Choosing Heat Exchangers

Strict Requirements

The main task of a heat exchanger is to convert energy from one medium to another, hence the name heat exchanger.
Heat exchangers are typically used for heat transfer from one medium to another but can also serve as pressure relievers, or to create a hydraulic separation between two mediums. Heat exchangers come in a variety of shapes and sizes depending on the application.

Different Types

The most common heat exchangers we have are liquid-to-liquid, air-to-liquid, and air-to-air. Price and performance are two key factors when sizing heat exchangers. It is useful to know what drives the price up or down. The most important factor affecting the price is the LMTD (Log Mean Temperature Difference). Simply put, this refers to the difference in temperature across the heat exchanger, i.e., temperature on side 1 and temperature on side 2.
A low LMTD equals a higher price but is more cost-effective for the plant as a whole. This is because there is less thermal loss between the media, and usually less pressure loss. Physically, a lower LMTD will result in increased area, which in turn leads to a higher price. Looking at the plant as a whole, a higher price, i.e., lower LMTD, can often be justified to reap the benefits of better operating conditions, i.e., lower electricity costs. The increased cost will normally pay itself back over time, about 3-5 years.

Sizing

We who size heat exchangers must consider various parameters, such as capacity, temperature, area, pressure loss, and the type of medium. For this, we use different sizing programs. Here, we can enter all your parameters and requirements and then present the optimal heat exchanger for you. It's important to note that even though an "off-the-shelf" heat exchanger may fit nicely into the project, it might not be the best choice.
Another important point is to choose the right medium for the job. A very good example of this is heat transfer fluid for different types of industries, especially the food industry. Normally, propylene glycol, which is non-toxic, is used. The downside is that it becomes very viscous at low temperatures. This leads to increased pressure loss, lower performance, and higher costs.