Title of Invention	"A GAS COOLING APPARATUS AND METHOD THEREOF"
Abstract	A gas cooling system has a tube or tubes (2) for a heat exchange medium. A gas to be cooled is flowed across the tube or tubes (2), being guided by a plurality of parallel plates (1). Water which is condensed on the plates (1) as the gas cools is collected and reintroduced into the gas to provide a cooled gas of high relative humidity.

Full Text

COOLING APPARATUS AND METHOD This invention relates to a gas cooling apparatus and a method of cooling. It is concerned to provide a method and means for cooling produce and in particular fresh fruit and vegetables to a temperature where wilting and other loss of freshness will be prevented or strongly retarded. Such cooling is by the maintenance of cooled air or other gas (hereinafter "air") around the harvested produce. The cooling apparatus which cools them may for large and permanent installations be the type of cooler known as an ice bank cooler such as for example our own Humidicool (trade mark) apparatus. Use of such apparatus ensures not only that the air is cooled to the desired temperature but that it maintains a high humidity, without which drying out or wilting of the produce may well occur even at a lowered temperature. Attempts to use conventional evaporators, as used in butchers cold rooms for this purpose, have not been particularly successful due to their poor thermodynamic design. Improvements in design are only achieved via expensive control valves, large increase in size and in consequence, complications and high cost. Conventional portable cooler equipment consists of a battery of tubes through which cooled indirect heat exchange medium flows. The tubes are positioned and separated by vertical plates which are comparatively close together and which both guide the air flow across the tubes and extend the effective heat exchanging surface of the tubes whereby to maximise the indirect heat exchange effect. As the air is cooled its saturation vapour point lowers and water is condensed onto the tubes or plates. This flows downwardly down the plates and is caught by a drip tray or the like and is removed to a drain. However, not all air is in direct contact with the tubes or plates and the net relative humidity of the cooled air which is the output from the device will rarely exceed 95% and will often be as low as 90%. The object of the present invention is to provide an air cooler which will give a cooled air output having a high relative humidity namely one above 95% and preferably in the region of 96 or 97%. To this end, the present invention provides an indirect heat exchange gas cooler in which a cooling medium is led through a tubular array for contact with the gas to be cooled, the tubular array being associated with a plurality of essentially horizontal plates sealed to the tubular array, there being a high-surface-area body beyond the downstream end of the tubular array for receiving condensed water from the array of plates and reintroducing it to contact with the cool gas stream. The high-surface-area body may be a cellulose honeycomb. A droplet catcher may follow the body, to minimize amounts of liquid water carried beyond the cooler. Preferably the tubular array consists primarily of vertically disposed tubes. A single tube may be disposed in a zig-zag formation across a parallel array of a plurality of plates. The invention also provides a method of providing cooled gas of high relative humidity which consists of cooling gas by passing it through an indirect cooling heat exchanger, collecting moisture condensed from the cooled gas on horizontal surfaces in the exchanger in a high-surface-area body an reintroducing the condensed and collected water by means of that body to the cooled gas at an output side of the heat exchanger. The method may further include catching entrained liquid water droplets downstream of the body. Movement of the condensed water to the downstream side of the heat exchanger may be assured by the gas flow itself. Accordingly, the present invention relates to a gas cooling apparatus having an indirect heat exchange gas cooler in which a cooling medium is led through a tubular array for contact with the gas to be cooled, the tubular array being associated with a plurality of essentially horizontal plates sealed to the tubular array, there being a high-surface-area body beyond the downstream end of the tubular array for receiving condensed water from the array of plates and reintroducing it to contact with the cool gas stream, wherein said apparels is droplet catcher provided at a downstream of the high-surface-area body, or at a downstream portion of the high-surface-area body. The presand invention also provides a method of providing cooled gas high relafive humidity by using the gas cooling apparotus described above, said process comprises the steps of (a) cooling the gas by passing it through an indirect heat exchange gas cooles' (b) collecting moisture condensed from the colled gas on harizontal surfaces in the exchanger in a high surface are a body; (c) re-introdncing the condensed collected water by means of that body to the cooled gas at on o/p side of the heat exchanges and (d) catching liquid water droplet downstream of the body using droplet catcher. Brief Description of the Accompanying Drawings: A particular embodiment of the invention will be described with reference to the accompanying drawings wherein: Figure 1 is a plan view of the embodiment; and Figure 2 is a sectional elevation along the line A to A in Figure 1; and Figure 3 is a part-section on the line B to B in Figure 1. In this air cooler which should produce air at a temperature of approximately 2.5°C and a relative humidity of 96 to 97%, a plurality of metal plates 1 are stacked parallel in an array between side chests 5, all within a casing 6. Indirect heat exchangers 2 are formed by convoluted tubes led through individual holes in the plates and expanded in situ to seal to the plates. In use, the tubes will be positioned with the principal straight runs 3 of the convolutions as far as possible vertical and the plates horizontal. A plurality of such tubes laterally side by side forms an array 4 and coolant liquid for indirect heat exchange with air is led into and from that array by header ducts (not shown). Gas to be cooled is blown over the array in the direction of the arrows 7 and