GB2258299A

GB2258299A - Humidifying

Info

Publication number: GB2258299A
Application number: GB9215951A
Authority: GB
Inventors: James Alan Aamodt
Original assignee: Fractal Inc
Current assignee: Fractal Inc
Priority date: 1991-07-27
Filing date: 1992-07-27
Publication date: 1993-02-03
Anticipated expiration: 2012-07-27
Also published as: GB9215951D0; GB2258299B

Abstract

Apparatus for and method of humidifying food or floral products in an at least partially enclosed space, say, a service case, wherein an intimate mixture of water and air, preferably, water vapour-saturated air, is injected intermittently, either at predetermined time intervals or on demand, into the space, the quantity, and, optionally, the temperature, of the so-injected air being controlled to cause water to condense on the surface of the food or floral products and to permit the so-condensed water to evaporate between injections of water vapour-saturated air, thereby extracting the latent heat of evaporation of the water from the food products to maintain the temperature and weight thereof within specified limits. The relative humidity of the circulating atmosphere in the space may be maintained at at least 80%. <IMAGE>

Description

HUMIDIFICATION DESCRIPTION This invention relates generally to humidification and is related especially, but not exclusively, to apparatus and an associated method for humidifying the atmosphere within a service case, for example, a pointof-sale cabinet for displaying food products, such as, cheese and fresh vegetables, meat, fish and the like, whose condition, such as, moisture content and appearance, are to be maintained at, say, an acceptable level and, preferably, whose display, and particularly core, temperature is to maintained within a predetermined temperature range, usually specified by a regulatory authority responsible for enforcing statutory requirements relating to the transportation of food products to, their s.torage and display in, and their subsequent sale from a retail outlet.

The invention may also be used to humidify the atmosphere in which floral products, such as, sprays and bunches of fresh flowers and pot plants, are displayed for resale.

It is known to humidify the atmosphere within a refrigerated storeroom containing food or floral products for subsequent point-of-sale display, to boost the humidity of the store room atmosphere to a sufficient level to maintain the moisture content of the stored and refrigerated products at an acceptable level, thereby preventing, or at least substantially reducing, average weight loss and, hence, shrinkage of the products. Humidification is usually provided in the form of a mist or plume of moisture injected into the store room via one or more nozzles and can, in certain circumstances, be provided at timed intervals or on demand in dependence upon a minimum humidity within the store room being detected.

It is also know to humidify a service case, such as, a point-of-sale display cabinet, containing food or floral products, particularly in a retail outlet, using a fine moisture mist introduced into the case as a plume via a nozzle(s) or as a random cloud from perforated pipes extending along at least part of the length of the case.

The main disadvantage associated with these known humidification arrangements for refrigerated store rooms and service cases, whether chilled or not and containing food or floral products,. is that the relative humidities of the atmospheres therewithin cannot be maintained at a sufficiently high level, to achieve the desired result, namely, to prevent deterioration of the food or floral products due to a reduction in moisture content thereof.

In the particular case of the humidified service case, a further, major disadvantage associated with the known arrangements, is that, although the food or floral products contained therein are subjected to a substantially continuous chilling operation provided by suitable refrigeration, they do tend to rise in temperature, particularly their core temperature, as a result of warming due to random circulation of comparatively warm air ingressing into the service case from an environment exterior thereof.

Also, existing service case humidification systems do not supply sufficient humidity to remove the latent heat of evaporation of water from any moisture on the surface of food or floral products stored and/or displayed in such a case whose temperature, as well as that of the associated food or floral products, can also be affected by other factors, such as: (a) periodic defrost cycles of any refrigerated system associated with the case, which will occur more frequently when the case is humidified; and/or (b) heat radiated from any. lamps within or adjacent the service case, whilst other shop fittings also tend to increase the temperature of both the case interior and the food products therein.

As a consequence of the disadvantages associated with these known humidification arrangements for stored and/or displayed food or floral products, the products themselves can shrink up to 10% of their original weight due to loss of moisture therefrom, as well as taking on a poor appearance! which, in the particular case of food products, can result in the loss of both product weight and sales.

Accordingly, it is an object of the present invention to provide apparatus for, and an associated method of, humidifying food or floral products, which overcomes or at least substantially reduces the disadvantages discussed above in relation to the known humidification arrangements.

