US20020095944A1 - Alternate path for refrigerant flow on a split system icemaker - Google Patents

Abstract

An ice-making machine and method that uses an accumulator to accumulate liquefied refrigerant when warm gasified refrigerant is supplied to the evaporator after a freeze cycle. During a harvest cycle, a set of valves operates to bypass the condenser and direct the discharged gasified refrigerant from the compressor through the accumulator and then to the evaporator. The warm gasified refrigerant converts the liquefied refrigerant to gaseous refrigerant. This enhances the suction pressure to the compressor during the next ensuing freeze cycle, thereby increasing the efficiency of the accumulator.

Description

RELATED APPLICATION
• This Application claims the benefit of U.S. Provisional Application No. 60/261,449, filed Jan. 12, 2001.[0001]
FIELD OF THE INVENTION
• This invention relates to a method and system that converts liquid refrigerant to a gas after a freeze cycle in an ice-making machine.[0002]
BACKGROUND OF THE INVENTION
• Ice-making machines generally include an evaporator, a refrigerant supply, a water supply and an ice bin. During a freeze cycle, the evaporator is cooled by liquid refrigerant provided by the refrigerant supply so as to form ice cubes from water provided by the water supply. During a subsequent harvest cycle, the evaporator is warmed by hot gas that is provided by the refrigerant supply to free the ice cubes, which then fall into the ice bin. The refrigerant supply includes a compressor, a condenser and valving connected in a refrigerant circuit with the evaporator. During the harvest cycle, the valving connects the compressor and evaporator via a bypass circuit that bypasses the condenser so as to supply the refrigerant in a gaseous state to warm the evaporator.[0003]
• As the freeze cycle ends and the harvest cycle begins, the liquefied refrigerant is partially warmed by the hot gas, but is still partly liquid as it is forced by the hot gas out of the evaporator to the compressor. This results in the compressor trying to compress the liquefied refrigerant, which is a task that it is not designed to handle. U.S. Pat. No. 5,105,632 describes one solution to this problem that involves the insertion of a pump down cycle between the freeze cycle and the harvest cycle. During the pump down cycle, the hot gas is circulated through the compressor and evaporator for a time sufficient to vaporize the refrigerant.[0004]
• Another solution to the aforementioned problem is to provide an accumulator between the evaporator and the compressor. The accumulator collects any liquefied refrigerant and passes only vaporized refrigerant onto the compressor. The accumulator is constructed to have a dip tube that includes a sized orifice, which serves as an oil return to the compressor. In a split system, in which a considerable distance separates the evaporator and the compressor, it is possible for larger amounts of refrigerant to be directed to the compressor during the harvest cycle. To accommodate the additional volume, the orifice is increased in size.[0005]
• Liquid refrigerant contained in the accumulator must be converted to gas. During the harvest cycle, hot refrigerant gas flowing into the evaporator continues on to the accumulator. However, the amount of heat contained in the refrigerant gas during the harvest cycle is insufficient to convert the liquid refrigerant in the accumulator to gas. Moreover, the harvest cycle has a short duration that has two negative effects. First, the heat removal ability of the compressor is greatly reduced during the beginning of the ensuing freeze cycle. This extends the freeze cycle, thereby reducing the daily production capacity of the ice-making machine. Second, liquid return to the compressor can be harmful over longer periods of time.[0006]
• There is a need to overcome the problem of converting liquid refrigerant to gaseous refrigerant during a harvest cycle.[0007]
SUMMARY OF THE INVENTION
• The method of the present invention supplies liquefied refrigerant to an evaporator during a freeze cycle and accumulates liquefied refrigerant during a subsequent cycle. Gasified refrigerant is supplied to the accumulator and to the evaporator during the subsequent cycle so as to warm the accumulated refrigerant and thereby assist in its conversion to a gaseous state and satisfy the aforementioned need.[0008]
• The ice-making machine of the present invention includes an evaporator, an accumulator, a compressor, a bypass line and a condenser connected in a circuit to supply liquefied refrigerant to the evaporator during a freeze cycle and gasified refrigerant to the evaporator during a subsequent cycle. The bypass line passes through the accumulator, which accumulates liquefied refrigerant during the subsequent cycle. A valve means connects the bypass line in the circuit during the subsequent cycle so that the gasified refrigerant bypasses the condenser and passes through the accumulator to thereby warm the accumulated liquefied refrigerant and assist in converting it to a gaseous state.[0009]
BRIEF DESCRIPTION OF THE DRAWINGS
• Other and further objects, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure and:[0010]
• FIG. 1 is a block diagram of an ice-making machine of the present invention; and[0011]
• FIG. 2 is a schematic diagram of the refrigerant supply of the ice-making machine of FIG. 1.[0012]
DESCRIPTION OF THE PREFERRED EMBODIMENT
• Referring to FIG. 1, an ice-making machine[0013]20 includes anevaporator22, awater supply24, arefrigerant supply26, anice bin28 and acontroller30.Controller30 controlswater supply24 andrefrigerant supply26 to produce ice forms, such as cubes or other shapes, during a freeze cycle, to harvest the ice forms during a harvest cycle as well as during other cycles used in ice making machinery. Thus, refrigerant supply26 supplies liquid refrigerant to coolevaporator22 during a freeze cycle. Water supply provides water to the cooled evaporator so as to produce the ice forms. During the harvest cycle, the refrigerant supply26 supplies a gasified refrigerant that warmsevaporator22, thereby freeing the ice forms, which fall intoice bin28.
• Referring to FIG. 2,[0014]refrigerant supply26 is shown for a split system that has anevaporator package32, acompressor package60 and acondenser package80.Evaporator package32 may be located in a room of a building where the ice making takes place. Thecompressor package60 and thecondenser package80 are located a considerable distance from theevaporator package32 to shield users from the noise of the compressor and condenser. Thecompressor package60 and thecondenser package80 may be located in the same location or in different locations. For example,evaporator package32 may be located in a first floor room andcompressor package60 andcondenser package80 may be located on the roof. Alternatively,compressor package60 may be located in a separate room andcondenser package80 may be on the roof.
• [0015]Evaporator package32 includesevaporator22 that is connected in acircuit52 with areceiver34, adrier36, anexpansion valve38, a solenoid valve40, adefrost valve42, acheck valve44 andhand valves46,48 and50.Hand valves46 and48, when open, connectcircuit52 tocompressor package60 viasupply line54 andreturn line56.Compressor package60 includescompressor62,accumulator64 andfilter68 that are connected in series to returnline56. Bypassline70 hasportion78 that is situated inaccumulator64.Valve arrangement72 has a normallyopen valve74 and a normally closedvalve76. During the freeze cycle,controller30 operatesvalve76 to its normally closed position andvalve74 to its normally open position so thatcondenser package80 is connected betweensupply line54 and adischarge output line79 fromcompressor62. During a subsequent cycle,controller30directs valve74 to close and directsvalve78 to open, so thatbypass line70 connectsdischarge output line79 ofcompressor62 to supplyline54, thereby bypassingcondenser package80.
• [0016]Condenser package80 includes acondenser82 and acondenser fan84.Condenser82 is connected acrosssupply line54 and the output ofvalve74.
• During freeze cycles,[0017]controller30 opensvalve74 and closesvalve76 and operatescompressor62 and condenser82 to provide cool liquid refrigerant throughsupply line54 toevaporator package32 andevaporator22. During a cycle occurring after a freeze cycle, e.g., a harvest cycle, controller30closes valve74 and opensvalve76. This connectsbypass line70 betweendischarge output line79 ofcompressor62 andsupply line54.Controller30 operatescompressor62 to supply warm gasified refrigerant viabypass line70 andsupply line54 toevaporator22. Liquefied refrigerant still inevaporator22 is forced out and accumulated inaccumulator64. Gasified refrigerant above the liquid level is transferred via adip tube66 tocompressor62. The warm gasified refrigerant flowing throughportion78 ofbypass line70 warms the accumulated liquefied refrigerant inaccumulator62, thereby assisting in its conversion to gasified refrigerant. The conversion of the accumulated liquefied refrigerant to a gaseous state during a harvest cycle increases the suction pressure inreturn line56 during the initial part of the ensuing freeze cycle, thereby increasing the efficiency ofaccumulator64.
• The present invention having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined in the appended claims.[0018]

