A heat exchanger is a device used to transfer heat between a solid object and a fluid, or between two or more fluids. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact.[1] They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and airflows past the coils, which cools the coolant and heats the incoming air. Another example is the heat sink, which is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant.
Shell and tube heat exchangers consist of series of tubes. One set of these tubes contains the fluid that must be either heated or cooled. The second fluid runs over the tubes that are being heated or cooled so that it can either provide the heat or absorb the heat required. A set of tubes is called the tube bundle and can be made up of several types of tubes: plain, longitudinally finned, etc. Shell and tube heat exchangers are typically used for high-pressure applications (with pressures greater than 30 bar and temperatures greater than 260 °C). This is because the shell and tube heat exchangers are robust due to their shape.
Several thermal design features must be considered when designing the tubes in the shell and tube heat exchangers: There can be many variations on the shell and tube design.
Typically, the ends of each tube are connected to plenums (sometimes called water boxes) through holes in tube sheets. The tubes may be straight or bent in the shape of a U, called U-tubes.
Highly Efficient designs , with shell diameters ranging from 4” to 50” (100 mm to1250 mm) produce heat transfer rates up to 3,00,000 BTU . Flow Rate are 25 m3 / hr to 5000 m3/hr and pressure up to “ 200 kg / cm2 and 100 kg / cm2 “.
It is a unique type of shell and tube heat exchanger. The tubes in the heli flow are arranged in parallel , starting with an inlet manifold on one end, and terminating at an outlet manifold on the opposite end. The tube bundled is wound into a helical pattern. This Coiled construction creates a spiral flow path for the fluid inside the coil.
A family of coiled , concentric tube heat exchanger, capable of handling pressures up to 200 kg /cm2 outer tube. With their long single chamber flow path and high effectiveness, these heat exchangers are n ideal choice for sample cooling or vapour condensation .