What is it:
Generally, evaporative cooling occurs when some means or product yields heat to evaporate water. The evaporation of a product any is a endothermic process, that is, to heat demand. This heat transfer may be forced (when supply heat) or induced (when we created conditions for the product remove heat from the middle). A well-known example of evaporative cooling is the cooling tower, a parcel of water because it is induced to evaporate, removing heat from the water, which cools by giving in this heat.
Evaporative air cooling, the same principle is used: the air gives energy (heat) for the water to evaporate, resulting in a stream of cold air at the outlet of the cooler.
History:
The man already use the evaporative cooling for a long time. Frescos of ancient Egypt (2500 BC) show slaves shaking jars (porous walls) with water, to cool the contents.
This is still done today in the filters and moringas of baked clay. A fraction of the stored water evaporates through the vessel wall, cooling the remaining liquid.
In ancient Rome and during the middle ages, water reservoirs with umidificadas walls were used. The genius of Leonardo Da Vinci led him to devise a swamp cooler in the shape of a water wheel.
Examples:
Although not always realized, with some frequency we feel the effects of evaporative cooling:
- When we approach a waterfall and we note the cooler air;
- When we came out of a pool (we leave the water, which is colder and we contacted the air that is hotter) and have that feeling cold;
- When, on a hot day, there is a “summer rain” and observe the almost instantaneous drop in temperature;
The wet bulb temperature (TBU) that is read on a thermometer with the bulb surrounded by moist gauze, is the temperature lower than the ambient air can take on the site, and corresponds to the condition of air saturated by water evaporation in the area next to the bulb.
Many other examples can be cited, but we believe that our reader has already understood the idea of EVAPORATIVE COOLING. It’s simple, but it never hurts to emphasize that it is with him that the Earth controls the temperature on your surface.
Principle:
The atmospheric air is a mixture of dry air and water vapor. For a given temperature and pressure condition this mixture has the ability to contain a maximum amount of water vapour (air saturated = 100% relative humidity or 100% RH). In practice this condition of saturated air is only observed during and just after a rain. Normally the air is unsaturated (UR 100 <%) and, therefore, able to absorb more moisture.
As drier air (lower UR), the greater the amount of water vapour that can be absorbed.
So there is this absorption is necessary for the water used pass of the liquid phase for the steam phase. This phase shift demand an amount of energy that is taken off the Middle, air, cooling it.
There is a basic principle in the physical-chemical reactions whereby the higher the contact surface between the reagents, the greater the speed of the reaction. Therefore, we must seek to increase the contact area between water and air as the air is already diluted and occupying all available space, we have the water to disperse.
Processes used:
A way to “expand” the water is through showers, sprays or atomization. Are very efficient methods, reaching high levels of humidification and temperature lowering. It is recommended, however, that this type of humidification is performed inside the cooler. When released into the environment, even though micro-pulverizada, water can find an already saturated region, which will not be absorbed by air and be rash, watering that stands in your way to the ground. Even systems with umidostatos and solenoid valves, cutting the flow of water when a given relative humidity is reached, tend to trickle in nozzles to stabilize water pressure in the system.
Another way adopted is to use contact surfaces, that is, using materials with high surface exposed. The water is distributed on top of hives or blankets and down preformed or random channels, watering around the middle. The air traverses across the hive or the blanket, coming into close contact with the middle and absorbing moisture soaked until well near the saturation.
The main advantages of this method are:
- The wet part of the system is restricted to the equipment;
- Never goes beyond the saturation point, because the breath just absorbs moisture that can hold, leaving the water surplus equipment;
- This process performs an air wash still, retaining dust and dirt in the Beehive or in manta, which are continuously washed by water surplus.
The overall results achieved by any of the systems described above depend on the flow of air is necessary to adequacy of flow and speed for which to obtain the best environmental conditions.
These considerations are normally taken into account by manufacturers of the equipment.
