SYSTEMS AND METHODS FOR DESIGNING COMPRESSORS.

Abstract

A method for designing an operable compressor for compressing a refrigerant. The method may include determining the operating conditions of the compressor. The method may also include weighting the operating conditions. The method further includes determining a compressor volume ratio based on the refrigerant and the weighted operating conditions.

Description

SYSTEMS AND METHODS FOR DESIGNING COMPRESSORS BACKGROUND OF THE INVENTION This section is intended to provide relevant background information to facilitate a better understanding of the various aspects of the described modalities. Accordingly, these statements should be read in light of this information and not as admissions of prior art. In general, heating, ventilation, and air conditioning (“HVAC”) systems circulate indoor air through low-temperature (for cooling) or high-temperature (for heating) sources, thereby adjusting the ambient air temperature. HVAC systems generate these low- and high-temperature sources, among other techniques, by taking advantage of a well-known physical principle: a fluid transitioning from gas to liquid releases heat, while a fluid transitioning from liquid to gas absorbs heat. Within a typical HVAC system, a refrigerant circulates through a closed-loop piping system that uses compressors and other flow control devices to manipulate the refrigerant's flow and pressure, causing it to change between liquid and gaseous phases. These phase transitions generally occur within the HVAC system's heat exchangers, which are part of the closed loop and are designed to transfer heat between the circulating refrigerant and the surrounding ambient air. As expected, the heat exchanger that provides heating or cooling to the climate-controlled space or structure is described as the "indoor" heat exchanger, and the heat exchanger that transfers heat to the surrounding outdoor environment is described as the "outdoor" heat exchanger. The refrigerant circulating between the indoor and outdoor heat exchangers—transitioning between phases along the way—absorbs heat from one location and releases it to the other. Those in the HVAC industry describe this cycle of heat absorption and release as pumping. To cool a climate-controlled indoor space, heat is pumped from the inside to the outside, and the indoor space is heated by doing the opposite, pumping heat from the outside to the inside. For both heating and cooling of indoor spaces, the efficiency of a typical HVAC system is largely determined by the efficiency of the compressor used to compress and discharge the gaseous refrigerant. Therefore, increased system efficiency and reduced operating costs can be achieved by increasing compressor efficiency and reducing compression losses. BRIEF DESCRIPTION OF THE FIGURES The design methods for a compressor are described with reference to the following figures. The same numbers are used in all figures to refer to similar features and components. The features depicted in the figures are not necessarily shown to scale. Certain features of the methods may be shown exaggerated or somewhat schematically, and some details of the elements may be omitted for the sake of clarity and conciseness. FIG. 1 is a block diagram of an HVAC system, according to one or more modes; FIG. 2 is a graph that represents a relationship between the pressure and specific volume of a refrigerant in an HVAC system; FIG. 3 is a graph that represents the normalized compressor losses as a function of the normalized compressor volume ratio for various refrigerants; FIG. 4 is a graph that represents the integrated energy efficiency ratio of the system (IEER) as a function of the compressor volume ratios; Figure 5 is a graph representing the normalized compressor losses as a function of the normalized compressor volume ratios for various refrigerants; and FIG. 6 is a block diagram of a computer system, according to one or more modalities. DETAILED DESCRIPTION OF THE INVENTION This disclosure describes systems and methods for designing a compressor. Furthermore, the methods and systems are developed to optimize the compressor's volume ratio—which, in certain configurations, increases efficiency and reduces pump losses during compressor operation. Returning now to the figures, FIG. 1 is an HVAC system 100 according to one modality. As represented, system 100 provides heating and cooling for a residential structure 102. However, the concepts described herein are applicable to numerous heating and cooling situations, including industrial and commercial environments. The described HVAC system 100 is divided into two main parts: the outdoor unit 104, which mainly comprises components for transferring heat with the environment outside the structure 102; and the indoor unit 106, which mainly comprises components for transferring heat with the air inside the structure 102. To heat or cool the illustrated structure 102, the indoor unit 106 draws in ambient indoor air through the returns 110, passes that air over one or more heating / cooling systems (i.e., heat or cooling sources), and then routes that conditioned air, whether heated or cooled, back to the various climate-controlled spaces 112 through ducts or ductwork 114—which are relatively large pipes that can be rigid or flexible. A fan 116 provides the driving force for circulating the ambient air through the returns 110 and the ducts 114. Furthermore, although in FIG.1 shows a split system; the described modalities can be applied equally to packaged or other system configurations. As shown, the HVAC 100 system is a dual-fuel system that has multiple heating elements, such as an electric heating element or a gas furnace 118. The gas furnace 118 located downstream (relative to airflow) of fan 32 burns gas Natural gas is used to produce heat in the