NL9200854A - METHOD AND APPARATUS FOR TREATING AGRICULTURAL AND GARDEN PRODUCTS IN A STORAGE ROOM. - Google Patents

Description

Short indication; Method and device for treating agricultural and horticultural products in a storage space.

The invention relates to a method according to the preamble of claim 1 as well as to a device according to the preamble of claim 5.

Such a method and such a device are known from applicant's brochure "All about potatoes by Tolsma." 7th edition, Emmeloord, 1990. This brochure concerns the storage and handling of potatoes. What is described therein, however, can in principle also be used for the storage and treatment of other agricultural and horticultural products, such as carrots, chicory, onions and cabbage.

In the methods known from this brochure, air is blown through the stored products from the side or from below during ventilation and when the harvested products are aerated. For example, the products may be stored in stacked boxes with openings in the side walls. A first row of these boxes is placed against a ventilation wall and successive rows are in turn placed against the arranged row. An overpressure is applied behind the ventilation wall and maintained, so that air flows through the boxes.

The products give off moisture to the passing air during ventilation, so that they are dried. The air drawn in can for instance have a lower temperature than the products. When the air is spread along the products, the temperature and the maximum absolute moisture content thereof increases, so that it takes away excess moisture from the products and ensures drying of the products. The warm air with the moisture absorbed from the products leaves the storage space by passing through the wall of the storage space. The passages are usually arranged in the upper area of the space, so that especially the ascended warm air, in which a lot of water vapor has been absorbed, leaves the space. When the products are aerated, a warm temperature and humidity are obtained over the storage space.

It has also been described, for cooling the products, in addition, a heat exchanger can be used in an upper part of the storage space. When cooling, cold air sinks and warm air rises until it is cooled by the heat exchanger and then sinks back down. A drying effect can be obtained during cooling, because water vapor from the air condenses against the heat exchanger during cooling.

A drawback of this method of storage and treatment of agricultural and horticultural products is that already with relatively small differences in temperature between the air blown into the space and the products there are temperature differences between the products present in the space, as a result of which in certain parts of the stock condensation occurs or long and intensive air recirculation is required to combat that condensation.

A further drawback is that the cooling installation with heat exchangers arranged in the top part of the space is laborious to install and difficult to reach for maintenance and cleaning. In addition to the heat exchanger, the compressor is also difficult to reach or is connected to the heat exchanger via long pipes and long pipes are required to drain condensation water.

The object of the invention is to provide a method and an apparatus with which the aforementioned drawbacks can be avoided.

With regard to the method according to the present invention, this object is achieved by applying the characterizing measures according to claim 1 in a method according to the type described in the preamble. As regards the device according to the invention, this object is achieved by applying the characterizing measures according to claim 5 to a device according to the type described in the preamble.

Because the air is blown out at a higher level than the level at which it is drawn in, the heat exchanger can be located in a lower part of the storage space, near the fan, while still allowing cooled air to be brought into an upper part of the storage space. This makes the heat exchanger easy to access for cleaning and maintenance, and only relatively short pipes for coolant and for draining condensation water are required.

The cool air blown above the products in the storage space, before it flows past the products, has the opportunity to spread, so that an even cooling of the products can be obtained. This prevents condensation. During recirculation, relatively large air velocity differences occur near the suction passages. However, this leads to little temperature differences in the storage space, because the air near the suction passage, which has now flowed past the products, has already reached a temperature close to the temperature of the products. In the known method, the air has the greatest velocity between the products near the blow-out passages, where it shows the greatest temperature difference with the products.

A further advantage of the method according to the invention is that locally applied blow-out passages suffice because the air can spread easily above the products. The device according to the invention can hereby be made very compact.

The invention will be further elucidated hereinbelow on the basis of a presently most preferred embodiment of the invention, reference being made to the drawing. 1 shows a cut-away side view of a storage space provided with a device according to an exemplary embodiment of the invention, fig. 2 shows a cut-away top view of a storage space according to fig. 1, fig. 3 shows a cut-away side view of a device as shown in fig. Figures 1 and 2, and Figure 4 are a cut-away perspective view of the device according to Figures 1-3.

