CN114484946A

CN114484946A - Chiller system with series flow evaporator

Info

Publication number: CN114484946A
Application number: CN202011172089.1A
Authority: CN
Inventors: 杨耀; 高兴顺
Original assignee: Johnson Controls Building Efficiency Technology Wuxi Co Ltd; Johnson Controls Technology Co
Current assignee: Johnson Controls Building Efficiency Technology Wuxi Co Ltd; Johnson Controls Technology Co
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2022-05-13

Abstract

A heating, ventilation, air conditioning and/or refrigeration (HVAC & R) system includes a first refrigerant circuit having a first evaporator configured to place a first refrigerant in heat exchange relationship with a conditioning fluid, wherein the first evaporator includes a first set of first tubes and a second set of first tubes configured to direct the conditioning fluid through the first evaporator. The HVAC & R system also includes a second refrigerant circuit having a second evaporator configured to place a second refrigerant in heat exchange relationship with the conditioning fluid, wherein the second evaporator includes a first set of second tubes and a second set of second tubes configured to direct the conditioning fluid through the second evaporator. The HVAC & R system further includes a conditioning fluid circuit configured to continuously circulate the conditioning fluid through the first set of first tubes, the second set of first tubes, the first set of second tubes, and the second set of second tubes.

Description

Chiller system with series flow evaporator

Background

This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. It should be noted, therefore, that these statements are to be read in this light, and not as admissions of prior art.

A chiller system or vapor compression system utilizes a working fluid (e.g., a refrigerant) that changes phase between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures within components of the chiller system. The chiller system may place the working fluid in a heat exchange relationship with a conditioning fluid (e.g., water) and may deliver the conditioning fluid to a conditioning plant and/or a conditioned environment served by the chiller system. In such applications, the conditioning fluid may be passed through downstream equipment (e.g., air handlers) to condition other fluids (e.g., air in a building).

A conventional chiller system includes a refrigerant circuit including, for example, a compressor, a condenser, and an evaporator. In some cases, a chiller system may include multiple refrigerant circuits, and each refrigerant circuit includes a respective compressor, condenser, and evaporator. The multiple refrigerant circuits may be operated individually or in conjunction with one another to condition a conditioning fluid for delivery to a conditioning apparatus. Unfortunately, existing chiller systems having multiple refrigerant circuits may be arranged in configurations that limit the performance and/or efficiency of the chiller system.

Disclosure of Invention

The following sets forth a summary of certain embodiments disclosed herein. It should be noted that these aspects are presented merely to provide the reader with a brief summary of these particular embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, the present disclosure may encompass a variety of aspects that may not be set forth below.

In an embodiment, a heating, ventilation, air conditioning and/or refrigeration (HVAC & R) system includes a first refrigerant circuit having a first evaporator configured to place a first refrigerant in heat exchange relationship with a conditioning fluid, wherein the first evaporator includes a first set of first tubes and a second set of first tubes configured to direct the conditioning fluid through the first evaporator. The HVAC & R system also includes a second refrigerant circuit having a second evaporator configured to place a second refrigerant in heat exchange relationship with the conditioning fluid, wherein the second evaporator includes a first set of second tubes and a second set of second tubes configured to direct the conditioning fluid through the second evaporator. The HVAC & R system further includes a conditioning fluid circuit configured to continuously circulate the conditioning fluid through the first set of first tubes, the second set of first tubes, the first set of second tubes, and the second set of second tubes.

In an embodiment, a heating, ventilation, air conditioning and/or refrigeration (HVAC & R) system includes: a first evaporator having a first lower tube bundle and a first upper tube bundle, wherein the first lower tube bundle and the first upper tube bundle are each configured to place a conditioning fluid in heat exchange relationship with a first refrigerant; and a second evaporator having a second lower tube bundle and a second upper tube bundle, wherein the second lower tube bundle and the second upper tube bundle are each configured to place the conditioning fluid in heat exchange relationship with a second refrigerant. The HVAC & R system further comprises: a conduit fluidly extending between the first evaporator and the second evaporator and fluidly coupling the first lower tube bundle and the second upper tube bundle; and a conditioning fluid circuit configured to circulate the conditioning fluid continuously through the second lower tube bundle, the second upper tube bundle, the conduit, the first lower tube bundle, and the first upper tube bundle.

In an embodiment, a chiller system includes a first refrigerant circuit having a first evaporator configured to place a first refrigerant in heat exchange relationship with a conditioning fluid, wherein the first evaporator includes a first plurality of first tubes and a second plurality of first tubes configured to direct the conditioning fluid through the first evaporator, the first plurality of first tubes defining a lower passage of the first evaporator, and the second plurality of first tubes defining an upper passage of the first evaporator. The chiller system further includes a second refrigerant circuit having a second evaporator configured to place a second refrigerant in heat exchange relationship with a conditioning fluid, wherein the second evaporator includes a first plurality of second tubes and a second plurality of second tubes configured to direct the conditioning fluid through the second evaporator, wherein the first plurality of second tubes define a lower passage of the second evaporator and the second plurality of second tubes define an upper passage of the second evaporator. The cooler system further includes a conduit fluidly coupled between the second plurality of second tubes and the first plurality of first tubes.