loses heat to the tubes. In doing so water will be condensed onto the tubes and onto the plates (which being metallic act as an extended heat exchange surface for the tubes). Vertical spacing between adjacent plates 1 is t preferably such that, in the absence of air flow, water would be attracted in capillary fashion to both the upper and lower plates; one such spacing is about 2.5 to 4 mm. However, at least most of the condensed water y will be caught upon the horizontal plates and will be V... blown along the plates by the air flow, rolling around them, until it reaches the downstream edge 8 of the heat exchange assembly. The length of the plates in the direction of air flow may be about 15 cm, which is short enough that there is little risk of the water freezing. At that downstream edge water will meet a mass 9 of a high-surface-area spongy or open cellular body, in this embodiment the material being a resin-impregnated cellulose honeycomb sheet such as Dufilite, with its honeycomb (hexagonal) apertures 10 (Figure 3) lying horizontal. Other materials such as wooden slats and formed plastics sheets may also be suitable. In the present embodiment there are two such sheets, each 100 mm thick, i.e. each having a 100 mm run of multiple hexagonal apertures for the air. Under the influence of the flowing air the liquid water is swept into the mass 9 and is dispersed upon its high surface area so that it is recontacted with the cooled air. As a result the water is taken up again by that air so as to raise its relative humidity. The effect of the high surface area body is not only to cause resumed contact between the water and the air flow but also to ensure homogeneity of temperature in the air flow at a time when it is capable of taking up water to a high relative humidity. In the prior art situation any air which is comparatively uncooled at the time of expulsion from the heat exchanger had no opportunity to take up moisture except from other air thereby leading to a reduced overall relative humidity. As can be seen from Figure 2 the device is equipped also with a droplet catcher 11 in the form of upwardly-pointing V ridges 12 defined by parallel sided sheets which may be of a high-surface-area material the same as or similar to that used in the body 10, as for example being further Dufilite honeycomb cut at an angle. In the present example each sheet is 50 mm in thickness, face to face. Droplets leaving the body 9 are caught by this which, if made of a high surface-area material also assists in recontact of the air with the liquid. The downward inclination of the second part of the V ensures that any remanant droplets in the gas stream are directed downwardly towards a drain in the base of the cooler. A mesh wall 14 retains the sheets forming the mass 9 and catcher 1. We claim: 1. A gas cooling apparatus having an indirect heat exchange gas cooler in which a cooling medium is led through a tubular array for contact with the gas to be cooled, the tubular array being associated with a plurality of essentially horizontal plates sealed to the tubular array, there being a high-surface-area body beyond the downstream end of the tubular array for receiving condensed water from the array of plates and reintroducing it to contact with the cool gas stream, wherein said apparatus is characterized by a droplet catcher provided at a downstream of the high-surface-area body or at a downstream portion of the high-surface area body.. 2. A gas cooling apparatus as claimed in claim 1 wherein the droplet catcher is made by a high-surface-area material. 3. A gas cooling apparatus as claimed in claim 2, wherein the droplet catcher high- surface-area body is a resin-impregnated cellulose honeycomb. 4. A gas cooling apparatus as claimed in any one of claims 1 to 3, wherein the droplet catcher has passages upwardly and subsequently inclined downwardly with respect to the downstream direction of gas flowing through the apparatus. 5. A gas cooling apparatus as claimed in any one of claims 1 to 4, wherein the high- surface-area body for reintroducing condensed water is a resin-impregnated cellulose honeycomb. 6. A gas cooling apparatus as claimed in any one of claims 1 to 5, wherein the indirect heat exchange gas cooler has one or more tubes convoluted in a direction perpendicular to the plates. 7. A gas cooling apparatus as claimed in claim 6, wherein there is a plurality of runs of said convoluted tubes connected between an inflow duct and an outflow duct. 8. A gas cooling apparatus as claimed in any one of claims 1 to 7, wherein adjacent plates in the plurality of essentially horizontal plates are spaced apart by a distance at which, in the absence of gas flow, surface tension of the water would cause it to contact both plates. 9. A gas cooling apparatus as claimed in claim 8, wherein the said spacing apart is about 2.5 to 4 mm. 10. A gas cooling apparatus as claimed in any one of claims 1 to 9, wherein the 'ength of the plates in the direction of air flow is about 15 cm. 11. A method of providing cooled gas of high relative humidity by using the gas cooling apparatus as claimed in claim 1, wherein said method comprises the steps of:: (a) cooling the gas by passing it through an indirect heat exchange gas cooler; (b) collecting moisture condensed from the cooled gas on horizontal surfaces in the exchanger in a high-surface-area body; (c) reintroducing the condensed and collected water by means of that body to the cooled gas at an output side of the heat exchanger; and (d) catching liquid water droplets downstream of the body using a droplet catcher. 12. A method as claimed in claim 11, wherein the collected water is impelled towards the gas output side of the heat exchanger by the gas flow. 13. A gas cooling apparatus having an indirect heat exchange gas cooler substantially as herein described with reference to the accompanying drawings. 14. A method of providing cooled gas of high relative humidity substantially as herein described with reference to the accompanying drawings.

Documents:

72-del-2000-abstract.pdf

72-del-2000-claims.pdf

72-del-2000-correspondence-others.pdf

72-del-2000-correspondence-po.pdf

72-del-2000-description (complete).pdf

72-del-2000-drawings.pdf

72-del-2000-form-1.pdf

72-del-2000-form-13.pdf

72-del-2000-form-19.pdf

72-del-2000-form-2.pdf

72-del-2000-form-26.pdf

72-del-2000-form-3.pdf

72-del-2000-petition-137.pdf