furnace tubes (not shown) that are wound through the gas furnace 118. These furnace tubes act as a heating element for the ambient indoor air that is exhausted from the fan 116, over the furnace tubes, and into the ductwork 114. However, the gas furnace 118 is generally operated when strong heating is required. During conventional heating and cooling operations, the air from the fan 116 is routed through an indoor heat exchanger 120 and into the ductwork 114. The fan 116, gas furnace 118, and indoor heat exchanger 120 can be packaged as an integrated air handling unit, or these components can be modular. In other embodiments, the positions of the gas furnace 118, indoor heat exchanger 120, and fan 116 can be reversed or rearranged. In at least one embodiment, the indoor heat exchanger 120 acts as a heating or cooling medium, adding or removing heat from the building, respectively, by manipulating the pressure and flow of refrigerant circulating within and between the indoor and outdoor units through the refrigerant lines 122. In another embodiment, the refrigerant may circulate only to cool (i.e., remove heat from) the building, with heating provided independently by another source, such as, but not limited to, the gas furnace 118. In other embodiments, there may be no heating of any kind. HVAC systems 100 that use refrigerant for both heating and cooling the building 102 are often described as heat pumps, while systems 100 that use refrigerant only for cooling are commonly described as air conditioners. Whatever the state of the indoor heat exchanger 120 (i.e., absorbing or releasing heat), the outdoor heat exchanger 124 is in the opposite state. More specifically, if heating is desired, the illustrated indoor heat exchanger 120 acts as a condenser, facilitating the transition of the refrigerant from a high-pressure gas to a high-pressure liquid and releasing heat in the process. The outdoor heat exchanger 124 acts as an evaporator, facilitating the transition of the refrigerant from a low-pressure liquid to a low-pressure gas, thereby absorbing heat from the outside environment. If cooling is desired, the outdoor unit 104 has flow control devices 126 that reverse the refrigerant flow, allowing the outdoor heat exchanger 124 to act as a condenser and the indoor heat exchanger 120 to act as an evaporator.The flow control devices 126 can also act as an expander to reduce the pressure of the refrigerant flowing through them. In other embodiments, the expander may be a separate device located either in the outdoor unit 104 or the indoor unit 106. To facilitate heat exchange between the ambient indoor air and the outdoor environment in the described HVAC system 100, the respective heat exchangers 120 and 124 have tubes that are coiled or threaded through heat exchange surfaces to increase the surface area of ​​contact between the pipe and the surrounding air or environment. The illustrated outdoor unit 104 may also include an accumulator 128 that helps prevent liquid refrigerant from reaching the inlet of a fixed volume ratio compressor 130. The outdoor unit 104 may include a receiver 132 that helps maintain sufficient refrigerant load distribution in the system 100. The size of these components is often defined by the amount of refrigerant used by the system 100. The fixed volume ratio compressor 130 receives low-pressure refrigerant gas from the indoor heat exchanger 120 if cooling is required, or from the outdoor heat exchanger 124 if heating is required. The fixed volume ratio compressor 130 then compresses the refrigerant gas to a higher pressure based on a compressor volume ratio, i.e., the ratio of a discharge volume (the volume of gas discharged from the fixed volume ratio compressor 130 after compression) to a suction volume (the volume of gas introduced into the fixed volume ratio compressor 130 before compression). In the illustrated embodiment, the compressor is a multi-stage compressor 130 that can transition between at least two volume ratios depending on whether heating or cooling is required.In other configurations, the 100 system can be set up to cool only or heat only, and the 130 fixed volume ratio compressor can be a single-stage compressor that has only one volume ratio. The volume ratio of a fixed volume ratio (VLR) compressor is a significant factor in determining the overall efficiency of the system. Therefore, having the optimal volume ratio for the fixed volume ratio compressor helps maximize system efficiency and minimize compressor losses for a fixed volume ratio compressor using a selected refrigerant, such as, but not limited to, R410A, R32, and R454B. The thermodynamic properties of the refrigerant must also be considered when selecting the optimal volume ratio, as the optimal volume ratio changes depending on the refrigerant used in the system.Furthermore, since the environmental conditions during the operation of the fixed volume ratio 130 compressor directly impact the efficiency of the fixed volume ratio 130 compressor, it is beneficial to calculate the compressor losses under several different environmental operating conditions to determine the optimum volume ratio. For example, FIG. 2 illustrates the compressor losses, i.e., the undercompression 200 of a refrigerant and the overcompression 202 of a refrigerant, for a specific refrigerant at a selected volume ratio 204. The curve 206 shown in FIG. 2 represents a polytropic process for the refrigerant and illustrates the relationship between the specific volume, which is directly related to the volume ratio, and the refrigerant pressure. The graph also shows the refrigerant pressure required to achieve the ideal specific volume and, therefore, the ideal volume ratio for the refrigerant under each of the four different ambient conditions 208, 210, 212, 214. The ideal specific volume for each of