Liquid/gas bypass

Claim 2

A refrigeration apparatus comprising a condenser, an expansion device, and an evaporator connected in series, and including a bypass valve connected in parallel with said expansion device and in series with both said condenser and said evaporator, said bypass valve opening to convey liquid refrigerant in response to a predetermined indicator of a high level of liquid refrigerant in said condenser and opening to convey vaporous refrigerant in response to a predetermined low load condition.

Claim 3

The refrigeration apparatus as recited in claim 1, wherein said expansion device is an orifice having a fixed opening.

Claim 4

The refrigeration apparatus as recited in claim 1, wherein said expansion device is an expansion valve having a variable opening.

Claim 5

The refrigeration apparatus as recited in claim 1, wherein said bypass valve is a two position valve having an open position and a closed position.

Claim 6

The refrigeration apparatus as recited in claim 1, wherein the extent of opening of said bypass valve is variable to provide modulated flow therethrough.

Claim 7

The refrigeration apparatus as recited in claim 1, further comprising a variable capacity compressor selectively operative in a loaded and an unloaded condition and having a refrigerant flow output rate that is greater when loaded than unloaded.

Claim 8

The refrigeration apparatus as recited in claim 6, wherein said compressor is a screw compressor having a slide valve whose position determines whether said compressor is operating loaded or unloaded.

Claim 9

The refrigeration apparatus as recited in claim 6, further comprising a compressor motor housing having a housing inlet and a housing outlet for conveying refrigerant through said housing, in parallel with said bypass valve, and in series with said expansion device said housing outlet being positioned near the bottom of said housing to facilitate the separation of liquid refrigerant from vaporous refrigerant.

Claim 10

The refrigeration apparatus as recited in claim 1, wherein said condenser is substantially filled with vaporous refrigerant and includes a condenser outlet for discharging refrigerant in series flow through said expansion device, and wherein said evaporator is substantially flooded with liquid refrigerant and includes an evaporator inlet for receiving refrigerant in series flow relationship with said expansion device.

Claim 11

The refrigeration apparatus as recited in claim 9, wherein said bypass valve is disposed in a bypass line having a bypass inlet connected to said condenser at a higher elevation then said condenser outlet.

Claim 12

The refrigeration apparatus as recited in claim 1, wherein said predetermined low load condition is when the temperature of a chilled fluid passing through said evaporator is below a predetermined lower limit.

Claim 13

The refrigeration apparatus as recited in claim 11, wherein said predetermined low load condition is when the temperature of a chilled fluid passing through said evaporator is below a predetermined lower limit for a predetermined period.

Claim 14

The refrigeration apparatus as recited in claim 7, wherein said predetermined low load condition is when said slide valve reaches a predetermined position.

Claim 15

The refrigeration apparatus as recited in claim 1, wherein said predetermined indicator of a high level of liquid refrigerant in said condenser is the occurrence of a predetermined thermodynamic condition characteristic of a low head condition.

Claim 16

The refrigeration apparatus as recited in claim 14, wherein said predetermined indicator of a high level of liquid refrigerant in said condenser is said predetermined thermodynamic condition occurring during a predetermined high load condition.

Claim 17

The refrigeration apparatus as recited in claim 15, wherein said predetermined high load condition is characterized by the temperature of a chilled fluid passing through said evaporator exceeding a predetermined upper temperature limit.

Claim 18

The refrigeration apparatus as recited in claim 16, wherein said predetermined high load condition is characterized by the temperature of a chilled fluid passing through said evaporator exceeding a predetermined upper temperature limit for a predetermined period.

Claim 19

The refrigeration apparatus as recited in claim 15, wherein said predetermined high load condition is characterized by a slide valve of a screw compressor reaching a predetermined position.