Figures 1 and 2 show a storage shed with a storage space 1, in which boxes 2 are arranged. These boxes 2 contain the agricultural and horticultural products to be stored and treated. The boxes are provided with ventilation openings (not shown) to promote air movement between the products. In Figures 3 and 4 only the device 4 is shown in more detail.

A device 4 according to an exemplary embodiment of the invention is placed next to a short wall 3 of the storage space 1.

The device 4 comprises a channel 5 in which a fan 6 is arranged. The device is further provided with a first suction passage 7 for the passage of air from the space 1 to the channel 5, a second suction passage 8 for the passage of air from the environment to the channel and blow-out passages 9, 10, 11 for the passage of air. air from the channel 5 to the space 1. Furthermore, the device comprises means 12 for opening and closing the suction passages 7 and 8.

The heat exchanger 13 communicates with the first suction port 7 and the blow-out passages 9, 10 and 11 are located at a higher level than the first suction port 7.

The device 4 is suitable for treating agricultural and horticultural products in a storage space 1 in order to dry and cool them, so that they remain in a good condition for a long time when stored in the storage space 1. The treatment comprises forced ventilation with outside air in order to dry the products, aeration by forced recirculation of air in the space 1 in order to obtain an even temperature distribution over the products present in the storage space 1, and cooling of the products.

According to the invention, the cooling is carried out by forcibly blowing cool air into the space 1 at a level above the products stored in the space and, during recirculation, air is drawn in at a level below the level at which it is blown into the space.

When the outside air has a sufficiently low temperature and moisture content, this can be done by ventilating with outside air. In that case, the first suction passage 7 is closed and the second suction passage 8 is released. The fan 6 then draws in air from the outside via the second suction port 8 and blows it out via the blow-out ports 9-11. Air can escape from space 1 through ventilation openings 15 arranged at the top of wall 3.

If the temperature or the moisture content of the outside air is too high, air can be recycled into the storage space 1, the air being cooled by means of the heat exchanger 13. For this purpose, the second suction passage 8 is closed and the first suction passage 7 is released. The air is then drawn in by the fan 6 via the heat exchanger 13 and the first suction port 7 and also blown out via the blow-out ports 9-11. The ventilation openings 15 should then preferably be closed.

At very low outside temperatures, both the first suction passage 7 and the second suction passage 8 can be opened to mix externally drawn air and warmer ambient air. For example, if it is desired that the air drawn in has a temperature of 4 ° C, while the temperature of air drawn in from the spacious air is 7 ° C and the temperature of air drawn in from outside is -2 ° C, the suction passages 7 and 8 are released so far that two parts of air is drawn in from space 1 onto one part of outside air.

With the method and the device according to the invention it is very simple to dry the products first and to cool them slightly by ventilation and then to cool the products further and, if necessary, to dry them by recirculation. The air is thereby cooled by means of the heat exchanger 13.

Thus, relatively little energy is used and relatively little condensation water and / or ice formation is obtained in the heat exchanger, when after a relatively warm, humid weather period a relatively cold weather period arrives again, recirculation with cooling can be switched back to ventilating with outside air, in order to save energy to save.

Because the air is blown out at a higher level than the level at which it is drawn in, the heat exchanger 13 can be arranged in a low-lying part of the storage space 1, near the first suction passage, while cooling air can still flow into an upper part of the storage space 1 are being brought. As a result, the heat exchanger 13 is easily accessible for cleaning and maintenance and only relatively short pipes for coolant and for draining condensation water are required.

The heat exchanger of the device 4 according to the exemplary embodiment shown in the drawing is designed as an evaporator 13. It is connected via a pipe 16 to a condenser arranged in a housing 17 outside the storage space 1 (not visible in the drawing). A compressor is also arranged in the housing 17. In addition to the heat released by the condenser, heat released by the compressor is thus also released outside the storage space 1. Of course, the evaporator-compressor-condenser unit can also be arranged to work in the opposite direction, if necessary, for heating the storage space 1.