Claims (13)

What is claimed is:

1. An ice-making machine comprising:

an evaporator, an accumulator, a compressor and a condenser connected in a circuit for the supply of liquefied refrigerant to said evaporator during a freeze cycle and of gasified refrigerant to said evaporator during a subsequent cycle, wherein said accumulator accumulates liquid refrigerant during said subsequent cycle;

a bypass line that passes through said accumulator; and

a valve means that connects said bypass line in said circuit during said subsequent cycle so that said gasified refrigerant bypasses said condenser and passes through said accumulator to thereby convert at least a portion of said accumulated liquefied refrigerant to a gaseous state.

2. The ice-making machine ofclaim 1, wherein said accumulator is disposed between said evaporator and said compressor.

3. The ice-making machine ofclaim 1, wherein said valve means disconnects said bypass line before another freeze cycle starts.

4. The ice-making machine ofclaim 1, wherein said subsequent cycle is a harvest cycle in which ice formed on said evaporator during said freeze cycle is harvested.

5. The ice making machine ofclaim 3, further comprising a controller that controls the operation of said valve means.

6. A method of making ice comprising:

a) supplying a liquefied refrigerant to an evaporator during a freeze cycle;

b) accumulating liquefied refrigerant during a subsequent cycle; and

c) supplying gasified refrigerant to said evaporator during said subsequent cycle in a manner whereby said accumulated liquefied refrigerant is converted to a gaseous state.

7. The method ofclaim 6, wherein said subsequent cycle is a harvest cycle in which ice formed on said evaporator during said freeze cycle is harvested.

8. The method ofclaim 6, wherein step b) accumulates liquefied refrigerant in an accumulator, and wherein step c) supplies said gasified refrigerant via a bypass line that passes through said accumulator.

9. An ice-making machine comprising:

an evaporator, an accumulator, a compressor and a condenser connected in a circuit for the supply of liquefied refrigerant to said evaporator during a freeze cycle and of gasified refrigerant to said evaporator during a subsequent cycle, wherein said evaporator is disposed in a first location and said accumulator, said compressor and said condenser are located remotely from said first location so that noise due to said compressor and said condenser is substantially reduced at said location, and wherein said accumulator accumulates an increased amount of liquid refrigerant during said subsequent cycle due to being located remotely from said location of said evaporator;

a bypass line that passes through said accumulator; and

a valve means that connects said bypass line in said circuit during said subsequent cycle so that said gasified refrigerant bypasses said condenser and passes through said accumulator to convert said accumulated liquefied refrigerant to a gaseous state.

10. The ice-making machine ofclaim 9, wherein said accumulator is disposed between said evaporator and said compressor.

11. The ice-making machine ofclaim 9, wherein said valve means disconnects said bypass line before another freeze cycle starts.

12. The ice-making machine ofclaim 9, wherein said subsequent cycle is a harvest cycle in which ice formed on said evaporator during said freeze cycle is harvested.

13. The ice making machine ofclaim 11, further comprising a controller that controls the operation of said valve means.

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