Hot gas defrost system for refrigeration systems and apparatus therefor

Claim 2

A liquid refrigerant vaporizer for use in a refrigeration system employing hot refrigerant fluid to defrost a coil or coils thereof, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow area of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith; and a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage.

Claim 3

A vaporizer as claimed in claim 1, wherein the said first, second and third flow passages are of rectangular configuration in plan and side elevation, and the said first and second common walls between the respective chambers are flat.

Claim 4

A vaporizer as claimed in claim 1, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first flow passage.

Claim 5

A vaporizer as claimed in claim 3, wherein the total flow area provided by all of the said bores is between 0.9 and 1.2 times the cross-sectional flow area of the first flow passage.

Claim 6

A vaporizer as claimed in claim 1, wherein the said bores are of flow area from 8 to 18 sq.mm (0.012 to 0.028 sq.in.) and the total flow area of all of the bores is adjusted by adjustment of the number of bores.

Claim 7

A vaporizer as claimed in claim 1, wherein the cross-sectional flow area of the second flow passage is between 0.5 and 1.5 times the corresponding area of the first flow passage.

Claim 8

A vaporizer as claimed in claim 6, wherein the cross-sectional flow area of the second flow passage is between 0.9 and 1.2 times the corresponding area of the first flow passage.

Claim 9

A vaporizer as claimed in claim 1, wherein the cross-sectional flow area of the third flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge line from the compressor outlet.

Claim 10

A vaporizer as claimed in claim 8, wherein the cross-sectional flow area of the third flow passage is between 0.9 and 1.2 times the corresponding flow area of the refrigerant system discharge line from the compressor outlet.

Claim 11

A hot refrigerant fluid defrost system for use in a refrigeration system for defrost of a coil or coils thereof, the system comprising: a controllable flow valve adapted for connection to the outlet of a compressor pump to receive hot compressed refrigerant fluid therefrom; a coil to be defrosted having an inlet and an outlet; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow are of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; and a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage.

Claim 12

A hot refrigerant fluid defrost system for use in a refrigeration system for defrost of a coil or coils thereof, the system comprising: a controllable flow valve adapted for connection to the outlet of a compressor pump to receive hot compressed refrigerant fluid therefrom; a coil to be defrosted having an inlet and an outlet; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow are of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; and a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage.

Claim 13

A defrost system as claimed in claim 10, wherein the said first, second and third flow passages are of rectangular configuration in plan and side elevation, and the said first and second common walls between the respective chambers are flat.

Claim 14

A defrost system as claimed in claim 10, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first flow passage.

Claim 15

A defrost system as claimed in claim 12, wherein the total flow area provided by all of the said bores is between 0.9 and 1.2 times the cross-sectional flow area of the first flow passage.

Claim 16

A defrost system as claimed in claim 10, wherein the said bores are of flow area from 8 to 18 sq.mm (0.012 to 0.028 sq.in.) and the total flow area of all of the bores is adjusted by adjustment of the number of bores.

Claim 17

A defrost system as claimed in claim 10, wherein the cross-sectional flow area of the second flow passage is between 0.5 and 1.5 times the corresponding area of the first flow passage.

Claim 18

A defrost system as claimed in claim 15, wherein the cross-sectional flow area of the second flow passage is between 0.9 and 1.2 times the corresponding area of the first flow passage.

Claim 19

A defrost system as claimed in claim 10, wherein the cross-sectional flow area of the third flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge flow line from the compressor outlet.

Claim 20

A defrost system as claimed in claim 17, wherein the cross-sectional flow area of the third flow passage is between 0.9 and 1.2 times the corresponding flow area of the refrigerant system discharge line from the compressor outlet.

Claim 21

A defrost system as claimed in claim 10, wherein the system is incorporated in a heat pump.

Claim 22

A defrost system as claimed in claim 10, and comprising a plurality of coils to be defrosted, wherein there is provided a single vaporizer connected to all of the coil outlets to receive refrigerant therefrom.

Claim 23

A refrigeration system comprising: a refrigerant compressor; a cooling coil having an inlet and an outlet; an expansion device for expanding and cooling refrigerant connected between the compressor and the cooling coil inlet; a controllable defrost control valve connected to the compressor outlet to receive hot compressed refrigerant fluid therefrom; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow are of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; and a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage.

