How does a finned heat exchanger work?

Take a look here; it might be helpful: http://bbs.hcbbs.com/viewthread.php?tid=182986&highlight=%B3%E1%C6%AC%CA%BD%BB%BB%C8%C8%C6%F7

Finned heat exchangers are used to enhance heat transfer for fluids with a low heat transfer coefficient, such as low-pressure gases and liquids with high viscosity, etc. The fins are divided into internal fins and external fins. It is used with air and low-temperature liquids; for cooling purposes, the air temperature should generally be 10–15 degrees lower than that of the liquid, otherwise it lacks economic viability.

Heat transfer principle of finned tubes: In heat exchangers made up of ordinary circular tubes (plain tubes), in many cases, the heat transfer coefficients of the fluid outside the tube and the fluid inside the tube with respect to the tube wall are different. The heat transfer coefficient refers to the amount of heat transferred per unit area of heat transfer surface and per unit temperature difference (the difference in temperature between the fluid and the wall), and it represents the capacity for heat transfer between the fluid and the wall. For example, the heat transfer coefficient when water condenses on a wall surface is: 10,000–20,000 W/(m²·°C). The heat transfer coefficient when water boils on a wall surface is: 5,000–10,000. The heat transfer coefficient when water flows over a wall surface is approximately: 2,000–10,000. The heat transfer coefficient when air or smoke flows over a wall surface is: 20–80. The heat transfer coefficient during natural convection of air is only: 5–10. It can be seen that there is a significant difference in the heat transfer capacity between fluids and wall surfaces. Now, consider a practical heat transfer scenario: water flows inside the circular tube, with a heat transfer coefficient of 5000 (---), while flue gas flows outside the tube, having a heat transfer coefficient of only 50 (---); there is thus a difference of 100 times between the two. When heat is transferred from inside the tube to outside, or from outside to inside, where does the \"bottleneck\" or \"maximum resistance\" in the heat transfer process occur? It is of course the flue gas side outside the tube, because the heat transfer coefficient on the flue gas side, that is, its heat transfer capacity, is the lowest, which limits the increase in heat transfer amount. Here, let’s take an example of a series resistor: in a series circuit composed of multiple resistors, if one of these resistors is much larger than the others, then this resistor will act as a \"bottleneck\" for the current. Only by reducing the value of this largest resistor can the current flowing through the series circuit be increased effectively. The same is true for the aforementioned heat transfer process. How can the heat transfer rate of circular tubes be increased? One of the most effective methods is to use an extended surface on the outer surface of the tube, that is, on the flue gas side, by making it a finned tube. Assuming that the actual heat transfer area of the finned tube is several times that of the outer surface area of the plain tube, although the heat exchange coefficient of the flue gas remains low, the heat transfer efficiency as reflected in the outer surface area of the plain tube **increases**, thereby enhancing the overall heat transfer process. With a constant total amount of heat transferred, this leads to reduced metal consumption in the equipment, improving its economic efficiency.

Hehe, what was said above is all very good; I’d like to add my opinion as well. A finned heat exchanger is one in which fins are added to one side of the tubes, thereby increasing the heat exchange area on that side and enhancing the heat exchange efficiency. Conventionally, there is a difference between internal fins and external fins; there have been many discussions on this topic in forums before, and I have compiled them here for the original poster’s reference. Fin-type heat exchangers versus ordinary tube heat exchangers: http://bbs.hcbbs.com/viewthread.php?tid=403634&highlight=%B3%E1%C6%AC%2B%BB%BB%C8%C8%C6%F7. The complete content can be found at the following link: http://bbs.hcbbs.com/search.php?searchid=3401&orderby=lastpost&ascdesc=desc&searchsubmit=yes

Finned heat exchangers mainly work by increasing the heat exchange area to achieve the desired heat exchange effect!

Finned heat exchangers are primarily used to enhance heat transfer on the side with a low heat transfer coefficient; in the case of convective heat transfer, the fins serve to disrupt the flow pattern and increase the heat exchange surface area