WO2001031262A1

WO2001031262A1 - Method and apparatus relating to conditioning of air

Info

Publication number: WO2001031262A1
Application number: PCT/AU2000/001303
Authority: WO
Inventors: William James Pitt
Original assignee: Coorara Pty Ltd
Priority date: 1999-10-22
Filing date: 2000-10-23
Publication date: 2001-05-03
Also published as: AU1115701A; AUPQ359099A0

Abstract

A method of treating air to assist in the keeping of materials such as fruit and vegetables which includes directing air through an evaporator coil (7) of a refrigeration unit to effect a reduction of the temperature of the air to a selected lower temperature, then subsequent to such further cooling of the air, but before directing such treated air across the materials to be preserved, the air is directed through a moisturizer (9) where water in the moisturizer has its water at a temperature substantially the same as the temperature of the air being directed into the moisturizer.

Description

METHOD AND APPARATUS RELATING TO CONDITIONING OF AIR

TECHNICAL FIELD

This invention relates to a method and apparatus for maintaining better conditions within an environment for keeping materials such as fruit and vegetables in a better condition longer.

BACKGROUND ART

It is currently known in relation to the keeping of fruit and vegetables that these materials can be kept for a longer time in a better state if, not only is the material kept at a selected low temperature, but that the air is maintained with a very high level of humidity.

Ideally, a humidity as close to 100% is considered to be best in many instances.

Currently however, techniques that are employed, to achieve both cold temperatures and high humidity air do not in fact achieve as high a humidity as is considered to be ideal and there are technical reasons for this.

An object of this invention is to propose both a method and an apparatus which will assist in providing an environ for the keeping of materials such as fruits and vegetables where the temperature of air surrounding the materials is kept within a selected low range but the humidity of such air is able to be established and maintainable at a higher level than has been hitherto achievable in practical circumstances.

DISCLOSURE OF THE INVENTION

In one form of this invention there is proposed a method of effecting preservation of materials which includes a refrigeration unit including an evaporator coil, means to direct air through such evaporator coil to effect a reduction of the temperature of the air to a selected lower temperature, and subsequent to such further cooling of the air, but before directing such treated air across the materials to be preserved, directing the air through a moisturizer where water in the moisturizer has its water at a temperature substantially the same as the temperature of the air being directed into the moisturizer.

In another form of the invention, this resides in an apparatus which is adapted to effect the said method and includes a chamber, means to move air within the chamber, including that air having passed from material to be preserved when placed in the chamber, across the coil or coils of an evaporator, an evaporator or evaporators connected to a refrigeration unit whereby to effect a reduction of temperature in relation to air passing across such evaporator coil or coils, and means to then direct air having been cooled by such an evaporator, into a moisturizer or moisturizers prior to direction of such moisturized air across the material to be preserved.

In preference, both in relation to the method and in relation to the apparatus, the moisturizer has a water reservoir, a header, and distribution means between the header and the reservoir so that water directed into the header will trickle or otherwise tumble down the distributing means through which the previously cooled air is directed.

In preference, there are separate means to effect a cooling of the water in the reservoir for one or more of the moisturizers so that the temperature of the water can, in a preliminary procedure, be brought to a temperature that is within a selected range of temperatures and generally close to the temperature selected for the temperature of air being directed into the moisturizer.

In preference, the extent of range of temperature of air in the first instance is within + or - 5 degrees C of the expected final air temperature and such that this water will then over a relatively short time change temperature to be within a much closer temperature range perhaps typically + or - 1 degree C.

In preference, a fan or fans is or are positioned so as to draw air across the material to be preserved so that, in the sequence of air flow, the fan or fans is or are located subsequent to the material to be preserved and prior to passage of air through the evaporator or evaporators.

The discovery in connection with this arrangement is that air exiting from a moisturizer or moisturizers can then result in air which, at a location where it is being directed through or over or around the material to be maintained, has both the selected temperature and a humidity which is higher than is generally otherwise achievable in such situations.

Typically, some fruits require 6°C temperature and are better preserved with substantially 100% humidity and this invention is very appropriate for this preservation requirement.

Other fruits such as bananas are better preserved at 13°C but again having 100% humidity and the equipment is again very appropriate for this.

The apparatus described can be operated in different modes so as to obtain different effects either as a part of the general preservation method or independently from this.

For instance, if the moisturizers are not operated by for instance circulating water through the water distribution arrangement, then the apparatus as a whole will operate simply as a cooler and in the traditional way, by keeping the air cool and cooling it after having taken heat from the material, will effect a drying of the air which in some circumstances is of advantage.

In another case, there is provided an electrical heating element within the air flow to effect an additional heating but again this is a different method but indicates that the apparatus itself can be changed and monitored for other purposes.

