Patent Description:
Generally, an HVACR system can include a refrigerant circuit having a compressor, a condenser, an expansion device, and an evaporator fluidly connected. The condenser can include a subcooler portion. A plurality of condensers can be connected in parallel in the refrigerant circuit.

<CIT> describes a cooling circuit system for a motor vehicle's air conditioning, comprising a first heat exchange section to condense a gaseous coolant, a gas/liquid separating device, and a second heat exchange section to cool and condense coolant flowing from the gas/liquid separating device.

<CIT> describes a refrigeration cycle having a compact receiver which is realized by eliminating a required refrigerant capacity for making a sight glass free of bubbles with a supercooler being made to hold a buffer amount of refrigerant.

<CIT> describes a flow regulator being disposed in at least one of the outlets of a condenser to regulate the fluid flow in the condenser.

<CIT> discloses a refrigerating device with a parallel arrangement of condensers, and a receiver to receive working fluid from the condensers.

A refrigeration unit for an HVACR system is disclosed, where a refrigeration unit according to the invention is defined by appended independent claim <NUM>. The refrigeration unit inter alia includes a refrigerant circuit, including a compressor, a plurality of condensers connected in parallel and each having a condenser portion and a subcooler portion, an expansion device, and an evaporator fluidly connected. A single receiver tank is fluidly connected to an output of the condenser portions of the plurality of condensers and an input of the subcooler portions of the plurality of condensers. A restrictor induces a pressure drop in a working fluid flowing from the subcooler portion of at least one of the plurality of condensers.

A method of operating a refrigeration unit according to the invention, as defined by appended independent claim <NUM>, is disclosed. The method inter alia includes compressing a working fluid by a compressor in a refrigerant circuit. The compressed working fluid is output to a plurality of condensers connected in parallel and each having a condenser portion and a subcooler portion in the refrigerant circuit. The compressed working fluid is received by the condenser portions of the plurality of condensers. The working fluid is condensed in the condenser portions and the condensed working fluid is output to a single receiver tank disposed fluidly between the condenser portion and the subcooler portion of one of the plurality of condensers. A pressure of the working fluid output from the subcooler portion of at least one of the plurality of condensers is reduced after the working fluid is output from the subcooler portion.

References are made to the accompanying drawings that form a part of this disclosure, and which illustrate embodiments in which the systems and methods described in this specification can be practiced.

The present invention relates to a refrigeration unit as defined by appended independent claim <NUM> and to an associated method as defined by appended independent claim <NUM>.

Some refrigeration units can include a plurality of microchannel condensers fluidly connected in parallel. According to an embodiment outside the scope of the invention as claimed, a receiver tank can be included on one of the plurality of microchannel condensers. Including the receiver tank may be desirable to, for example, reduce an amount of hardware for the refrigeration unit, reduce a cost of the unit, or the like. Placing the receiver tank on one of the plurality of condenser coils can, for example, result in an imbalance of refrigerant between the plurality of condenser coils. The imbalance of refrigerant can cause refrigerant exiting the condenser coils to be at different temperatures depending upon the particular condenser coil. This can in turn result in an underperforming refrigeration unit, unpredictable or irregular operation of the refrigeration unit, or the like.

A refrigeration unit, as used in this specification, includes a machine having a refrigerant circuit and that can exchange heat with a process fluid (e.g., water, air, glycol, or the like) via a heat transfer relationship with a working fluid of the refrigerant circuit. A refrigeration unit that uses a liquid process fluid (e.g., water, glycol, or the like) may be referred to as a chiller, liquid chiller, or the like. A refrigeration unit that uses a gaseous process fluid (e.g., air or the like) may be referred to as an air conditioner, heat pump, or the like.

An air-cooled chiller, as used in this specification, includes a chiller in which a process fluid for exchanging heat with a condenser in the refrigerant circuit is air. That is, in an air-cooled chiller, the condenser may exchange heat with air, and an evaporator of the refrigerant circuit can exchange heat with a process fluid that includes, for example, water, glycol, combinations thereof, or the like.

A microchannel condenser, as used in this specification, includes a heat exchanger having a plurality of flat tubes with fins located between the flat tubes extending between a plurality of headers.

Aspects described herein can be applied to, for example, split systems, unitary equipment, rooftop equipment, or the like.