the four ambient conditions 208, 210, 212, 214 will be calculated using methods known to those skilled in the art. The four selected ambient operating conditions may correspond to the ambient conditions used by an organization, such as the Air Conditioning, Heating and Cooling Institute (AHRI), when determining system efficiency using a known efficiency standard, such as the Integrated Energy Efficiency Ratio (IEER), the Seasonal Energy Efficiency Ratio (SEER), or the Seasonal Heating Performance Factor (HSPF). However, the invention is not limited thereby. There may be one, two, three, five, or more ambient conditions used to determine compressor losses. Furthermore, the ambient operating conditions may be established based on the intended geographic location of the system, rather than the operating conditions established by an organization such as AHRI for a specific efficiency standard. Since a fixed volume ratio compressor operates at a single volume ratio and therefore a single specific volume, there will be losses in the compressor due to either undercompression 200, where the refrigerant is not compressed enough to achieve the ideal specific volume, or overcompression 202, where the refrigerant is compressed above the pressure required to achieve the ideal specific volume, when the compressor operates under each of the ambient conditions 208, 210, 212, 214. The compressor losses under each ambient condition 208, 210, 212, 214 are found by calculating the area above the curve for refrigerant that is undercompressed 200, or below the curve for refrigerant that is overcompressed 202, between the specific volume and associated pressure related to the selected volume ratio and the ideal specific volume and associated pressure for ambient condition 208, 210, 212, 214.Additional losses due to friction, leaks, or other sources known to those skilled in the art may also be included when determining the total compressor losses. After calculating the compressor losses under each environmental condition, these losses can be weighted according to the estimated time the fixed-volume-ratio compressor 130 will spend in each operating condition during its lifetime. Once the weights have been applied to the compressor losses under each operating condition, the total compressor losses under the weighted environmental conditions can be calculated for a range of volume ratios to determine the optimum volume ratio for minimizing compressor losses. Compressor losses can be calculated for volume ratios within a range of 1.5 to 3.5. However, compressor losses can also be calculated for volume ratios below 1.5 and above 3.5 if necessary to find the volume ratio with the lowest compressor losses.A graph representing the volume ratios and their associated compressor losses can be seen in FIG. 3. However, the volume ratios and associated losses have been normalized based on Refrigerant 1 to show that the optimum volume ratio, the lowest point on the respective curves, will change according to the refrigerant. Alternatively or in addition to calculating the compressor losses for the fixed volume ratio compressor 130, the system efficiency 100 can be determined for a system using fixed volume ratio compressors that have known volume ratios according to a known efficiency standard, such as IEER, SEER, or HSPF. The system efficiency can be calculated for volume ratios within a range of 1.5 to 2.5, as shown in Figure 4, to determine the volume ratio associated with the highest system efficiency—the highest point on the curve. However, the system efficiency can also be calculated for volume ratios below 1.5 and above 3.5 if necessary to find the volume ratio associated with the highest system efficiency. Furthermore, Figure 4 represents the system efficiency for a single refrigerant. As discussed previously, the overall system efficiency and the most efficient volume ratio will vary depending on the refrigerant used in the system. A similar methodology can be used to determine the optimum efficiency ratios for multistage compressors used with systems that operate as both heating and cooling systems. However, in such cases, compressor losses and / or system efficiency are calculated separately for heating and cooling operations. The total losses or system efficiencies can then be calculated for the compressor stage associated with heating and the compressor stage associated with cooling, as shown in Figure 5, to determine the optimum volume ratio for each stage. The methodology can also be applied to fixed-volume-ratio compressors with multiple cooling stages, where the compressor losses and / or system efficiency are calculated separately for each cooling stage.Then the optimal volume ratio for each stage of the multi-stage compressor can be determined. Figure 6 is a block diagram of a computer system 600 that can be used to calculate compressor losses for fixed volume ratio compressors 130 that have known volume ratios and system efficiencies for HVAC systems that include compressors that have known volume ratios, as described above. The computer system 600 includes at least a processor 602, a non-transient computer-readable medium 604, an optional network communication module 606, optional input / output devices 608, and an optional display 610, all interconnected through a system bus 612.Software instructions executable by the processor 602 to implement software instructions stored within the computer system 600 according to the illustrative modalities described herein, may be stored on the non-transient computer-readable medium 604 or some other non-transient computer-readable medium. Although not explicitly shown in FIG. 6, it will be acknowledged that the 600 computer system can connect to one or more public and / or private networks via appropriate network connections. It will also be acknowledged