Abstract:
A continuously operable portable icemaker charged with an ammonia solution and pressured to about 450 pounds per square inch with hydrogen and powered with a source of heat to cause percolation of the ammonia solution acts to freeze water charged into a removable refillable cylindrical vessel.

Description:
This is a continuation-in-part of Ser. No. 08/774,630 filed Dec. 30, 1996, entitled &#34;Portable Icemaker&#34;, now U.S. Pat. No. 5,715,691, issued Feb. 10, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     Improvements over the original patent include: 
     use of higher pressure to minimize exchanger size: 
     use of aluminum with a corrosion inhibitor to minimize weight; 
     formation of ice in an easily removable cylindrical shape around a central evaporator tube or freezing component; 
     simplification of the icemaker components; and in a preferred embodiment 
     arrangement of the icemaker components to make maximum use of the chimney effect to maximize air flow to improve heat transfer. 
     This patent covers both a free standing unit and a unit made with suitable hooks to allow the unit to be transported and held in the proper upright position by hooking to a side of a normal insulated cooler chest. 
     The ice is formed from water poured into a container with an inner central cylindrical opening that fits closer than one sixteenth of an inch around the cylindrical evaporator tube or evaporator. 
     SUMMARY OF THE INVENTION 
     The invention equipment comprises a percolator, a flash separator, a cooler to cool liquid draining from the flash separator, an ammonia condenser, a cylindrical ammonia evaporator, a cylindrical ice container with a central opening sized to fit closely over the ammonia evaporator, an ammonia absorber, and a receiver that acts as a separator. The invention further comprises necessary interconnecting piping for the units, and a source of heat to cause said percolator to operate after the unit is charged with an ammonia -water solution and pressured to about four hundred and fifty pounds per square inch with hydrogen. Operation of the percolator causes vaporized ammonia to carry the vaporized ammonia and hot water to the top of a standpipe in the flash separator; the ammonia vapor enters and is condensed by air cooling in the ammonia condenser. The condensed ammonia gravity flows into the center tube of the ammonia evaporator; the liquid ammonia exits into the hydrogen filled jacket of the evaporator and vaporizes, taking up heat to cause water to freeze in the ice container. The vaporized ammonia and hydrogen stream are joined by the weak liquid ammonia stream exit the flash cooler at a point exit the evaporator and at the inlet to the ammonia absorber. The vaporized ammonia in the ammonia and hydrogen stream is absorbed in the weak ammonia stream to form a strong ammonia liquid stream that flows into the receiver. In the receiver the hydrogen separates and recycles back into the jacket of the ammonia evaporator. The strong ammonia liquid stream recycles back to the percolator; thus the unit operates continuously as long as heat is supplied to cause percolation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a cut-a-way side view of the major components indicating a preferred arrangement. 
     FIG. 2 shows a top view of the unit. 
     FIG. 3 shows a side view of the unit. 
     FIG. 4 shows a view of the ice container with a valve that is opened to allow easy ice removal. 
    
    
     DESCRIPTION OF THE INVENTION 
     The invention may best be described from the drawings. In FIG. 1 an inside view of the components is shown indicating a preferred arrangement to make optimum use of the chimney effect to increase cooling air velocity and thereby increase heat exchange to minimize size of the heat exchangers. With the use of about one percent by weight of glycerin in the ammonia-water-hydrogen charge aluminum is a suitable material of construction and is the preferred material in order to minimize weight of the unit. Other ferrous metals could be used. For operation the unit is charged with approximately the volume of twenty-eight percent aqua ammonia required to fill one half of receiver 27, and all of the volume required to fill percolator 7 and flash separator 19. The unit is then pressured to about 450 pounds per square inch gauge. The burner 5 is then started by opening the needle type control valve to get a very low flame. In about thirty minutes the charging valve 6 is opened to bleed off liquid until only gas is being purged. The unit should be repressured with hydrogen to about four hundred and fifty pounds per square inch. At this point the unit is restarted. Percolator 7 will be carrying vaporized ammonia and liquid through the percolator pipe into flash separator 19. The ammonia vapor will travel overhead to enter condenser coils 11 in the first chimney 13. The liquid ammonia exiting the condenser coils will flow out the inner evaporator tube 16 into the outer jacket 15 that is filled with hydrogen gas returning through line 17 from receiver 27. Helium or argon should be equally suitable to hydrogen for this use. In this atmosphere the ammonia evaporates by taking up heat from the water containing cylinder 29. The water containing cylinder 29 fits within less than one thirty second of an inch around the evaporator outer jacket to facilitate the heat transfer. Weak ammonia liquor flows from the bottom of flash separator 19 to tie into the weak ammonia liquor cooler 21 and through the outlet line 20 to flow into the outlet line from the outer jacket 15 which is the inlet line to absorber coils 23 at point 25 which is just below the elevation of the percolator outlet tube 18. The ammonia vapor and hydrogen are contacting the weak liquor and the ammonia vapor is absorbing in the weak liquor to form a strong ammonia liquor as the fluids pass through the sloping absorber coils 23 to empty into receiver 27. The receiver acts as a strong ammonia liquor-hydrogen separator and hydrogen recycles back to the evaporator outer jacket 15 and the strong ammonia liquor recycles back to the inlet of the percolator 7. 
     In FIG. 2 a top view of the outer case 2 of the unit is shown. Three compartments in the unit form three chimneys 8, 12, and 13. Opening 9, FIG. 1 allows air to flow into the bottom of the first chimney 8; opening 14 allows air to flow into the bottom of the second chimney 12; and opening 10 allows air to flow into the third chimney 13. A front door of the case 45, FIG. 3, allows access to the unit components and forms the chimneys when closed. Removable extendable legs 40 allow the unit to be used as a free standing ice maker and hooks 41 allow the unit to be hooked to the side of a normal transportable cooler. 
     In FIG. 3 a right side view of the unit is shown. Door 44 allows access to install or remove propane bottle 1 or other suitable heat sources to replace burner 5. Other suitable heat sources would include electricity, solar energy and even a candle. Door 45 on the front of the unit allows access to the components of the unit. Door 43 allows installation and removal of ice container 29. Opening 10 allows air to flow into the third chimney 13 and expanded metal cover 30 covers the top of the chimneys 8, 12, and 13. 
     In FIG. 4 a view of the ice container 50 is shown. The container 50 has a water tight screw cap 52 and a central opening 51 sized to fit closer than one thirty second of an inch around the evaporator outer jacket 15, FIG. 1. The container 50 is not filled completely full to allow for expansion as the water freezes into ice. Valve 53 may be opened to allow for easier removal of the ice from container 50 by preventing formation of a vacuum as the ice cylinder slides out of the container. Although a plastic or stainless steel could be used the preferred material of construction for the ice container is aluminum.