One aspect of the invention provides apparatus for humidifying food or floral products, preferably chilled food or floral products, contained in an at least partially enclosed space, such as, a service case, which apparatus comprises means arranged to inject moisture intermittently into the space, characterised in that said means is arranged to inject the moisture intermittently into the space in the form of an intimate mixture of water and air, such that, in use of the apparatus, the quantity, and, optionally, the temperature, of the so-injected water/air mixture is such as to cause water to condense on the surface of the products contained in the space and to permit the so-condensed water to evaporate between injections of the water/air mixture into the space, thereby extracting the latent heat of evaporation of the water from the products, to maintain the temperature and water content thereof substantially within respective specified limits.

Another aspect of the invention provides apparatus for humidifying food or floral products, preferably chilled food or floral products, contained in an at least partially enclosed space, such as, a service case, which apparatus comprises means arranged to inject moisture intermittently into the space, characterised in that said means is arranged to inject the moisture intermittently into the space in the form of water vapour-saturated air, such that, in use of the apparatus, the quantity, and, optionally, the temperature, of the so-injected water vapoursaturated air is such as to cause water to condense on the surface of the products contained in the space and to permit the so-condensed water to evaporate between injections of the water vapour-saturated air into the space, thereby extracting the latent heat of evaporation of the water from the products, to maintain the temperature and water content thereof substantially within respective specified limits.

Yet another aspect of the invention resides in a method of humidifying food or floral products, preferably chilled food or floral products, contained in an at least partially enclosed space, which method comprises injecting moisture intermittently thereinto, characterised in that the moisture is provided in the form of an intimate mixture of water and air, such that the quantity, and, optionally, the temperature, of the so-injected intimate water/air mixture is controlled so as to cause water to condense on to the surface of the products, and to permit the so-condensed water to evaporate between injections of the water/air mixture, such that the latent heat of evaporation of the water is extracted from the products to maintain the temperature and water content thereof substantially within respective specified limits.

A fourth aspect of the invention resides in a method of humidifying food or floral products, preferably chilled food or floral products, contained in an at least partially enclosed space, which method comprises injecting moisture intermittently thereinto, characterised in that the moisture is provided in the form of water vapour-saturated air, such that the quantity, and, optionally, the temperature, of the soinjected water vapour-saturated air is controlled so as to cause water to condense on to the surface of the products, and to permit the so-condensed water to evaporate between injections of the water vapoursaturated air, such that the latent heat of evaporation of the water is extracted from the products to maintain the temperature and water content thereof substantially within respective specified limits.

Preferably, the quantity and, optionally, the temperature of the intimate water/air mixture or the water vapour-saturated air injected intermittently into the space may also be such as to maintain the relative humidity of the atmosphere within the space at at least 80%.

The invention also provides apparatus for, as well as an associated method of, humidifying food or floral products, preferably chilled food or floral products, contained in an at least partially enclosed space, such as, a service case, the apparatus including means arranged to inject moisture intermittently into the space, characterised in that said means is arranged to inject the moisture intermittently into the space in the form of an intimate mixture of water and air in such a quantity, and, optionally, at such a temperature, as to maintain the relative humidity of the atmosphere within the space at at least 80%.

Preferably, the intimate mixture of water and air is in the form of. water vapour-saturated air.

Moreover, the invention provides a method of humidifying food or floral products contained in an at least partially enclosed space, such as, a service case, comprising injecting moisture intermittently into the space, characterised in that the moisture is provided in the form of an intimate mixture of water and air in such a quantity, and, optionally, at such a temperature, as to maintain the relative humidity of the atmosphere in the space at at least 80%.

Preferably, the intimate water/air mixture is provided as water vapour-saturated air.

Distribution of the so-injected water/air mixture, such as, water vapour-saturated air, throughout substantially the whole of the space may be effected by means of a fan or other suitable circulating device, with water vapour-saturated air preferably being injected intermittently into the space in the form of a plume from a suitably shaped and dimensioned nozzle.

Alternatively, the plume may be of such a velocity as to provide sufficient distribution of the water vapoursaturated air throughout substantially the whole of the space, without fan assistance.

