Ventilation – Having protecting air current – Including plural – layered currents
Reexamination Certificate
2003-01-08
2004-03-09
Lu, Jiping (Department: 3749)
Ventilation
Having protecting air current
Including plural, layered currents
C454S188000
Reexamination Certificate
active
06702663
ABSTRACT:
BACKGROUND
(1) Field of the Invention
The invention relates to an arrangement for producing an air partition on a passage between rooms with different air temperatures. The invention may be applied to passages leading to objects for which the temperature of the air has to be maintained at a constant level, for example in warehouse facilities for storing perishable foods, chemicals, or other substances and materials requiring a constant temperature. The invention may also be applied to cooling chambers or refrigerating rooms.
(2) Prior Art
A variety of systems exist for producing air veils (or screens), air curtains or air partitions. These variations include those intended for screening off passages between rooms with greatly varying temperature levels. Partitioning passages leading to refrigerating rooms present a special problem. Relatively strong currents of compensation air are produced due to the great difference in the density of air having a warm or normal temperature level outside the refrigerating room, and the cold air prevailing within the refrigerating room. Also, the water vapor contained in the warmer air condenses on the interface between the different layers of air, producing an ice fog. The ice fog leads to icing phenomena in the passage. The icing occurs particularly in the area of impact of the air veils, as well as along the camber of the passage since the compensating flow and the load of moisture is the strongest in that area.
U.S. Pat. No. 2,775,187 describes an air flow barrier that prevents compensating air currents in an opening between two rooms at different temperature levels. The air flow barrier comprises a pair of air ducts of the same size that are arranged above the delimitation of the opening and within a cooling chamber. The air ducts are extended on flow chambers arranged on the jamb of the opening. These flow chambers have a curved front wall, a fixed plane back wall, a rib connecting the back wall and the front wall for separating the currents of air coming from the air ducts, and air-blowing nozzles located in the front wall. The nozzles are aligned in the longitudinal direction of the flow chambers and are set at a defined angle in relation to each other. The air ducts are connected with ventilators aspirating air from the respective room. A pair of air veils is produced in this way, flowing slightly away from each other and across the opening. The temperature of the air veils corresponds with the given temperature of the room air that is aspirated for producing the air veils. A drawback of this known solution is that the formation of ice fog is not prevented.
An air screen according to DE-PS 971 345 for room passages represents an advanced solution for preventing external air from flowing in through a passage due to difference between the temperature of the external air and the room air. This patent has air jets exiting from an air-blowing slot on one side of the passage and the room wall with an angle that is continuously changing or step by step over the clear height of the opening. The differences in the rate of inward flow prevailing on the opening in accordance with the height are taken into account in this manner.
The air “door” known from DE-PS 10 95 497 for dryers and industrial furnaces uses blowing slot areas whose angles can be adjusted, so that the blowing directions and ejection distances (or ranges) of the air jets respond to changing conditions by rotating individual or several nozzle sections against each other around their longitudinal axes.
However, neither of these references are intended or suited for screening off a passage leading to a refrigeration room. This problem is addressed by an air veil arrangement which, according to a company prospectus of the firm F. H. Biddle B. V. Kootstertille (Netherlands), is referred to as a “MAT-Frigoschleier”, and known also from EP 06 45 588. According to these documents, the passage is swept by a veil of air that consists of at least three partial air currents flowing in the vertical direction for the purpose of separating the room air of a deep freezing chamber from external air. The partial air outer currents are formed by the respective room air; the one or more center currents of air are taken from the dry room air of the deep-freezing chamber and heated before they flow out. This prevents condensation of water vapor contained in the warm external air on the interface with the dry cold air.
Ice fog is produced in connection with this solution, and the formation of ice fog and icing cannot be avoided in the areas that are farthest removed from the blowing nozzles, and in the area of the floor. This is caused by induction effects leading to mixing between the partial air currents, and between the partial air currents and the room air adjacent to the latter, as well as to the eddying of the partial air currents in the area of impingement. This eddying may cause portions of the relatively moist partial flow of warm air, which is loaded with moisture, to penetrate the refrigeration room. However, the load of water vapor is condensed there, resulting in icing.
These effects are amplified by the difference between the density of the cold air of the refrigeration room and the warm external air, and by the tendency to pressure compensation based on the difference in the density. The horizontal arrangement of the blowing nozzles above the passage and the formation of at least three partial air currents require relatively high expenditure for generating the required flow volume and the required flow rate so as to safely sweep the entire passage and prevent compensation currents.
Preventing induction from occurring between the partial currents of air is known from DE 199 32 708 A1. The arrangement produces a veil of air in a passage leading to a low-temperature chamber by supplying an air-blowing nozzle both inside and outside of the low-temperature chamber that is supplied with dry and heated air exclusively aspirated from the low-temperature chamber. The blowing directions are adjusted so that a crossing of the air currents takes place. In particular, the center blowing direction of the blowing nozzle arranged in the low-temperature chamber intersects the plane of the door. However, icing can be avoided only if the partitioning of the low-temperature chamber against compensation currents is cut back.
A combination of the known solutions fails to lead to a satisfying result. Accordingly, in spite of a multi-faceted search over many years, it has not been possible to resolve the screening off of rooms with air at different temperature levels because of the problem posed by ice fog formation and icing phenomena.
SUMMARY
The present invention provides for the separation of air in a passage between rooms with different air temperatures while avoiding icing phenomena in conjunction with a significant reduction of compensation currents as well as expenditures.
The air intake (or suction) part of a first ventilator is arranged in a cooler room. The pressure side of this first ventilator is connected to a heating device that has at least one heating element and a device for controlling the loading temperature. The device is connected to a sensor arranged in a warmer room for detecting the partial pressure of the water vapor. The output of the heating device is connected to at least one first blowing nozzle, which is arranged in the cooler room vertically next to the passage. It is provided with a slot outlet extending over the entire height of the passage. A pair of first blowing nozzles are arranged in the cooler room on each of the two sides of the passage. These air-blowing nozzles are connected with the outlet of the heating device.
A second ventilator with an air intake part is located in the warmer room. A pair of second air-blowing nozzles is connected to the pressure side of this air intake part. These second air nozzles are arranged in the warmer room vertically on both sides of the passage, and provided with slot outlets extending over the entire height of the passage.
The slot ou
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