Evaporator systems are the heart of many industries. And its efficiency depends upon the efficiency of its heat exchange process. For the good working of the evaporator, it has a heat exchanger. What it is?
The heat exchanger is equipment in the evaporator system used for perfect heat exchange between two separated medium. Whether the two media are separated by a plate or tube. They are greatly used in evaporation plants, wastewater plants, chemical plants, food industry, etc. One common use of the heat exchanger is in a car radiator. Let’s see how the heat exchange process happens in the evaporator system:
How does heat exchange happen in the Evaporator System?
Heat exchange happens in three broadways according to their arrangement of flow.
- The first one is parallel-flow heat exchangers- the two medium enter the exchanger from the same entry point and exit out by traveling parallel to each other and exchanging heat between them.
- The second one is, counter-flow heat exchangers- the two medium flows in opposite direction to each other and exchanges heat among them. It is seen that it provides a more efficient heat exchange.
- The third one is cross-flow heat exchange-the fluids flow approximately perpendicular to one another through the heat exchanger.
What are the factors responsible for effective heat exchange?
- For efficient working, heat exchangers are designed to have maximum contact surface area between two fluids.
- By reducing resistance to the flow of medium increases efficiency.
- The fins or corrugations inside of the wall increase surface area thus increasing the efficiency of the heat exchanger.
- The low viscosity of the medium is good for the efficiency of the heat exchanger.
How heat exchange occurs in a different evaporator system?
Plate evaporator– A plate evaporator has a heat exchanger in which heat exchange occurs through metal plates placed between two mediums. Plate evaporator is much efficient over the conventional way of evaporation by providing greater surface area for heat exchange. It greatly affects heat exchange.
Film evaporator– evaporation occurs in the tubes and sometimes outside the vertical or horizontal tubes. The fluid will make a film along the walls of the tube, progressing upwards or downwards. In film evaporators, the efficiency of heat exchange is determined by liquid properties (viscosity), film layer thickness, and the difference in temperature across the layer of film. Thin-film evaporator aid inefficient heat exchange. The advantage of having a horizontal film evaporator heat exchanger is it provides a high heat exchange coefficient and thus compact structure.
This process of heat exchange in the film evaporator system is the same in falling film, rising film, vertical tubes or horizontal tube evaporators.
The efficiency of heat exchange is important in plants like
- Wastewater treatment plant.
- For concentrating juices of food extracts.
- Chemical industries like paints, putties, acid evaporators, etc.
- Pharmacological industries.