The temperature differential between the preferably chilled food or floral products and the injected, water vapour-saturated air, may be controlled, such that a so-called "sacrificial" layer of water is formed by condensation upon the surface of the chilled products for subsequent evaporation and resultant extraction of latent heat therefrom, thereby maintaining the core temperature of the products within specified limits. Also, such condensation maintains the water content of the products at a satisfactory level.

A timer may be employed to cause intermittent injection of water vapour-saturated air into the space at predetermined time intervals, for example, for 1 minute in every 10 minutes. Alternatively, such injection may be on demand, in dependence upon the monitored relative humidity within the space, in which case, a humidistat, or other suitable humidity monitoring device, may be used to monitor the relative humidity, with associated means arranged to cause injection of water vapour-saturated air into the space on receipt of a signal from the humidistat indicative of a predetermined minimum relative humidity monitored thereby. Further, such humidity monitoring device may be employed to terminate injection of the water/air mixture when the monitored relative -humidity within the space reaches a predetermined maximum level.Thus, the device can be used to operate the injection means between specified maximum and minimum relative humidity levels within the space.

It is to be appreciated that various factors can affect the relative humidity within the space. For instance, background humidity can be caused by evaporation of the sacrificial water layer from the products and sudden increases in humidity can occur in a refrigerated space in which the products are displayed, due to defrosting cycles of the refrigeration equipment. Further, a high ambient humidity can cause an increase in the background humidity within the space, particularly when the ambient relative humidity outside the space can be as high as 95%. In this case, a relative humidity monitoring device may be used to monitor any air being recycled through the apparatus for subsequently mixing with water and then injection, as a water/air mixture, into the space in which the products are displayed.

High relative humidity within the space can cause overwetting of the products displayed therein.

It is an important feature of the inventive apparatii and methods disclosed above that sufficient moisture is supplied to the surface of the food or floral products contained in the space, in order to provide the sacrificial layer of moisture, which can provide a heat insulative layer during defrosting cycles of any associated refrigeration means and, also, during injection of humidity into the space which may cause the temperature of the air within the space to rise for a short period of time. Further, the problem of temperature rise within the space due to any other factors, such as, lighting and heat generated from other shop fittings, can be reduced substantially when sufficient levels of humidity are provided within the space in accordance with the present invention.

Moreover, the water content of the products can be substantially maintained, to reduce weight loss and to maintain appearance thereof.

An embodiment of apparatus in accordance with the invention and for carrying out the inventive method of humidifying food or floral products contained in a serve-over point-of-sale display cabinet in a retail outlet, will now be described by way of example and with reference to the accompanying drawing which is a diagrammatic elevation of the apparatus.

Referring to the drawing, apparatus for elevating and maintaining 80-95% relative humidity levels of the atmosphere within a chilled, serve-over point-of-sale display cabinet containing food products, such as, cheese, red meat, delicatessen items, seafood and the like, or floral products, such as, fresh cut flowers or pot plants, comprises an inlet 1, and an associated isolating valve 2, for supplying mains water or equivalent to a water filter 3 containing activated carbon for removing chlorine and other undesirable organic compounds from the mains water or equivalent, the device 3 preferably being installed beneath the display cabinet (not shown).

The so-filtered water is passed from the water filter 3 to a chiller 4 via piping 5, where the filtered water is chilled to approximately 50C (410F).

Electrical power is supplied to the water chiller 4 via a mains lead 6.

Then, the filtered and chilled water at approximately 50C (410F) is fed to an ultraviolet purifier 7 via piping 8 where any undesirable bacteria remaining in the filtered and chilled water is killed.

This purifier 7 is also electrically powered from the mains via another lead 9.

From the bacteriological, ultraviolet purifier 7, water is fed, via piping 10, to a regulator indicated generally at 11 and comprising a throttling valve 12, a reverse osmosis strainer 13 and a pressure regulator 14 with an associated gauge 15.

An air compressor 16 is powered electrically via a mains lead 17 and includes a timer 18.

An airline 19 extends from the manifold 20 of the compressor 16 to an air-actuable valve 21 which is also connected via piping 22 to the outlet 23 of the pressure regulator 14.

The airline 19 between the compressor manifold 20 and the valve 21 is arranged concentrically within the piping 22 from the pressure regulator 14, to pre-cool the compressed air which is subsequently fed to a low velocity, humidification nozzle 24 via an airline 25.