<FIG> is a schematic diagram of a refrigerant circuit <NUM>. The refrigerant circuit <NUM> generally includes a compressor <NUM>, a condenser <NUM>, an expansion device <NUM>, and an evaporator <NUM>. The compressor <NUM> can be, for example, a scroll compressor. It will be appreciated that the compressor can be other types of compressors such as, but not limited to, a screw compressor, reciprocating compressor, centrifugal compressor, or the like. The refrigerant circuit <NUM> is an example and can be modified to include additional components. For example, the refrigerant circuit <NUM> can include other components such as, but not limited to, an economizer heat exchanger, one or more flow control devices, a receiver tank, a dryer, a suction-liquid heat exchanger, or the like.

The refrigerant circuit <NUM> can generally be applied in a variety of systems used to control an environmental condition (e.g., temperature, humidity, air quality, or the like) in a space (generally referred to as a conditioned space). Examples of such systems include, but are not limited to, HVACR systems, transport refrigeration systems, or the like.

The compressor <NUM>, condenser <NUM>, expansion device <NUM>, and evaporator <NUM> are fluidly connected. The refrigerant circuit <NUM> can be configured to be a cooling system (e.g., an air conditioning system) capable of operating in a cooling mode. The refrigerant circuit <NUM> can be configured to be a heat pump system that can operate in both a cooling mode and a heating/defrost mode.

The refrigerant circuit <NUM> can operate according to generally known principles. The refrigerant circuit <NUM> can be configured to heat or cool a liquid process fluid (e.g., a heat transfer fluid or medium such as, but not limited to, water, glycol, or the like), in which case the refrigerant circuit <NUM> may be generally representative of a liquid chiller system. The refrigerant circuit <NUM> can alternatively be configured to heat or cool a gaseous process fluid (e.g., a heat transfer medium or fluid such as, but not limited to, air or the like), in which case the refrigerant circuit <NUM> may be generally representative of an air conditioner or heat pump.

In operation, the compressor <NUM> compresses a working fluid (e.g., a heat transfer fluid such as a refrigerant or the like) from a relatively lower pressure gas to a relatively higher-pressure gas. The relatively higher-pressure gas is also at a relatively higher temperature, which is discharged from the compressor <NUM> and flows through the condenser <NUM>. According to the present invention as claimed, the condenser <NUM> includes a plurality of condenser coils connected in parallel. Further, according to the present invention as claimed, the condenser <NUM> includes, in each condenser coil, a condenser portion and a subcooler portion that are fluidly connected. The working fluid flows through the condenser <NUM> and rejects heat to a process fluid (e.g., air or the like), thereby cooling the working fluid. The cooled working fluid, which is now in a liquid form, flows to the expansion device <NUM>. In an embodiment in which the condenser <NUM> includes a subcooler portion, the liquid working fluid can flow through the subcooler portion prior to flowing to the expansion device <NUM>. In the subcooler portion, the working fluid may be further subcooled. The expansion device <NUM> reduces the pressure of the working fluid. As a result, a portion of the working fluid is converted to a gaseous form. The working fluid, which is now in a mixed liquid and gaseous form flows to the evaporator <NUM>. The working fluid flows through the evaporator <NUM> and absorbs heat from a process fluid (e.g., water, glycol, air, or the like) heating the working fluid, and converting it to a gaseous form. The gaseous working fluid then returns to the compressor <NUM>. The above-described process continues while the refrigerant circuit is operating, for example, in a cooling mode (e.g., while the compressor <NUM> is enabled). It is to be noted that a refrigeration unit according to the present invention as claimed further comprises the other features mentioned in appended independent claim <NUM>.

<FIG> and <FIG> are perspective views of a refrigeration unit <NUM>, according to an embodiment, which is an embodiment of the present invention if it comprises all features of appended independent claim <NUM>. <FIG> shows a perspective view of a first end of the refrigeration unit <NUM> and <FIG> shows a perspective view of a second end, opposite the first end, of the refrigeration unit <NUM>. A portion A of <FIG> is removed to show a view into the refrigeration unit <NUM>. A portion B of <FIG> is removed to show a view into the refrigeration unit <NUM>. <FIG> is an end view of a front end of the refrigeration unit <NUM>. <FIG> will be generally described, with some reference made to specific figures throughout.

The refrigeration unit <NUM> can, for example, be an air-cooled chiller in an embodiment. In embodiments according to the claimed invention, the refrigeration unit <NUM> includes a refrigerant circuit, such as the refrigerant circuit <NUM> shown and described in accordance with <FIG> above. In an embodiment, the refrigeration unit <NUM> can operate the refrigerant circuit <NUM> to exchange heat with a process fluid (e.g., water, glycol, combinations thereof, or the like). The process fluid can, for example, be provided to one or more pieces of HVACR equipment within a building to control an environmental variable (e.g., temperature, humidity, or the like) in a conditioned space (e.g., one or more rooms) of the building.