Claim 24

A refrigeration system comprising: a refrigerant compressor; a cooling coil having an inlet and an outlet; an expansion device for expanding and cooling refrigerant connected between the compressor and the cooling coil inlet; a controllable defrost control valve connected to the compressor outlet to receive hot compressed refrigerant fluid therefrom; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow are of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; and a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage.

Claim 25

A refrigeration system as claimed in claim 21, wherein the said first, second and third flow passages are of rectangular configuration in plan and side elevation, and the said first and second common walls between the respective chambers are flat.

Claim 26

A refrigeration system as claimed in claim 21, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first flow passage.

Claim 27

A refrigeration system as claimed in claim 23, wherein the total flow area provided by all of the said bores is between 0.9 and 1.2 times the cross-sectional flow area of the first flow passage.

Claim 28

A refrigeration system as claimed in claim 21, wherein the said bores are of flow area from 8 to 18 sq.mm (0.012 to 0.028 sq.in.) and the total flow area of all of the bores is adjusted by adjustment of the number of bores.

Claim 29

A refrigeration system as claimed in claim 21, wherein the cross-sectional flow area of the second flow passage is between 0.5 and 1.5 times the corresponding area of the first flow passage.

Claim 30

A refrigeration system as claimed in claim 26, wherein the cross-sectional flow area of the second flow passage is between 0.9 and 1.2 times the corresponding area of the first flow passage.

Claim 31

A refrigeration system as claimed in claim 21, wherein the cross-sectional flow area of the third annular flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge flow line from the compressor outlet.

Claim 32

A refrigeration system as claimed in claim 28, wherein the cross-sectional flow area of the third annular flow passage is between 0.9 and 1.2 times the corresponding flow area of the refrigerant system discharge line from the compressor outlet.

Claim 33

A refrigeration system as claimed in claim 21 and incorporated into a heat pump.

Claim 34

A refrigeration system as claimed in claim 21, and comprising a plurality of coils to be defrosted, wherein there is provided a single vaporizer connected to all of the coil outlets to receive refrigerant therefrom.

Claim 35

A liquid refrigerant vaporizer for use in a refrigeration system employing hot refrigerant fluid to defrost a coil or coils thereof, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow area of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith; a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 36

A liquid refrigerant vaporizer for use in a refrigeration system employing hot refrigerant fluid to defrost a coil or coils thereof, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow area of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith; a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 37

A vaporizer as claimed in claim 32, wherein the said first, second and third flow passages are of rectangular configuration in plan and side elevation, and the said first and second common walls between the respective chambers are flat.

Claim 38

A vaporizer as claimed in claim 32, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first flow passage.

Claim 39

A vaporizer as claimed in claim 34, wherein the total flow area provided by all of the said bores is between 0.9 and 1.2 times the cross-sectional flow area of the first flow passage.

Claim 40

A vaporizer as claimed in claim 32, wherein the said bores are of flow area from 8 to 18 sq.mm (0.012 to 0.028 sq.in.) and the total flow area of all of the bores is adjusted by adjustment of the number of bores.

Claim 41

A vaporizer as claimed in claim 32, wherein the cross-sectional flow area of the second flow passage is between 0.5 and 1.5 times the corresponding area of the first flow passage.

Claim 42

A vaporizer as claimed in claim 37, wherein the cross-sectional flow area of the second flow passage is between 0.9 and 1.2 times the corresponding area of the first flow passage.

Claim 43

A vaporizer as claimed in claim 32, wherein the cross-sectional flow area of the third flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge line from the compressor outlet.

Claim 44

A vaporizer as claimed in claim 39, wherein the cross-sectional flow area of the third flow passage is between 0.9 and 1.2 times the corresponding flow area of the refrigerant system discharge line from the compressor outlet.

Claim 45

A hot refrigerant fluid defrost system for use in a refrigeration system for defrost of a coil or coils thereof, the system comprising: a controllable flow valve adapted for connection to the outlet of a compressor pump to receive hot compressed refrigerant fluid therefrom; a coil to be defrosted having an inlet and an outlet; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow are of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 46

A hot refrigerant fluid defrost system for use in a refrigeration system for defrost of a coil or coils thereof, the system comprising: a controllable flow valve adapted for connection to the outlet of a compressor pump to receive hot compressed refrigerant fluid therefrom; a coil to be defrosted having an inlet and an outlet; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow are of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 47

A defrost system as claimed in claim 41, wherein the said first, second and third flow passages are of rectangular configuration in plan and side elevation, and the said first and second common walls between the respective chambers are flat.