The air-actuable valve 21 is also connected to the nozzle 24 by piping 26 through which water from the valve 21 is fed thereto.

In use of the apparatus in putting the inventive method into effect, mains water or equivalent is fed to the inlet 1 through a 100 mesh per square inch particle strainer (not shown) into the activated carbon filter 3, through the piping 5 into the chiller 4, through the further piping 8 into the bacteriological, ultraviolet purifier 7 with associated pre-filter (also not shown) and subsequently into the pressure regulator 11.

As an alternative, a reactivated reverse osmosis unit can be used instead of the bacteriological ultraviolet purifier 7, although either can be equipped with filters selected for different areas to take into account any local water contamination, such as, aluminium, lead, pesticides, nitrates, tryhalomethanes and the like.

With valves 2 and 12 open, the water pressure is reduced to less than 5 psi at the pressure regulator 14 and the timer 18 is set to operate for a desired time period of, say, 30 seconds at predetermined time intervals of, say, 1 minute. With the electric power turned on, the water pressure is adjusted steadily to ensure a smooth delivery via a low velocity humidification nozzle 24. Water pressure can be reduced to as low as 1 psi, depending on the number of nozzles 24 (only one shown) employed, with a subsequent but necessary reduction in the working injection cycle to provide another desired time period of, for example, 1 minute at another set of time intervals of, for example, 10 minutes.The humidity within the display cabinet (not shown) with which the nozzle 24 is associated, is checked using a hygrometer and the apparatus is regulated to maintain the relative humidity within the cabinet at 80-95%, depending upon the type of food or floral products on display.

From the nozzle(s) 24 is emitted a plume of water vapour-saturated air, resulting from the air actuable valve 21 turning on the water supply from the regulator 14 when compressed air is timed from the compressor 16.

The water vapour-saturated air is injected intermittently into the cabinet, with the so-injected air being circulated within the cabinet by means of a fan (not shown) or at a sufficient plume velocity if no fan assistance is used. By adjusting the frequency of injection of the water vapour-saturated air into the cabinet from the nozzle 24 using the timer 18 controlling the temperature of the so-injected air, the relative humidity of the atmosphere within the cabinet can be maintained between, say, 80% and 95%.

Alternatively or in addition thereto, relative humidity monitoring equipment (not shown) can be incorporated into the apparatus to monitor the relative humidity of the atmosphere within the cabinet, whereby water vapour-saturated air is injected into the cabinet on demand, to maintain the relative humidity of the cabinet atmosphere at the desired level. For instance, red meat, delicatessen foods, seafood and floral service display cabinets require a relative humidity of from 85% to 95% whereas a cheese or floral display cabinet requires a slightly lower relative humidity of, say, 80%.

The monitoring equipment is also used to monitor a predetermined maximum relative humidity within the cabinet, whereby injection of water vapour-saturated air thereinto is terminated when the maximum relative humidity level is reached.

By maintaining the relative humidity at the desired level or within the desired range, dehydration otherwise caused by rapid movement of dry air within the cabinet is reduced greatly and, thus, product weight and condition are substantially maintained.

Also, the shelf life and condition of the food products are extended, with their appearance also being substantially maintained at a desired level. Further, overwetting of the products due to undesirably high humidity levels can be substantially avoided.

Within the display cabinet, the effect on the temperature of the food products resulting from the intermittent injection of the water vapour-saturated air and the subsequent circulation by fan at around 0.1 to 0.5 metres per second at 50C, is that the soinjected water vapour-saturated air is distributed throughout the cabinet by such circulatory movement.

Contrary to what one would expect, the relative humidity of the atmosphere within the cabinet is maintained for a considerable length of time at the desired level.

Even with the water vapour-saturated air being chilled and at a temperature of about 50C, the difference in the temperature of the moisture in the atmosphere of the cabinet interacts with the lower surface temperature of the chilled food or floral products therein, thereby creating a layer of condensed water thereon.

This layer of condensed water on the food or floral products is sacrificial, in that it can evaporate, thereby extracting its latent heat of evaporation from the products, to effect cooling thereof. This effect assists in maintaining the food or floral products within the prescribed temperature range and, particularly, in maintaining- the core temperature of the products within the specified regulatory limits of, say, up to 80C for delicatessen products: Such evaporation will normally take place between injections of the water vapour-saturated air by the nozzle 24, as the temperature of the atmosphere within the cabinet gradually rises between such injections, albeit by a comparatively small extent.

