GB2225845A

GB2225845A - Ice bank coolers

Info

Publication number: GB2225845A
Application number: GB8827449A
Authority: GB
Inventors: Peter Sutherland Reed
Original assignee: THERMAL ENGINEERING SYSTEMS LI
Current assignee: THERMAL ENGINEERING SYSTEMS LI
Priority date: 1988-11-24
Filing date: 1988-11-24
Publication date: 1990-06-13
Anticipated expiration: 2008-11-24
Also published as: GB8827449D0; GB2225845B

Abstract

An ice bank cooler has air lines (5) from which bubbles issue for agitating the water as it is frozen by a heat exchanger (4). Apertures for these bubbles are at the bottom of the air lines and the pressure in those lines is maintained at least equal to the external pressure, so that water does not enter and damage the air lines. <IMAGE>

Description

ICE BANK COOLERS The present invention relates to ice bank coolers which operate in a two-part cycle, which cycle comprises (i) a part in which water is cooled and frozen by cooling means and (ii) a part in which the cooling means is inoperative and the ice melts, so absorbing heat from the environment.

The effect is analogous to a storage heater, and usually part (i) above occurs during a cheap-rate electricity period e.g. the night. Such coolers are used in rapid cooling applications, and long-term vegetable storage.

Such ice bank coolers are known, and typically comprise a tank containing water, heat exchange coils acting as a cooling means, and an air pipe beneath the heat exchange pipes with holes through its upper surface. Air is forced from the holes in the pipe to create turbulence during part (ii) of the cycle, thereby to increase the rate and evenness of melting of the ice and so increase the rate of heat absorption from the environment. In part (i) of the cycle the air pipe is full of water.

The ice bank coolers are typically provided with ice probes, being devices which detect the amount of ice in the tank, and serve to prevent a continuation of part (i) of the cycle if there is too much ice in the tank.

We have discovered that, if the ice probe's tail and the refrigeration part (i) of the cycle continues, it is possible for ice to form as a solid mass around the air pipe. In this condition, the water in the air pipe may freeze and split or damage the air pipe.

The present invention solves this problem by providing an ice bank cooler in which the holes of the air pipe are located through the lower surface of the air pipe, and a non-return valve is provided in the air pipe to maintain air pressure in the pipe at least substantially equal to that of the surrounding water.

By means of this arrangement, water is prevented from entering the air pipe during part (i) of the cycle so that the risk of damage resulting from ice forming in the airpipe is avoided.

In a second aspect, the invention provides a method of causing turbulence in a tank of water of an ice bank cooler by bubbling air from a lower surface of an air pipe and monitoring the air present in the pipe at at least the pressure of the surrounding water at all times.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: F re l is a schematic cut-away elevation of an embodiment of the present invention; Figure 2 is a schematic cross-sectional representation of part of a prior art ice bank cooler in normal operating conditions; Figure 3 is a schematic cross-sectional representation of the ice bank cooler of Figure 2 in abnormal operating conditions; Figure 4 is a schematic cross-sectional representation of the embodiment of Figure 1 in abnormal operating conditions: Referring firstly to Figure 1, an ice bank cooler 1 comprises a tank 2 containing water 3. Passing through the tank is a heat exchange pipe 4 which serves to cool the water 3. The cooler operates in a two part cycle.In part (i) of the cycle, coolant is pumped through the heat exchange pipe 4 so as to cool and freeze the water surrounding it. In part (ii) of the cycle, the supply of collant is halted and the ice surrounding the heat exchange pipe 4 melts, while absorbing heat from the environment.

An air pipe 5 is provided having holes 6 along its length.

Air is forced from the holes by a pump (not shown) during part (ii) of the cycle so as to increase the rate and evenness of melting of the ice.

An ice probe, shown diagrammatically at 7 detects the extent of the ice forming around the heat exchange pipe 4 in part (i) of the cycle and activates a control mechanism to prevent further formation of ice if a limit is exceeded.

In Figure 2 there is shown the ice formation 8 around the heat exchange pipes 9 of an ice bank cooler of the prior art in normal operation in part (i) of the cycle. In the prior art coolers, the air pipes 10 have apertures 11 through their upper surfaces so that the air pipe is full of water during this part of the cycle.

In Figure 3 there is shown the ice formation 12 around the heat exchange pipes 13 of an ice bank cooler of the prior art in an abnormal operating condition because of the failure of ice probes to stop the formation of ice in part (i) of the cycle. In this condition, the ice 12 surrounds the air pipes 15 which are full of water, and cause the freezing of that water, hence damaging the air pipes 15.

In the embodiment of the present invention shown in Figure 1, the holes 6 of the air pipe 5 are provided through the lower surface thereof via holes 17 and a non-return valve 15 is also provided in the air pipe 5. The non-return valve 15 ensures that the air pressure in the air pipe 5 is at least substantially equal to that of the surrounding water so that, during part (i) of the cycle, water is unable to enter the air pipe 5. As a result, as shown in Figure 4 when ice 16 is formed around heat exchange pipes 4 during an abnormal operating condition of an ice bank cooler which is an embodiment of the present invention so as to surround the air pipes 5 thereof, and, since there is no water present in the air pipe 5, no ice is formed within that air pipe 5.

Claims

1. An ice-bank cooler having an air pipe for causing turbulence in water as it is frozen by a heat-exchanger of the cooler, the air pipe having holes in a lower surface thereof and a non-return valve to maintain air pressure in the pipe at least substantially equal to that of the water.

2. An ice bank cooler substantially as herein described with reference to and as illustrated in Figures 1 and 4 of the accompanying drawings.

3. A method of causing turbulence in water in an ice-bank cooler during freezing of that water which includes passing air into the water from holes in a lower surface of air-pipes passing through the water.

4. A method according to Claim 3 which includes the further step of ceasing passing air into the water and maintaining the pressure of air in the pipe at at least the pressure of the water, at all times.

5. A method according to Claim 3, substantially as herein described with reference to the accompany drawings.