that software instructions can be loaded onto the non-transient, computer-readable medium 604 from a CD-ROM or other appropriate storage medium via wired or wireless means. Additional examples include: Example 1 is a method for designing an operable compressor to compress a refrigerant. The method includes determining the compressor's operating conditions. The method also includes weighting the operating conditions. The method further includes determining a compressor volume ratio based on the refrigerant and the weighted operating conditions. In Example 2, the modalities of any preceding paragraph or combination thereof also include where the weighting of operating conditions includes estimating the time spent in each operating condition during the compressor's useful life. The weighting of operating conditions also includes weighting the operating conditions based on the estimates Lfrcn Ln / zznz / E / YiAi of time. In Example 3, the modalities of any preceding paragraph or combination thereof also include where the determination of operating conditions includes estimating the operating conditions for the compressor at a selected geographical location. In Example 4, the modalities of any preceding paragraph or combination thereof also include where the operating conditions and the weights of the operating conditions are selected on the basis of an efficiency standard. In Example 5, the modalities of any preceding paragraph or combination thereof further include where the determination of the compressor volume ratio includes calculating at least one of the compressor efficiencies or compressor losses for multiple compressor volume ratios based on the refrigerant and weighted operating conditions. The determination of the compressor volume ratio further includes selecting the compressor volume ratio that has the highest compressor efficiency or the lowest compressor losses. In Example 6, the modalities of any preceding paragraph or combination thereof further include where the compressor volume ratios comprise compressor volume ratios within a range of 1.5 to 3.5. In Example 7, the modalities of any preceding paragraph or combination thereof also include where the compressor is a multistage compressor. Furthermore, determining the compressor operating conditions includes determining a first set of operating conditions corresponding to a first compressor stage. Determining the compressor operating conditions also includes determining a second set of operating conditions corresponding to a second compressor stage. In addition, weighting the operating conditions comprises weighting the operating conditions within the respective sets of operating conditions. Furthermore, determining a compressor volume ratio includes determining a compressor volume ratio for the first compressor stage based on the refrigerant and the first set of weighted operating conditions.Determining a compressor volume ratio also includes determining a compressor volume ratio for the second compressor stage based on the refrigerant and the second set of weighted operating conditions. In Example 8, the modalities of any preceding paragraph or combination thereof also include manufacturing a compressor based on the determined compressor volume ratio. Example 9 is an HVAC system. The HVAC system includes an evaporator, a condenser, an expander, and a compressor. The compressor is designed to compress a refrigerant and has a volume ratio. The volume ratio is determined based on the refrigerant and weighted operating conditions. In Example 10, the modalities of any preceding paragraph or combination of the Lbcn Ln / Zznz / E / YIAI also include where the weighted operating conditions are based on the time spent in each of the multiple operating conditions for a selected geographical location during the compressor's lifetime. In Example 11, the modalities of any preceding paragraph or combination thereof also include where the weighted operating conditions are selected based on an efficiency standard. In Example 12, the modalities of any preceding paragraph or combination thereof further include where the volume ratio has at least one of the lowest compressor losses based on the refrigerant and weighted operating conditions or the highest compressor efficiency based on the refrigerant and weighted operating conditions of a group of compressor volume ratios. In Example 13, the modalities of any preceding paragraph or combination thereof further include where the group of compressor volume ratios comprises compressor volume ratios within a range of 1.5 to 3.5. In Example 14, the modalities of any preceding paragraph or combination thereof further include where the compressor is a multi-stage compressor having a first volume ratio and a second volume ratio, wherein the first volume ratio is determined on the basis of the refrigerant and a first set of weighted operating conditions and the second volume ratio is determined on the basis of the refrigerant and a second set of weighted operating conditions. Example 15 is a method for designing an operable compressor to compress a refrigerant. The method includes determining the compressor's operating conditions. The method also includes weighting the operating conditions. The method further includes determining a compressor volume ratio based on the refrigerant and the weighted operating conditions. The method also includes manufacturing a compressor based on the determined compressor volume ratio. In Example 16, the modalities of any preceding paragraph or combination thereof also include where the weighting of operating conditions includes estimating the time spent in each operating condition during the compressor's useful life. The weighting of operating conditions also includes weighting the operating conditions based on the time estimates. In Example 17, the