Drawings

Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

FIG. 1 is a perspective view of a building that may utilize an embodiment of a heating, ventilation, air conditioning and/or refrigeration (HVAC & R) system in a commercial environment in accordance with an aspect of the present disclosure;

FIG. 2 is a schematic view of an embodiment of a vapor compression system according to an aspect of the present disclosure;

FIG. 3 is a schematic diagram of an embodiment of an HVAC & R system having multiple refrigerant circuits illustrating evaporators in the multiple refrigerant circuits in a series flow arrangement in accordance with an aspect of the present disclosure;

FIG. 4 is a side view of an embodiment of evaporators in multiple refrigerant circuits in a series flow arrangement, illustrating the evaporators in an aligned configuration, according to an aspect of the present disclosure;

FIG. 5 is a top plan view of an embodiment of evaporators in multiple refrigerant circuits in a series flow arrangement, illustrating the evaporators in a side-by-side configuration, in accordance with an aspect of the present disclosure;

FIG. 6 is an axial view of an embodiment of evaporators in multiple refrigerant circuits in a series flow arrangement, illustrating the evaporators in a side-by-side configuration, according to an aspect of the present disclosure; and

fig. 7 is a schematic diagram of an embodiment of an HVAC & R system having multiple refrigerant circuits, illustrating a control system and evaporators in the multiple refrigerant circuits in a series flow arrangement, according to an aspect of the present disclosure.

Detailed Description

One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present disclosure, the articles "a," "an," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be noted that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

Embodiments of the present disclosure relate to heating, ventilation, air conditioning and/or refrigeration (HVAC & R) systems, such as chiller systems. HVAC & R systems may include a vapor compression system through which refrigerant is directed to heat and/or cool a conditioning fluid. As an example, a vapor compression system may include a compressor configured to pressurize refrigerant and direct the pressurized refrigerant to a condenser configured to cool the pressurized refrigerant. An evaporator of the vapor compression system may receive the cooled refrigerant and may place the cooled refrigerant in heat exchange relationship with the conditioning fluid to absorb thermal energy or heat from the conditioning fluid to cool the conditioning fluid. The cooled conditioned fluid may then be directed to conditioning equipment (such as air handlers and/or terminal units) for conditioning air supplied to a building or other conditioned space.

In some embodiments, the vapor compression system may include a plurality of refrigerant circuits, and each refrigerant circuit includes a respective compressor, condenser, and evaporator. For example, evaporators in multiple refrigerant circuits may cooperatively cool a conditioning fluid used with a conditioning apparatus. In other words, the evaporators may be operated to cool a common flow of conditioned fluid. Some evaporators are configured to cool a conditioning fluid via tubes forming a flow path defining a plurality of channels through the evaporator. For example, in a dual pass evaporator, the conditioning fluid may be directed through a first tube bank of the evaporator in a first direction, and the flow of the conditioning fluid may be reversed (e.g., via a waterbox of the evaporator) and then directed through a second tube bank of the evaporator in a second direction opposite the first direction.

Existing systems having multiple (e.g., two) refrigerant circuits typically include evaporators packaged together and configured to cool a conditioning fluid by alternately directing the conditioning fluid between the evaporators. For example, existing systems may direct a conditioning fluid sequentially through a first (e.g., lower) tube bundle or channel of a first evaporator and then through a first (e.g., lower) tube bundle or channel of a second evaporator. Thereafter, the flow direction of the conditioning fluid may be reversed, and the conditioning fluid may be sequentially directed through a second (e.g., upper) tube bundle or channel of the second evaporator, and then through a second (e.g., upper) tube bundle or channel of the first evaporator. Unfortunately, the configuration of existing systems may result in a higher than desired approach temperature of the evaporator, which may result in reduced heat transfer between the refrigerant and the conditioning fluid, increased energy consumption (e.g., of the compressors in the multiple refrigerant circuits) and/or reduced capacity of the multiple refrigerant circuits.

Accordingly, there is presently recognized a need to improve the operation of HVAC systems having multiple refrigerant circuits by reducing the evaporator approach temperature(s) of the HVAC & R system. In this manner, the refrigerant pressure in the evaporator may be increased, which may reduce the lift of the HVAC & R system (e.g., the difference between the condenser refrigerant pressure and the evaporator refrigerant pressure), and thus reduce the work done by the compressor of the HVAC & R system. Accordingly, the energy consumption of the HVAC & R system is reduced. To reduce evaporator approach temperatures, the evaporators in the multiple refrigerant circuits may be arranged in a series flow arrangement. As used herein, "series flow" refers to the passage of conditioning fluid first through one evaporator of the HVAC & R system, and then through the passage of the other evaporator of the HVAC & R system. In other words, the conditioning fluid received from the conditioning apparatus first passes through the first evaporator of the HVAC & R system, then passes through the second evaporator of the HVAC & R system, and then is directed back to the conditioning apparatus. As discussed in detail below, arranging the evaporators in multiple refrigerant circuit systems in series achieves the efficiency gains and cost reductions associated with HVAC & R systems.

Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an application for a heating, ventilation, air conditioning and/or refrigeration (HVAC & R) system. Generally, such systems can be applied in a range of environments both within the HVAC & R field and outside of that field. HVAC & R systems may provide cooling for data centers, electrical devices, freezers, chillers, or other environments by vapor compression refrigeration, absorption refrigeration, or thermoelectric cooling. However, in currently contemplated applications, HVAC & R systems may be used in residential, commercial, light industrial, and any other application for heating or cooling a volume or enclosed space such as a home, building, structure, and the like. Additionally, HVAC & R systems may be used in industrial applications, where appropriate for basic cooling and heating of various fluids.

