How well your evaporative cooling media performs has direct consequences in daily operations, and energy expenses for many applications. Understanding how the design parameters of evaporative media, such as flute angle and flute height, can influence performance and efficiency is essential for optimizing cooling systems in various applications, from the industrial HVAC and commercial markets to large-scale data centers.
Both flute angle and flute height play significant roles in dictating the efficiency and pressure drop characteristics of evaporative media. By examining how these parameters affect the surface area available for evaporation, airflow resistance, water distribution uniformity, and droplet formation, we can gain insights into how to tailor the design of evaporative media for specific cooling requirements.
In this article, we delve into the intricate interplay between flute angle, flute height, and the performance of evaporative media. We explore the trade-offs and considerations involved in optimizing cooling efficiency while managing airflow resistance.
First, it is paramount to determine how to measure the flute height and flute angle, and which flute angle affects the air or water. Both of these characteristics can be manipulated and changed to provide maximum efficiency.
The flute height, also known as the amplitude, is determined by measuring the distance between the crest and the trough of the corrugated substrate.
The configuration of the flutes within the evaporative media is crucial to maximizing water distribution and heat exchange efficiency. Adjusting the flute height, flute angle, and media depth allows you to create an evaporative solution tailored to your performance needs.
For example, the flute angle could be constructed in a 45/15 or a 30/30 configuration depending on the velocity of the system and your performance requirements. The flute height could also be customized to allow for more surface area to increase cooling efficiency. These customizations vary the contact area between the air and the water, optimizing surface area and efficiency within the system.
The flute angle determines the geometry of the channels through which air flow passes through the media block while contacting the flutes that transport water for the process of evaporation–thus providing cooler air to the desired space. There are a few ways to determine the flute angle of the media.
One option is to use an angle gauge or protractor to find the angle of the flute. A more common method is to visually inspect the media block and determine what the angle of incidence would be in relation to the normal.
Again, a visual inspection can be performed to determine which flute angle carries the water versus which allows the air to flow through the media. When looking at a side profile of the media, the flute angle that carries more water is directed towards the entering air side of the media. This promotes directional trajectory of the potential water entrainment to flow towards the air inlet and reduces potential droplets from exiting the airstream.
The primary performance parameters of all cooling systems are cooling efficiency and pressure drop, no matter what is being cooled. The flute height in evaporative media impacts both efficiency and pressure drop. Balancing the advantages and disadvantages of changing the flute height is an integral part of design and production.
In order to ensure adequate cooling operation and heat absorption, all evaporative cooling systems must maintain uniform and even water distribution. If the flute height decreases, this allows for a smaller flute from crest to trough, thus providing more sheets per media block and contact between the water and the incoming airstream.
With a smaller flute height and increased contact area, a greater quantity of latent heat is transferred by evaporation. Flute height can impact the distribution of water over the volume of the media, and smaller flute height or amplitude can improve the effectiveness.
Therefore, the increase in heat energy transferred increases the cooling efficiency of the media. It is important to note that with higher velocities there can be a potential to increase the droplet formation thus running the risk of entrainment.
On the other hand, reducing the flute height can increase the airflow’s resistance and turbulence, therefore, raising the system pressure drop. Inversely, a flute height that is too short will not provide sufficient geometry to facilitate proper evaporation.
While reducing the flute height can improve the performance of evaporative media, producing a steeper flute air flow angle can provide a higher efficiency. The steeper flute angle results in an increase of contact points between the water stream and airflow. This promotes enhanced heat transfer and improved cooling effectiveness.
Inversely, larger flute angles for the air flow produce increased tortuous and sinuous airflow paths increasing the pressure drop across the media. Typically, in flute configuration of media, the shallower flute angle is dedicated to the airflow to reduce resistance through the media while the steeper angle configuration transfers the water distribution through the pad. When a steeper angle is used for the airflow, this improves efficiency while increasing pressure drop. Synchronicity of flute angle and height is vital to ensure a balance between pressure and efficiency without sacrificing one for the other.
Similarly to flute height, the specific flute angle can promote even water distribution across the media resulting in greater wetting, thus a better cooling efficiency. It is imperative to follow recommended guidelines for operation to reduce the potential for entrainment in the airstream. This is typically a function of face velocity and should be observed and verified to be performing within the proper envelope.
The relationship between flute height and flute angle can be seen from test data in the charts below. The data below compares the efficiency and pressure drop of Kuul Origin media and Kuul MicroTech media at varying face velocity settings for varying depths. One can observe how changing the flute angle and flute height affects the performance. Kuul Origin media features the flute angles 45⁰ and 15⁰ and a 7mm flute height, and Kuul MicroTech media features the flute angles 45⁰ and 45⁰ and a 5mm flute height for this example.
By decreasing the flute height and increasing the airflow flute angle, the 3” depth media can provide a very similar efficiency profile as the 8” depth media. This is also true for the efficiency profile for 4” depth media versus the 10” depth media.
The improvement in efficiency is directly correlated to the increased air and water contact area, thus providing the user with a potentially streamlined evaporative cooling configuration without sacrificing efficiency. Therefore, the ability to reduce the depth of media used in a system can provide maximum space saving and optimization.
Providing a thinner depth media that matches the cooling efficiency of thicker depth media not only ensures optimal performance but also offers significant space-saving advantages for end users. By maintaining the same level of cooling effectiveness in a slimmer design, the footprint required for installation is reduced, optimizing valuable space in environments where all areas must be utilized and the media design is streamlined.
Streamlined design allows for greater flexibility in placement and installation, accommodating diverse spatial constraints without compromising on cooling capabilities. Ultimately, by delivering comparable cooling efficiency in a thinner profile, manufacturers empower users to maximize space utilization and optimize their cooling infrastructure for enhanced productivity and cost-effectiveness.
While this improvement in efficiency and reduction in media depth is a fundamental benefit to the user, it is crucial to understand the pressure drop increases significantly compared to the wider media depths at the adjusted flute angle and height. The first chart above shows how the 3” depth media has a similar pressure drop as the 10” depth media.
Therein, it can be noted the 4” depth media pressure drop value is similar to the 12” depth media. Thus, the advantages of improved efficiency must be weighed against the overall system’s increase in total pressure drop.
In conclusion, flute height and flute angle play crucial roles in determining the efficiency and pressure drop of evaporative media.
The flute angle determines the geometry of channels within the media, influencing airflow resistance and evaporative efficiency. Smaller flute heights provide greater surface area for the air and water to exchange heat through the process of evaporation, enhancing cooling efficiency, but this also increases pressure drop. While steeper flute angles will result in higher evaporative efficiency, the steeper profile will generate a higher pressure drop.
Through experimentation and testing, the balance of evaporative media performance and the combination of flute geometry can produce significant gains for any adiabatic precooling, direct, or indirect cooling system.
Our team of engineering experts can assist you in optimizing the design of your evaporative cooling media. We offer in-depth analysis and guidance on the ideal flute angle and height for your specific cooling needs, ensuring that your system operates at maximum efficiency. By tailoring the design parameters of your evaporative media, we help you achieve sustainable cooling solutions that save on energy costs and promote a healthier environment.
Contact us today to learn more about how our expertise in evaporative cooling media design can benefit your operations and enhance the performance of your cooling systems.
Nicole Jones is an Application Engineer at Condair. She is instrumental in developing innovative solutions that keep cooling systems operating at peak efficiency.
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