WO2003019091A1

WO2003019091A1 - Hollow panel for ice making

Info

Publication number: WO2003019091A1
Application number: PCT/NL2002/000540
Authority: WO
Inventors: Willem Frederik Jense
Original assignee: Jense Systemen BV
Current assignee: Jense Systemen BV
Priority date: 2001-08-22
Filing date: 2002-08-13
Publication date: 2003-03-06
Anticipated expiration: 2004-02-22
Also published as: NL1018799C2

Abstract

A hollow panel (1) comprises a cavity (2) through which flow can take place, with a feed (3) and a discharge (4) for heat transfer medium, which panel is intended to form part of an industrial device for making ice.Cooling means for intermittently supplying cold liquid (5) to the cavity such that the water supplied to the outer surface of the panel can freeze to form an ice crust; and heating means for supplying hot medium, for instance a gas (8), to the cavity in alternation with the operation of said cooling means such that a formed ice crust detaches from the panel; at least in the lowermost zone of the cavity (2) there is present a gas supply which connects to a feed and which is provided with a row of gas passage openings (7) extending over substantially the whole width of the cavity, and that a discharge (13) connects to the uppermost zone of the cavity.

Description

HOLLOW PANEL FOR MAKING ICE

The invention relates to a hollow panel comprising a cavity through which flow can take place, with at least one feed and at least one discharge for heat transfer medium, in particular a two-phase medium, which panel is intended to form part of an industrial device for making ice, said device comprising: said panel in at least more or less vertical position; wetting means for supplying water to an outer surface of the panel; cooling means for intermittently supplying cold liquid to the cavity such that the water supplied to the outer surface of the panel can freeze to form an ice crust which adheres to this outer surface; and heating means for supplying hot medium, for instance a gas, to the cavity in alternation with the operation of said cooling means such that a formed ice crust detaches from the panel.

Such a hollow panel is known. It is intended to form part of a freezing installation, using which ice can be manufactured on industrial scale. For this purpose the hollow panel is arranged in an industrial device having a circuit with a two-phase medium which flows through the hollow panel and first cools the panel during one cycle, so that the water flowing thereover can freeze to an ice crust, and heats the panel in a subsequent phase, so that the boundary layer of the ice crust melts and the formed ice crust can be released from the panel and drop downward. In a known panel use is made for the defrosting phase of heated gas with a temperature of for instance 30°C, which is admitted into the cavity on the upper side of the panel via a feed, and at least partly condenses to liquid which leaves the cavity on the underside. It has been found that the defrosting phase of a freezing/defrosting cycle leaves something to be desired.

It is an object of the invention to embody a panel of the known type such that the described drawbacks of the prior art do not occur.

With a view hereto, the panel according to the invention has the special feature that at least in the lowermost zone of the cavity there is present a gas supply which connects to a feed and which is provided with a row of gas passage openings extending over substantially the whole width of the cavity, and that a discharge connects to the uppermost zone of the cavity. With this construction according to the invention is achieved that the heating medium moves with a high degree of homogeneity along the whole surface of the panel for heating, whereby the defrosting phase takes place very effectively, i.e. in a short time and without any inaccessible areas. A very simple embodiment has the feature that the gas supply is a tube.

This latter variant can have the special feature that the tube extends inside the cavity and is provided with gas passage openings. An alternative has the special feature that the tube extends outside the panel and the panel inside the tube is provided with gas passage openings.

Yet another embodiment has the feature that the panel is manufactured by laying two metal plates one on the other, mutually connecting said plates at their edges in medium-tight and pressure-resistant manner by welding, mutually connecting the plates by welding at discrete welding zones distributed over the surface, arranging at random at least one feed for medium under pressure, supplying medium under pressure to this feed such that the plates move apart while plastically deforming so as to form the cavity, while maintaining the connection at the position of the welding zones, and that the gas supply is embodied as a row of welding zones which are situated on the underside of the panel and between which gas passage openings have formed due to supply of the pressure medium, which thus formed gas supply connects to a feed.

In this latter embodiment the welds can be formed by seam-welding, spot welding, laser welding, friction welding or any other suitable welding method. The advantage of laser welding is that the weld pattern can meet set requirements in very simple manner by means of computer control.

In order to ensure the best possible homogeneity of the heating gas in the cavity, the panel can advantageously have the special feature that the gas supply is embodied such that the gas flow rate generated thereby has substantially the same value over the whole width of the cavity. An embodiment of this latter inventive concept has the feature that the cross-sectional area decreases in downstream direction relative to the supply. The pressure drop along the length of the gas supply is hereby effectively compensated. Yet another embodiment of this described inventive concept has the special feature that the mutual distance between the gas passage openings decreases in downstream direction relative to the supply.