modalities of any preceding paragraph or combination thereof also include where the determination of operating conditions includes estimating the operating conditions of the compressor at a selected geographical location. In Example 18, the modalities of any preceding paragraph or combination thereof also include where the operating conditions and the weights of the operating conditions are selected on the basis of an efficiency standard. In Example 19, the modalities of any preceding paragraph or combination thereof also include where the determination of the compressor volume ratio includes Lfrcn Ln / zznz / E / YiAi calculate at least one compressor efficiency or compressor loss for multiple compressor volume ratios based on refrigerant and weighted operating conditions. Determining the compressor volume ratio also includes selecting the compressor volume ratio that has the highest compressor efficiency or the lowest compressor losses. In Example 20, the modalities of any preceding paragraph or combination thereof also include where the compressor is a multistage compressor. Furthermore, determining the operating conditions of the compressor includes determining a first set of operating conditions corresponding to a first stage of the compressor. Determining the operating conditions of the compressor also includes determining a second set of operating conditions corresponding to a second stage of the compressor. In addition, weighting the operating conditions comprises weighting the operating conditions within the respective sets of operating conditions. Furthermore, determining a compressor volume ratio includes determining a compressor volume ratio for the first stage of the compressor based on the refrigerant and the first set of weighted operating conditions.Determining a compressor volume ratio also includes determining a compressor volume ratio for the second compressor stage based on the refrigerant and the second set of weighted operating conditions. Certain terms are used throughout the description and claims to refer to particular features or components. As someone skilled in the art will appreciate, different people may refer to the same feature or component by different names. This document does not purport to distinguish between components or features that differ in name but not in function. For the preceding modalities and examples, a non-transient, computer-readable medium may comprise instructions stored therein, which, when executed by a machine, cause the machine to perform operations. These operations comprise one or more characteristics similar or identical to the characteristics of the methods and techniques described above. The physical structures of such instructions may be operated by one or more processors. A system for implementing the described algorithm may also include an electronic device and a communications unit. The system may also include a bus, where the bus provides electrical conductivity between the system components. The bus may include an address bus, a data bus, and a control bus, each configured independently.The bus can also use common conductor lines to provide one or more addresses, data, or control signals, the use of which can be regulated by one or more processors. The bus can be configured so that system components can be distributed. The bus can also be arranged as part of a communication network that allows communication with control sites located remotely from the system. In various system configurations, peripheral devices such as displays, additional storage memory, and / or other control devices can operate in conjunction with one or more processors and / or memory modules. These peripheral devices can be configured to operate Lfrcn ίη / ζζηζ / E / γίΛΐ together with the display unit(s) with instructions stored in the memory module to implement the user interface for managing the display of anomalies. Such a user interface can operate together with the communication unit and the bus. Various system components can be integrated so that processing identical or similar to the processing schemes discussed herein can be performed with respect to various modalities. In an effort to provide a concise description of these modalities, not all the features of an actual implementation may be described in the specification. It should be noted that in developing any actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific objectives, such as meeting system-related and business-related constraints, which may vary from one implementation to another. Furthermore, it should be appreciated that such a development effort could be complex and time-consuming, but it would nevertheless be a routine design, fabrication, and manufacturing task for those with ordinary experience who benefit from this description. References throughout this specification to a modality, a modality, a modality, modalities, some modalities, certain modalities, or similar language mean that a particular aspect, structure, or feature described in relation to that modality may be included in at least one modality of this specification. Therefore, these phrases or similar language throughout this specification may, but do not necessarily, all refer to the same modality. The described methods should not be interpreted or otherwise used as limiting the scope of the description, including the claims. It should be fully recognized that the different teachings of the discussed methods may be employed separately or in any combination suitable for producing the desired results. Furthermore, a person skilled in the art will understand that the description has broad application, and that the discussion of any method is intended only as an example of that method and is not intended to suggest that the scope of the description, including the claims, is limited to that method.

