FR2761760A1 - Hot air cooler - Google Patents

Abstract

The hot, dry air cooler comprises a casing (1) including a water tank (3). A fan (7) with an external rotor induces hot air through the special cartridge (2). There is a water flow regulating system (4). The apparatus operates on the principle of absorption the air heat by endothermic evaporation of the water permanently humidifying the cartridge walls which are placed in the hot air stream. The water brought to the cartridge walls is regulated to adapt to the water consumption so as to modulate the air temperature within a given range. The cartridge vertical evaporation walls are of unwoven cloth and placed in the hot air flow upstream of the fan and in the same casing. The independent water tank is replenished periodically.

Description

Hot and dry air cooling device
compact and inexpensive
The present invention relates to a range of devices intended to improve the comfort of people confined in difficult conditions of ambient heat and dryness. It offers a simple and effective solution, adapted to various conditions of use and at the best cost.

These devices are offered for a wide range of applications with fresh air flow rates ranging from 10 to 100 meters per hour. 115 do not require any special maintenance and consume little energy (3 to 20
Wh depending on the model). 115 are connected to a mains socket, 220 or 115 VAC, 50 or 60 Hz, and in cars to the cigarette lighter (or to a fitted outlet). 115 can also run on a battery (for models with low energy consumption), independently, to be taken on a trip or in places where there is no electricity source. They are light (0.6 to 1.2 ka) and not bulky. They are reliable, guaranteed for 20 thousand hours of operation.

 There are already patented projects in this field, without practical realization, of air humidification or "room or local air conditioning" apparatus comprising a fan as well as means of water supply including a water tank disposed downstream of said fan, based on the principle of spraying water (French patent NO 1,411,179), or entrainment of water which descends en masse on the elongated elements, placed in a flow fast air (rev. 1, line 15 of French patent NO 2,546,614).

All these projects are characterized by a large air flow and a significant water consumption (2 L / h given for a device according to patent NO 2.546.614) which is projected into the air and gives a feeling of freshness by watering; this can cause damage without providing a lasting solution to the heat problem. In a confined space, the air is quickly saturated and no longer absorbs water which continues to be poured en masse. These devices are intended rather to humidify the air in an open space, provided you keep people and objects that do not like water away from the device.

The description of patent NO 2,546,614 confirms this thesis: "For example, the air conditioning device according to the invention, for a fan with a diameter of 250 mm and a power of 40 W (flow rate 500 m / / h) makes it possible to lower the temperature of a room from 15 to 20 as follows: b) in Seville (400C, 38% humidity) the blowing temperature is 320C, the water consumption is around 2 I./h. "
An analysis of this result demonstrates: a) atmospheric air at 400C and 38% humidity already contains 22.6 g of water / mJ (100% saturated air contains 59.6 g of water / not). At the blowing temperature of 320C, the air is saturated with 37.2 g of water / mJ, therefore a maximum additional supply is 13.6 g of water / m. In a space of 40 m (approx. 15 m of surface) saturation is reached with consumption equal to: 40 mJ x 13.6 g / m = = 520 g of water, i.e. after a quarter of operating hours. After that, water continues to be projected into the air which can no longer absorb it and pours out in front of the device.

After one hour of operation there is damage.

b) there is total confusion between the statements: (Device) "allows to drop the temperature of a room" and "the supply temperature is 320C" which suggests that the room temperature dropped from SOC.

However, there is no relation between the blowing temperature at the outlet of the appliance and the temperature at any point far from the room which has not varied.

c) We can clearly see the reason why the fan is placed upstream of the tank and the elongated elements (it works under overpressure). This is so as not to drown the engine with water which descends en masse on the said elements and is carried along by a powerful flow.

d) The lower tank (26) for receiving the water flowing by gravity through the elongated elements (rev. 8, lines 18, 19), exposed to the wind, in view of the amount of water coming down, whatever its capacity will overflow quickly.

It is difficult to see this device installed in a moving vehicle, as it is stipulated in the description (p. 7, line 11) e) "The elongated elements, made of filter paper or foam" (rev. 5), " in sheets, folded in half and passed around every other support so as to have their ends free, hanging downwards "(rev.9).

At the first gust of the fan, these elements will twist by pouring the water flowing outside the device and obstructing the passage of air.

It follows that the air conditioning apparatus according to this invention is not feasible.

The present invention aims to improve the comfort of people placed in front of these devices by cooling and humidifying the blown air to make it breathable, in a room or in an overheated, ventilated room, while avoiding the drawbacks described above. She sets a more modest but realistic goal. The concept is completely different.