The cool air blown above the products in the storage space 1 has ample opportunity to spread before it flows past the products, so that an even cooling of the products is obtained. This prevents condensation. During recirculation, relatively large air speed differences only occur near the first suction passage 7. However, this leads to little temperature differences in the storage space 1, because air present near the suction passage 7 has meanwhile flowed past the products, so that the temperature thereof deviates only slightly from the temperature of the products.

The closely spaced blow-out passages 9-11 are sufficient to obtain an even distribution of the air displacement through the space 1, because the air can spread easily above the products. The device according to the invention can hereby be made very compact.

Instead of a plurality of blow-out passages 9-11 directed in different directions, it is also possible, for example, for a single blow-out passage with a width adapted to the width of the wall 3 or several blow-out passages distributed along the wall 3 or over the surface of the space 1. to bring. However, such embodiments are less compact than the exemplary embodiment shown in the drawing.

During recirculation, the air is drawn in near the floor of the storage space. This offers the advantage that an air flow supported by convection between the products can be obtained near the floor. As a result, downward flow can also be maintained in areas where the products are stacked relatively densely and where the air resistance is relatively high. In the known method, in which cold air is blown in from below or from the side, the cold air will come to a standstill in areas where the flow resistance is relatively large, so that products above those parts are not reached by the cooling and drying air flow. These warm, moist products then cause condensation against neighboring colder products.

When the device 4 is used in a storage space as shown in the drawing, for example, no ventilation wall is required, against which the boxes 2 are placed. As a result, 4 columns can also stand on the side of the device. Suction of the air can easily take place near the floor. Optionally, the boxes can be placed at suitable locations with a mutual space 14 in order to promote an even distribution of the air displacement.

When a ventilation wall is used, relatively large air velocities are also achieved in a large part of the stock of products, especially where the temperature of the air differs most strongly from the temperature of the products. Because the products are stacked on average closer to the walls of each box 2 than in the middle thereof, considerable differences in air velocity occur between the center of the box and the areas near the wall. For a large part of the boxes, this results in a steep temperature gradient between the center and the outer part of each of those boxes. This often leads to condensation.

In the method according to the invention, the cool air spreads over the products and then drops down relatively slowly, so that the differences in air speed remain relatively small due to the greater resistance near the outer parts of the boxes. In turn, temperature differences in each box 2 thus remain relatively limited.

The means for opening and closing the suction passages 7 and 8 are designed as a diverter valve 12 movable between a first and a second position, which in the first position (see Figures 3 and 4) closes the first suction passage 7 and the second release suction port 8, in the second position (see fig. 1) closes the second suction passage 8 and releases the first suction passage 7 and in intermediate positions releases the first and second suction passage each in part.

Thus, with a single valve 12, both suction passages 7 and 8 can be closed or released alternately and the ratio between the quantities of air drawn in by the first and the second suction passage can also be controlled. The valve is also easy to operate.

The suction passages 7 and 8 open into a chamber 18, the fan 6 being arranged in a part of the duct 5 adjoining that chamber 18 and the duct 5 being designed as a delivery duct, the discharge passage being at a distance above the chamber 18 The device according to the exemplary embodiment shown in the drawing hereby has a particularly compact form. In addition, the device 4 can be easily manufactured in different embodiments, of which the blow-out passages 9-11 are situated in a height adapted to the height of the space by giving the supply channel 5 a corresponding length. Chamber 18 can always be of identical design.

The second suction passage 8 is bounded by a channel wall 19, which is slidable in the passage direction in the chamber 18. As a result, the distance over which the outer end of the channel wall 19 protrudes from the chamber 18 can be adapted to the thickness of the wall 3 to which the device 4 adjoins, so that the outer end of the channel wall 19 approximately in the plane of the outside of the wall 3 is located. The outer end of the channel wall 19 can for instance be provided with a grid 20.

The diverter valve 12 is connected via a lower hinge connection 21 to the channel wall 19 and connects in its second position (see fig. 1) against the inner end of the channel wall 19, whereby the second suction passage 8 is closed. The diverter valve 12 has a length such that in the first position (see figures 3 and 4) the free edge thereof, when the channel wall 19 is in its extreme outwardly extended position, is still above the top edge of the first suction passage 7 on the wall of the connect the chamber 18 on the side of the first suction port 7. The side edges of the valve 12 adjoin the adjacent side walls of the chamber 18. Thus, regardless of the position of the channel passage 19 relative to the chamber 18, an adequate seal of the first suction passage 7 and the second suction passage 8 can always be obtained if the shuttle valve 12 is in the first position.