Claim 48

A defrost system as claimed in claim 41, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first flow passage.

Claim 49

A defrost system as claimed in claim 43, wherein the total flow area provided by all of the said bores is between 0.9 and 1.2 times the cross-sectional flow area of the first flow passage.

Claim 50

A defrost system as claimed in claim 41, wherein the said bores are of flow area from 8 to 18 sq.mm (0.012 to 0.028 sq.in.) and the total flow area of all of the bores is adjusted by adjustment of the number of bores.

Claim 51

A defrost system as claimed in claim 41, wherein the cross-sectional flow area of the second flow passage is between 0.5 and 1.5 times the corresponding area of the first flow passage.

Claim 52

A defrost system as claimed in claim 46, wherein the cross-sectional flow area of the second flow passage is between 0.9 and 1.2 times the corresponding area of the first flow passage.

Claim 53

A defrost system as claimed in claim 41, wherein the cross-sectional flow area of the third flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge flow line from the compressor outlet.

Claim 54

A defrost system as claimed in claim 48, wherein the cross-sectional flow area of the third flow passage is between 0.9 and 1.2 times the corresponding flow area of the refrigerant system discharge line from the compressor outlet.

Claim 55

A defrost system as claimed in claim 41, wherein the system is incorporated in a heat pump.

Claim 56

A defrost system as claimed in claim 41, and comprising a plurality of coils to be defrosted, wherein there is provided a single vaporizer connected to all of the coil outlets to receive refrigerant therefrom.

Claim 57

A refrigeration system comprising: a refrigerant compressor; a cooling coil having an inlet and an outlet; an expansion device for expanding and cooling refrigerant connected between the compressor and the cooling coil inlet; a controllable defrost control valve connected to the compressor outlet to receive hot compressed refrigerant fluid therefrom; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow are of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 58

A refrigeration system comprising: a refrigerant compressor; a cooling coil having an inlet and an outlet; an expansion device for expanding and cooling refrigerant connected between the compressor and the cooling coil inlet; a controllable defrost control valve connected to the compressor outlet to receive hot compressed refrigerant fluid therefrom; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising: first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow are of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; a refrigerant fluid flow restriction at or connected to the third flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 59

A refrigeration system as claimed in claim 52, wherein the said first, second and third flow passages are of rectangular configuration in plan and side elevation, and the said first and second common walls between the respective chambers are flat.

Claim 60

A refrigeration system as claimed in claim 52, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first flow passage.

Claim 61

A refrigeration system as claimed in claim 54, wherein the total flow area provided by all of the said bores is between 0.9 and 1.2 times the cross-sectional flow area of the first flow passage.

Claim 62

A refrigeration system as claimed in claim 52, wherein the said bores are of flow area from 8 to 18 sq.mm (0.012 to 0.028 sq.in.) and the total flow area of all of the bores is adjusted by adjustment of the number of bores.

Claim 63

A refrigeration system as claimed in claim 52, wherein the cross-sectional flow area of the second flow passage is between 0.5 and 1.5 times the corresponding area of the first flow passage.

Claim 64

A refrigeration system as claimed in claim 57, wherein the cross-sectional flow area of the second flow passage is between 0.9 and 1.2 times the corresponding area of the first flow passage.

Claim 65

A refrigeration system as claimed in claim 52, wherein the cross-sectional flow area of the third annular flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge flow line from the compressor outlet.

Claim 66

A refrigeration system as claimed in claim 59, wherein the cross-sectional flow area of the third annular flow passage is between 0.9 and 1.2 times the corresponding flow area of the refrigerant system discharge line from the compressor outlet.

Claim 67

A refrigeration system as claimed in claim 52 and incorporated into a heat pump.

Claim 68

A refrigeration system as claimed in claim 52, and comprising a plurality of coils to be defrosted, wherein there is provided a single vaporizer connected to all of the coil outlets to receive refrigerant therefrom.

