The disadvantage of the double-pipe heat exchanger is that it covers a large area. At the same time, the metal consumption per unit heat transfer area is much, about 5 times that of the shell-and-tube heat exchanger. There are many pipe joints, which are easy to leak and large flow resistance.
While double pipe heat exchangers offer simplicity and ease of maintenance, shell and tube systems cater to higher capacity and efficiency demands. With Torq N Seal's advanced sealing solutions, you can maximize the performance and lifespan of either type, ensuring your operations run smoothly and effectively.
Double pipe units are easier to dismantle and clean, whereas shell and tube systems, due to their complexity and size, require more effort and specialized tools like high-pressure tube plugs for maintenance.
These double-pipe heat exchangers are also called hairpin heat exchangers, and they can be used when one stream is a gas, viscous liquid, or small in volume. These heat exchangers can be used under severe fouling conditions because of the ease of cleaning and maintenance.
The disadvantage of the double-pipe heat exchanger is that it covers a large area. At the same time, the metal consumption per unit heat transfer area is much, about 5 times that of the shell-and-tube heat exchanger. There are many pipe joints, which are easy to leak and large flow resistance.
Alloy 321 Stainless Steel
Alloy 321 is a stainless steel with great heat resistance at temperatures of up to 870°C, which makes it perfect for application in heat exchangers. It also demonstrates good thermal conductivity.
Researchers have investigated the use of nanofluids - fluids containing nanoparticles that boost thermal characteristics - to improve the performance of heat exchangers. The use of nanofluids can improve the efficiency of double-pipe heat exchangers.
A plate heat exchanger is the lowest cost option because it can achieve high heat transfer coefficients — with pure counter current flow — giving the most efficient heat transfer and lowest surface area.
Fouling: Fouling is the buildup of unwanted material, such as scale, sediment, or biological growth, on the heat transfer surfaces of the heat exchanger. This can reduce heat transfer efficiency, increase pressure drop, and lead to equipment damage or failure.
Disadvantages The provision of a separate waste stack increases initial and maintenance cost. When pipes are fixed externally, the number required for the system tend to be unsightly.
Heat pipes have been extensively tested for decades. Their typical lifespan is at least 20 years and can go through thousands of freeze-thaw cycles without damage.
A heat pipe can transfer up to 1000 times more thermal energy, than copper (good conductor, K = 385 W/m-K), with less than 57 °C/m drop in temperature.
In a double pipe heat exchanger, we have a large pipe with a small pipe inside it concentrically, and all the heat transfer occurs in the larger pipe. As a conductive barrier, a small pipe flows one fluid through its interior and another fluid flows between the inner and outer pipes.
Shell and tube heat exchangers can last up to 25 or more years. The life of a heat exchanger is based on many factors, including metallurgy, process chemistry, operating conditions, upset conditions, the type of heat exchanger, the condition of the components, and regular maintenance.
Double-pipe heat exchangers can handle various fluids, including liquids, gases, and mixtures. This versatility makes them suitable for different applications where various substances must be cooled or heated. These heat exchangers offer flexibility in terms of flow configurations.
Carrier: Carrier is renowned for its innovative technology and reliable products. Their heat exchangers are designed for efficiency and durability, making them a top choice. Trane: With a focus on building a better future, Trane manufactures heat exchangers that prioritize energy efficiency and performance.
Heat transfer is most efficient by convection, then by conduction; radiation is the least efficient and slowest means of heat transfer.
Cocurrent flow: Both fluids flow in the same direction. This is the simplest and most efficient type of heat exchanger but does not allow for temperature cross (the outlet of cold fluid to be hotter than the outlet of hot fluid, or vice-versa).
The design of double-pipe heat exchangers offers further benefits due to its construction since the U-shape bend in the hairpin design creates an allowance for thermal expansion of the fluid.
For the inner pipe, DH is equal to the diameter of the pipe, and for the outer pipe it is the difference between the pipes radii. Adhere to the typical values in Table 1 to evaluate Re. The Reynolds numbers for the inner and outer pipes are about 1800 and 1000, respectively.
Plate heat exchangers are up to five times more efficient than shell-and-tube designs with approach temperatures as close as 1°F. Heat recovery can be increased substantially by simply exchanging existing shell-and-tubes for compact heat exchangers.
types of flow arrangement are possible in a double-pipe heat exchanger: parallel flow and counter flow.
It is possible—and often recommended—to save money by purchasing an oversized heat exchanger: look for one that's 30%–40% larger than what's required so that excess heat can be recycled back into the process loop or stored in tanks for later use (this is called “recovery”).