Refrigeration evaporators play a fundamental role in any refrigeration or freezing system, whether incorporated in a compact system or as a stand-alone unit. But do you really know what an evaporator is or how it works?
In refrigeration, an evaporator is the heat exchanger where the refrigerant circulating inside the refrigeration circuit absorbs the thermal energy from the environment, which is then cooled. This is how the state of the refrigerant changes from liquid to vapour, giving it its name. As a result, the refrigerant evaporates to absorb the temperature or energy from the environment to be cooled.
It function relies on transmitting, as efficiently as possible, the thermal energy from the environment to be cooled (it can be a cold room or a secondary fluid as in the case of indirect refrigeration systems) to the fluid that is evaporating (in this case the main refrigerant).
We can make different classifications of evaporators; among them, we differentiate:
For a correct selection of a refrigeration evaporator, we must consider a series of factors such as the cooling load required by our refrigeration equipment, the relative humidity, the range, and the air speed required.
In addition, we will have to pay attention to other factors such as the thermal jump, i.e., the temperature difference between the inside of the chamber and the refrigerant used. It is essential to find a balance in the thermal gap because the smaller the thermal gap, the greater the efficiency. In this way, it will work with lower compression rates and the equipment will save energy. However, on the other hand, it will also be more expensive, and the initial investment will be higher.
The power rating of an evaporator affect by the thermal jump, the temperature inside the chamber and the refrigerant used. How do we calculate the nominal power?
In addition to this, it is important to know the effect on the relative humidity. Knowing the design evaporating temperature and the working temperature, we will obtain the thermal jump.
As the temperature rise increases, the relative humidity inside the chamber will decrease.
Relative humidity is an important parameter in the design of cold rooms, as each product needs a different relative humidity to be preserved in the best conditions and to conserve all its properties. The most demanding products are mainly fresh products, while in freezing chambers, for example, its role is less relevant.
As we increase the thermal jump, the power transferred will also increase. This occurs because of the behaviour of the heat exchanger and can be explained by the heat transfer equations that model this type of heat exchanger.
INTARCON has a wide range of refrigeration evaporators based on the maximum efficiency of our equipment, adapted to any type of cold room and to the needs of the products to be cooled. In addition, our range of refrigeration evaporators are available with CO2, NH3, glycol… technologies. Our equipment stands out for incorporating:
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