In the illustrated embodiment, the refrigeration unit <NUM> includes a first circuit 102A and a second circuit 102B. The circuits 102A, 102B can be the same, according to an embodiment. In an embodiment, the circuits 102A, 102B can be different. It will be appreciated that the number of circuits 102A, 102B included in the refrigeration unit <NUM> may be determined by, for example, a capacity of the refrigeration unit <NUM>. That is, in an embodiment, the refrigeration unit <NUM> may include a single circuit 102A or 102B, while another embodiment can include a plurality of refrigerant circuits 102A and 102B, or more. For simplicity of the description that follows, the circuits will generally be referred to as the circuit <NUM>. It will be appreciated that the description is applicable to the circuit 102A and the circuit 102B.

The refrigeration unit <NUM> includes a frame <NUM>. The frame <NUM> provides a structure in which the circuit <NUM> and its corresponding components may be located. The circuit <NUM> generally includes a refrigerant circuit such as the refrigerant circuit <NUM> in <FIG>. In the circuit <NUM>, a plurality of condensers <NUM>, <NUM>, <NUM>, and <NUM> are connected in parallel, as required by the present invention as claimed.

The condensers <NUM> - <NUM> can be microchannel condensers. It will be appreciated that embodiments described may be applicable to condensers other than microchannel condensers, although the benefits obtained may be relatively greater for embodiments including microchannel condensers.

The plurality of condensers <NUM> - <NUM> include a condenser portion 106A, 108A, 110A, 112A and a subcooler portion 106B, 108B, 110B, 112B, as required by the present invention as claimed. The condenser portions 106A - 112A can be connected to the subcooler portions 106B - 112B via fluid lines or the like. In a refrigeration unit according to the present invention as claimed, the connections include a single receiver tank, an example of which is further described below. In operation, the condenser portions 106A - 112A can provide a liquid refrigerant to the subcooler portions 106B - 112B. In this illustrated configuration, two of the condensers <NUM>, <NUM> are disposed in a slanted arrangement, and two of the condensers <NUM>, <NUM> are disposed vertically. It will be appreciated that the arrangement can vary, for example, depending upon a capacity of the refrigeration unit <NUM>. For example, the vertically disposed condensers <NUM>, <NUM> may not be present in an embodiment. In an embodiment, the refrigeration unit <NUM> may include the circuit 102A and not the circuit 102B. In such an embodiment, the vertically disposed condensers <NUM>, <NUM> may not be present. It will be appreciated that these condenser arrangements are not intended to be limiting.

The circuit <NUM> also includes a compressor (e.g., compressor <NUM> in <FIG>), an expansion device (e.g., expansion device <NUM> in <FIG>), and an evaporator (e.g., evaporator <NUM> in <FIG>). The refrigeration unit <NUM> also includes a plurality of condenser fans <NUM>. The plurality of condenser fans <NUM> can be axial fans, in an embodiment. The condenser fans <NUM> are configured to draw a process fluid (e.g., air) across the condensers <NUM> - <NUM> to facilitate a heat exchange between the working fluid within the condensers <NUM> - <NUM> and the process fluid. In an embodiment, the condenser fans <NUM> can function according to generally known principles.

The circuit <NUM> also includes a receiver tank <NUM> (<FIG>). The receiver tank <NUM> is fluidly connected to the condenser portions 106A - 112A on an inlet side 116A of the receiver tank <NUM> and fluidly connected to the subcooler portions 106B - 112B on an outlet side 116B of the receiver tank <NUM>. That is, the receiver tank <NUM> can be disposed between the condenser portions 106A - 112A and the subcooler portions 106B - 112B. In an embodiment, this location can be selected to ensure that the working fluid is a saturated liquid when entering the subcooler portions 106B - 112B.

A single receiver tank <NUM> is included in the circuit <NUM>. In an embodiment, the refrigeration unit <NUM> can include two receiver tanks <NUM> - one receiver tank <NUM> fluidly connected to the circuit 102A and another receiver tank <NUM> fluidly connected to the circuit 102B. The receiver tank <NUM> can provide additional volume for the working fluid (e.g., refrigerant or the like). This additional volume can, for example, enable operation at a variety of operating conditions for the refrigeration unit <NUM>. Including a single receiver tank <NUM> for the circuit <NUM> can, for example, reduce an amount of materials for manufacturing the refrigeration unit <NUM> relative to a configuration that includes a plurality of receiver tanks. In an embodiment, reducing the amount of materials can, for example, reduce a cost of the refrigeration unit <NUM>.