In preference, a filter is provided whereby air subsequent to passage through the materials is first passed through the filter before being passed through.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of this invention it will now be described with reference to a preferred embodiment which will be described with the assistance with drawings wherein;

Figure 1 is a cross sectional view in plan of an installation arranged to effect the method of the invention and also which is in accordance with the apparatus of the embodiment, the drawing being a schematic drawing,

Figure 2 is a plan view of a second embodiment,

Figure 3 is a perspective part cutaway view of a third embodiment showing some of the elements in dotted outline,

Figure 4 is a plan view of a fourth embodiment,

Figure 5 is a side elevation cross sectional view of a detail of the previous embodiments showing the path of air through a humidifier with header and footer tank, and

Figure 6 is a cross sectional view showing an arrangement according to a fifth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring in detail to the drawings, there is shown in Figure 1 a chamber 1 with insulated walls 1 a and an access door 1 b which has in it an apparatus 2 which has for its purpose to establish and then keep air that is to pass across the food to be preserved the food areas being shown at 3, at a selected temperature and at a humidity of 99%.

Accordingly there is provided fan 5 which is arranged to draw air from the chamber 1 , through the food areas 3 and direct this through a filter 6 and then through an evaporator coil 7 which is controlled through refrigerator means so that the evaporator coil will cool the air and maintain this air generally at the temperature selected and for this embodiment this is 6°C.

The air is then directed through the respective moisturizers 9 and then exit the apparatus through outlets 10.

The air is then directed by reason of the position of the outlets and the shape of the chamber 1 and removable covers 11 to be directed again to pass across the material to be preserved and in this case this is appropriately fruit.

The moisturizers 9 each include a header 12, a lower most reservoir 13, and a pump 14 such that the water is pumped from the reservoir 13 into the header 12 to then trickle down the distributor means 15 so as to be substantially exposed to the passage of the cool air.

The temperature of the water within the humidifier is, in this embodiment, by reason of being in the passage of air flow after the air has passed through the evaporator but before it is directed over the food and by reason of being recirculated without being subject to other cooling or substantial heating effects by reason of the effluxion of time reach substantially the temperature of the air passing through the humidifier.

Results, in trials conducted, has shown that using this arrangement the humidity is able to be raised to and be maintained at greater than 99%. Further more this humidity is able then to be maintained over a long keeping period. Further, by locating a filter at the entry location of the air into the evaporator and thereafter into the humidifier allows contaminants that are likely to be collected by the air passing the food to be kept from passing through into the humidifier water. This then further assists in the apparatus to be kept operating without the need to replace water at least so often with a result of exposure for a time of lower humidity while elements are being cleaned or replaced.

Prior art units have difficulty in achieving such a high humidity and also have other problems. In one prior example the attempt to humidify includes inundating with water an evaporator coil so that the water is caused to pass over heat exchange plates as a part of the coil. The water is cooled and therefore used to refrigerate the air. Any cooling of air (when it is below the dew point of the air) removes moisture from air. (The further below the air temperature, ie the longer the operating temperature difference, the lower the resultant relative humidity.) An evaporator coil does not have the same temperature presented on all parts so that any water is caused to cover parts with different temperatures. Also, an evaporator coil with heat exchange plates is not designed to be conducive to smooth flow of water so that a result is that air picks up water mist making a subsequent area wet but not achieving the several percentage points extra in humidity which make for a significant advantage in the effectiveness of this invention.

Now referring to Figure 2 there is a chamber 20, with insulated walls 21 and an access door which has in it an apparatus 23 which has for its purpose to establish and then keep air that is to pass across the food to be preserved the food areas being shown at 24, at a selected temperature and at a humidity of greater than 99%.

Accordingly there is provided fan 26 which is arranged to draw air from the chamber 20, through the food areas 24 and direct this through a filter 27 and then through an evaporator coil 28 which is controlled through refrigerator means so that the evaporator coil will cool the air and maintain this air generally at the temperature selected and for this embodiment this is 4°C.

The air is then directed by diverter 29 to then pass through the respective moisturizers 30 and then exit the apparatus through outlets 31.

The air is then directed by reason of the position of the outlets and the shape of the chamber 20 and removable covers 22 to be directed again to pass across the material to be preserved and in this case this is appropriately fruit.

The moisturizers 30 are each located to a side of the central evaporator coil which therefore provides for ample space for these to be of good size.

In this embodiment also then, the temperature of the water within the humidifier is by reason of being in the passage of air flow after the air has passed through the evaporator but before it is directed over the food and by reason of being recirculated without being subject to other cooling or substantial heating effects by reason of the effluxion of time reach substantially the temperature of the air passing through the humidifier.

The embodiment shown in Figures 3 and 4 differs from that shown in Figure 2 only in so far that the food arrangement 40 is slightly different and there are shown two fans 41 and 42, a filter at 43, an evaporator 44 attached to a refrigeration unit and an upper cover 45. A divertor 46 and humidifiers 47 and 48 show how the elements are further arranged to ensure the further air flow passage.

Figure 5 shows more detail of a humidifier suitable for this application including a body 50, water distribution area 51 , a footer tank or reservoir 52 and support matrix material 53. Water passes through apertures 54 to run down the material lengths so as to provide a substantial surface area to passing air 55 and 56. The air is then directed out through director 57.

