motor and the second motor in response to a third working condition.

In one or more embodiments, the centrifugal compressor further includes a first compression chamber disposed at an end portion of the housing close to the first motor and including a first suction port and a first discharge port, the first suction port communicating with an outlet of the evaporator; a second compression chamber disposed at an end portion of the housing close to the second motor and including a second suction port and a second discharge port, the second suction port communicating with the first discharge port, and the second discharge port communicating with an inlet of the condenser; a first impeller disposed inside the first compression chamber and driven by the first motor; and a second impeller disposed inside the second compression chamber and driven by the second motor.

In one or more embodiments, there are at least two first impellers and/or at least two second impellers.

In one or more embodiments, a rotation speed of the first motor and a rotation speed of the second motor are able to be controlled independently of each other.

In one or more embodiments, the first motor and the second motor are coaxially disposed, the first impeller is directly fixed to an output shaft of the first motor, and the second impeller is directly fixed to an output shaft of the second motor.

In one or more embodiments, the centrifugal compressor further includes a first bypass flow path, a second bypass flow path, a first switching device, and a second switching device. The first bypass flow path is located between the first suction port and the first discharge port and bypasses the first impeller. The second bypass flow path is located between the second suction port and the second discharge port and bypasses the second impeller. The first switching device selectively communicates with the first bypass flow path or communicates with a compression flow path, the compression flow path being located between the first suction port and the first discharge port and passing through the first impeller. The second switching device selectively communicates with the second bypass flow path or communicates with a compression flow path, the compression flow path being located between the second suction port and the second discharge port and passing through the second impeller.

In one or more embodiments, the controller is configured to: turn on the first motor and turn off the second motor in response to the first working condition, causing the first switching device to selectively communicate with the compression flow path, the compression flow path being located between the first suction port and the first discharge port and passing through the first impeller, and causing the second switching device to selectively communicate with the second bypass flow path; turn off the first motor and turn on the second motor in response to the second working condition, causing the first switching device to selectively communicate with the first bypass flow path, and causing the second switching device to selectively communicate with the compression flow path, the compression flow path being located between the second suction port and the second discharge port and passing through the second impeller; and turn on the first motor and the second motor in response to the third working condition, causing the first switching device to selectively communicate with the compression flow path, the compression flow path being located between the first suction port and the first discharge port and passing through the first impeller, and causing the second switching device to selectively communicate with the compression flow path, the compression flow path being located between the second suction port and the second discharge port and passing through the second impeller.

In one or more embodiments, the first switching device includes a first bypass valve and a first variable guide vane, the first bypass valve being disposed in the first bypass flow path, and the first variable guide vane being disposed corresponding to the first suction port. The second switching device includes a second bypass valve and a second variable guide vane, the second bypass valve is disposed in the second bypass flow path, and the second variable guide vane is disposed corresponding to the second suction port.

In one or more embodiments, the first bypass valve is a one-way valve that allows unidirectional flow from the first suction port to the first discharge port, and the second bypass valve is a one-way valve that allows unidirectional flow from the second suction port to the second discharge port.

In one or more embodiments, the controller is configured to: turn on the first motor and turn off the second motor, and open the first variable guide vane and close the second variable guide vane in response to the first working condition; turn off the first motor and turn on the second motor, and close the first variable guide vane and open the second variable guide vane in response to the second working condition; and turn on the first motor and the second motor, and open the first variable guide vane and the second variable guide vane in response to the third working condition.

It should be noted that working principles, features, advantages, and the like of a refrigeration heat pump unit according to this application will be explained below by way of embodiments. However, it should be understood that all descriptions are only given for exemplification and therefore these embodiments should not be understood as forming any limitation on this application.

In addition, for any single technical feature described or implicit in the embodiments mentioned herein, or any single technical feature illustrated or implicit in the drawings, this application still allows any combination or deletion between these technical features (or their equivalents) without any technical obstacles, thereby obtaining more other embodiments of this application that may not be directly mentioned herein.

A centrifugal refrigeration heat pump unit generally requires high compression ratio, and therefore requires more than three stages of impellers to meet a high compression ratio requirement. In existing configurations, a multi-stage centrifugal compressor for a centrifugal refrigeration heat pump unit is provided, in which a plurality of impellers are mounted on a rotating shaft, such a structure allows a plurality of impellers to operate at the same rotation speed, so that it is difficult to achieve a high-efficiency design in double-working condition (cold water preparation and hot water preparation) applications.