Energy involved:
When 1 liter of water (1 kg) evaporates, consumes approximately 580 kcal. It’s the same amount of energy needed to cool 58 liters of water from 30° C up to 20° c. Or to cool air ³ 208m (242kg) the same 30° C up to 20° c.
As you can see by the numbers above, the energy involved in the phase change of water (latent heat) is a great variation in temperature (heat sensitive).
We have here the answer to a question quite frequent: the use of ice water improves the efficiency of the cooler? No, because the gain in temperature reduction is negligible outside the obtained by evaporation.
Temperature reduction:
According to the above, we know that a reduction of temperature is greater the smaller the relative humidity of the air. Thus, for the same temperature at the entrance to the cooler, we can have different output as temperatures vary the relative humidity of the air at the entrance.
The “table of temperature reduction through evaporative cooling system” in annex presents the values obtained for equipment with hives of humidification.
Properly designed and manufactured equipment, two rules of thumb may be taken to know the temperatures to be achieved in a particular region.
- Cold air temperature will be approximately 1° C above the wet bulb temperature (TBU) trapped air.
- Cold air temperature will be approximately 3° C below the outlet temperature of the water of a cooling tower if any on site (since this is operating properly).
One very important fact to notice is that the relative humidity varies over the course of a normal day. Considering that the absolute humidity (grams of water/kg dry air) does not change much throughout the day, unless it rains occur or is close to regions covered by water (sea, rivers, dams, etc.), the relative humidity will vary inversely with temperature. Thus, the hotter the day, the lower the relative humidity and best evaporative cooling performance.
The curves “Performance standard on a Typical Summer Day” show the temperatures resulting from the evaporative system in a typical day of summer in the air captured function for different weather conditions.
Evaporative Cooling applications:
We have the evaporative system has application in almost every type of environment with a range of uses much more comprehensive than traditional air conditioning and ventilation.
Therefore, small to large spaces, sparsely populated areas to large adensamentos, of locations with low thermal load to large heat generators, leisure areas workplaces, everyone can benefit from the advantages of evaporative cooling.
There are still those environments where the relative humidity is high maintenance requirement of the industrial process conditions. In such environments, depending on the desired humidity can be used air renewal total, partial or even null.
As an example, we mention below some of the numerous possible applications:
- Academies
- Airports
- Sheds in General
- Industrial environments in General
- Electroplating
- Common areas of shopping centers
- Gyms, sports
- Auditoriums
- Farms
- Aviaries
- Churches
- Banks
- Hatcheries
- Bars
- Textile industries
- BINGOs
- Pulp and paper industries
- Clubs
- Winter gardens
- Bowling alleys
- Dry cleaners
- Paint booths
- Auctions
- Cabins of substations
- Shops
- Fermentation Chambers
- Markets and grocery stores
- Cooled cameras
- Workshops
- Houses of spectacles
- Theme parks
- Cinemas
- Food courts
- Industrial kitchens
- Restaurants
- Flocks of animals in General
- Industrial cafeterias
- Deposits
- Control rooms
- Schools
- General machinery rooms
- Offices
- Supermarkets
- Subway stations
- Temples
- Greenhouses for plants, mushrooms, fruits and vegetables, etc.
- Rail and road terminals
- Trade fairs and conventions
Evaporative system installation Requrements:
Air renewal
Soon after going through an evaporative cooling system, the air has high relative humidity to your close to saturation. To enter the environment the air heats, beat the existing thermal loads on site and reducing UR without, however, go back to original levels (before the cooling). If this air cooler recirculates, the efficiency will be lower with each new passage, tending to be null after a few recirculates. We would then a situation of high temperature and humidity, which is very uncomfortable.
Thus, the fundamental condition of total renovation.
Exhaustion and openings
As a common ventilation process, total air renewal involves exhaustion or apertures compatible with the flow of air admitted. Thus, doors, Windows, vents or exhaust fans are generally welcome. There is only the need to verify the layout the same to optimize air circulation throughout the environment.