The illustrated embodiment shows an HVAC & R system for building environmental management that may utilize a heat exchanger. The building 10 is cooled by a system including a cooler 12 and a boiler 14. As shown, the cooler 12 is disposed on the roof of the building 10, and the boiler 14 is located in the basement; however, the cooler 12 and boiler 14 may be located in other equipment rooms or areas beside the building 10. The chiller 12 may be an air-cooled or water-cooled device that implements a refrigeration cycle to cool water or other conditioning fluid. Chiller 12 is housed within a structure that may include one or more refrigeration circuits, free cooling systems, and associated equipment such as pumps, valves, and piping. For example, the cooler 12 may be a single encapsulated rooftop unit. The boiler 14 is a closed vessel in which water is heated. Water from the cooler 12 and boiler 14 is circulated through the building 10 by a water conduit 16. Water conduits 16 lead to air handlers 18 (e.g., conditioning equipment) located on various floors and within portions of building 10.

The air handlers 18 are coupled to a duct system 20 that is adapted to distribute air between the air handlers 18 and may receive air from an external air inlet (not shown). Air handler 18 includes a heat exchanger that circulates cold water from chiller 12 and hot water from boiler 14 to provide heated or cooled air to a conditioned space within building 10. A fan within air handler 18 draws air through the heat exchanger and directs the conditioned air to an environment within building 10, such as a room, apartment, or office, to maintain the environment at a specified temperature. The control, here shown as including a thermostat 22, may be used to specify the temperature of the conditioned air. The control device 22 may also be used to control the flow of air through and from the air handler 18. Other devices may be included in the system, such as control valves that regulate water flow and pressure and/or temperature sensors or switches that sense the temperature and pressure of the water, air, etc. Further, the control devices may include computer systems that are integrated or separate from other building control or monitoring systems and even systems that are remote from the building 10.

Fig. 2 is a schematic diagram of an embodiment of a vapor compression system 30 of an HVAC & R system including a refrigerant circuit 34 configured to cool a conditioning fluid (e.g., water). For example, the vapor compression system 30 may be part of an air-cooled chiller. However, it should be noted that the disclosed technology can be combined with a variety of other types of coolers (such as water-cooled coolers). The refrigerant circuit 34 is configured for circulating a working fluid, such as a refrigerant, with a compressor 36 (e.g., a screw compressor) disposed along the refrigerant circuit 34. The refrigerant circuit 34 also includes a flash tank 32, a condenser 38, an expansion valve or device 40, and a liquid cooler or evaporator 42. The components of the refrigerant circuit 34 effect heat transfer between the working fluid and other fluids (e.g., conditioning fluid, air, water) to provide cooling to an environment such as the interior of the building 10.

Some examples of working fluids that may be used as refrigerants in vapor compression system 30 are Hydrofluorocarbon (HFC) -based refrigerants such as, for example, R-410A, R-407, R-134a, Hydrofluoroolefins (HFO), "natural" refrigerants such as ammonia (NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbon-based refrigerants, water vapor, refrigerants having a low Global Warming Potential (GWP), or any other suitable refrigerant. In some embodiments, the vapor compression system 30 may be configured to efficiently utilize a refrigerant having a normal boiling point of about 19 degrees celsius (66 degrees fahrenheit or less) at one atmosphere (relative to an intermediate pressure refrigerant such as R-134a, also referred to as a low pressure refrigerant). As used herein, "normal boiling point" may refer to the boiling point temperature measured at one atmosphere of pressure.

The vapor compression system 30 can further include a control panel 44 (e.g., a controller) having an analog-to-digital (a/D) converter 46, a microprocessor 48, a non-volatile memory 50, and/or an interface board 52. In some embodiments, the vapor compression system 30 can use one or more of a Variable Speed Drive (VSD)54 and a motor 56. Motor 56 can drive compressor 36 and can be powered by VSD 54. VSD 54 receives Alternating Current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source and provides power having a variable voltage and frequency to motor 56. In other embodiments, the motor 56 may be powered directly by an AC or Direct Current (DC) power source. The motors 56 can include any type of electric motor that can be powered by the VSD 54 or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or other suitable motor.

The compressor 36 compresses the refrigerant vapor and may deliver the vapor to an oil separator 58 that separates oil from the refrigerant vapor. The refrigerant vapor is then directed to a condenser 38, and the oil is returned to the compressor 36. The refrigerant vapor delivered to the condenser 38 may transfer heat to the cooling fluid in the condenser 38. For example, the cooling fluid may be ambient air 60 forced across the heat exchanger coils of the condenser 38 by a condenser fan 62. The refrigerant vapor may condense to a refrigerant liquid in the condenser 38 due to heat transfer with a cooling fluid (e.g., ambient air 60).

The liquid refrigerant exits the condenser 38 and then passes through a first expansion device 64 (e.g., expansion device 40, electronic expansion valve, etc.). The first expansion device 64 may be a flash tank feed valve configured to control the flow of liquid refrigerant to the flash tank 32. The first expansion device 64 is also configured to reduce the pressure (e.g., expand) of the liquid refrigerant received from the condenser 38. During the expansion process, a portion of the liquid may evaporate, and thus, the flash tank 32 may be used to separate the vapor from the liquid received from the first expansion device 64. Additionally, as the liquid refrigerant experiences a pressure drop as it enters the flash tank 32 (e.g., as a result of a rapid increase in volume as it enters the flash tank 32), the flash tank 32 may further expand the liquid refrigerant.

