What You Need to Know About Evaporative Cooling
Many modern houses across Australia are equipped with cooling systems that employ evaporative cooling to deliver natural, healthy, and clean air without using too much energy. We all have heard of these evaporative cooling systems at some point, and some of us probably have these in our homes. The greatest thing about this technological marvel is that it doesn’t use artificial refrigerants.
If you’ve been searching “what is evaporative cooling” on the good old internet, then stay on this page. Here, we’ll discuss the principle behind evaporative cooling, how modern evaporative cooling systems work, and why they are good for your home and the environment.
Evaporative Cooling: What Is It?
Also known as adiabatic cooling, it is a cooling process that works on the principle of water evaporation. Through this cooling and ventilation technique, air is cooled down to a comfortable temperature.
Water is evaporated in a stream of air and passes from a liquid to gas during the evaporative cooling process. This transition requires energy. The source of energy is heat, which is extracted from the air, thereby cooling the air down.
The evaporative cooling process can be applied in different ways, such as:
- Direct evaporative cooling
- Indirect evaporative/adiabatic cooling
- Two-stage evaporative cooling (indirect/direct evaporative cooling)
Two-stage evaporative cooling uses both direct and indirect techniques to cool the air. The first cooling step is indirect, using cold recirculation water to pre-cool the ambient air in a heat exchanger. The air reaches a dry and wet bulb, and the temperature is lower than the outside air when leaving the heat exchanger since moisture is not present.
The second step is direct. This time, the air is cooled further through the wet evaporative media. The result of this two-step cooling process is that the air is brought down to a much lower temperature. This means that the air is not capable of containing high amounts of humidity.
How do evaporative cooling systems work?
It’s important to note that cooling through evaporation is a natural occurrence, just like how our perspiration evaporates and absorbs heat to cool our body. Cooling systems are designed from the principle of evaporative cooling in which water must have heat applied to it to change from the liquid state to vapour. As mentioned above, this heat is taken from the water that remains in the liquid state, which results in a cooler liquid.
With the same principle as perspiration, evaporative cooling systems provide cooling for buildings and machinery. They use water as a refrigerant. Cooling towers in buildings are a heat-rejection device as they cool down the water and discharge warm air to the atmosphere.
Note: “Cooling tower” in the HVAC industry refers to open- and closed-circuit heat-rejection equipment.
What happens in an HVAC system?
Now that we’ve answered your question, “what is evaporative cooling,” let’s take a closer look at what happens in an HVAC system. So, the sun shining on buildings and computers generates heat. Air handlers, which are tied to the refrigerant through heat exchangers, pick up heat.
As the heat finds its way through the system, it boils the water refrigerant from a liquid to a vapour. Water then passes through a heat exchanger where the refrigerant vapour undergoes condensation for the heat to transfer to the water. Cooling towers cool the warm water returning from the heat exchanger to be reused later.
Open-circuit cooling towers return the warm water from the heat exchanger to be sprayed over the part called fill. The heat transfer between the water and air takes place in the fill, which provides the surface area for the water to evaporate. Cool water is then ready to absorb more heat from the heat exchanger, looping back to the beginning of the process.
Is evaporative cooling important?
By means of a two-stage process, evaporative cooling is a highly sustainable and energy-efficient method. It provides a comfortable and productive climate for office buildings, manufacturing plants, production facilities, and distribution centres. In an indirect/direct cooling system, only 10% of the total energy needed for traditional mechanical cooling systems to work is used.
It does not recirculate the warm, polluted indoor air, unlike mechanical cooling systems. Instead, it ventilates 100% fresh, filtered, cooled, and absolutely clean air into a room or building. This is why the indoor air quality substantially improves when an evaporative cooling system is used over a traditional mechanical one.
Below are some of the benefits of using evaporative cooling systems:
- Clean air
- Low energy consumption
- No chemicals or refrigerants
- Reduced risk of bacteria and virus
- Virtually maintenance-free
With 90% lower energy consumption, they are an environmentally friendly alternative. In general, two-stage evaporative cooling systems cool up to 7 degrees Celsius than single-step systems. They also bring up to 60% less moisture in the air than direct cooling systems.
Do buildings and homes need evaporative coolers?
Evaporative coolers deliver a very clean air quality. This is because they have air pre-filtering in them. They combine it with slight humidity to remove bacteria and slow down the spread of bacteria and viruses in the air, making them an indispensable part of every home and building.
More cooling can be done by means of evaporation if the air is drier and the day is hotter. States that have a dry, hot climate in summer abound with evaporative coolers. This is because a simple fan only circulates warm air, so most people secure evaporative coolers.
In Victoria, for example, evaporative coolers draw outside warm air through wet honeycomb pads, which create an evaporative effect before distributing cooler air via ducting.
In Closing
In places where the climate gets really dry and hot during the summer, evaporative cooling systems serve as people’s protection from the scorching heat. Technology has come a long way, and most cooling systems today are as energy-efficient and environmentally friendly as they could ever be. As they don’t use artificial refrigerants, homeowners can rest easy knowing that they can enjoy cool air without having to worry about possibly inhaling toxic chemicals.
We hope we answered your question “what is evaporative cooling.” Here at Gasman, we provide maintenance and repair services to ensure your evaporative coolers serve their purpose on unbearably hot days in the summer. Call us to book our evaporative cooling service.