Including a single receiver tank <NUM> instead of multiple receiver tanks can cause a maldistribution of the working fluid throughout the plurality of condensers <NUM> - <NUM>. This maldistribution can, for example, lead to unpredictable operating results. To resolve this maldistribution of the working fluid, and in accordance with the present invention as claimed, at least one of the fluid lines leaving the subcooler portions 106B - 112B includes a restrictor <NUM>.

The restrictor <NUM> causes a pressure drop in the working fluid. The pressure drop can assist with properly distributing the working fluid throughout the refrigerant circuit of the circuit <NUM>. The restrictor <NUM> can be a device as shown and described in <FIG>, according to an embodiment. In an embodiment, the restrictor <NUM> can be a modification in diameter of the fluid lines of the circuit <NUM>. For example, in an embodiment a diameter of the fluid lines could be modified to induce a pressure drop. In an embodiment, a length of the fluid lines could be modified to induce a pressure drop. In an embodiment, a turn can be included in the fluid lines to induce a pressure drop. The restrictor <NUM> can reduce a flow of the working fluid to two of the condenser coils <NUM> - <NUM>. In the illustrated embodiment, the condensers <NUM> and <NUM> may be restricted. By restricting the flow of the working fluid to the two condenser coils, the working fluid may be balanced among the condensers <NUM> - <NUM>. The restrictor <NUM> is placed in a fluid line <NUM> having working fluid flowing therethrough in which the working fluid is a subcooled liquid. That is, the restrictor <NUM> can be placed downstream of the subcooler portions 106B - 112B of the circuit <NUM> (e.g., in a location between an outlet of the subcooler portions 106B - 112B and the expansion device <NUM>). The placement and pressure drop selected can be based on a pressure drop resulting from the working fluid flowing through the receiver tank <NUM>.

The particular location of the receiver tank <NUM> and the restrictor <NUM> can be, for example, based on a location at which fluid lines connecting the condensers <NUM> - <NUM> in parallel are merged. In <FIG> and <FIG>, fluid line <NUM> represents a location at which the working fluid from condensers <NUM>, <NUM> is merged with the working fluid from the condensers <NUM>, <NUM>. The restrictor <NUM> can be placed in fluid line <NUM> at a location that is downstream of the merging of the working fluid between the condensers <NUM>, <NUM> and the condensers <NUM>, <NUM>. In an embodiment, the fluid line <NUM> can represent a location for the restrictor <NUM> which provides a relatively greater redistribution of the working fluid, and accordingly, can provide a relatively greater advantage relative to other placements for the restrictor <NUM>. It will be appreciated that the restrictor <NUM> can be placed in other fluid lines, but the redistribution effect may be relatively less than the redistribution effect when the restrictor <NUM> is placed in the fluid line <NUM>. In an embodiment, a plurality of restrictors <NUM> can be included. In operation, the restrictor <NUM> can result in a uniform or substantially uniform temperature of the working fluid leaving the subcooler portions 106B - 112B of the circuit <NUM>.

<FIG> show various views of an embodiment of the restrictor <NUM>. <FIG> shows a front view, <FIG> shows a sectional view, and <FIG> shows a detailed partial view. The figures will be generally referred to, with some reference being made to specific figures.

In the illustrated embodiment, the restrictor <NUM> includes a plate <NUM> having an aperture <NUM> therethrough. The plate <NUM> and the aperture <NUM> are substantially circular subject to, for example, manufacturing tolerances or the like. In an embodiment, an outer surface 120A of the plate <NUM> can be secured to an inner surface of a fluid line. In an embodiment, the plate <NUM> can be similar to a washer. The aperture <NUM> is generally smaller than a fluid line in which the restrictor <NUM> is placed. As a result, the plate <NUM> acts as an orifice and increases a pressure drop of the working fluid flowing therethrough. The plate <NUM> includes an outer diameter D1 and an inner diameter D2. In an embodiment, the outer diameter D1 can be selected based on a fluid line in which the restrictor <NUM> is placed. For example, in an embodiment, the outer diameter D1 of the restrictor <NUM> can be can be selected to be approaching, but less than, an inner diameter of the fluid line. In an embodiment, the inner diameter D2 can be selected to control a pressure drop of the working fluid flowing therethrough. In an embodiment, the inner diameter D2 can be from about <NUM> percent to about <NUM> percent of the outer diameter D <NUM>. In an embodiment, the inner diameter D2 can be from about <NUM> percent to about <NUM> percent of the outer diameter D1. In an embodiment, the inner diameter D2 can be from about <NUM> percent to about <NUM> percent of the outer diameter D1. It will be appreciated that these percentages are examples and can vary beyond the stated ranges.