The mains water supplied to the humidification apparatus via the inlet 1 may only be refrigerated if the water is above, say, 15.50C (600F). As it is not usually that hot in some environments it would not normally be necessary to use the in-line chiller 4.

It may be necessary, however, to use a W water purifier running continuously to effectively kill bacteria and such may warm the water supply sufficiently to require a chiller.

Because of the potential water heating problems associated with the use of W purification techniques, if used effectively and continuously, it is preferred to use a reverse osmosis water purification system.

However, some situations may require W purification in which case, the extra cost associated with the provision of a chiller may have to be incurred.

Such a W purification technique is disclosed in British Patent Application No. (Publication No. ), wherein a W light source operating at a bacteriacidal wavelength is located immediately upstream of the injection nozzle 24. This arrangement is adapted to prevent overheating of the W light source, particularly when the rate of flow of the water supply is comparatively low, say, 0.03 litres per minute. When sch overheating occurs, the rise in temperature of the source causes a shift in the wavelength of the W light so generated and the new wavelength may not possess bacteriacidal properties.

This arrangement is particularly useful in circumstances where bacterial growth can occur in the vicinity of the injection nozzle and, indeed, upstream thereof within the apparatus itself.

Claims

1. Apparatus for humidifying food or floral products, preferably chilled food or floral products, contained in an at least partially enclosed space, such as, a service case, which apparatus comprises means arranged to inject moisture intermittently into the space, characterised in that said means is arranged to inject the moisture intermittently into the space in the form of an intimate mixture of water and air, such that, in use of the apparatus, the quantity, and, optionally, the temperature, of the so-injected water/air mixture is such as to cause water to condense on the surface of the products contained in the space and to permit the so-condensed water to evaporate between injections of the water/air mixture into the space, thereby extracting the latent heat of evaporation of the water from the products, to maintain the temperature and water content thereof substantially within respective specified limits

2. Apparatus for humidifying food or floral products, preferably chilled food or floral products, contained in an at least partially enclosed space, such as, a service case, which apparatus comprises means arranged to inject moisture intermittently into the space, characterised in that said means is arranged to inject the moisture intermittently into the space in the form of water vapour-saturated air, such that, in use of the apparatus, the quantity, and, optionally,the temperature, of the so-injected water vapoursaturated air is such as to cause water to condense on the surface of the products contained in the space and to permit the so-condensed water to evaporate between injections of the water vapour-saturated air into the space, thereby extracting the latent heat of evaporation of the water from the products, to maintain the temperature and water content thereof substantially within respective specified limits.

3. Apparatus according to claim 1 or 2, characterised in that said injection means is arranged to control the quantity, and, optionally, the temperature, of the intimate water/air mixture or water vapour-saturated air, as the case may be, injected intermittently into the space to maintain the relative humidity of the atmosphere within the space at at least 80%.

4. Apparatus according to claim 1, 2 or 3, characterised by means arranged to circulate the soinjected water/air mixture or water vapour-saturated air, as the case may be, within the space.

5. Apparatus according to claim 4, characterised in that said circulating means comprises a fan, preferably circulating at, say, about 0.1 to 0.5 metres per second.

6. Apparatus according to any preceding claim, characterised by means arranged to inject the water/air mixture or water vapour-saturated air, as the case may be, into the space in the form of a plume whose shape and velocity is sufficient to distribute the soinjected water/air mixture of water vapour-saturated air throughout substantially the whole of the space.

7. Apparatus according to any preceding claim, characteried by timer means arranged to cause intermittent injection of water/air mixture or water vapour-saturated air, as the case may be, into the space at predetermined time intervals, for example, for 1 minute in every 11 minutes.

8. Apparatus according to any preceding claim, characterised by means arranged to cause intermittent injection of water/air mixture orwater vapour-saturated air, as the case may be, into the space on demand, in dependence upon the monitored relative humidity of the atmosphere within the space.

9. Apparatus according to claim 8, characterised by means for monitoring the relative humidity of the atmosphere within the space and means arranged to cause injection of water/air mixture or water vapoursaturated air, as the case may be, into the space on receipt of at signal from the relative humidity monitoring means indicative of a predetermined minimum relative humidity monitored thereby.