The vapor in the flash tank 32 may exit and flow to the compressor 36. For example, the vapor may be drawn to an intermediate stage or discharge stage (e.g., a non-suction stage) of the compressor 36. A valve 66 (e.g., an economizer valve, a solenoid valve, etc.) may be included in the refrigerant circuit 34 to control the flow of vapor refrigerant from the flash tank 32 to the compressor 36. In some embodiments, when the valve 66 is open (e.g., fully open), additional liquid refrigerant within the flash tank 32 may evaporate and provide additional subcooling of the liquid refrigerant within the flash tank 32. The enthalpy of the liquid refrigerant collected in the flash tank 32 may be lower than the enthalpy of the liquid refrigerant exiting the condenser 38 due to expansion in the first expansion device 64 and/or the flash tank 32. Liquid refrigerant may flow from the flash tank 32, through a second expansion device 68 (e.g., expansion device 40, an orifice, etc.), and to the evaporator 42. In some embodiments, the refrigerant circuit 34 may also include a valve 70 (e.g., a drain valve) configured to regulate the flow of liquid refrigerant from the flash tank 32 to the evaporator 42. For example, the valve 70 may be controlled (e.g., via the control panel 44) based on the suction superheat of the refrigerant.

The liquid refrigerant delivered to the evaporator 42 may absorb heat from a conditioning fluid, which may be the same or different from the cooling fluid used in the condenser 38. The liquid refrigerant in the evaporator 42 may undergo a phase change to become vapor refrigerant. For example, the evaporator 42 may include one or more tube bundles fluidly coupled to a supply line 72 and a return line 74 that are connected to a cooling load. A conditioning fluid (e.g., water, oil, calcium chloride brine, sodium chloride brine, or any other suitable fluid) of the evaporator 42 enters the evaporator 42 via a return line 74 and exits the evaporator 42 via a supply line 72. The evaporator 42 may reduce the temperature of the conditioning fluid in the tube bundle via heat transfer with the refrigerant so that the conditioning fluid may be utilized to provide cooling to the conditioned environment. The tube bundle in evaporator 42 may include a plurality of tubes and/or a plurality of tube bundles. In some embodiments, the tubes or tube bundles may define a plurality of passages through the evaporator 42. In any event, the refrigerant vapor exits the evaporator 42 and returns to the compressor 36 through a suction line to complete the refrigerant cycle.

In some cases, the HVAC & R system may include multiple refrigerant circuits configured to individually and/or cooperatively cool the conditioning fluid. As disclosed herein, the present embodiments include HVAC & R systems having multiple refrigerant circuits, wherein evaporators in the multiple refrigerant circuits are arranged in series flow arrangement (e.g., with respect to flow of conditioning fluid through the evaporators). In other words, the evaporators are arranged, fluidly coupled and/or packaged such that the conditioning fluid received from the cooling load passes first through one evaporator of one refrigerant circuit, then through another evaporator of another refrigerant circuit, and then is directed back to the cooling load. For example, the conditioning fluid may be first sequentially directed through the channels of one evaporator and then sequentially directed through the channels of another evaporator. In this manner, the evaporator approach temperature(s) of the HVAC & R system may be reduced, which may result in increased efficiency and reduced costs associated with the HVAC & R system.

With this in mind, FIG. 3 is a schematic diagram of an embodiment of an HVAC & R system 100 having multiple refrigerant circuits 34. More specifically, the HVAC & R system 100 includes a first refrigerant circuit 102 (e.g., a vapor compression circuit) having a first compressor 104, a first condenser 106, a first expansion device 108, and a first evaporator 110, and a second refrigerant circuit 112 (e.g., a vapor compression circuit) having a second compressor 114, a second condenser 116, a second expansion device 118, and a second evaporator 120. Each refrigerant circuit 34 is configured to circulate a respective refrigerant through itself, configured to operate in a manner similar to that described above with reference to the refrigerant circuit 34 shown in fig. 2. It should be noted that each refrigerant circuit 34 may also include components other than those shown in fig. 3, such as one or more of the components illustrated in the refrigerant circuit 34 of fig. 2. In some embodiments, the first refrigerant circuit 102 and the second refrigerant circuit 112 may be packaged together in a single packaged unit (e.g., a rooftop unit).

As described above, the first evaporator 110 and the second evaporator 120 of the HVAC & R system 100 are arranged in a series flow arrangement. Specifically, the first evaporator 110 and the second evaporator 120 are configured to define a portion of a conditioning fluid flow path or loop 124 that extends from the cooling load 122 (e.g., the air handler 118), sequentially through the