The refrigeration heat pump unit of the present disclosure provides a high-efficiency design capable of double-working condition (cold water preparation and hot water preparation) applications.

As shown in, a refrigeration heat pump unitin some embodiments includes a refrigerant circuit formed by a centrifugal compressor, a condenser, a throttling device (not shown), and an evaporator. The centrifugal compressorincludes a housing, a first motor, a second motor, a first compression chamber, a second compression chamber, a first impeller, a second impeller, and a controller.

The first motorand the second motorare both disposed inside the housing, and the second motoris disposed opposite to the first motor. The first motorand the second motorare both motors with independent output shafts and bearings. By allowing the first motorand the second motorto share one housing, a structure of the centrifugal compressormay be designed in a more compact form, which facilitates cost reduction in manufacturing the centrifugal compressor. By disposing such that the first motorand the second motorare opposite to each other, that is, an output end of the first motorand an output end of the second motorface in two substantially opposite directions, respectively, a structure layout of the centrifugal compressorcan be more reasonable, which also facilitates pipe connection in the refrigeration heat pump unit.

The first compression chamberis disposed at an end portion of the housingclose to the first motor, and includes a first suction portand a first discharge port, the first suction portcommunicating with an outlet of the evaporator. The second compression chamberis disposed at an end portion of the housingclose to the second motorand includes a second suction portand a second discharge port, the second suction portcommunicating with the first discharge port, and the second discharge portcommunicating with an inlet of the condenser. The first impelleris disposed inside the first compression chamberand is driven by the first motor, and the second impelleris disposed inside the second compression chamberand is driven by the second motor.

The controlleris configured to turn on the first motorand turn off the second motorin response to a first working condition, turn off the first motorand turn on the second motorin response to a second working condition, and turn on the first motorand the second motorin response to a third working condition. That is, the first motorand the second motormay be alternatively or simultaneously turned on according to the working condition. In this manner, on one hand, the normalized part load value (NPLV) of the refrigeration heat pump unitis improved, and on the other hand, the operation reliability of the refrigeration heat pump unitis improved through a redundant design.

In addition, it may be understood that in a multi-stage centrifugal compressor, blades of different levels of impellers may differ in geometry, size, number, and the like. Specifically, referring to, levels of a first impeller, a first impeller, a second impeller, and a second impellerare gradually increased in this order, so that designs between the respective impellers are generally different. Since designs of the first impellerand the second impellerare different, the centrifugal compressorhas different processing effects on a refrigerant between a case where the first motoris separately turned on to drive the first impellerand a case where the second motoris separately turned on to drive the second impeller, so that the centrifugal compressoris allowed to operate efficiently in a larger range of working conditions.

In some embodiments, as shown in, a first variable guide vaneis disposed upstream of the first impeller, that is, at a position corresponding to the first suction port, and a second variable guide vaneis disposed upstream of the second impeller, that is, at a position corresponding to the second suction port. By adjusting opening angles of the first variable guide vaneand the second variable guide vane, flow rates of the refrigerant entering the first compression chamberand the second compression chambercan be adjusted in response to a change of a load.

In some embodiments, other structures that may be used to adjust a flow rate of a refrigerant entering a compression chamber may be used instead of the first variable guide vaneand the second variable guide vanein some embodiments.

In some embodiments, as shown in, there are two first impellers, and there are two second impellers.

In some embodiments, as shown in, there are two first impellersand one second impeller.

In some embodiments, as shown in, there are one first impellerand two second impellers.

In some embodiments, as shown in, the first motorand the second motorare coaxially disposed, the first impelleris directly fixed to an output shaft of the first motor, and the second impelleris directly fixed to an output shaft of the second motor. By directly fixing the first impellerand the second impellerto the output shafts of the first motorand the second motor, respectively, a lift of the centrifugal compressorcan be increased under a working condition requiring a high compression ratio, so as to meet the requirements of the specific working condition.

In some embodiments, the output shaft of the first motorand the output shaft of the second motormay be staggered from each other to match arrangement of a unit.

In some embodiments, the output shaft of the first motoris connected to a rotating shaft provided with the first impellerthrough a transmission mechanism, thereby driving the first impeller. Similarly, the output shaft of the second motoris connected to a rotating shaft provided with the second impellerthrough a transmission mechanism, thereby driving the second impeller. By disposing the transmission mechanism, a rotation speed of the impeller can be adjusted without changing a motor frequency.

In some embodiments, a rotation speed of the first motorand a rotation speed of the second motorare able to be controlled independently of each other. In this manner, it is advantageous to allow both the first motorand the second motorto work at a more suitable rotation speed, thereby more flexibly meeting requirements under more working conditions.