Claim 69

A liquid refrigerant vaporizer for use in a refrigeration system employing hot refrigerant fluid to defrost a coil or coils thereof, the vaporizer comprising: first inner, second middle and third outer pipes mounted one within the other to provide a first inner flow passage in the first inner pipe, a second annular flow passage between the first inner and second middle pipes, and a third annular flow passage between the second middle and third outer pipes; wherein the first inner pipe is adapted for connection at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in its wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the inner wall of the second middle pipe for heat exchange therewith; wherein the total flow area provided by all of the said bores is at least 0.5 times the cross-sectional flow area of the first inner flow passage; wherein the second middle pipe is of heat conductive material, the second annular flow passage is closed at one end and is adapted for connection at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second annular flow passage is at least 0.5 times the cross-sectional flow are of the first inner flow passage; and wherein the third annular flow passage has an inlet thereto and an outlet therefrom for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the outer wall of the second middle pipe for vaporization thereby; a refrigerant fluid flow restriction at or connected to the third annular flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second annular flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 70

A liquid refrigerant vaporizer for use in a refrigeration system employing hot refrigerant fluid to defrost a coil or coils thereof, the vaporizer comprising: first inner, second middle and third outer pipes mounted one within the other to provide a first inner flow passage in the first inner pipe, a second annular flow passage between the first inner and second middle pipes, and a third annular flow passage between the second middle and third outer pipes; wherein the first inner pipe is adapted for connection at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil under defrost, is closed at the other end, and is provided in its wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the inner wall of the second middle pipe for heat exchange therewith; wherein the total flow area provided by all of the said bores is at least 0.5 times the cross-sectional flow area of the first inner flow passage; wherein the second middle pipe is of heat conductive material, the second annular flow passage is closed at one end and is adapted for connection at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second annular flow passage is at least 0.5 times the cross-sectional flow are of the first inner flow passage; and wherein the third annular flow passage has an inlet thereto and an outlet therefrom for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the outer wall of the second middle pipe for vaporization thereby; a refrigerant fluid flow restriction at or connected to the third annular flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the second annular flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 71

A refrigerant vaporizer as claimed in claim 63, wherein the expansion chamber comprises a piece of pipe of between 1.5 and 3 times the diameter of the hot gas line in which it is connected.

Claim 72

A refrigerant vaporizer as claimed in claim 63, wherein the increase in back pressure produced by the fluid flow restriction is between 20% and 70% of the pressure in the absence of the fluid flow restriction.

Claim 73

A refrigerant vaporizer as claimed in claim 63, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first annular flow passage.

Claim 74

A refrigerant vaporizer as claimed in claim 66, wherein the total flow area provided by all of the said bores is between 0.9 and 1.2 times the cross-sectional flow area of the first inner flow passage.

Claim 75

A refrigerant vaporizer as claimed in claim 63, wherein the first, second and third pipes are all of circular cross-section and are concentric with one another.

Claim 76

A refrigerant vaporizer as claimed in claim 63, wherein the said bores are of flow area from 8 to 18 sq.mm (0.012 to 0.028 sq.in.) and the total flow area of all of the bores is adjusted by adjustment of the number of bores.

Claim 77

A refrigerant vaporizer as claimed in claim 63, wherein the fluid flow restrictor is directly attached to the third outer pipe at the outlet therefrom, and the expansion chamber is directly attached to the fluid flow restrictor.

Claim 78

A refrigerant vaporizer as claimed in claim 63, wherein the cross-sectional flow area of the second annular flow passage is between 0.5 and 1.5 times the corresponding area of the first innermost flow passage.

Claim 79

A refrigerant vaporizer as claimed in claim 71, wherein the cross-sectional flow area of the second annular flow passage is between 0.9 and 1.2 times the corresponding area of the first innermost flow passage.

Claim 80

A refrigerant vaporizer as claimed in claim 63, wherein the cross-sectional flow area of the third outermost annular flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system dischargeline from the compressor outlet.

Claim 81

A refrigerant vaporizer as claimed in claim 72, wherein the cross-sectional flow area of the third outermost annular flow passage is between 0.9 and 1.2 times the corresponding flow area of the refrigerant system dischargeline from the compressor outlet.