evaporators

110 and 120, and back to the cooling load 122. As described in further detail below, each of the first evaporator 110 and the second evaporator 120 can include a plurality of passages (e.g., a plurality of tube passages, a plurality of tube bundles, a plurality of sets of tubes, etc.) configured to direct a conditioning fluid therethrough. According to the series flow arrangement, the HVAC & R system 100 is configured to direct the conditioned fluid received from the cooling load 122 first through the passages of one evaporator and then through the passages of another evaporator before directing the conditioned fluid back to the cooling load 122. For example, in the illustrated embodiment, the HVAC & R system 100 (e.g., the conditioning fluid circuit 124) is configured to direct the conditioning fluid first through the second evaporator 120 and then through the first evaporator 110 before directing the conditioning fluid back to the cooling load 122. However, in other embodiments, the HVAC & R system 100 may be configured to direct the conditioned fluid first through the first evaporator 110 and then through the second evaporator 120 before directing the conditioned fluid back to the cooling load 122. The disclosed series flow arrangement enables lowering of individual evaporator approach temperatures and/or combined evaporator approach temperatures of the first evaporator 110 and/or the second evaporator 120. Thus, the refrigerant pressure within the first evaporator 110 and/or the second evaporator 120 may be increased, which may reduce the lift of the first refrigerant circuit 102 and/or the second refrigerant circuit 112, respectively. Accordingly, energy consumption of the first compressor 104 and/or the second compressor 114 may be reduced, thereby enabling a reduction in costs associated with operating the HVAC system 100.

FIG. 4 is a side view of an embodiment of a first evaporator 110 and a second evaporator 120 of the HVAC & R system 100 connected in a series flow arrangement 150 with respect to the flow of conditioning fluid therethrough. More specifically, the first evaporator 110 and the second evaporator 120 are positioned in an aligned configuration (e.g., aligned along a longitudinal axis of the first evaporator 110 and the second evaporator 120). The configuration shown in fig. 4 may also be referred to as an end-to-end arrangement. Further, while the series flow arrangement 150 disclosed herein is described with reference to an embodiment having the first evaporator 110 and the second evaporator 120, in other embodiments, the series flow arrangement 150 may be utilized with other types of heat exchangers (such as condensers) and/or other numbers of heat exchangers.

In the illustrated configuration, the HVAC & R system 100 (e.g., the conditioning fluid circuit 124) is configured to direct the conditioning fluid from the cooling load 122 first through the second evaporator 120, then through the first evaporator 110, and then back to the cooling load 122. The first evaporator 110 and the second evaporator 120 are each configured as a two-pass heat exchanger. That is, the first evaporator 110 includes a first passage 152 and a second passage 154, and the second evaporator 120 includes a first passage 156 and a second passage 158. Each of the

channels

152, 154, 156, and 158 may be defined by a respective set of tubes (e.g., a respective tube bundle) configured to direct a conditioning fluid therethrough.

In each of the first evaporator 110 and the second evaporator 120, heat is exchanged between the conditioning fluid and the respective refrigerant guided through the first evaporator 110 and the second evaporator 120. That is, the first refrigerant (as indicated by arrow 160) passing through the first refrigerant circuit 102 may be directed into the shell 162 of the first evaporator 110, and heat may be transferred from the first refrigerant 160 to the conditioning fluid passing through the tubes of the first and

second passages

152, 154 of the first evaporator 110. Similarly, the second refrigerant (as indicated by arrow 164) passing through the second refrigerant circuit 112 may be directed into the shell 166 of the second evaporator 120, and heat may be transferred from the second refrigerant 164 to the conditioning fluid passing through the tubes of the first and

second passages

156, 158 of the second evaporator 120. In some embodiments, the first evaporator 110 and/or the second evaporator 120 can be configured as a flooded evaporator, while in other embodiments, the first evaporator 110 and/or the second evaporator 120 can be configured as a falling film evaporator.

In the illustrated embodiment, the series flow arrangement 150 of the first evaporator 110 and the second evaporator 120 receives a conditioning fluid (represented by arrow 168) via an inlet 170 of the second evaporator 120. That is, the conditioning fluid from the cooling load 122 is directed into the series flow arrangement 150 via the inlet 170. The inlet 170 directs the conditioned fluid into a first tank 172 of the second evaporator 120. The first tank 172 is divided into a first section 174 and a second section 176 by a baffle 178 that effects fluid separation of the first section 174 and the second section 176. From the first section 174 of the first tank 172, the conditioning fluid is directed through a first tube bundle 180 (e.g., a set of tubes) defining a first tube lane 156 of the second evaporator 120, as indicated by arrow 182. In the illustrated embodiment, the first tube lane 156 is a lower tube lane of the second evaporator 120, but in other embodiments the first tube lane 156 can be an upper tube lane or an intermediate tube lane.

From the first tube lane 156, the conditioning fluid is directed to a second tank 184 of the second evaporator 120. The second tank 184 reverses the flow of the conditioning fluid through the second evaporator 120 (as indicated by arrow 186) thereby directing the conditioning fluid through the second passage 158 of the second evaporator 120. Specifically, the conditioning fluid is directed through a second tube bundle 188 (e.g., a set of tubes) passing through the second pass 158 (as indicated by arrow 190), which is an upper pass of the second evaporator 120. The conditioned fluid is then directed into the second section 176 of the first tank 172 and from there discharged from the second evaporator 120 via the outlet 192 of the second evaporator 120.

After the conditioning fluid circulates through the second evaporator 120, the conditioning fluid then circulates through the first evaporator 110. Specifically, as indicated by arrow 193, the conditioning fluid is directed from the second evaporator 120 to the first evaporator 110 via a conduit (e.g., a transfer conduit) 194 that fluidly couples the outlet 192 of the second evaporator 120 with the inlet 196 of the first evaporator 110. First evaporator 110 has a similar construction and/or configuration as second evaporator 120, and the conditioning fluid is directed through first evaporator 110 in a manner similar to that described above with reference to second evaporator 120. For example, the inlet 196 of the first evaporator 110 directs the conditioning fluid into the first tank 198 of the first evaporator 110. The first tank 198 is divided into a first section 200 and a second section 202 by a baffle 204 that enables fluid separation of the first section 200 and the second section 202. From the first section 200 of the first waterbox 198, the conditioning fluid is directed through a first tube bundle 206 defining a first tube passage 152 of the first evaporator 110, as indicated by arrow 208. In the illustrated embodiment, the first tube passage 152 is a lower tube passage of the first evaporator 110, but in other embodiments, the first tube passage 152 can be an upper tube passage or an intermediate tube passage.