In some embodiments, according to an application scenario of a refrigeration heat pump system, the rotation speed of the first motorand the rotation speed of the second motormay be controlled in a linkage manner, thereby simplifying operation of the controllerto ensure a stable operation of the unit.

Operations of a refrigeration heat pump system in some embodiments under working conditions will be described below with reference to.

Under the first working condition, which may be, for example, a high-load low-lift working condition for preparing cold water, the controllerturns on the first motorand turns off the second motor. After exiting from the outlet of the evaporator, the refrigerant first enters the first compression chamberthrough the first suction portand is compressed and accelerated by the first impeller, then exits the first compression chamberthrough the first discharge port, then enters the condenserfor heat exchange after sequentially passing through the connecting pipeand the second compression chamber, and then exits the condenser, and enters the evaporatorafter being throttled for heat exchange to absorb heat to prepare the cold water. Since the second motoris in a turned-off state, the refrigerant is not compressed and accelerated after entering the second compression chamber, but simply flows through the second compression chamber, in other words, the second compression chamberonly functions as a passage.

Under the second working condition, which may be, for example, a low-load low-lift working condition for preparing cold water, the controllerturns off the first motorand turns on the second motor. After exiting from the outlet of the evaporator, the refrigerant first sequentially passes through the first compression chamberand the connecting pipe, then enters the second compression chamberthrough the second suction portand is compressed and accelerated by the second impeller, then exits the second compression chamberthrough the second discharge portand enters the condenserfor heat exchange, and then exits the condenser, and enters the evaporatorafter being throttled for heat exchange to absorb heat to prepare the cold water. Since the first motoris in a turned-off state, the refrigerant is not compressed and accelerated after entering the first compression chamber, but simply flows through the first compression chamber, in other words, the first compression chamberonly functions as a passage.

Under the third working condition, which may be, for example, a high-lift working condition for preparing hot water, the controllerturns on the first motorand the second motor. The refrigerant first enters the first compression chamberthrough the first suction portand is compressed and accelerated by the first impeller, passes through the connecting pipe, then enters the second compression chamberthrough the second suction portand is compressed and accelerated by the second impeller, then exits the second compression chamberthrough the second discharge portand enters the condenserfor heat exchange to prepare the hot water, and then exits the condenser, and enters the evaporatorafter being throttled for heat exchange.

It should be noted that the above descriptions of the load, the lift, and the application corresponding to the first working condition, the second working condition, and the third working condition are merely examples. It can be understood that when to turn on the first motor, when to turn on the second motor, and when to turn on the first motorand the second motorsimultaneously can be set according to an application scenario and an operating condition of the unit. Whether to turn on the first motoror the second motoris not directly related to high or low of the load, high or low of the lift, preparation of hot water or cold water. For example, when the first motorneeds to be serviced, it is directly selected to turn on the second motorto ensure operation of the unit.

In some embodiments, as shown in, the centrifugal compressorfurther includes a first bypass flow path, a second bypass flow path, a first switching device, and a second switching device. The first bypass flow pathis located between the first suction portand the first discharge portand bypasses the first impeller. The second bypass flow pathis located between the second suction portand the second discharge portand bypasses the second impeller. The first switching deviceselectively communicates with the first bypass flow pathor communicates with a compression flow path, the compression flow path being located between the first suction portand the first discharge portand passing through the first impeller. The second switching deviceselectively communicates with the second bypass flow pathor communicates with a compression flow path, the compression flow path being located between the second suction portand the second discharge portand passing through the second impeller.

In some embodiments, as shown in, the first switching deviceincludes a first bypass valveand a first variable guide vane, the first bypass valvebeing disposed in the first bypass flow path, and the first variable guide vanebeing disposed corresponding to the first suction port. The second switching deviceincludes a second bypass valveand a second variable guide vane, the second bypass valveis disposed in the second bypass flow path, and the second variable guide vaneis disposed corresponding to the second suction port.

In some embodiments, the controlleris configured to: turn on the first motorand turn off the second motorin response to the first working condition, causing the first switching deviceto selectively communicate with the compression flow path, the compression flow path being located between the first suction portand the first discharge portand passing through the first impeller, and causing the second switching deviceto selectively communicate with the second bypass flow path; turn off the first motorand turn on the second motorin response to the second working condition, causing the first switching deviceto selectively communicate with the first bypass flow path, and causing the second switching deviceto selectively communicate with the compression flow path, the compression flow path being located between the second suction portand the second discharge portand passing through the second impeller; and turn on the first motorand the second motorin response to the third working condition, causing the first switching deviceto selectively communicate with the compression flow path, the compression flow path being located between the first suction portand the first discharge portand passing through the first impeller, and causing the second switching deviceto selectively communicate with the compression flow path, the compression flow path being located between the second suction portand the second discharge portand passing through the second impeller.

