SYSTEM FOR DRYING AND/OR COOLING AN AIRFLOW
The invention relates to a system for drying and/or cooling an airflow, comprising: at least one cooling device for cooling an airflow, comprising:—at least one cooling channel with an inflow opening for the airflow for cooling and an outflow opening for the cooled airflow,—at least one evaporating channel separated from the cooling channel by a transfer wall and having an inflow opening which is connected for medium throughflow to the outflow opening of the cooling channel, and an outflow opening, and—means for wetting the side of the transfer wall directed toward the evaporating channel, and a drying device for drying the airflow, comprising:—a drying channel with an inflow opening for the airflow for drying and an outflow opening for the dried air-flow, wherein the outflow opening of the cooling channel of the or a cooling device and/or the outflow opening of the evaporating channel of the or a cooling device is connected for medium throughflow to the inflow opening of the drying device.
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The invention relates to a system for drying and/or cooling an airflow, comprising:
at least one cooling device for cooling an airflow, comprising:
-
- at least one cooling channel with an inflow opening for the airflow for cooling and an outflow opening for the cooled airflow,
- at least one evaporating channel separated from the cooling channel by a transfer wall and having an inflow opening which is connected for medium throughflow to the outflow opening of the cooling channel, and an outflow opening, and
- means for wetting the side of the transfer wall directed toward the evaporating channel, and
a drying device for drying the airflow, comprising:
-
- a drying channel with an inflow opening for the airflow for drying and an outflow opening for the dried airflow.
Such a cooling device is for instance known from NL-C-1030538. Reference is made to this patent publication for an example of the operation of a cooling device which can be applied in the system according to the present invention. A drying device, for instance known from NL-C-1029822, wherein reference is made to this patent publication for an example of the operation of a drying device which can be applied in the system according to the present invention, is normally arranged upstream of the cooling device so that the airflow is dehumidified before it flows into the cooling device. A warm, moist airflow can in this way be drawn from the area surrounding the system into the inflow opening of the drying channel of the drying device and there dehumidified, after which the airflow is cooled in the cooling device to a cool, dry airflow which can be used for random purposes. This cool, dry airflow can for instance be supplied to a space. It is noted that other types of dryer and cooling device are also suitable for the system according to the invention.
The invention has for its object to provide such a system for drying and/or cooling an airflow, whereby the airflow is dehumidified efficiently, or at least effectively, in the drying device.
For this purpose the system of the type according to the invention stated in the preamble has the feature that the outflow opening of the cooling channel of the cooling device and/or the outflow opening of the evaporating channel of the cooling device is connected for medium throughflow to the inflow opening of the drying device.
It has been found by applicant that the efficiency of a drying device of a moist airflow increases with the relative humidity of the airflow. The airflow coming from the outflow opening of the cooling channel of the cooling device and/or the outflow opening of the evaporating channel of the cooling device usually has a higher relative humidity than the ambient air, whereby the drying device can dry the airflow coming from the cooling device efficiently. The relative humidity of the airflow is increased in the cooling channel in that at a constant absolute humidity of the airflow the temperature of the airflow decreases, this resulting in an increase in the relative humidity. The relative humidity of the airflow is increased in the evaporating channel of the cooling device in that the airflow cools by means of evaporation of the moisture applied to the transfer wall and thereby absorbs heat via the transfer wall from the airflow flowing through the cooling channel. The temperature of the airflow in the evaporating channel will increase due to the heat absorption, whereby this airflow can absorb more moisture. Due to the evaporation of the moisture and the temperature increase both the absolute and the relative humidity of the air in this way increase, and this relative humidity will be higher than the relative humidity of ambient air.
The relative humidity of the airflow in the system according to the invention is therefore increased in the cooling device, after which the airflow is dehumidified in the drying device. The air which is efficiently dehumidified in this manner can for instance be supplied to a space where dry air is desired or, if desired, be used for any random application. The air to be dehumidified can for instance be ambient air, which is for instance drawn into the inflow opening of the cooling channel of the cooling device. Optionally or additionally, the ambient air can also be another random airflow.
The system according to the invention is therefore distinguished from the known system in that it is now precisely the cooling device which is arranged upstream of the drying device instead of downstream. It would seem contradictory to first increase the relative humidity of an airflow before drying it, but according to the invention it is precisely this which increases the efficiency of the drying device. The air which is dried efficiently in this manner can be used for air drying processes or for air cooling processes.