Thermal Insulation
This is an item that, if present, always helps. For new facilities, however, is expendable, unlike HVAC systems for air conditioning. It turns out that the costs of installation and operation of evaporative systems are so much more than those of air conditioning, which turns out to be cheaper to increase the capacity of the evaporative system, designed to insulate roofs and walls.
In fact, in some cases, only the cost of the thermal insulation of the given environment was greater than the cooling system installed.
Furthermore, the operation of the latter involves only the blowers and/or exhaust and circulation pumps or sprinkling of water, meaning somewhere around 1/10 the power consumed by a traditional air conditioning system.
Water quality
As a general rule, we recommend the use of drinking water in evaporative coolers.
Water with high levels of minerals, mainly calcium (water “hard”), should be avoided because the concentration of soluble solids tends to increase with the evaporation (only pure water evaporates) and, from a certain point, there will be supersaturation and precipitation of minerals. This can be noticed by the formation of deposits on the surface of the hive or blanket.
If you need to use this type of water, it is necessary to maintain a continuous bleed (bleed-off) in order to avoid the occurrence of incrustation.
Water with mineral deficiency, on the other hand, tends to compensate for this lack picking up minerals from the hives, weakening the enrijecedora resin.
With respect to PH, the ideal is located in 7 to 8, and acceptable values between 6 and 9.
Treatment of Water
Since the air is washed when passing through the BEC, it removed particles tend to aggregate in the humidifier and this being loaded by water to the reservoir. Between these particles are fungi, bacteria, algae, etc., which, in humidity, can proliferate.
When operating this proliferation is quite reduced by aeration of the water and by the action of oxygen as oxidant of microorganisms. When stopped, however, the growth of colonies that can generate unpleasant odors in the next match of the equipment.
To prevent this from occurring, some action must be taken, namely:
- Chlorination of the water in the reservoir rocks of chlorine;
- Continuous purging through drain that can be adjusted according to the dirt from the air captured;
- Drainage and periodic cleaning of the reservoir to remove accumulated dirt;
- When is turn off the equipment, disconnect first the bomb and leave the fan running dry the element (from 10 to 30 minutes, depending on the humidity of the air captured); should the equipment be turned off for a long time, a weekend for example, depleting the reservoir and fill it when you go to turn it on.