In some embodiments, when the refrigerant does not need to be compressed and accelerated by the first impeller, the refrigerant is avoided to pass through the first impeller, but directly reaches a position of the first discharge portthrough the first bypass flow path, thereby avoiding a problem of refrigerant flow loss caused by factors such as collision with the first impeller. Similarly, when the refrigerant does not need to be compressed and accelerated by the second impeller, the refrigerant is avoided to pass through the second impeller, but directly reaches a position of the second discharge portthrough the second bypass flow path, thereby avoiding a problem of refrigerant flow loss caused by factors such as collision with the second impeller.

In some embodiments, as shown in, the first bypass valveis a one-way valvethat allows unidirectional flow from the first suction portto the first discharge port, and the second bypass valveis a one-way valvethat allows unidirectional flow from the second suction portto the second discharge port. That is, the first bypass valveand the second bypass valvecan only that allows unidirectional flow (along pointing of arrow) from an impeller inlet side to an impeller outlet side, and thus a backflow of the refrigerant on a relatively high-pressure side due to the disposition of the first bypass flow pathor the second bypass flow pathcan be prevented. In addition, since the first bypass valveand the second bypass valveare both one-way valves, the first bypass valveand the second bypass valvecan automatically open and close in response to a state change of the first variable guide vaneand the second variable guide vane, instead of being controlled by way of electric control, thereby simplifying a control mode for the first bypass valveand the second bypass valve, and facilitating improvement of the operation reliability of the unit.

In some embodiments, the first bypass valveand the second bypass valvemay both be electrically controlled valves.

Operations of the refrigeration heat pump system in some embodiments will be described below with reference to.

Under the first working condition, the controllerturns on the first motorand turns off the second motor, and opens the first variable guide vaneand closes the second variable guide vane. In this case, a pressure at the first discharge portis higher than a pressure at the first suction port, so that the one-way valveremains in a closed state. Since the second variable guide vaneis in a closed state, a high-pressure refrigerant can impact the one-way valve, and then cause the one-way valveto be conducted. A dotted arrow inshows a flow direction of the refrigerant, and as shown in, after exiting from the outlet of the evaporator, the refrigerant first enters the first compression chamberthrough the first suction portand is compressed and accelerated by the first impeller, then exits the first compression chamberthrough the first discharge port, then enters the condenserfor heat exchange after sequentially passing through the connecting pipeand the one-way valve, and then exits the condenser, and enters the evaporatorafter being throttled for heat exchange.

Under the second working condition, the controllerturns off the first motorand turns on the second motor, and closes the first variable guide vaneand opens the second variable guide vane. In this case, a pressure at the second suction portdrops, and the one-way valveis automatically conducted. A pressure at the second discharge portis higher than the pressure at the second suction port, so that the one-way valveremains in the closed state. A dotted arrow inshows a flow direction of the refrigerant, and as shown in, after exiting from the outlet of the evaporator, the refrigerant first sequentially passes through the first bypass flow pathand the connecting pipe, then enters the second compression chamberthrough the second suction portand is compressed and accelerated by the second impeller, then exits the second compression chamberthrough the second discharge portand enters the condenserfor heat exchange, and then exits the condenser, and enters the evaporatorafter being throttled for heat exchange.

Under the third working condition, the controllerturns on the first motorand the second motor, and opens the first variable guide vaneand the second variable guide vane. In this case, the pressure at the first discharge portis higher than the pressure at the first suction port, so that the one-way valveremains in the closed state. The pressure at the second discharge portis higher than the pressure at the second suction port, so that the one-way valveremains in the closed state. A dotted arrow inshows a flow direction of the refrigerant, and as shown in, the refrigerant first enters the first compression chamberthrough the first suction portand is compressed and accelerated by the first impeller, then enters the second compression chamberthrough the second suction portafter passing through the connecting pipeand is compressed and accelerated by the second impeller, then exits the second compression chamberthrough the second discharge portand enters the condenserfor heat exchange, and then exits the condenser, and enters the evaporatorafter being throttled for heat exchange.

The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of this application shall be included in the protection scope of this application.