The proposed solution is characterized by:
a) A low and adjustable water supply, adaptable to the conditions of use. This supply of water is regulated so that it can permanently humidify the walls of the special cartridge without flow. There is no reservoir for receiving excess water. By regulating the water supply, the blowing temperature can be adjusted within a certain range. In the closed position, the device operates like an ordinary fan.

Between the closed position and the maximum flow position, there is a regulation range to adapt to the ambient conditions.

b) The operation is based on the principle of absorption of heat by the evaporation of water which permanently humidifies the walls of the special cartridge placed in a flow of low pressure air, generated by a fan, itself placed downstream of the cartridge at the outlet of the device. The endothermic evaporation reaction takes place inside the device and not outside, as is the case for devices which proceed by spraying or by entraining water by a powerful flow.

The air passing through the cartridge loses heat and leaves the cooled and humidified device. The low pressure air flow promotes water absorption and flows without turbulence.

As already mentioned, the evaporation of water is a strongly endothermic reaction. The latent heat of evaporation of the water at the wall temperature approx. 200C, is 592.6 calJg.

The specific heat of the air, at atmospheric pressure, is 288 cal./mJx deg.

The heat absorbed by the evaporation of one g. of water, therefore makes it possible to lower the temperature of a cubic meter of air by 20C. For an air flow of 20 m3 / h, and for a water consumption of 80 g / h, the difference in air temperatures at the inlet and at the outlet of the device is therefore 80C.

If this device is placed in the conditions cited in Seville (400C, 38% humidity), for an air flow of 20 n / h and a modest water consumption of 80 g / h, the air passing through l The device takes care of 4 g of water per cubic meter and leaves refreshed with 80C with 11% additional humidity, that is to say at 49%. Given the ambient heat conditions, it is reasonable to charge more, with a water consumption of the order of 120 to 150 g / h and to lower the blowing temperature by 12 to 15 OC, without inconvenience by excessive humidity people seated in front of this appliance. In this same room, ventilated, it can be used continuously without fear of excessive accumulation of moisture, which will evacuate slowly and stabilize at an acceptable level, and lastingly improve the comfort of the occupants.

The same blowing temperature drop is obtained with the hourly consumption of 80 g of water for this device as with 2000 g for the other, without undergoing the consequences described above, hence the advantage of metering the flow rate of water and the principle of evaporation inside the device, and not outside, of the water dispersed by the spraying process, or by entraining the droplets in a strong air stream .

With another, more powerful version of the device, additionally comprising a moisture absorption module at the entrance of the device, or with other static moisture absorption means (e.g.

commercial chemical absorbers) placed in the treated room, it can be maintained durably in said room or an enclosure, confined, the temperature and humidity conditions of the air at a constant level, pleasant to live.

As it has already been written, the functioning of this device is based on the principle of absorption of heat from the air passing through, by the evaporation of the water inside it. The hot and dry air in contact with the wet walls of the special cartridge is charged with moisture and loses heat. The quantity of frigories supplied by the system, in a time interval, is a function of the quantity of water transformed into vapor during this time; this being a function of the flow rate and the additional degree of humidity of
The air, relative to the ambient, acquired during its passage through the device. This additional degree of humidity depends on the temperature, the dryness of the air, and the surface of the damp walls exposed to the contact with the flow of vacuum air, generated by the suction fan. Said fan, flat with external rotor with paddles fixed directly on the rotor, is placed in a box, forming the casing of the device, downstream of the cartridge (suction), thus creating a flow of low pressure air, passing through the cartridge , which promotes evaporation.

The implementation of this principle consists in exposing a large wet surface and permanently supplied with water in contact with the flow of hot air while respecting the pressure drop authorized by the specifications of the fan used. In a device with a 1201120 mm section, 1 to 3 m of walls can be deployed (depending on the model), these being swept by air on both sides, i.e. a surface of contact with the flow of 2 to 6 m .

For larger and more powerful devices, the deployed surface is related to the desired flow rate and the conditions of use.

The choice of fan is defined aerodynamically by the air flow required for a given static pressure value 11 there is a wide choice of compact and silent industrial fans with various static flow rates and pressures, to build a range of devices suitable for Terms of use.

Technically and commercially, a device intended for use in a large room and in extreme conditions of temperature and drought cannot be the same as that used in a car or cabin in a milder climate. This is part of the development before the release of the catalog of commercial proposals.