10. Apparatus according to claim 8, characterised by means for monitoring the relative humidity of the atmosphere within the space and means arranged to terminate injection of the water/air mixutre or water vapour-saturated air, as the case may be, into the space on receipt of a signal from said monitoring means indicative of a predetermined maximum relative humidity monitored thereby.

11. Apparatus according to any preceding claim, characterised by means arranged to control the temperature of the water/air mixture or water vapoursaturated air to be injected into the space.

12. Apparatus according to any preceding claim, characterised by means located immediately upstream of said injection means, for bacterialogically purifying the water with ultra-voilet light.

13. A method of humidifying food or floral products, preferably chilled food or floral products, contained in an at least partially enclosed space, such as, a service case, which method comprises injecting moisture intermittently thereinto, characterised in that the moisture is provided in the form of an intimate mixture of water and air, such that the quantity, and, optionally, the temperature, of the so-injected intimate water/air mixture is controlled so as to cause water to condense on to the surface of the products, and to permit the so-condensed water to evaporate between injections of the water/air mixture, such that the latent heat of evaporation of the water is extracted from the products to maintain the temperature and water content thereof substantially within respective specified limits.

14. A method of humidifying food or floral products, preferably chilled food or floral products, contained in an at least partially enclosed space, which method comprises injecting moisture intermittently thereinto, characterised in that the moisture is provided in the form of water vapour-saturated air, such that the quantity, and, optionally, the temperature, of the soinjected water vapour-saturated air is controlled so as to cause water to condense on to the surface of the products, and to permit the so-condensed water to evaporate between injections of the water vapour saturated air, such that the latent heat of evaporation of the water is extracted from the products to maintain the temperature and water content thereof substantially within respective specified limits.

15. A method according to claim 13 or 14, characterised in that the quantity, and, optionally, temperature of the water/air mixture or water vapoursaturated air, as the case may be, injected intermittently into the space is controlled to maintain the relative humidity of the atmosphere within the space at at least 80%.

16. A method according to any of claims 13 to 15, characterised in that the water/air mixture or water vapour-saturated air, injected into the space is circulated therearound by a fan.

17. A method according to claim 16, characterised in that the so-injected water/air mixture or water vapoursaturated air is circulated around the space at about 0.1 to 0.5 metres per second.

18. A method according to any of claims 13 to 17, characterised in that the water/air mixture or water vapour-saturated air is injected into the space in the form of a plume whose velocity is sufficient to distribute the so-injected air throughout substantially the whole of the space.

19. A method according to any of claims 13 to 18, characterised in that the water/air mixture .or water vapour-saturated air is injected into the space at predetermined time intervals, for example, for 1 minute in every 11 minutes.

20. A method according to any of claims 13 to 19, characterised in that the air/water mixture or water vapour-saturated air is injected into the space on demand, in dependence upon a monitored relative humidity of the atmosphere within the space.

21. A method according to claim 20, characterised in that the relative humidity of the atmosphere within the space is monitored, preferably by a humidistat, and water/air mixture or water vapour-saturated air is injected into the space on receipt of a signal indicative of a monitored, predetermined minimum relative humidity.

22. A method according to claim 20 or 21, characterised in that the relative humidity of the atmosphere within the space is monitored, preferably by a humidistat, and injection of the water/air mixture or water vapour-saturated air into the space is terminated on receipt of a signal indicative of a monitored predetertined maximum relative humidity.

23. A method according to any of claims 20 to 22 characterised in that water is bacterialogically purified with ultra-voilet light immediately prior to its injection into the space.

24. Apparatus for humidifying food or floral products contained in an at least partially enclosed space, including means arranged to inject intermittently into the space water vapour-saturated air, the quantity, and, optionally, the temperature, of the so-injected air being such as to maintain the relative humidity within the space at at least 80%.

25. A method of humidifying food or floral products contained in an at least partially enclosed space, comprising injecting intermittently into the space water vapour-saturated air in such a quantity, and, optionally, at such a temperature, as to maintain the relative humidity of the atmosphere in the space at at least 80%.

26. A serve-over service case incorporating apparatus according to any of claims 1 to 12, and 24.