Claim 82

A hot refrigerant fluid defrost system for use in a refrigeration system for defrost of a coil or coils thereof, the system comprising: a controllable flow valve adapted for connection to the outlet of a compressor pump to receive hot compressed refrigerant fluid therefrom; a coil to be defrosted having an inlet and an outlet; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising first inner, second middle and third outer pipes mounted one within the other to provide a first inner flow passage in the first inner pipe, a second annular flow passage between the first inner and second middle pipes, and a third annular flow passage between the second middle and third outer pipes; wherein the first inner pipe is adapted for connection at one end to the coil outlet so as to receive the fluid exiting from the coil, is closed at the other end, and is provided in its wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the inner wall of the second middle pipe for vaporization thereby; wherein the total flow area provided by all of the said bores is between 0.5 and 1.5 times the cross-sectional flow area of the first inner flow passage; wherein the second middle pipe is of heat conductive material, the first annular flow passage is closed at one end and is adapted for connection at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second annular flow passage is at least 0.5 times the cross-sectional flow are of the first inner flow passage; and wherein the third annular flow passage has an inlet thereto and an outlet therefrom for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the outer wall of the second middle pipe for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; a refrigerant fluid flow restriction at or connected to the third annular flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the third annular flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 83

A hot refrigerant fluid defrost system for use in a refrigeration system for defrost of a coil or coils thereof, the system comprising: a controllable flow valve adapted for connection to the outlet of a compressor pump to receive hot compressed refrigerant fluid therefrom; a coil to be defrosted having an inlet and an outlet; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising first inner, second middle and third outer pipes mounted one within the other to provide a first inner flow passage in the first inner pipe, a second annular flow passage between the first inner and second middle pipes, and a third annular flow passage between the second middle and third outer pipes; wherein the first inner pipe is adapted for connection at one end to the coil outlet so as to receive the fluid exiting from the coil, is closed at the other end, and is provided in its wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the inner wall of the second middle pipe for vaporization thereby; wherein the total flow area provided by all of the said bores is between 0.5 and 1.5 times the cross-sectional flow area of the first inner flow passage; wherein the second middle pipe is of heat conductive material, the first annular flow passage is closed at one end and is adapted for connection at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second annular flow passage is at least 0.5 times the cross-sectional flow are of the first inner flow passage; and wherein the third annular flow passage has an inlet thereto and an outlet therefrom for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the outer wall of the second middle pipe for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; a refrigerant fluid flow restriction at or connected to the third annular flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the third annular flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 84

A system as claimed in claim 75, wherein the expansion chamber comprises a piece of pipe of between 1.5 and 3 times the diameter of the hot gas line in which it is connected.

Claim 85

A system as claimed in claim 75, wherein the increase in back pressure produced by the fluid flow restriction is between 20% and 70% of the pressure in the absence of the fluid flow restriction.

Claim 86

A system as claimed in claim 75, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first annular flow passage.

Claim 87

A system as claimed in claim 78, wherein the total flow area provided by all of the said bores is between 0.9 and 1.2 times the cross-sectional flow area of the first inner flow passage.

Claim 88

A system as claimed in claim 75, wherein the said bores are of flow area from 8 to 18 sq.mm (0.012 to 0.028 sq.in.) and the total flow area of all of the bores is adjusted by adjustment of the number of bores.

Claim 89

A system as claimed in claim 75, wherein the first, second and third pipes are all of circular cross-section and are concentric with one another.

Claim 90

A system as claimed in claim 75, wherein the fluid flow restrictor is directly attached to the third outer pipe at the outlet therefrom, and the expansion chamber is directly attached to the fluid flow restrictor.

Claim 91

A system as claimed in claim 75, wherein the cross-sectional flow area of the second annular flow passage is between 0.5 and 1.5 times the corresponding area of the first innermost flow passage.

Claim 92

A system as claimed in claim 83, wherein the cross-sectional flow area of the second annular flow passage is between 0.9 and 1.2 times the corresponding area of the first innermost flow passage.

Claim 93

A system as claimed in claim 75, wherein the cross-sectional flow area of the third outer annular flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge flow line from the compressor outlet.

Claim 94

A system as claimed in claim 85, wherein the cross-sectional flow area of the third outermost annular flow passage is between 0.9 and 1.2 times the corresponding flow area of the refrigerant system dischargeline from the compressor outlet.

Claim 95

A system as claimed in claim 75, wherein the refrigeration system is incorporated in a heat pump.

Claim 96

A system as claimed in claim 75, and comprising a plurality of coils to be defrosted, wherein there is provided a single vaporizer connected to all of the coil outlets to receive refrigerant therefrom.

