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 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; 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 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 area of the first inner flow passage; 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; and 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.

Claim 3

A refrigerant vaporizer as claimed in claim 1, 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 4

A refrigerant vaporizer as claimed in claim 2, wherein the increase in back pressure produced by the fluid flow restriction is between 40% and 60% of the pressure in the absence of the fluid flow restriction.

Claim 5

A refrigerant 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 annular flow passage.

Claim 6

A refrigerant vaporizer as claimed in claim 4, 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 7

A refrigerant vaporizer as claimed in claim 1, wherein the first, second and third pipes are all of circular cross-section and are concentric with one another.

Claim 8

A refrigerant 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 9

A refrigerant vaporizer as claimed in claim 1, wherein the fluid flow restrictor is directly attached to the third outer pipe at the outlet therefrom.

Claim 10

A refrigerant vaporizer as claimed in claim 1, 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 11

A refrigerant vaporizer as claimed in claim 9, 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 12

A refrigerant vaporizer as claimed in claim 1, 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 13

A refrigerant vaporizer as claimed in claim 11, 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 14

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 heat exchange therewith; the total flow area provided by all of the said bores being 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; 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 oute 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; and 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.

Claim 15

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 heat exchange therewith; the total flow area provided by all of the said bores being 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; 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 oute 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; and 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.

Claim 16

A system as claimed in claim 13, 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 17

A refrigerant vaporizer as claimed in claim 14, wherein the increase in back pressure produced by the fluid flow restriction is between 40% and 60% of the pressure in the absence of the fluid flow restriction.

Claim 18

A refrigerant vaporizer as claimed in claim 13, 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 19

A refrigerant vaporizer as claimed in claim 16, 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 20

A system as claimed in claim 12, 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 21

A system as claimed in claim 13, wherein the first, second and third pipes are all of circular cross-section and are concentric with one another.

Claim 22

A system as claimed in claim 13, wherein the fluid flow restrictor is directly attached to the third outer pipe at the outlet therefrom.

Claim 23

A system as claimed in claim 13, 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 24

A refrigerant vaporizer as claimed in claim 21, 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 25

A system as claimed in claim 13, 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 26

A refrigerant vaporizer as claimed in claim 23, 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 27

A system as claimed in claim 13, wherein the refrigeration system is incorporated in a heat pump.

Claim 28

A system as claimed in claim 13, 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 29

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 heat exchange therewith; the total flow area provided by all of the said bores being 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 third annular flow passage is at least 0.5 times the cross-sectional flow area of the first inner flow passage; 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 oute 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; and 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.

Claim 30

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 heat exchange therewith; the total flow area provided by all of the said bores being 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 third annular flow passage is at least 0.5 times the cross-sectional flow area of the first inner flow passage; 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 oute 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; and 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.

Claim 31

A system as claimed in claim 27, 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 32

A refrigerant vaporizer as claimed in claim 28, wherein the increase in back pressure produced by the fluid flow restriction is betweein 40% and 60% of the pressure in the absence of the fluid flow restriction.

Claim 33

A refrigerant vaporizer as claimed in claim 27, 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 34

A refrigerant vaporizer as claimed in claim 30, 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 35

A system as claimed in claim 27, wherein the first, second and third pipes are all of circular cross-section and are concentric with one another.

Claim 36

A system as claimed in claim 27, 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 37

A system as claimed in claim 27, wherein the fluid flow restrictor is directly attached to the third outer pipe at the outlet therefrom.

Claim 38

A system as claimed in claim 27, 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 39

A refrigerant vaporizer as claimed in claim 35, wherein the cross-sectional flow area of the second annular flow passage is between 0.9 and 1.2times the corresponding area of the first innermost flow passage.

Claim 40

A system as claimed in claim 27, 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 41

A refigerant vaporizer as claimed in claim 37, 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 42

A refrigeration system as claimed in claim 27 and incorporated into a heat pump.

Claim 43

A system as claimed in claim 27, 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.