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How to determine adiabatic efficiency? │MET MANN

24/03/2022
How to determine adiabatic efficiency? │MET MANN
The adiabatic efficiency of an evaporative air conditioner is the most fundamental part to determine the temperature of descent and humidity that will provide us the equipment during his operation
The basic principle of an adiabatic cooling process consists of passing a certain volume of air through a hygroscopic panel soaked in water.
 

"Adiabatic efficiency is essential to determine the temperature drop of any evaporative cooler"

The intake or intake air has temperature and humidity properties that normally correspond to those outside the room to be air-conditioned. This air, by making it pass through a soaked hygroscopic panel, enters an adiabatic process of natural cooling where the air gives up its heat to the water and evaporates, after this process, the treated air is driven inside the room to be heated and is It improves the thermal sensation, we reduce thermal stress and we improve the quality of the air thanks to constant renewal.


 

"To obtain a greater temperature drop in an adiabatic process, it is essential that the inlet velocity be as low as possible."

 

In an adiabatic process, the speed of entry to the hygroscopic panel is essential to obtain the greatest drop in temperature.
 
For example; if the air velocity is 1 m/s, a drop in temperature of up to 15ºC will be achieved and at 2.5 m/s the drop will correspond to 13ºC, in addition to running the risk of dragging drops into the air driven by the fan .
 
As we can see in the following graph, depending on the thickness of the panel and the input speed, the efficiency of the panel is different.
 

 

Efficiency saturation panels PAD MANN type 5090-15

 

¿How to determine the Saturation Efficiency of an Evaporative Cooler?

Evaporative air conditioners use the adiabatic cooling method and it is essential to know the real value of saturation efficiency to be sure of offering a good adiabatic air conditioning system.

Currently, we have detected some inaccurate data in some products and we consider it important to explain how in a very simple way to extract the real value of the saturation efficiency.

To extract this value, the following data is required:

- Equipment air flow

- Surface in m2 of the hygroscopic panel

- Type of panel used and thickness

 

Once the data is collected, the next step is to determine the rate of entry into the evaporative cooler. To define this value, the unit′s air flow must be divided by the useful m2 of hygroscopic panel of the evaporative air conditioner.

As an example, we are going to take one of our evaporative air conditioners as a reference.

 
Model: AD-15-V-100-015

Actual air flow: 11,418 m3/h

Panel surface: 2.84 m2

Hygroscopic panel type: 5090

Panel thickness: 100mm

Formula used

Air flow ÷ Panel surface = m/h ÷ 3600 = m/s

Obtained result:

11.418 m3/h / 2,84 m2 = 4.020 m/h / 3600 seconds = 1,116 m/s

 

 

Once the air speed in m/s is obtained, we must draw a line on the graph and we will be able to obtain the actual saturation efficiency of the evaporative cooler.

In this case, with an air speed of 1.11 m/s and using a 100mm thick 5090 panel, the saturation efficiency is 90%.
 
 
With the saturation efficiency data of the evaporative cooler, we are able to determine the properties of the treated air using the Mollier diagram.

With this simple exercise, we can check that the data provided by the manufacturers of evaporative air conditioners are real and thus be able to compare equipment with similar features.

 

You can access our entire range of evaporative or adiabatic air conditioning equipment at EVAPORATIVE AIR COOLERS



Do you want more information?

You can contact us at Tel. +34 93 851 15 99

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