Claim 97

A refrigeration system comprising: a refrigerant compressor; a cooling coil having an inlet and an outlet; an expansion device for expanding and cooling refrigerant connected between the compressor and the cooling coil inlet; a controllable defrost control valve connected to the compressor outlet to receive hot compressed refrigerant fluid therefrom; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising first inner, second middle and third outer pipes mounted one within the other to provide a first innermost flow passage in the first inner pipe, a second annular flow passage between the first inner and second middle pipes, and a third annular flow passage between the second middle and third outer pipes; wherein the first inner pipe is adapted for connection at one end to the coil outlet so as to receive the fluid exiting from the coil, is closed at the other end, and is provided in its wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the inner wall of the second middle pipe for vaporization thereby; wherein the total flow area provided by all of the said bores is between 0.5 and 1.5 times the cross-sectional flow area of the first inner flow passage; wherein the second middle pipe is of heat conductive material, the first annular flow passage is closed at one end and is adapted for connection at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second annular flow passage is at least 0.5 times the cross-sectional flow area of the first inner flow passage; and wherein the third annular flow passage has an inlet thereto and an outlet therefrom for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the outer wall of the second middle pipe for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; a refrigerant fluid flow restriction at or connected to the third annular flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the third annular flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 98

A refrigeration system comprising: a refrigerant compressor; a cooling coil having an inlet and an outlet; an expansion device for expanding and cooling refrigerant connected between the compressor and the cooling coil inlet; a controllable defrost control valve connected to the compressor outlet to receive hot compressed refrigerant fluid therefrom; and a liquid refrigerant vaporizer connected to the coil for vaporizing liquid fluid issuing from the coil outlet to prevent its delivery to the compressor inlet, the vaporizer comprising first inner, second middle and third outer pipes mounted one within the other to provide a first innermost flow passage in the first inner pipe, a second annular flow passage between the first inner and second middle pipes, and a third annular flow passage between the second middle and third outer pipes; wherein the first inner pipe is adapted for connection at one end to the coil outlet so as to receive the fluid exiting from the coil, is closed at the other end, and is provided in its wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the inner wall of the second middle pipe for vaporization thereby; wherein the total flow area provided by all of the said bores is between 0.5 and 1.5 times the cross-sectional flow area of the first inner flow passage; wherein the second middle pipe is of heat conductive material, the first annular flow passage is closed at one end and is adapted for connection at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second annular flow passage is at least 0.5 times the cross-sectional flow area of the first inner flow passage; and wherein the third annular flow passage has an inlet thereto and an outlet therefrom for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the outer wall of the second middle pipe for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlet for delivery of the fluid thereto; a refrigerant fluid flow restriction at or connected to the third annular flow passage outlet for producing an increase in back pressure of the refrigerant fluid in the third annular flow passage; and an expansion chamber connected to the outlet of the flow restriction immediately downstream thereof for re-evaporation of liquid refrigerant that has passed through the flow restriction.

Claim 99

A system as claimed in claim 89, wherein the expansion chamber comprises a piece of pipe of between 1.5 and 3 times the diameter of the hot gas line in which it is connected.

Claim 100

A system as claimed in claim 89, wherein the increase in back pressure produced by the fluid flow restriction is between 20% and 70% of the pressure in the absence of the fluid flow restriction.

Claim 101

A system as claimed in claim 89, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first annular flow passage.

Claim 102

A system as claimed in claim 92, wherein the total flow area provided by all of the said bores is between 0.9 and 1.2 times the cross-sectional flow area of the first inner flow passage.

Claim 103

A system as claimed in claim 89, wherein the first, second and third pipes are all of circular cross-section and are concentric with one another.

Claim 104

A system as claimed in claim 89, wherein the said bores are of flow area from 8 to 18 sq.mm (0.012 to 0.028 sq.in.) and the total flow area of all of the bores is adjusted by adjustment of the number of bores.

Claim 105

A system as claimed in claim 89, wherein the fluid flow restrictor is directly attached to the third outer pipe at the outlet therefrom.

Claim 106

A system as claimed in claim 89, wherein the cross-sectional flow area of the second annular flow passage is between 0.5 and 1.5 times the corresponding area of the first innermost flow passage.

Claim 107

A system as claimed in claim 97, wherein the cross-sectional flow area of the second annular flow passage is between 0.9 and 1.2 times the corresponding area of the first innermost flow passage.

Claim 108

A system as claimed in claim 89, wherein the cross-sectional flow area of the third outermost annular flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge flow line from the compressor outlet.

