The two-stage evaporative cooling system, also known as direct or indirect cooling, is the most advanced and technologically developed cooling system, using the utilizing evaporative cooling technology.
This cooling option is energy efficient in comparison with the refrigerant cooling technology, which only provides with standard air conditioning.
It is important for you to know that the refrigerant cooling technology is not suitable for all cooling application.
To understand the requirement of your home two-stage evaporative cooling system, read on and find out the details.
What is evaporative cooling?
The evaporative cooling is one of the most well-known and most reliable methods that help in providing with pleasant and cool air during the hot and humid summer days. The evaporative cooling system is an alternative to air conditioning system which helps in pumping the refrigerant through the compression and evaporative cycles.
The evaporative cooling system is really simple to understand. Take the example of your own body, it has a built in evaporative cooling system and we call it ‘Perspiration.’ When the temperature is warm we sweat, and when the sweat starts evaporating is the time our body cools down.
It is the heat energy, which changes the water to vapor. This phase is called Evaporative cooling.
Types of evaporative cooling system
There are numerous types of evaporative coolers. They are:
Direct Evaporative Cooling System and Indirect Evaporative Cooling System
Two-Stage Direct Evaporative Cooling System
How evaporative cooling system works
Let us now understand how an evaporative cooling system actually works.
The warm exterior air passes through a heat exchanger or a dampened pad, where the airstream cools down as the moisture from the air is evaporated. The evaporative cooling goes a long way, it was known before the refrigerant based cooling system came into being.
This kind of air conditioning system is also commonly known as the ‘Swamp Cooler.’ The name gained its popularity because the older systems most often produce a pungent smell which was ‘swampy.’
The latest version of the evaporative cooling systems uses less electricity, reducing its consumption to almost 60% in comparison to the refrigerant based AC system. This system is available in the window, portable and whole-house configuration.
- The Window unit come in various different sizes, and requires more space than a window air conditioner.
- The Portable unit has been designed keeping in mind for cooling only a single room. However, large capacity units are also available.
- Whole-house evaporative coolers are fixed on the roof of the house, from where it delivers the cool pleasant air through the ductwork of the house.
How does the two-stage evaporative cooling system works?
There are two-stages of the evaporative cooling system. They are:
Stage 1: At the first stage the hot air from outside is passed inside the heat exchanger which is then cooled by the evaporation occurring outside. At this initial stage, the air which comes inside the air stream does not pick any extra moisture
Stage 2: In the next stage, this very air that is passed through the water soaked pad (this is where the additional cooling takes place) picks up some extra humidity.
In this simple yet efficient way, the two-stage evaporative cooling system is able to provide with additional cool air, with relative humidity, ranging from 50%-65%. The direct evaporative cooling system simply cools the air around 70% removing the humidity.
According to the research that has been conducted by the American Society of Heating and Engineers (ASHRAE), the two-stage evaporative cooler will use 60%-75% less electricity in contrast with the conventional refrigerant AC system.
However, it is really import for you to know that this cooling system is best suited for places which has hot and dry climate.
The cooling effect of the evaporative cooler completely depends on the rate of evaporation and condition of the air within the cooler. The environment, the temperature and the humidity plays the most important and significant role.
It is necessary for the temperature to be high enough so that evaporation can easily take place and the relative humidity (RH) should be low enough for water to vapor quickly so that it can cool the surrounding air.
The water quality also plays an important role in evaporation and also in maintaining the system. It can only allow cooling to 10 degree Celsius that too under optimal conditions. If you require the temperature to be lower than you will need a different cooling technology.
The importance of Relative Humidity (RH) of Air
Relative Humidity of the Air plays an important role in measuring the amount of water vapor from the air, as a percentage of maximum quantity which the air is capable of holding, at a particular temperature.
When the RH of the air is low, this means that there is only a particular amount and quantity of water that the air is able to hold.
This very condition in which the air is able to hold the extra or additional moisture, ensuring that all the other conditioning is favorable, then the rate of evaporation will go on to be a bit higher, hence, the making the efficiency of the evaporative cooling system higher.
Benefits of installing the evaporative cooling system
There are numerous benefits of installing the evaporative cooling system in your home or work place. They are:
- It has the same price as the air-conditioners and provide with better cooling system
- It is less expensive to install
- It consumes less electricity hence affordable and cheap to run
- Maintenance is affordable (Very few parts need fixing and ever fewer part breaks)
- Do not use chemical refrigerants
- Adds moisture to the dry air
- Environmental friendly
- Best suited for the hot and dry climate
Disadvantages of installing the evaporative cooling system
There are however, some disadvantages of using an evaporative cooling system, although it is quite similar in cost compared with an evaporative cooler, it takes more space, almost twice the size of an air conditioner. It also requires regular maintaining.
It requires a constant water supply, hence, making it difficult to use on areas where there is shortage of water or areas that are extreme aridity.
The evaporative coolers removes the problem of old stale air, but the continuous supply of bring in the fresh air from outside might also bring contaminants and odor. It should be well equipped with proper filters if you are using it at home, where someone suffers from severe allergy or with asthma.
These above mentioned disadvantages are not a problem if you are using a two-stage evaporative cooler, but in case of direct cooling system, it places a major concern.
Adjusting the Air flow
It is really important for you to adjust the flow of air and control the temperature inside your home. An evaporative cooling system completely depends on the balance of proper air maintenance.
To limit the level of humidity, it is important that you ensure that the volume of air flows has the same frequency as the air that is pumped in and out. You can simply attain the air flow balance by installing the ducts in every room or just ventilate the room when the cooling system is not in use.
You must also ensure that at least one window should be open a bit, so that enough air pressure can be circulated around the room, however, the door of that particular room should be closed.