In order to make the described pressure drop as controllable as possible, the panel can have the special feature that the total area of the gas passage openings is smaller than 0.1 x the infeed cross-sectional area of the gas supply.

Particularly in the case a short defrosting phase is desired, even in the case where a panel has a substantial height, the panel can have the feature that at least one further additional gas supply extends above said gas supply.

Such a gas supply can be embodied in any desired, technically expedient manner.

The freezing phase proceeds in the same manner as according to the prior art. During defrosting of the ice the warm gas with a temperature of for instance 10°C- 80°C is carried into the liquid in the cavity via the gas passage openings and distributed uniformly over the whole width of the panel. Heating of the liquid hereby takes place. The liquid thereby begins to boil and vapour is created. The vapour is drawn off and compressed by the usual compressor, thereby creating warm gas once again, which is again injected into the panel.

The invention provides the advantage that relatively small pressure changes occur in the panel compared to the prior art, whereby smaller plate ' thicknesses can be used without the danger of fatigue occurring. The known art generally requires large and expensive valves. According to the invention the gas is drawn off directly by the compressor, whereby suction gas valves are no longer necessary.

Described is a device wherein warm gas is injected into the top of the panel. This gas condenses to liquid in the panel cavity. This is removed from the cavity from the underside. This liquid cannot be guided directly to the compressor, since a compressor is after all only able to compress gas and cannot process liquid. It is therefore necessary that the liquid, the condensed gas, is first evaporated before it can be guided to the compressor. A suction valve is therefore necessary in this device.

A further great drawback of the known device is the occurrence of high pressures in the panel in the defrosting phase, whereby greater plate thicknesses are necessary to prevent fatigue. The known device further requires large and expensive suction gas valves. These valves must be controlled, which also makes the control system relatively complicated.

The invention will now be elucidated with reference to the annexed drawings. In the drawings :

Fig. 1 shows a schematic cross-sectional view of a panel according to the invention in a first embodiment; Fig. 2 shows the lower zone of a panel in the second embodiment;

Fig. 3 is a view corresponding with Fig. 1 of a third embodiment; Fig. 4 shows the cross-section IV-IV from Fig. 3; Fig. 5 shows a cross-section through a lower zone of a variant; and

Fig. 6 shows a view corresponding with Fig. 1 of a fifth embodiment. Fig. 1 shows a hollow panel 1, comprising a cavity 2 through which flow can take pace, with a feed 3 for hot gas (during the defrosting phase) and a discharge 4 for gas. The panel consists of two, for instance stainless steel plates which are mutually coupled gas and liquid-tightly in suitable manner. Medium, for instance a two-phase medium which can consist of liquid and/or gas, can flow through cavity 2 via feed 3 and discharge 4, and vice versa.

During the freezing phase the panel, which is disposed in vertical position or in slightly inclining position relative to the vertical, is wetted by spray means (not shown) , whereby on the slightly upward directed outer surface of the panel an ice crust is formed under the influence of the cold liquid 5 situated in cavity 2. This liquid is formed in known manner in a cooling circuit, of which a compressor forms part. This is an aspect which is generally known and therefore not elucidated further. Once an ice crust of substantial thickness has formed in for instance 10 minutes, it has to be removed for use where required. For this purpose hot gas with a temperature of some tens of degrees Celsius is admitted into cavity 2 via gas supply 3. For this purpose the gas supply 3 is embodied as a tube 6 (the cross-sectional form of which can in principle be chosen as desired) situated on the underside of cavity 2, which tube 6 is provided with gas passage openings 7. The gas flow 8 is carried into the liquid 5 via gas passage openings 7. A cloud of small gas bubbles 9 is hereby formed which ensure that the liquid 5 heats up and begins to boil, whereby gas is discharged again via gas discharge 4, whereby the compressor present between discharge 4 and feed 3 can function in the correct manner. A compressor is after all only capable of processing gas. As shown schematically in the drawing, gas bubbles 9 are distributed over panel 1 with a great measure of homogeneity, whereby defrosting can take place without blind spots and in a relatively short time.

Gas passage openings 7 are arranged downstream of feed 3 and with a decreasing mutual distance in order to compensate the pressure drop along tube 6. This ensures a good homogeneity of the gas flow over the width of panel 1.

