Tubular heat exchangers

The simplest heat exchanger is the double pipe type which consists of two centric pipes with the cold stream flowing usually in the inner tube and the heating medium in the annulus. It operates in either co-current or counter-current flow.

The concentric tube heat exchanger is the most common type of the tubular heat exchanger. The hot liquid, or steam, flows through the outer jacket and the cold liquid flows through the inner tube.

The shell and tube heat exchangers are less expensive than other types of food heat exchangers especially when high loads are transferred. They can be operating at higher temperature and pressures (e.g. steam at 6 bar and 160 ° C) than plate heat exchangers. Shell and tube exchangers are tubular consisting of bundles of parallel tubes inside a larger cylindrical jacket (shell).

In a type of tubular exchanger known as a Joule effect heater, the tube wall is electrically heated. The length of most commercial tubular system has been standardized at six meters; therefore, tubular heat exchangers are long and thin in terms of their geometry.

Most tabular heat exchanger now use corrugations on the shell and tubes to enhance heat transfer with the heating and cooling media, typically water. Tubular heat exchangers are suitable for heating or cooling highly viscous products and where relatively high pressure must be applied.

They are therefore utilized for the bulk in-flow sterilization of products containing solid particles or for the heat treatment of cooling of tomato paste prior to aseptic packaging.

For fruit juices with fibers of up to 15 mm length and for relatively water-like foods, a multitube tubular heat exchanger is preferably used. Also fluid of moderate to high viscosity with only small particulates will flow through a multitube heat exchanger without problem.
Tubular heat exchangers