The plate <NUM> can have a portion of material 120B that extends between the outer diameter D1 and the inner diameter D2. The portion of material 120B can have a length L. It will be appreciated that the length L can be defined as the outer diameter D1 minus the inner diameter D2. In an embodiment, the plate <NUM> can have an edge <NUM> of the material 120B at the aperture <NUM> that is slightly rounded. This can, for example, cause a smoother transition of the flow of the working fluid flowing through the aperture <NUM>.

<FIG> is a perspective view of another refrigeration unit <NUM> for an HVACR system, according to an embodiment. Features of <FIG> can be the same as or similar to features of <FIG> described above.

The refrigeration unit <NUM> can, for example, be a rooftop air conditioning unit, according to an embodiment. The refrigeration unit <NUM> includes a refrigerant circuit such as the refrigerant circuit <NUM> shown and described in accordance with <FIG> above. In an embodiment, the refrigeration unit <NUM> can operate the refrigerant circuit <NUM> to exchange heat with a process fluid (e.g., air or the like). The process fluid can, for example, be provided to a building to control an environmental variable (e.g., temperature, humidity, or the like) in a conditioned space (e.g., one or more rooms) of the building.

In the illustrated embodiment, the refrigeration unit <NUM> includes a first circuit 202A and a second circuit 202B. The circuits 202A, 202B can be the same, according to an embodiment. In an embodiment, the circuits 202A, 202B can be different. It will be appreciated that the number of circuits 202A, 202B included in the refrigeration unit <NUM> may be determined by, for example, a capacity of the refrigeration unit <NUM>. That is, in an embodiment, the refrigeration unit <NUM> may include a single circuit 202A or 202B, while another embodiment can include a plurality of refrigerant circuits 202A and 202B, or more. For simplicity of the description that follows, the circuits will generally be referred to as the circuit <NUM>. It will be appreciated that the description is applicable to the circuit 202A and the circuit 202B.

The refrigeration unit <NUM> includes a condenser and compressor section 206A and an evaporator and fan section 206B. In operation, the condenser and compressor section 206A includes one or more compressors (e.g., compressor <NUM> in <FIG>) and a plurality of condensers connected in parallel (e.g., condensers <NUM> - <NUM> as in <FIG>) for the circuit <NUM>. The refrigeration unit <NUM> includes a single receiver (e.g., the receiver tank <NUM> in <FIG>) and a restrictor (e.g., the restrictor <NUM> in <FIG>), in accordance with the invention as claimed in appended independent claim <NUM>. The circuit <NUM> includes a restrictor (e.g., restrictor <NUM> in <FIG>) and an evaporator (e.g., evaporator <NUM> in <FIG>) in the evaporator and fan section 206B. The evaporator and fan section 206B can exchange heat between the refrigerant in the circuit <NUM> and a gaseous process fluid (e.g., air or the like) to provide air to the conditioned space of the building.

In embodiments in accordance with the claimed invention, the refrigeration unit <NUM> comprises all of the features of appended independent claim <NUM>.

The terminology used in this specification is intended to describe particular embodiments and is not intended to be limiting. The terms "a," "an," and "the" include the plural forms as well, unless clearly indicated otherwise. The terms "comprises" and/or "comprising," when used in this specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components.

Claim 1:
A refrigeration unit (<NUM>, <NUM>) for a heating, ventilation, air conditioning, and refrigeration system, comprising:
a refrigerant circuit (102A, 102B), including:
a compressor (<NUM>), a plurality of condensers (<NUM>-<NUM>) connected in parallel and each having a condenser portion (106A-112A) and a subcooler portion (106B-112B), an expansion device (<NUM>), and an evaporator (<NUM>) fluidly connected;
a single receiver tank (<NUM>) that is fluidly connected to an output of the condenser portions (106A-112A) of the plurality of condensers (<NUM>-<NUM>) and an input of the subcooler portions (106B-112B) of the plurality of condensers (<NUM>-<NUM>); and
a restrictor (<NUM>) to induce a pressure drop in a working fluid flowing from the subcooler portion (106B-112B) of at least one of the plurality of condensers (<NUM>-<NUM>).