From the first tube passage 152, the conditioning fluid is directed into the second tank 210 of the first evaporator 110. The second tank 210 reverses the flow of the conditioning fluid through the first evaporator 110 (as indicated by arrow 212) thereby directing the conditioning fluid through the second passage 154 of the first evaporator 110. Specifically, the conditioning fluid is directed through a second tube bundle 214 passing through a second pass 154 (as indicated by arrow 216), which is an upper pass of the first evaporator 110. The conditioned fluid is then directed into the second section 202 of the first tank 198 and from there is discharged from the first evaporator 110 via the outlet 218 of the first evaporator 110, as indicated by arrow 220. Thereafter, the conditioned fluid is directed back to the cooling load 122 for conditioning air or another fluid.

As described above, the series flow arrangement 150 of the first evaporator 110 and the second evaporator 120 enables reducing the evaporator approach temperature of the first evaporator 110 and/or the second evaporator 120. As will be appreciated, the respective temperature difference entering and exiting the conditioning fluid for each of the first evaporator 110 and the second evaporator 120 may also be reduced. For example, the difference between the temperature of the conditioning fluid exiting the second evaporator 120 via the outlet 192 and the saturated evaporating temperature of the second refrigerant 164 may be less than the temperature difference of the prior systems described above. As a result, the pressure of the second refrigerant 164 exiting the second evaporator 120, and thus the suction pressure of the second refrigerant 164, may be greater than the suction pressure of existing systems, which enables a reduction in the energy consumption of the second compressor 114. Similarly, the difference between the temperature of the conditioning fluid exiting the first evaporator 110 via outlet 218 and the saturated evaporating temperature of the first refrigerant 160 may be less than the temperature difference of prior systems. As a result, the pressure of the first refrigerant 160 leaving the first evaporator 110, and thus the suction pressure of the first refrigerant 160, may be greater than the pressure of existing systems, which enables a reduction of the energy consumption of the first compressor 104. In this manner, the operating cost of the HVAC & R system 100 may be reduced. Indeed, while the average refrigerant temperature and/or the average conditioning fluid temperature of the first evaporator 110 and the second evaporator 120 may rise slightly, the overall benefits and efficiency gains of the HVAC & R system 100 may be realized with the benefits described herein utilizing the series flow arrangement 150.

Another benefit of the series flow arrangement 150 of the first evaporator 110 and the second evaporator 120 relates to the manufacture of the HVAC & R system 100. As described above, the first evaporator 110 and the second evaporator 120 have similar configurations and/or constructions and are connected via the conduit 194. Thus, in some embodiments, a heat exchanger having a common or single design may be manufactured and mass produced for use as each of the first evaporator 110 and the second evaporator 120. Accordingly, the design and manufacturing costs of the HVAC & R system 100 may be reduced. Further, the location of the first and

second evaporators

110, 120 relative to each other may be selected according to the desired configuration, packaging, and/or implementation of the HVAC & R system 100, and suitable embodiments of the conduit 194 may be cost effectively manufactured or produced to achieve the fluid coupling of the first and

second evaporators

110, 120. Similarly, the configuration and/or orientation of the

inlets

170 and 196,

outlets

192 and 218 may be readily selected or adjusted accordingly.

FIG. 5 is a top view of an embodiment of a first evaporator 110 and a second evaporator 120 of an HVAC & R system 100 connected in a series flow arrangement 150. Similarly, fig. 6 is an axial view of the embodiment of the first evaporator 110 and the second evaporator 120 shown in fig. 5. More specifically, the first evaporator 110 and the second evaporator 120 in the illustrated embodiment are positioned or arranged in a side-by-side configuration (e.g., positioned such that the lengths of the first evaporator 110 and the second evaporator 120 are adjacent or immediately adjacent to each other). The embodiment of fig. 5 and 6 has similar elements and element numbers to the embodiment of fig. 4 and is configured to operate in a similar manner to that described above. As described above, the series flow arrangement 150 of the first evaporator 110 and the second evaporator 120 enables advantageous selection of the relative arrangement of the first evaporator 110 and the second evaporator 120, while also enabling cost reduction associated with the manufacture and operation of the HVAC & R system 100. Indeed, the first evaporator 110 and the second evaporator 120 may have other configurations relative to each other, such as a stacked configuration, in a series flow arrangement 150.

FIG. 7 is a schematic diagram of an embodiment of an HVAC & R system 100 having multiple refrigerant circuits 34 including a first evaporator 110 and a second evaporator 120 in a series flow arrangement 150. The illustrated embodiment also includes features that enable selective and/or adjustable control of the HVAC & R system 100. For example, the HVAC & R system 100 includes a controller 240 (e.g., control panel 44) having a memory 242 (e.g., non-volatile memory 50) and a processor 244 (e.g., microprocessor 48). The controller 240 may be included with the control panel 44 or separate from the control panel. The memory 242 may be a mass storage device, a flash memory device, a removable memory, or any other non-transitory computer readable medium that includes instructions for execution by the processor 244. Memory 242 may also include volatile memory, such as Random Access Memory (RAM), and/or non-volatile memory, such as hard disk memory, flash memory, and/or other suitable memory formats. The processor 244 may execute instructions stored in the memory 242 to adjust the operation of the HVAC & R system 100.