Claim 109

A system as claimed in claim 99, wherein the cross-sectional flow area of the third outermost annular flow passage is between 0.9 and 1.2 times the corresponding flow area of the refrigerant system dischargeline from the compressor outlet.

Claim 110

A refrigeration system as claimed in claim 89 and incorporated into a heat pump.

Claim 111

A system as claimed in claim 89, and comprising a plurality of coils to be defrosted, wherein there is provided a single vaporizer connected to all of the coil outlets to receive refrigerant therefrom.

Claim 112

A hot refrigerant fluid defrost system for use in a refrigeration system including a plurality of parallel-connected cooling coils to be defrosted, each coil having an inlet and an outlet; the system comprising: a controllable flow valve adapted for connection to the outlet of a compressor pump to receive hot compressed refrigerant fluid therefrom; the plurality of parallel-connected cooling coils and a liquid refrigerant vaporizer connected to the coil outlets for vaporizing liquid fluid issuing therefrom to prevent its delivery to the compressor inlet, the vaporizer comprising first inner, second middle and third outer pipes mounted one within the other to provide a first inner flow passage in the first inner pipe, a second annular flow passage between the first inner and a second middle pipes, and a third annular flow passage between the second middle and third outer pipes; wherein the first inner pipe is adapted for connection at one end to the coil outlets so as to receive the fluid exiting from the coils, is closed at the other end, and is provided in its wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the inner wall of the second middle pipe for heat exchange therewith; wherein the total flow area provided by all of the said bores is between 0.5 and 1.5 times the cross-sectional flow area of the first inner flow passage; wherein the second middle pipe is of heat conductive material, the first annular flow passage is closed at one end and is adapted for connection at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second annular flow passage is at least 0.5 times the cross-sectional flow area of the first inner flow passage; and wherein the third annular flow passage has an inlet thereto and an outlet therefrom for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the outer wall of the second middle pipe for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlets for delivery of the fluid thereto; and a corresponding plurality of refrigerant fluid flow restrictions of controllable flow capacity, one for each of said plurality of coils, each connected between the inlet of its respective coil and the third annular flow passage outlet, the restriction producing an increase in back pressure of the refrigerant fluid in the third annular flow passage.

Claim 113

A hot refrigerant fluid defrost system for use in a refrigeration system including a plurality of parallel-connected cooling coils to be defrosted, each coil having an inlet and an outlet; the system comprising: a controllable flow valve adapted for connection to the outlet of a compressor pump to receive hot compressed refrigerant fluid therefrom; the plurality of parallel-connected cooling coils and a liquid refrigerant vaporizer connected to the coil outlets for vaporizing liquid fluid issuing therefrom to prevent its delivery to the compressor inlet, the vaporizer comprising first inner, second middle and third outer pipes mounted one within the other to provide a first inner flow passage in the first inner pipe, a second annular flow passage between the first inner and a second middle pipes, and a third annular flow passage between the second middle and third outer pipes; wherein the first inner pipe is adapted for connection at one end to the coil outlets so as to receive the fluid exiting from the coils, is closed at the other end, and is provided in its wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the inner wall of the second middle pipe for heat exchange therewith; wherein the total flow area provided by all of the said bores is between 0.5 and 1.5 times the cross-sectional flow area of the first inner flow passage; wherein the second middle pipe is of heat conductive material, the first annular flow passage is closed at one end and is adapted for connection at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second annular flow passage is at least 0.5 times the cross-sectional flow area of the first inner flow passage; and wherein the third annular flow passage has an inlet thereto and an outlet therefrom for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the outer wall of the second middle pipe for heat exchange therewith, the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlets for delivery of the fluid thereto; and a corresponding plurality of refrigerant fluid flow restrictions of controllable flow capacity, one for each of said plurality of coils, each connected between the inlet of its respective coil and the third annular flow passage outlet, the restriction producing an increase in back pressure of the refrigerant fluid in the third annular flow passage.

Claim 114

A system as claimed in claim 103, wherein the increase in back pressure produced by the said fluid flow restrictions is between 20% and 70% of the pressure in the absence of the fluid flow restriction.

Claim 115

A system as claimed in claim 104, wherein the increase in back pressure produced by the said fluid flow restrictions is between 40% and 60% of the pressure in the absence of the fluid flow restriction.

Claim 116

A system as claimed in claim 103, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first annular flow passage.

Claim 117

A system as claimed in claim 103, wherein the cross-sectional flow area of the second annular flow passage is between 0.5 and 1.5 times the corresponding area of the first innermost flow passage.