Claims

1. A method for designing an operable compressor for compressing a refrigerant, characterized in that the method comprises: determining the operating conditions of the compressor; weighting the operating conditions; and determining a compressor volume ratio based on the refrigerant and the weighted operating conditions.

2. The method according to claim 1, characterized in that the weighting of the operating conditions comprises: estimating the time spent in each operating condition during the useful life of the compressor; and weighting the operating conditions based on the time estimates.

3. The method according to claim 1, characterized in that the determination of the operating conditions comprises estimating the operating conditions for the compressor at a selected geographical location.

4. The method according to claim 1, characterized in that the operating conditions and the weightings of the operating conditions are selected on the basis of an efficiency standard.

5. The method according to claim 1, characterized in that the determination of the compressor volume ratio comprises: calculating at least one of the compressor efficiencies or compressor losses for multiple compressor volume ratios based on the refrigerant and weighted operating conditions; and selecting the compressor volume ratio that has the highest compressor efficiency or the lowest compressor losses.

6. The method according to claim 5, characterized in that the compressor volume ratios comprise compressor volume ratios within a range of 1.5 to 3.

5.

7. The method according to claim 1, characterized in that: the compressor is a multi-stage compressor; the determination of the operating conditions of the compressor comprises: determining a first set of operating conditions corresponding to a first stage of the compressor; and determining a second set of operating conditions corresponding to a second stage of the compressor; the weighting of the operating conditions comprises weighting the operating conditions within the respective sets of operating conditions; the determination of a compressor volume ratio comprises: determining a compressor volume ratio for the first stage of the compressor based on the refrigerant and the first set of weighted operating conditions;and determine a compressor volume ratio for the second compressor stage based on the refrigerant and the second set of weighted operating conditions.

8. The method according to claim 1, characterized in that it further comprises manufacturing a compressor based on the determined compressor volume ratio.

9. An HVAC system, characterized in that it comprises an evaporator; a condenser; an expander; and a compressor operable to compress a refrigerant and having a volume ratio, wherein the volume ratio is determined based on the refrigerant and weighted operating conditions.

10. The system according to claim 9, characterized in that the weighted operating conditions are based on the time spent in each of the multiple operating conditions for a selected geographical location during the compressor's lifetime.

11. The system according to claim 9, characterized in that the weighted operating conditions are selected on the basis of an efficiency standard.

12. The system according to claim 9, characterized in that the volume ratio has at least one of the lowest compressor losses based on the refrigerant and weighted operating conditions or the highest compressor efficiency based on the refrigerant and weighted operating conditions of a group of compressor volume ratios.

13. The system according to claim 12, characterized in that the group of compressor volume ratios comprises compressor volume ratios within a range of 1.5 to 3.

5.

14. The system according to claim 9, characterized in that the compressor is a multi-stage compressor having a first volume ratio and a second volume ratio, wherein the first volume ratio is determined based on the refrigerant and a first set of weighted operating conditions and the second volume ratio is determined based on the refrigerant and a second set of weighted operating conditions.

15. A method for designing an operable compressor for compressing a refrigerant, characterized in that the method comprises: determining the operating conditions of the compressor; weighting the operating conditions; and determining a compressor volume ratio based on the refrigerant and the weighted operating conditions; and manufacturing a compressor based on the determined compressor volume ratio.

16. The method according to claim 15, characterized in that the weighting of the operating conditions comprises: estimating the time spent in each operating condition during the useful life of the compressor; and weighting the operating conditions based on the time estimates.

17. The method according to claim 15, characterized in that the determination of the operating conditions comprises estimating the operating conditions of the compressor at a selected geographical location.

18. The method according to claim 15, characterized in that the operating conditions and the weightings of the operating conditions are selected on the basis of an efficiency standard.

19. The method according to claim 18, characterized in that the determination of the compressor volume ratio comprises: calculating at least one of the compressor efficiencies or compressor losses for multiple compressor volume ratios based on the refrigerant and weighted operating conditions; and selecting the compressor volume ratio that has the highest compressor efficiency or the lowest compressor losses.

20. The method according to claim 15, characterized in that: the compressor is a multi-stage compressor; the determination of the operating conditions of the compressor comprises: determining a first set of operating conditions corresponding to a first stage of the compressor; and determining a second set of operating conditions corresponding to a second stage of the compressor; the weighting of the operating conditions comprises weighting the operating conditions within the respective sets of operating conditions; the determination of a compressor volume ratio comprises: determining a compressor volume ratio for the first stage of the compressor based on the refrigerant and the first set of weighted operating conditions; and determining a compressor volume ratio for the second stage of the compressor based on the refrigerant and the second set of weighted operating conditions.

Images