The controller 240 may be configured to control operation of components of the HVAC & R system 100, such as components of the first refrigerant circuit 102 and the second refrigerant circuit 104 described herein. In some embodiments, the controller 240 may adjust the operation of the HVAC & R system 100 based on feedback received by the controller 240 (such as feedback received from the sensors 246 of the HVAC & R system 100). One or more of the sensors 246 may be configured to detect an operating parameter of the HVAC & R system 100, such as a temperature or pressure of the first refrigerant 160 circulated by the first refrigerant circuit 102, a temperature or pressure of the second refrigerant 164 circulated by the second refrigerant circuit 104, a temperature of the conditioning fluid, an operating mode of the HVAC & R system or components thereof, an operating load or capacity of the HVAC & R system, an ambient temperature, another suitable operating parameter, and/or any combination thereof. Further, one or more of the sensors 246 may be positioned at any desired location to detect an operating parameter, such as any desired location along the first refrigerant circuit 102, the second refrigerant circuit 104, and/or the flow path of the conditioning fluid (e.g., the conditioning fluid circuit 124).

The controller may adjust the operation of the HVAC & R system 100 based on the received feedback. In some embodiments, the operation of the first refrigerant circuit 102 and the second refrigerant circuit 104 may be adjusted based on the operating load of the HVAC & R system 100. For example, when the HVAC & R system 100 is operating at 50% capacity, the first refrigerant circuit 102 and the second refrigerant circuit 104 (e.g., the compressor 104 and the compressor 114) may each be operating at 50% capacity via the controller 240. As another example, when the HVAC & R system 100 is operating at 75% capacity, the first refrigerant circuit 102 may be operating at 100% capacity and the second refrigerant circuit 104 may be operating at 25%.

In some cases, the controller 240 may control the operation of the HVAC & R system 100 such that one refrigerant circuit operates while the other refrigerant circuit does not. For example, where the HVAC & R system 100 is operating at 25% capacity, the controller 240 may suspend operation of the second refrigerant circuit 104 and may operate the first refrigerant circuit 102. To this end, the HVAC & R system 100 (e.g., the conditioning fluid circuit 124) may include a bypass line configured to direct the conditioning fluid from the cooling load 122 through the first evaporator 110 and back to the cooling load 122 such that the flow of the conditioning fluid bypasses the second evaporator 120. In the illustrated embodiment, a bypass valve (e.g., a three-way valve) 248 is disposed along conduit 194 and may be actuated (e.g., via controller 240) to enable bypassing of second evaporator 120 and to enable flow of conditioned fluid from cooling load 122 to first evaporator 110 (as indicated by arrow 250).

Technical effects of the above-described embodiments and features include improvements in the operation and manufacture of HVAC & R systems (e.g., chillers) having multiple refrigerant circuits, such as increased operating efficiency and reduced costs associated with the operation and manufacture of HVAC & R systems. In particular, the series flow arrangement of evaporators in multiple refrigerant circuits enables reducing the evaporator approach temperature of HVAC & R systems. In this way, the refrigerant pressure in the evaporator may be increased, which may reduce the lift of the HVAC & R system and, thus, reduce the work performed by the compressor of the HVAC & R system. Accordingly, the energy consumption of the HVAC system is reduced. Additionally, the series flow arrangement enables cost-effective manufacturing of HVAC & R systems in a variety of different structural configurations or arrangements.

While only certain features of the present embodiments have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure. Further, it should be noted that certain elements of the disclosed embodiments may be combined or interchanged with one another.

The technology presented and claimed herein makes reference to and applies to specific examples that significantly improve the substance and practical nature of the technical field and are therefore not abstract, intangible or purely theoretical. Further, if any claim appended to the end of this specification contains one or more elements designated as "means for [ performing ] [ function ] or" step for [ performing ] [ function ], it is intended that such elements be construed in accordance with 35u.s.c.112 (f). However, for any claim that contains elements specified in any other way, it is intended that such elements not be construed in accordance with 35u.s.c.112 (f).

Claims

1. A heating, ventilation, air conditioning and/or refrigeration (HVAC & R) system comprising:

a first refrigerant circuit comprising a first evaporator configured to place a first refrigerant in heat exchange relationship with a conditioning fluid, wherein the first evaporator comprises a first set of first tubes and a second set of first tubes configured to direct the conditioning fluid through the first evaporator;

a second refrigerant circuit comprising a second evaporator configured to place a second refrigerant in heat exchange relationship with the conditioning fluid, wherein the second evaporator comprises a first set of second tubes and a second set of second tubes configured to direct the conditioning fluid through the second evaporator; and

a conditioning fluid circuit configured to continuously circulate the conditioning fluid through the first set of first tubes, the second set of first tubes, the first set of second tubes, and the second set of second tubes.

2. The HVAC & R system of claim 1, wherein the first set of first tubes defines a lower passage of the first evaporator and the second set of first tubes defines an upper passage of the first evaporator.