Equipment platforms
Depending on the installation to be made, it will be necessary to use brackets or platforms for equipment support. One should always take into account two factors:
- Safety;
- Practicality.
At the time of service the equipment, it is important to be able to ensure that this is done in a practical way and without risk to the operator.
For equipment installed up to 3 m above the ground, the platform/floor must have support and body guard.
| Temp. Outside | R.h. External | Temp. Resulting | Temp Reduction. | Temp. Outside | R.h. External | Temp. Resulting | Temp Reduction. |
|---|---|---|---|---|---|---|---|
| 22° C | 20% | 12.5 | 9.5 | 34° C | 20% | 21 | 13 |
| 25% | 13 | 9 | 25% | 22 | 12 | ||
| 30% | 14 | 8 | 30% | 23 | 11 | ||
| 35% | 14.5 | 7.5 | 35% | 24 | 10 | ||
| 40% | 15 | 7 | 40% | 25 | 9 | ||
| 45% | 15.5 | 6.5 | 45% | 26 | 8 | ||
| 50% | 16.5 | 5.5 | 50% | 27 | 7 | ||
| 55% | 17 | 5 | 55% | 28 | 6 | ||
| 60% | 18 | 4 | 60% | 28.5 | 5.5 | ||
| 65% | 18.5 | 3.5 | 65% | 29 | 5 | ||
| 70% | 19 | 3 | 70% | 30 | 4 | ||
| 75% | 19.5 | 2.5 | 75% | 31 | 3 | ||
| 23° C | 20% | 13 | 10 | 35° C | 20% | 21.5 | 13.5 |
| 25% | 14 | 9 | 25% | 22.5 | 12.5 | ||
| 30% | 15 | 8 | 30% | 24 | 11 | ||
| 35% | 15.5 | 7.5 | 35% | 25 | 10 | ||
| 40% | 16 | 7 | 40% | 25.5 | 9.5 | ||
| 45% | 16.5 | 6.5 | 45% | 27 | 8 | ||
| 50% | 17.5 | 5.5 | 50% | 28 | 7 | ||
| 55% | 18 | 5 | 55% | 28.5 | 6.5 | ||
| 60% | 18.5 | 4.5 | 60% | 29.5 | 5.5 | ||
| 65% | 19 | 4 | 65% | 30 | 5 | ||
| 70% | 20 | 3 | 70% | 31 | 4 | ||
| 75% | 20.5 | 2.5 | 75% | 31.5 | 3.5 | ||
| 24° C | 20% | 13.5 | 10.5 | 36° C | 20% | 22.5 | 13.5 |
| 25% | 14.5 | 9.5 | 25% | 23.5 | 12.5 | ||
| 30% | 15.5 | 8.5 | 30% | 24.5 | 11.5 | ||
| 35% | 16 | 8 | 35% | 25.5 | 10.5 | ||
| 40% | 17 | 7 | 40% | 26.5 | 9.5 | ||
| 45% | 17.5 | 6.5 | 45% | 27.5 | 8.5 | ||
| 50% | 18 | 6 | 50% | 28.5 | 7.5 | ||
| 55% | 19 | 5 | 55% | 29.5 | 6.5 | ||
| 60% | 19.5 | 4.5 | 60% | 30.5 | 5.5 | ||
| 65% | 20 | 4 | 65% | 31 | 5 | ||
| 70% | 20.5 | 3.5 | 70% | 32 | 4 | ||
| 75% | 21 | 3 | 75% | 32.5 | 3.5 | ||
| 25° C | 20% | 14.5 | 10.5 | 37° C | 20% | 23 | 14 |
| 25% | 15.5 | 9.5 | 25% | 24 | 13 | ||
| 30% | 16 | 9 | 30% | 25.5 | 11.5 | ||
| 35% | 17 | 8 | 35% | 26.5 | 10.5 | ||
| 40% | 18 | 7 | 40% | 27.5 | 9.5 | ||
| 45% | 18.5 | 6.5 | 45% | 28.5 | 8.5 | ||
| 50% | 19 | 6 | 50% | 29.5 | 7.5 | ||
| 55% | 20 | 5 | 55% | 30 | 7 | ||
| 60% | 20.5 | 4.5 | 60% | 31 | 6 | ||
| 65% | 21 | 4 | 65% | 32 | 5 | ||