From a technical point of view, it is a device that is simple to manufacture (see fig. 1). Externally it is a plastic case (1) in the shape of the letter U, forming a casing of the device, in which is placed a special cartridge (2), upstream of the fan (7), itself placed in a housing adapted to its shape in the same case, and phonically isolated from said case. This cartridge (2), which is removable, is made up of walls, preferably vertical and parallel to the axis of the device, in a strip of fabric (or of another material) preferably nonwoven (of lower cost), water-repellent and resistant The water that permanently wets the exposed walls on its two sides in contact with the flow of hot and dry air is transformed into vapor and to do this it absorbs the heat of the air, which leaves refreshed, humidified and freed of impurities, retained by the damp walls. In the event of a temporary excess flow, the western water is absorbed by a sponge (10) on which the cartridge rests, and then it is discharged to the outside through an orifice (8) located at the bottom of the casing (1). . t
The cover of the box (1) consists of one (or more) water reserve (3) accompanied in the form of a removable box, fixed on the box (1), hermetically closed to the outside by a cover ( 11), also removable, and this reserve can be permanently supplied by an orifice (9) located on the cover, in the event of continuous operation of the device.

The reserve capacity is provided for an operating autonomy of 3 to 5 hours (i.e. 300-500g)
The bottom of the tank is provided with a regulation system (4) for the flow of water and its distribution over the walls of the cartridge (2). The water flow is adjusted by a handle (5) located on the front of the device.

This regulated feeding system allows optimal use of the device, adapted to the conditions of the environment of temperature and drought, very variable. The water flow can be easily adapted to consumption without excess or defect.

The ends of the device at the inlet and outlet are fitted with protective grills (6).

Dust and smoke particles suspended in the air settle on the damp walls of the cartridge. For hygienic reasons, it is therefore recommended to change the cartridge periodically, if the device is used in a dusty environment.

The markets concerned by these devices are mainly those of regions with hot and dry climate, but also of regions with moderate climate during the summer periods.

For a modest price these devices make it possible to improve comfort and reduce the fatigue of people confined in premises or in overheated vehicles.

It is an air conditioning substitute accessible to all. n does not require any particular installation, it is fixed with suction cups (13), or with an elastic support (12), phonically isolated from the base by soft rubber sleeves (14).

Claims (7)

 Claims  special cartridge (2), characterized in that the operation of said device is based on the principle of absorption of heat from the air by the endothermic evaporation reaction, without dispersion, inside the device, of the water which permanently humidifies the walls of the special cartridge (2), placed in a flow of hot, depressed air, generated by the fan (7).  1) Apparatus for cooling hot and dry air, compact and inexpensive, comprising: - a casing (l) forming the casing of the apparatus and its cover, water reserve (3); - an external rotor fan (7) with paddles fixed directly on the rotor, which draws hot air through the cartridge (2) - a special cartridge (2), - a system for regulating the water flow (4) as well as its distribution over the walls of the 2) air cooling device according to claim 1., characterized in that the supply of water which permanently humidifies the walls of the special cartridge (2) is regulated to adapt the consumption of the water of each appliance under the conditions of use, without excess, and in this way modulate the blowing temperature within a certain range. 3) air cooling device according to claims 1 and 2, .characterized in that the special cartridge (2), with evaporation walls, preferably vertical, in resistant water-repellent material, preferably in non-woven fabrics woven, is placed in a hot air flow, low pressure, upstream of the fan (7), in the same case (1) as the latter. 4) air cooling device according to any one of the preceding claims, characterized in that the special cartridge (2), designed as a specific part, independent of the tank (4), is removable to be changed periodically (by hygiene measure) if the appliance operates in a dusty or smoky environment. 5) air cooling device according to any one of the preceding claims, characterized in that the external rotor fan (7), with blades fixed directly on the rotor, is placed in a housing adapted to its shape in the same case (1) as the special cartridge (2), downstream of the latter, and phonically isolated from said case (1). 6) air cooling device according to any one of the preceding claims, characterized in that said device with a moderate air flow and with a low water consumption, allows to lower the blowing temperature, compared ambient, in a range up to 15 "C, depending on the ambient conditions of use and the setting of the device, and considerably improving the comfort of people sitting in front of it, in a ventilated room , without risk of excessive moisture accumulation. 7) air cooling device according to any one of the preceding claims, characterized in that said device, in a version using a fan having a substantial static pressure, associated with a moisture absorption module, placed at the input of the device, or to other static absorption means (for example commercial chemical moisture absorbers) makes it possible to maintain the temperature and humidity conditions in a confined room or enclosure, at a constant level and pleasant to live.