3. The HVAC & R system of claim 2, wherein the first evaporator comprises a water tank configured to receive the conditioning fluid from the first set of first tubes, reverse a flow direction of the conditioning fluid through the first evaporator, and direct the conditioning fluid into the second set of first tubes.

4. The HVAC & R system of claim 2, wherein the first set of second tubes defines a lower passage of the second evaporator and the second set of second tubes defines an upper passage of the second evaporator.

5. The HVAC & R system of claim 4, wherein the conditioning fluid circuit includes a conduit extending from an outlet of the second evaporator to an inlet of the first evaporator, the outlet of the second evaporator configured to direct the conditioning fluid from the second set of second tubes toward the conduit, and the inlet of the first evaporator configured to direct the conditioning fluid from the conduit toward the first set of first tubes.

6. The HVAC & R system of claim 1, wherein the first evaporator comprises an outlet, the second evaporator comprises an inlet, the outlet is configured to direct the conditioning fluid toward a cooling load, and the inlet is configured to receive the conditioning fluid from the cooling load.

7. The HVAC & R system of claim 1, wherein the first evaporator and the second evaporator are arranged in an end-to-end configuration with respect to each other.

8. The HVAC & R system of claim 1, wherein the first evaporator and the second evaporator are arranged in a side-by-side configuration relative to each other.

9. The HVAC & R system of claim 1, comprising a chiller having the first refrigerant circuit and the second refrigerant circuit, wherein the first refrigerant circuit comprises a first condenser configured to place the first refrigerant in heat exchange relationship with ambient air, and the second refrigerant circuit comprises a second condenser configured to place the second refrigerant in heat exchange relationship with ambient air.

10. A heating, ventilation, air conditioning and/or refrigeration (HVAC & R) system comprising:

a first evaporator comprising a first lower tube bundle and a first upper tube bundle, wherein the first lower tube bundle and the first upper tube bundle are each configured to place a conditioning fluid in heat exchange relationship with a first refrigerant;

a second evaporator comprising a second lower tube bundle and a second upper tube bundle, wherein the second lower tube bundle and the second upper tube bundle are each configured to place the conditioning fluid in heat exchange relationship with a second refrigerant;

a conduit fluidly extending between the first evaporator and the second evaporator and fluidly coupling the first lower tube bundle and the second upper tube bundle; and

a conditioning fluid circuit configured to circulate the conditioning fluid continuously through the second lower tube bundle, the second upper tube bundle, the conduit, the first lower tube bundle, and the first upper tube bundle.

11. The HVAC & R system of claim 10, wherein the conditioning fluid circuit is configured to direct the conditioning fluid from a cooling load to the second lower tube bundle and to direct the conditioning fluid from the first upper tube bundle to the cooling load.

12. The HVAC & R system of claim 10, wherein the first lower tube bundle defines a first pass of the first evaporator and the first upper tube bundle defines a second pass of the first evaporator.

13. The HVAC & R system of claim 12, wherein the second lower tube bundle defines a first pass of the second evaporator and the second upper tube bundle defines a second pass of the second evaporator.

14. The HVAC & R system of claim 10, comprising:

a first refrigerant circuit including the first evaporator, a first compressor, and a first condenser, wherein the first condenser is configured to place the first refrigerant in heat exchange relationship with ambient air; and

a second refrigerant circuit including the second evaporator, a second compressor, and a second condenser, wherein the second condenser is configured to place the second refrigerant in heat exchange relationship with ambient air,

wherein the first refrigerant circuit and the second refrigerant circuit are fluidly separated from each other.

15. A chiller system comprising:

a first refrigerant circuit comprising a first evaporator configured to place a first refrigerant in heat exchange relationship with a conditioning fluid, wherein the first evaporator comprises a first plurality of first tubes and a second plurality of first tubes configured to direct the conditioning fluid through the first evaporator, wherein the first plurality of first tubes define a lower passage of the first evaporator and the second plurality of first tubes define an upper passage of the first evaporator;

a second refrigerant circuit comprising a second evaporator configured to place a second refrigerant in heat exchange relationship with the conditioning fluid, wherein the second evaporator comprises a first plurality of second tubes and a second plurality of second tubes configured to direct the conditioning fluid through the second evaporator, wherein the first plurality of second tubes define a lower passage of the second evaporator and the second plurality of second tubes define an upper passage of the second evaporator; and

a conduit extending between and fluidly coupling the second plurality of second tubes and the first plurality of first tubes.

16. The chiller system of claim 15 wherein the first evaporator, the second evaporator and the conduit are configured to direct the conditioning fluid through the second plurality of second tubes, the first plurality of second tubes, the conduit, the first plurality of first tubes and the second plurality of first tubes in series.

17. The chiller system of claim 15 wherein the first refrigerant circuit comprises a first air-cooled condenser, the second refrigerant circuit comprises a second air-cooled condenser, and the first refrigerant circuit and the second refrigerant circuit are fluidly separated from one another.

18. The chiller system of claim 15 wherein the first evaporator and the second evaporator are positioned in an end-to-end arrangement with respect to each other.

19. The chiller system of claim 15 wherein the first evaporator and the second evaporator are positioned in a side-by-side arrangement with respect to each other.

20. The chiller system of claim 15, comprising a controller configured to adjust operation of the first refrigerant circuit and the second refrigerant circuit independently of one another based on feedback received from one or more sensors of the chiller system.