| 70% | 21.5 | 3.5 | 70% | 33 | 4 | ||
| 75% | 22 | 3 | 75% | 33.5 | 3.5 | ||
| 26° C | 20% | 15.5 | 10.5 | 38° C | 20% | 24 | 14 |
| 25% | 16 | 10 | 25% | 25 | 13 | ||
| 30% | 17 | 9 | 30% | 26 | 12 | ||
| 35% | 18 | 8 | 35% | 27 | 11 | ||
| 40% | 19 | 7 | 40% | 28.5 | 9.5 | ||
| 45% | 19.5 | 6.5 | 45% | 29.5 | 8.5 | ||
| 50% | 20 | 6 | 50% | 30.5 | 7.5 | ||
| 55% | 21 | 5 | 55% | 31 | 7 | ||
| 60% | 21.5 | 4.5 | 60% | 32 | 6 | ||
| 65% | 22 | 4 | 65% | 33 | 5 | ||
| 70% | 22.5 | 3.5 | 70% | 34 | 4 | ||
| 75% | 23 | 3 | 75% | 34.5 | 3.5 | ||
| 27° C | 20% | 16 | 11 | 39° C | 20% | 24.5 | 14.5 |
| 25% | 17 | 10 | 25% | 26 | 13 | ||
| 30% | 17.5 | 9.5 | 30% | 27 | 12 | ||
| 35% | 18.5 | 8.5 | 35% | 28 | 11 | ||
| 40% | 19 | 8 | 40% | 29 | 10 | ||
| 45% | 20 | 7 | 45% | 30 | 9 | ||
| 50% | 21 | 6 | 50% | 31 | 8 | ||
| 55% | 22 | 5 | 55% | 32 | 7 | ||
| 60% | 22.5 | 4.5 | 60% | 33 | 6 | ||
| 65% | 23 | 4 | 65% | 34 | 5 | ||
| 70% | 23.5 | 3.5 | 70% | 35 | 4 | ||
| 75% | 24 | 3 | 75% | 35.5 | 3.5 | ||
| 28° C | 20% | 17 | 11 | 40° C | 20% | 25 | 15 |
| 25% | 17.5 | 10.5 | 25% | 26.5 | 13.5 | ||
| 30% | 18.5 | 9.5 | 30% | 28 | 12 | ||
| 35% | 19 | 9 | 35% | 29 | 11 | ||
| 40% | 20 | 8 | 40% | 30 | 10 | ||
| 45% | 21 | 7 | 45% | 31 | 9 | ||
| 50% | 21.5 | 6.5 | 50% | 32 | 8 | ||
| 55% | 22.5 | 5.5 | 55% | 33 | 7 | ||
| 60% | 23 | 5 | 60% | 34 | 6 | ||
| 65% | 24 | 4 | 65% | 35 | 5 | ||
| 70% | 24.5 | 3.5 | 70% | 35.5 | 4.5 | ||
| 75% | 25 | 3 | 75% | – | – | ||
| 29° C | 20% | 17.5 | 11.5 | 41° C | 20% | 26 | 15 |
| 25% | 18.5 | 10.5 | 25% | 27.5 | 13.5 | ||
| 30% | 19.5 | 9.5 | 30% | 28.5 | 12.5 | ||
| 35% | 20 | 9 | 35% | 30 | 11 | ||
| 40% | 21 | 8 | 40% | 31 | 10 | ||
| 45% | 22 | 7 | 45% | 32 | 9 | ||
| 50% | 22.5 | 6.5 | 50% | 33 | 8 | ||
| 55% | 23.5 | 5.5 | 55% | 34 | 7 | ||
| 60% | 24 | 5 | 60% | 35 | 6 | ||
| 65% | 24.5 | 4.5 | 65% | 36 | 5 | ||
| 70% | 25.5 | 3.5 | 70% | – | – | ||
| 75% | 26 | 3 | 75% | – | – | ||
| 30° C | 20% | 18 | 12 | 42° C | 20% | 26.5 | 15.5 |
| 25% | 19 | 11 | 25% | 28 | 14 | ||
| 30% | 20 | 10 | 30% | 29 | 13 | ||
| 35% | 21 | 9 | 35% | 30.5 | 11.5 | ||
| 40% | 22 | 8 | 40% | 31.5 | 10.5 | ||
| 45% | 22.5 | 7.5 | 45% | 33 | 9 | ||
| 50% | 23.5 | 6.5 | 50% | 34 | 8 | ||
| 55% | 24 | 6 | 55% | 35 | 7 | ||
| 60% | 25 | 5 | 60% | 36 | 6 | ||
| 65% | 25.5 | 4.5 | 65% | – | – | ||
| 70% | 26.5 | 3.5 | 70% | – | – | ||
| 75% | 27 | 3 | 75% | – | – | ||
| 31° C | 20% | 19 | 12 | 43° C | 20% | 27.5 | 15.5 |
| 25% | 20 | 11 | 25% | 29 | 14 | ||
| 30% | 21 | 10 | 30% | 30 | 13 | ||
| 35% | 21.5 | 9.5 | 35% | 31 | 12 | ||
| 40% | 22.5 | 8.5 | 40% | 32.5 | 10.5 | ||