In Figure 6 this is a roof unit that has however the features described which is to say a fan 60, a filter 61 , an evaporator 62 connected as a part of a refrigeration unit not shown so that this is kept cold, and a humidifier 63. The humidifier 63 has a water distribution area on top and a footer reservoir 64. (This reservoir may at times be remotely mounted within the chamber 65 and incorporate a distribution pump.) This allows for the temperature of the water to be brought to be the temperature close to that of the air as it passes therethrough. The chamber 65 has an access door 66, insulated walls 67 and holds materials for long keeping at 68. These can be any material which is better kept with low temperatures and very high humidity.

Perishable materials such as fruit and vegetables, flowers, and meat which are natural materials are better if not dehydrated during storage.

From experiments conducted thus far, this then results in a very high humidity indeed being able to be maintained so that the air will maintain by reason of physical passage through trickling water, capture additional moisture rather than effecting some form of saturation by reason of change of heat or otherwise.

The advantage of having a very high humidity is that where perishable food is to be cooled, then higher air velocity over the material can be used to thereby speed the rate at which the material can be cooled. If the humidity is very close to 100%, then the velocity can be much higher without dehydrating the food over a given period than if say the humidity is even just slightly below this at 95%.

In other words, there is every significant advantage in getting perishable foods colder quicker than by having the humidity at a very high level and the difference can be that some foods with a process of the prior art might keep for 2 weeks in an acceptable condition whereas using the humidity obtainable in this invention the same food can be kept in an acceptable condition for 3 months. As will be seen in the embodiment, the moisturizer is located downstream from the refrigerant cooler and the temperature of the air is then generally cooled to the selected temperature prior to entry into the moisturizer.

Claims

1. A method of treating air to assist in the keeping of materials such as fruit and vegetables which includes directing air through an evaporator coil of a refrigeration unit to effect a reduction of the temperature of the air to a selected lower temperature, then subsequent to such further cooling of the air, but before directing such treated air across the materials to be preserved, the air is directed through a moisturizer where water in the moisturizer has its water at a temperature substantially the same as the temperature of the air being directed into the moisturizer.

2. A method as in claim 1 further characterized in that the moisturizer has a water reservoir, a water distribution area, and moisturizer media between the water distribution area and the reservoir so that water directed into the header will trickle or tumble down the moisturizing media through which the previously cooled air is directed.

3. A method as in either of claims 1 or 2 further characterized in that the there are separate means to effect a cooling of the water in the reservoir for one or more of the moisturizers so that the temperature of the water can in a preliminary procedure be brought to a temperature that is within a selected range and generally close to the temperature selected for the temperature of air being directed into the moisturizer.

4. A method as in any one of the preceding claims further characterized in that a fan or fans is or are positioned so as to draw air across the materials to be preserved so that, in air passage sequence, the fan or fans is or are located subsequent to the material to be preserved and prior to a position where the air is caused to pass through the evaporator coil or coils.

5. A method as in any one of the preceding claims further characterized in that there is a filter located before the evaporator so that air from passing over the material will first pass through the filter and then through the evaporator.

6. A method as in any one of the preceding claims further characterized in that there is a chamber and air that is directed in accord with any of the preceding claims is recirculated within the chamber.

7. A method as in any one of the preceding claims further characterized in that the air is cooled to a temperature within the range of from 1 to 20 degrees centigrade and a humidity of approximately 99% is maintained within the air as it is directed over the material to be kept in good condition.

8. An apparatus for assisting in effecting preservation of materials such as fruit and vegetables, means to move air, an evaporator or evaporators connected to a refrigeration unit whereby to effect a reduction of temperature in relation to air passing across such evaporator coil or coils, and means to then direct such air having been cooled by such an evaporator, into a moisturizer or moisturizers prior to direction of such moisturized air across the material to be preserved, the arrangement being such that the temperature of water within the moisturizer will be caused to reach and be sustained at a temperature substantially the same as the temperature of the air being directed into the moisturizer.

9. An apparatus for assisting in effecting preservation of materials such as fruit and vegetables including a chamber, means to move air within the chamber, including shapes and ducts such that air having passed from material to treated when placed in the chamber, is directed across a coil or coils of an evaporator, an evaporator or evaporators connected to a refrigeration unit whereby to effect a reduction of temperature in relation to air passing across such evaporator coil or coils, and means to then direct air having been cooled by such a evaporator, into a moisturizer or moisturizers prior to direction of such moisturized air across the material to be preserved.

10. An arrangement for assisting in effecting preservation of materials including a chamber which is appropriately insulated and which has in it an apparatus to establish and then keep the air that is to pass across the food to be preserved, at a selected temperature and as high a humidity as is possible further including fans which are arranged to draw air from the chamber and direct this through a filter and then through an evaporator coil which is controlled through refrigerator means so that the evaporator coil will cool the air and maintain this air generally at the temperature selected and for this embodiment we shall select 6 degrees centigrade.