The means for closing the second suction passage 8 - in the device 4 according to the present exemplary embodiment, these are formed by the change valve 12 - are preferably thermally insulated. This limits thermal losses during recirculation. In the device according to the exemplary embodiment shown in the drawing, it is moreover counteracted that in hot humid weather and a heat exchanger / moisture in operation condenses against the outside of the valve 12 in the second position. Preferably, the channel wall 19 is also thermally insulated, so that thermal losses along and condensation against the part thereof projecting into the chamber 18 are also prevented.

It is also possible to place the heat exchanger in such a way that air drawn in from the outside as well as from the storage space 1 passes along it. For this purpose, the heat exchanger can for instance be arranged at the top of the chamber 18 or in the channel 5. This makes it possible, during cooling by ventilation, to cool the drawn-in ambient air before it is blown into the storage space 1. This is advantageous under conditions where the ambient air has, for example, a lower absolute moisture content than the air in the storage space 1, but this moisture content is not sufficiently low to use this ambient air without cooling.

Claims (11)

Method for treating agricultural and horticultural products in a storage space (1), comprising forced ventilation with outside air, aeration by forced recirculation of air in the space (1), and cooling, characterized in that it cooling is carried out by forced blowing of air in the space (1) at a level above the products stored in the space (1) and, during recirculation, suction is carried out at a level below the level at which it is blown into the space (1). Method according to claim 1, characterized in that the cooling is carried out by forced recirculation of cooled air in dependence on the temperature and the moisture content of the ambient air compared to the temperature and the moisture content of the air in the storage space (1). or by ventilating with ambient air. Method according to claim 2, characterized in that, during cooling by ventilation, the air drawn in is cooled before it is blown into the storage space (1). Method according to one of the preceding claims, characterized in that the air is drawn in near the floor of the storage space (1) during recirculation. An apparatus for treating agricultural and horticultural products in a storage space (1), comprising a duct (5), a fan (6) in that duct, a first suction passage (7) for the passage of air from the space (1) to the channel (5), a second suction passage (8) for the passage of air from the environment to the channel (5) and an outlet passage (9-11) for the passage of air from the channel (5 ) to the room (1), means (12) for opening and closing the suction passages (7 and 8), and a heat exchanger (13) for cooling air, characterized in that the heat exchanger (13) communicates with the first suction passage (7) and the discharge passage (9, 10, 11) is at a higher level than the first suction passage (7). Device according to claim 5, characterized in that the means for opening and closing the suction passages (7 and 8) are designed as a diverter valve (12) movable between a first and a second position, which valve is position closes the first intake port (7) and releases the second intake port (8), in the two position closes the second intake port (8) and releases the first intake port (7) and in intermediate positions the first and the second intake port (8 ) each partially releases. Device according to claim 5 or 6, characterized in that the suction passages (7 and 8) open into a chamber (18), the fan (6) is arranged in a part of the duct (adjacent to that chamber (18)). 5) and the channel (5) is designed as a delivery channel (5), the outlet passage (9-11) being located at a distance above the chamber (18). Device according to claim 7, characterized in that the second suction passage (8) is bounded by a channel wall (19), which is movable in the passage direction in the chamber (18). Device according to claims 6 and 8, characterized in that the diverter valve (12) is hingedly connected to the channel wall (19) along its bottom edge, sealingly connecting in its first position to an obliquely rearwardly inclined inner end of the channel wall (19). and in its second position, regardless of the position of the channel wall (19) relative to the chamber (18), with its free edge above the first suction passage (7) on a wall of the chamber (18) on the side of said suction passage (7) and with its side edges connect side walls of the chamber (18), which connect to said wall on the side of said suction passage (7). Device according to any one of claims 5-9, characterized by at least two blow-out passages (9-11) directed in different directions. Device according to any one of claims 5-10, characterized in that the means for closing the second suction passage (8) are thermally insulated.