| 45% | 23.5 | 7.5 | 45% | 33.5 | 9.5 | ||
| 50% | 24.5 | 6.5 | 50% | 34.5 | 8.5 | ||
| 55% | 25 | 6 | 55% | 35.5 | 7.5 | ||
| 60% | 26 | 5 | 60% | 36.5 | 6.5 | ||
| 65% | 26.5 | 4.5 | 65% | – | – | ||
| 70% | 27 | 4 | 70% | – | – | ||
| 75% | 28 | 3 | 75% | – | – | ||
| 32° C | 20% | 19.5 | 12.5 | 44° C | 20% | 28 | 16 |
| 25% | 20.5 | 11.5 | 25% | 29.5 | 14.5 | ||
| 30% | 21.5 | 10.5 | 30% | 31 | 13 | ||
| 35% | 22.5 | 9.5 | 35% | 32 | 12 | ||
| 40% | 23.5 | 8.5 | 40% | 33.5 | 10.5 | ||
| 45% | 24 | 8 | 45% | 34.5 | 9.5 | ||
| 50% | 25 | 7 | 50% | 35.5 | 8.5 | ||
| 55% | 26 | 6 | 55% | 36.5 | 7.5 | ||
| 60% | 27 | 5 | 60% | – | – | ||
| 65% | 27.5 | 4.5 | 65% | – | – | ||
| 70% | 28 | 4 | 70% | – | – | ||
| 75% | 29 | 3 | 75% | – | – | ||
| 33° C | 20% | 20.5 | 12.5 | 45° C | 20% | 29 | 16 |
| 25% | 21.5 | 11.5 | 25% | 30 | 15 | ||
| 30% | 22.5 | 10.5 | 30% | 31.5 | 13.5 | ||
| 35% | 23 | 10 | 35% | 33 | 12 | ||
| 40% | 24 | 9 | 40% | 34 | 11 | ||
| 45% | 25 | 8 | 45% | 35.5 | 9.5 | ||
| 50% | 26 | 7 | 50% | 36.5 | 8.5 | ||
| 55% | 27 | 6 | 55% | – | – | ||
| 60% | 28 | 5 | 60% | – | – | ||
| 65% | 28.5 | 4.5 | 65% | – | – | ||
| 70% | 29 | 4 | 70% | – | – | ||
| 75% | 30 | 3 | 75% | – | – |
Maintenance of Air coolers
IMPORTANT: whenever you perform some maintenance on the cooler, it is necessary to disconnect the input power circuit breaker inside the switchboard and flag “UNDER MAINTENANCE”.Never trust only turn the off button that is on the door of the control panel.
Instructions:
BEC Lines/BEV/BEW/BRP/BU
- Disconnect the cooler next to the Control Board;
- Close the water supply and open the drain valve on the cooler;
- Unlock the latches (or screws) located next to the cooler lid and open it;
- Remove pre-filters and clean them with water;
- Remove the beehives and wash with plenty of water, taking care if it is used high pressure machine (vap or similar) and always using the water jet (fan-shaped), with a distance of approx. 80 cm of the hives because the water pressure can damage them;
- Remove the cap of Ø3/4 “water and wash your interior, unclogging the holes;
- Wash the water tank;
- Open the water supply and close the drain valve on the cooler;
- Mount the equipment in the reverse sequence of disassembly, paying attention to the correct position of the beehives and water, which should be + 4 cm from the exterior face of the hives.
Checks:
- Check if the drain pump is working;
- Check if the water pump is working;
- Check if the hives are fitted in the correct position, as indication on their sides.
Our trained team can perform maintenance for any Evaporative Coolers.