In another embodiment of the system according to the invention the outflow opening of the drying device is connected for medium throughflow to the inflow opening of the cooling channel of the or a cooling device.
The dehumidified air is hereby cooled once again to a cool, dry airflow which can be used as desired. This cool, dry airflow can for instance be supplied to a space.
In an embodiment of the system according to the invention the system comprises two cooling devices, wherein the outflow opening of the drying device is connected for medium throughflow to the inflow opening of the cooling channel of the one cooling device, and wherein the outflow opening of the cooling channel of the other cooling device and/or the outflow opening of the evaporating channel of the other cooling device is connected for medium throughflow to the inflow opening of the drying device.
In another embodiment of the system according to the invention the system comprises a heat exchanger which is connected on the one side for medium throughflow to the outflow opening of the cooling channel of the cooling device and/or the outflow opening of the evaporating channel of the cooling device, and which is connected on the other side for medium throughflow to the inflow opening of the drying device and/or the inflow opening of the cooling channel of the cooling device.
In such a system the cooled airflow is not supplied to a space but brought into heat-transferring contact in the heat exchanger with a heat or cold-transferring medium. The temperature of the cooled airflow will increase here, while the heat or cold-transferring medium will cool. The heat or cold-transferring medium can be a second airflow, for instance ambient air, which is drawn into the heat exchanger, cooled and subsequently supplied to a space. The heat or cold-transferring medium can also be water, which water is cooled in the heat exchanger. This cooled water can for instance be used to cool a building.
The heat exchanger can be any random type of heat exchanger, wherein the flows are in counterflow.
The heat exchanger is for instance connected on the one side for medium throughflow to the outflow opening of the cooling channel of the cooling device and connected on the other side for medium throughflow to the inflow opening of the cooling channel of the cooling device and/or the inflow opening of the drying device, wherein the outflow opening of the cooling channel and/or the outflow opening of the evaporating channel of the cooling device is connected for medium throughflow to the inflow opening of the drying device.
This system has the advantage that the cooled airflow is discharged from the outflow opening of the cooling channel of the cooling device to the heat exchanger, while the airflow from the outflow opening of the evaporating channel of the cooling device, which airflow has a higher temperature than the airflow coming from the cooling channel, is carried to the inflow opening of the drying device.
The system is for instance a closed system in respect of at least the airflow. This has the advantage that the system is independent of the outdoor climate.
In a closed system means can moreover be present for adjusting the air pressure in the system. The value for the air pressure in the system can for instance lie between 0.5 bar—3 bar. The air pressure can particularly be 0.5 bar, 1 bar or 2 bar.
A higher air pressure has the advantage that fewer grams of water per kilogram of air have to be extracted from the airflow than at a lower air pressure in order to cool the air by a determined number of degrees. A lower air pressure has on the other hand the advantage that a lower temperature of the airflow can be achieved at a constant absolute humidity than at a higher pressure. It is therefore possible to opt for a determined air pressure subject to the application of the system.
In a practical embodiment the drying device comprises drying means for drying the airflow. Such drying means are hygroscopic and absorb moisture from the airflow through absorption and/or adsorption. Examples of such drying means are for instance, though not exclusively, silica gel, ammonium nitrate, calcium chloride, carbonyl fluoride, magnesium sulphate, sodium chloride, sodium sulphate, sodium propionate, a (p(AA)) sodium salt.
The drying means are preferably of a type wherein the amount of moisture which the drying means can absorb relative to the dry weight of the drying means increases with a rise in the relative air humidity.
With such drying means the drying device will be able to absorb more moisture from the airflow in efficient manner at a higher relative air humidity than at a lower relative air humidity.
From a determined value of the relative air humidity the amount of moisture which the drying means can absorb relative to the dry weight of the drying means particularly increases at least more or less exponentially with a rise in the relative air humidity.
Determined salts for instance show such a more or less exponential curve from a determined value of the relative air humidity, whereby the moisture absorption of the drying means takes place in highly efficient manner at a high relative air humidity of the airflow above this determined value.