Claim 20

A refrigeration apparatus comprising: (a) a variable capacity compressor selectively operative in a loaded and an unloaded condition with a refrigerant flow output rate of said compressor being greater when loaded than unloaded; (b) a condenser being substantially filled with vaporous refrigerant and having a condenser outlet for discharging refrigerant in series flow through an expansion device; (c) an evaporator being substantially flooded with liquid refrigerant and including an evaporator inlet for receiving refrigerant in series flow relationship with said expansion device, said compressor, condenser, expansion device, and evaporator all being connected in series flow relationship; (d) a bypass line connected in parallel with said expansion device, said bypass line having a bypass inlet connected to said condenser at a higher elevation than said condenser outlet and having a bypass outlet connected to said evaporator; and (e) a bypass valve disposed in said bypass line, said valve opening in response to a predetermined low load condition and opening in response to a predetermined indicator of a high level of liquid refrigerant in said condenser, whereby said bypass line in conjunction with said bypass valve controls the level of liquid refrigerant in said condenser and provides a hot gas bypass during low load conditions.

Claim 21

A refrigeration apparatus comprising: (a) a variable capacity compressor selectively operative in a loaded and an unloaded condition with a refrigerant flow output rate of said compressor being greater when loaded than unloaded; (b) a condenser being substantially filled with vaporous refrigerant and having a condenser outlet for discharging refrigerant in series flow through an expansion device; (c) an evaporator being substantially flooded with liquid refrigerant and including an evaporator inlet for receiving refrigerant in series flow relationship with said expansion device, said compressor, condenser, expansion device, and evaporator all being connected in series flow relationship; (d) a bypass line connected in parallel with said expansion device, said bypass line having a bypass inlet connected to said condenser at a higher elevation than said condenser outlet and having a bypass outlet connected to said evaporator; and (e) a bypass valve disposed in said bypass line, said valve opening in response to a predetermined low load condition and opening in response to a predetermined indicator of a high level of liquid refrigerant in said condenser, whereby said bypass line in conjunction with said bypass valve controls the level of liquid refrigerant in said condenser and provides a hot gas bypass during low load conditions.

Claim 22

The refrigeration apparatus as recited in claim 19, wherein said expansion device is an orifice having a fixed opening.

Claim 23

The refrigeration apparatus as recited in claim 19, wherein said expansion device is an expansion valve having a variable opening.

Claim 24

The refrigeration apparatus as recited in claim 19, wherein said bypass valve is a two position valve having an open position and a closed position.

Claim 25

The refrigeration apparatus as recited in claim 19, wherein the extent of opening of said bypass valve is variable to provide modulated flow therethrough.

Claim 26

The refrigeration apparatus as recited in claim 19, wherein said compressor is a screw compressor having a slide valve whose position determines whether said compressor is operating loaded or unloaded.

Claim 27

The refrigeration apparatus as recited in claim 19, further comprising a compressor motor housing having a housing inlet and a housing outlet for conveying refrigerant through said housing in parallel with said bypass valve, and in series with said expansion device said housing outlet being located near the bottom of said housing to separate liquid refrigerant from vaporous refrigerant.

Claim 28

The refrigeration apparatus as recited in claim 19, wherein said predetermined low load condition is when the temperature of a chilled fluid passing through said evaporator is below a predetermined lower limit.

Claim 29

The refrigeration apparatus as recited in claim 26, wherein said predetermined low load condition is when the temperature of a chilled fluid passing through said evaporator is below a predetermined lower limit for a predetermined period.

Claim 30

The refrigeration apparatus as recited in claim 24, wherein said predetermined low load condition is when said slide valve reaches a predetermined position.

Claim 31

The refrigeration apparatus as recited in claim 19, wherein said predetermined indicator of a high level of liquid refrigerant in said condenser is the occurrence of a predetermined thermodynamic condition characteristic of a low head condition.

Claim 32

The refrigeration apparatus as recited in claim 29, wherein said predetermined indicator of a high level of liquid refrigerant in said condenser is said predetermined thermodynamic condition occurring during a predetermined high load condition.