Claim 118

A system as claimed in claim 103, wherein the cross-sectional flow area of the third outer annular flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge flow line from the compressor outlet.

Claim 119

A refrigeration system comprising: a refrigerant compressor; a plurality of parallel-connected cooling coils to be defrosted, each having an inlet and an outlet; an expansion device for expanding and cooling refrigerant connected between the compressor and the cooling coil inlets; a controllable defrost control valve connected to the compressor outlet to receive hot compressed refrigerant fluid therefrom; and a liquid refrigerant vaporizer connected to the coil outlets for vaporizing liquid fluid issuing therefrom to prevent its delivery to the compressor inlet, the vaporizer comprising first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil outlets, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow area of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith; the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlets for delivery of the fluid thereto; and a corresponding plurality of refrigerant fluid flow restrictions of controllable flow capacity, one for each of said plurality of coils, each connected between the inlet of its respective coil and the third annular flow passage outlet, the restrictions producing an increase in back pressure of the refrigerant fluid in the third annular flow passage.

Claim 120

A refrigeration system comprising: a refrigerant compressor; a plurality of parallel-connected cooling coils to be defrosted, each having an inlet and an outlet; an expansion device for expanding and cooling refrigerant connected between the compressor and the cooling coil inlets; a controllable defrost control valve connected to the compressor outlet to receive hot compressed refrigerant fluid therefrom; and a liquid refrigerant vaporizer connected to the coil outlets for vaporizing liquid fluid issuing therefrom to prevent its delivery to the compressor inlet, the vaporizer comprising first, second and third chambers the interiors of which constitute respective first, second and third flow passages, the first and second passages having a first wall in common and the second and third passages having a second wall in common; wherein the first flow passage is connected at one end into the refrigeration system so as to receive refrigerant fluid exiting from the coil outlets, is closed at the other end, and is provided in the said first common wall with a plurality of bores distributed along its length so that the refrigerant fluid flowing therein exits therefrom through the bores to impinge against the said second common wall for heat exchange therewith; the total flow area provided by all of the said bores being at least 0.5 times the cross-sectional flow area of the first flow passage; wherein the said second common wall is of heat conductive material, the second flow passage is closed at one end and is connected at its other end into the refrigeration system for delivery of the refrigerant fluid therefrom; wherein the cross-sectional flow area of the said second flow passage is at least 0.5 times the cross-sectional flow area of the first flow passage; and wherein the third flow passage has an inlet thereto and an outlet therefrom to the remainder of the refrigeration system for the hot refrigerant fluid, the inlet and the outlet being spaced from one another for the hot refrigerant fluid to contact the said second common wall for heat exchange therewith; the inlet being connected to the said controllable flow valve for the flow therethrough to be controlled by the valve, and the outlet being connected to the coil inlets for delivery of the fluid thereto; and a corresponding plurality of refrigerant fluid flow restrictions of controllable flow capacity, one for each of said plurality of coils, each connected between the inlet of its respective coil and the third annular flow passage outlet, the restrictions producing an increase in back pressure of the refrigerant fluid in the third annular flow passage.

Claim 121

A system as claimed in claim 109, wherein the increase in back pressure produced by the same fluid flow restrictions is between 20% and 70% of the pressure in the absence of the fluid flow restriction.

Claim 122

A system as claimed in claim 110, wherein the increase in back pressure produced by the said fluid flow restrictions is between 40% and 60% of the pressure in the absence of the fluid flow restriction.

Claim 123

A system as claimed in claim 109, wherein the total flow area provided by all of the bores is not more than 1.5 times the cross-sectional flow area of the first annular flow passage.

Claim 124

A system as claimed in claim 109, wherein the cross-sectional flow area of the second annular flow passage is between 0.5 and 1.5 times the corresponding area of the first innermost flow passage.

Claim 125

A system as claimed in claim 109, wherein the cross-sectional flow area of the third outermost annular flow passage is between 0.5 and 1.5 times the corresponding flow area of the refrigerant system discharge flow line from the compressor outlet.

Claim 126

A system as claimed in claim 109, wherein the said first, second and third flow passages are of rectangular configuration in plan and side elevation, and the said first and second common walls between the respective chambers are flat.

Claim 127

A system as claimed in claim 109, wherein the said first, second and third flow passages are constituted by respective concentric pipes of circular cross-section.