The invention will be further elucidated hereinbelow with reference to figures shown in a drawing, in which:
The airflows are designated in the figures with arrows. Where an arrow splits into two or more continuous arrows means that parts of the airflow are separated and these partial airflows flow to different destinations. The flow rate of the different partial airflows and the ratios of different partial airflows can be variable, and in that case be adjusted as desired.
The air which flows into the inflow opening of cooling channel 10, and the relative humidity of which is increased in cooler 1, can for instance be ambient air. In the system according to
In a system according to
In
The distribution of the airflows can otherwise be adjusted as desired. In
It may also be the case that a part of the cooled airflow coming from the outflow opening of cooling channel 10 of cooler 1 is mixed with the airflow coming from evaporating channel 12 of cooler 1, and that this mixture is guided to dryer 2. The amount of moisture to be dried in grams per kg of air is thus reduced, and due to the drying the rise in the temperature of the airflow is relatively lower than if only the warm, moist airflow coming from evaporating channel 12 is guided to dryer 2.
The Mollier diagrams of
The invention is not limited to the shown embodiments, but also extends to variants within the scope of the appended claims.
The stated and shown ratios of the airflows serve only for the purpose of illustration and should in no way be interpreted as being limitative.
Claims
1. A system for drying and/or cooling an airflow, comprising:
- at least one cooling device for cooling an airflow, comprising: at least one cooling channel with an inflow opening for the airflow for cooling and an outflow opening for the cooled airflow, at least one evaporating channel separated from the cooling channel by a transfer wall and having an inflow opening which is connected for medium throughflow to the outflow opening of the cooling channel, and an outflow opening, and means for wetting the side of the transfer wall directed toward the evaporating channel, and a drying device for drying the airflow, comprising: a drying channel with an inflow opening for the airflow for drying and an outflow opening for the dried airflow,
- characterized in that
- the outflow opening of the cooling channel of the cooling device and/or the outflow opening of the evaporating channel of the cooling device is connected for medium throughflow to the inflow opening of the drying device.
2. The system as claimed in claim 1, wherein the outflow opening of the drying device is connected for medium throughflow to the inflow opening of the cooling channel of the or a cooling device.
3. The system as claimed in claim 1, comprising two cooling devices, wherein the outflow opening of the drying device is connected for medium throughflow to the inflow opening of the cooling channel of the one cooling device, and wherein the outflow opening of the cooling channel of the other cooling device and/or the outflow opening of the evaporating channel of the other cooling device is connected for medium throughflow to the inflow opening of the drying device.
4. The system as claimed in claim 1, comprising a heat exchanger which is connected on the one side for medium throughflow to the outflow opening of the cooling channel of the cooling device and/or the outflow opening of the evaporating channel of the cooling device, and which is connected on the other side for medium throughflow to the inflow opening of the drying device and/or the inflow opening of the cooling channel of the cooling device.
5. The system as claimed in claim 4, wherein the heat exchanger is connected on the one side for medium throughflow to the outflow opening of the cooling channel of the cooling device and connected on the other side for medium throughflow to the inflow opening of the cooling channel of the cooling device and/or the inflow opening of the drying device, and wherein the outflow opening of the cooling channel and/or the outflow opening of the evaporating channel of the cooling device is connected for medium throughflow to the inflow opening of the drying device.
6. The system as claimed in claim 5, wherein the system is a closed system in respect of at least the airflow.
7. The system as claimed in claim 6, wherein the value for the air pressure in the system is between 0.5 bar-3 bar.
8. The system as claimed in claim 1, wherein the drying device comprises drying means for drying the airflow.
9. The system as claimed in claim 8, wherein the amount of moisture which the drying means can absorb relative to the dry weight of the drying means increases with a rise in the relative air humidity.
10. The system as claimed in claim 9, wherein from a determined value of the relative air humidity the amount of moisture which the drying means can absorb relative to the dry weight of the drying means increases at least more or less exponentially with a rise in the relative air humidity.
Type: Application
Filed: Dec 22, 2011
Publication Date: Dec 19, 2013
Applicant: OPTIMAIR HOLDING B.V. (Tuk)
Inventors: Willem Meijer (Zelhem), Arthur Van Der Lee (Tuk)
Application Number: 13/997,027
International Classification: F24F 6/02 (20060101);