Claim 33

The refrigeration apparatus as recited in claim 30, wherein said predetermined high load condition is characterized by the temperature of a chilled fluid pasing through said evaporator exceeding a predetermined temperature limit.

Claim 34

The refrigeration apparatus as recited in claim 31, wherein said predetermined high load condition is characterized by the temperature of a chilled fluid passing through said evaporator exceeding a predetermined temperature limit for a predetermined period.

Claim 35

The refrigeration apparatus as recited in claim 30, wherein said predetermined high load condition is characterized by a slide valve of a screw compressor reaching a predetermined position.

Claim 36

A refrigeration apparatus comprising: (a) a variable capacity screw compressor having a slide valve whose position controls said compressor to operate between a loaded and an unloaded condition, said compressor having a refrigerant flow output rate that is greater when loaded than unloaded to meet a varying temperature conditioning demand; (b) a condenser having a greater volume of vaporous refrigerant than liquid refrigerant and having a condenser outlet for discharging refrigerant in series flow through an orifice having a fixed opening; (c) a flooded evaporator having a plurality of heat exchanger tubes substantially submerged in liquid refrigerant and including an evaporator inlet for receiving refrigerant in series flow relationship with said orifice, said compressor, condenser, orifice, and evaporator all being connected in series flow relationship; (d) a bypass line connected in parallel with said orifice, said bypass line having a bypass inlet connected to said condenser at a higher elevation than said condenser outlet and having a bypass outlet connected to said evaporator; and (e) a bypass valve disposed in said bypass line, said valve opening in response to a predetermined low load condition and opening in response to a predetermined thermodynamic condition characteristic of a low head.

Claim 37

A refrigeration apparatus comprising: (a) a variable capacity screw compressor having a slide valve whose position controls said compressor to operate between a loaded and an unloaded condition, said compressor having a refrigerant flow output rate that is greater when loaded than unloaded to meet a varying temperature conditioning demand; (b) a condenser having a greater volume of vaporous refrigerant than liquid refrigerant and having a condenser outlet for discharging refrigerant in series flow through an orifice having a fixed opening; (c) a flooded evaporator having a plurality of heat exchanger tubes substantially submerged in liquid refrigerant and including an evaporator inlet for receiving refrigerant in series flow relationship with said orifice, said compressor, condenser, orifice, and evaporator all being connected in series flow relationship; (d) a bypass line connected in parallel with said orifice, said bypass line having a bypass inlet connected to said condenser at a higher elevation than said condenser outlet and having a bypass outlet connected to said evaporator; and (e) a bypass valve disposed in said bypass line, said valve opening in response to a predetermined low load condition and opening in response to a predetermined thermodynamic condition characteristic of a low head.

Claim 38

The refrigeration apparatus as recited in claim 34, wherein said predetermined thermodynamic condition characteristic of a low head is the temperature of said refrigerant in said condenser falling below a predetermined temperature limit.

Claim 39

The refrigeration apparatus as recited in claim 34, wherein said predetermined thermodynamic condition characteristic of a low head is the pressure of said refrigerant in said condenser falling below a predetermined pressure limit.

Claim 40

The refrigeration apparatus as recited in claim 34, wherein said predetermined thermodynamic condition characteristic of a low head is the temperature of a condenser coolant falling below a predetermined temperature limit.

Claim 41

The refrigeration apparatus as recited in claim 34, wherein said predetermined thermodynamic condition characteristic of a low head is a pressure differential between said condenser and said evaporator falling below a predetermined limit.

Claim 42

The refrigeration apparatus as recited in claim 34, wherein said predetermined thermodynamic condition characteristic of a low head is a temperature differential of the temperature of said vaporous refrigerant in said condenser minus the temperature of said liquid refrigerant in said evaporator falling below a predetermined limit.

Claim 43

The refrigeration apparatus as rectied in claim 34, wherein said predetermined thermodynamic condition characteristic of a low head is a temperature differential of a condenser coolant entering said condenser minus a chilled fluid leaving said evaporator falling below a predetermined limit.