Fig. 2 shows an embodiment in which a tube 10 connecting onto feed 3 is provided with gas passage openings 7 placed at equal mutual distances, but wherein tube 10 has a form tapering downstream relative to feed 3 in order to ensure a good uniformity of the gas flow rate .

Fig. 3 shows a panel 11 which is manufactured by laying two metal plates one on the other, mutually connecting the plates on their periphery in medium-tight and pressure-resistant manner by seam-welding, mutually connecting the plates by laser welding at discrete welding zones 16 distributed over the surface, arranging a feed 12 for hot gas (during the defrosting phase) and a discharge 13, supplying medium under high pressure to the or each feed/discharge made such that the plates move apart while plastically deforming so as to form a cavity 13, while maintaining the connection at the position of welding zones 16. Other than in the embodiments according to Fig. 1 and 2, the gas supply in the embodiment according to Fig. 3 is embodied by means of a row of welding zones 14 which are situated on the underside of panel 11 and between which gas passage openings 15 have formed due to supply of the pressure medium, which thus formed gas supply connects to feed 12.

Welding zones 14 and 16 are formed in this embodiment by laser welding with circular patterns. Any other suitable pattern and any other suitable welding method can however¹ also be employed.

Reference numeral 17 designates the peripheral weld seam formed by seam welding.

Fig. 4 shows cross-section IV-IV from Fig. 3. Apparent is the generally cushion-like character of panel 1, wherein at the position of peripheral weld seam 17 and welding zones 16 the two stainless steel plates 18, 19 are mutually connected while leaving clear the cavity 20 through which can flow liquid and gas.

Fig. 5 shows the bottom part of a panel 21, the peripheral weld seam 17 of which is enclosed by a gas supply tube 22 through which can flow heated gas under pressure which can be admitted into the liquid 5 in cavity 26 via holes 23 in stainless steel plates 24, 25.

Finally, Fig. 6 shows a panel 30 with two gas supplies 3, 3', to which tubes 27, 28 connect with gas passage openings 29 through which heated gas can flow. An even greater defrosting speed can be realized with this latter embodiment.

Claims

1. Hollow panel comprising a cavity through which flow can take place, with at least one feed and at least one discharge for heat transfer medium, in particular a two-phase medium, which panel is intended to form part of an industrial device for making ice, said device comprising: said panel in at least more or less vertical position; wetting means for supplying water to an outer surface of the panel; cooling means for intermittently supplying cold liquid to the cavity such that the water supplied to the outer surface of the panel can freeze to form an ice crust which adheres to this outer surface; and heating means for supplying hot medium, for instance a gas, to the cavity in alternation with the operation of said cooling means such that a formed ice crust detaches from the panel; characterized in -that: at least in the lowermost zone of the cavity there is present a gas supply which connects to a feed and which is provided with a row of gas passage openings extending over substantially the whole width of the cavity, and that a discharge connects to the uppermost zone of the cavity.

2. Panel as claimed in claim 1, characterized in that the gas supply is a tube.

3. Panel as claimed in claim 2, characterized in that the tube extends inside the cavity and is provided with gas passage openings.

4. Panel as claimed in claim 2, characterized in that the tube extends outside the panel and the panel inside the tube is provided with, gas passage openings.

5. Panel as claimed in claim 1, characterized in that the panel is manufactured by laying two metal plates one on the other, mutually connecting said plates at their edges in medium-tight and pressure-resistant manner by welding, mutually connecting the plates by welding at discrete welding zones distributed over the surface, arranging at random at least one feed for medium under pressure, supplying medium under pressure to this feed such that the plates move apart while plastically deforming so as to form the cavity, while maintaining the connection at the position of the welding zones, and that the gas supply is embodied as a row of welding zones which are situated on the underside of the panel and between which gas passage openings have formed due to supply of the pressure medium, which thus formed gas supply connects to a feed.

6. Panel as claimed in claim 1, characterized in that the gas supply is embodied such that the gas flow rate generated thereby has substantially the same value over the whole width of the cavity.

7. Panel as claimed in claim 6, characterized in that the cross-sectional area decreases in downstream direction relative to the supply.

8. Panel as claimed in claim 6, characterized in that the mutual distance between the gas passage openings decreases in downstream direction relative to the supply.

9. Panel as claimed in claim 1, wherein the total area of the gas passage openings is smaller than 0.1 x the infeed cross-sectional area of the gas supply.

10. Panel as claimed in claim 1, characterized in that at least one further additional gas supply extends above said gas supply.