All About The Corrugations on Heat Transfer Plates
There is the general perception that the effectiveness of any plate heat exchanger (PHE) is only dependent on qualities such as the build makeup, the materials used in development, maintenance routines and also the environment in which the heat exchanger operates in and in what conditions it operates on.
Even with all the above playing a significant role as to how a plate heat exchanger can be effective, there is still one major factor that plays a very important role- the corrugation on the stainless-steel plates of the PHE. There has been little research on this topic over the years with industries just simply going for a piece of equipment proposed by manufacturers to soothe their needs with really little to no work done on the research end as to what factors they might be missing out on.
Most of the inquiries we receive are based on the application of the heat exchanger that the customer/industry requires. After our sales engineer understands that requirement and the application, we design and plan the equipment. One of the major steps in designing is selecting the right type of stainless steel plates in our stock. So, how does one select the best type of plate to be used for the perfect heat exchanger? First, let’s discuss the significance and the types of corrugations on the stainless-steel plate.
What are the corrugations in plate heat exchangers and why are they important?
The regular plate heat exchanger (PHE), as the name states make the use of steel plates as a process of regulating heat. This is achieved with the plates in question having well-coordinated spaces in between them. These spaces are then filled with fluids such as water or other liquids which move interchangeably against each other thereby regulating temperature in the process.
Corrugation on plates not only facilitate this process but also increase the mechanical strength of the plates and turbulence in the flow. Corrugation angle and corrugation depths are very important factors to be considered when designing any PHE as PHEs might look similar from the outside, but they have a noticeable difference in operating levels when paired side by side.
PHEs make use of liquids of opposite temperatures to function with corrugated plates serving as the separation mechanism. As per few researches conducted, corrugation plates with small depths are less likely to have residues deposited in the due course of time because of high-speed turbulence effect, but those with higher depths are difficult to manufacture. Thus, the best corrugation depth is 4-5 mm.
The corrugation technique applied can be of two types, via-a-viz sinus or offset. In the sinus profile corrugations are at the same depths and heights and gives a flatter result as opposed to the offset profile which results in a more refined and curvy finish.
Taking everything into account, for situations where round the clock operation is needed, it is best to go with a heat exchanger which has sufficient corrugation depths; such as in the areas of refrigeration or pharmaceuticals. These industries have little need for cleaning on the long run thereby reducing the risks of the heat exchanger being out of operation.
Types of corrugation and their properties
Now, as mentioned above, the two main factors which are taken into consideration while selecting the corrugation on the plates while building any heat exchanger are the angle and the depth of corrugations, we classify the corrugation types based on these two attributes:
As the name suggests, in the obtuse corrugation type, the magnitude of the angles is more than 90° and hence result in longer thermal paths as well as a high rate of heat transfers. However, they have high-pressure drops. On the other hand, in acute corrugation type, the angles are smaller than 90° in magnitude, and hence it is preferred in cases where the required pressure drop is low. Each corrugation design suits a particular purpose thereby making it important to decide which proper corrugation angle which would give a minimum number of plate’s maximum level of effectiveness.
Some examples of applications where Obtuse or Acute angle is required.
|OBTUSE ANGLED CORRUGATION||ACUTE ANGLED CORRUGATION|
|Applied in liquid heat exchangers depending on the desired results||Applied in the case of gas heat exchangers as pressure needs to be kept low|
|Applied in situations whereby pressure drop isn’t really a factor to be worried about like in Marine applications||Applied in the oil and gas sector as a simple spike in pressure can have catastrophic implications|
|Is the most common corrugation pattern due to its high heat transfer rates and stronger thermal paths||Less common as it centralizes its basis on low pressure which in turn diminished heat transfer rates.|
The corrugation on plates enhances turbulence at higher velocities which results in heat transfer but in a case whereby heat transfer is required to be as minimal as possible the corrugation technique needs to be more advanced.
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