July 29, 2015
It makes life easier for engineering students when the title of a mechanism illustrates function so concisely. The label, shell and tube heat exchanger, implies the shape and form of a common industrial appliance. The shell is simply a pressure vessel and the tubes are a set of hollow conduits located within the shell. The purpose of this configuration is to place two different fluids close enough together so that the thermal properties of one fluid influences the other. Note, while the two energy carriers are influencing each other, the two fluids never come into contact.
The basic explanation mentioned above creates an image of one fluid flowing through the vessel and a separate fluid flowing through a network of tubes. Both the shell side and the tube side (technical terms that differentiate the subsystems) use inlet and outlet ports, thus there is a steady flow of the two fluids. The primary principle in this design involves the conductance of energy between the walls of the tubes and the fluid within the shell. The configuration of the tubes creates maximum cross-sectional area coverage between the two thermal components without creating a physical profile that would otherwise occupy enormous areas within an operational facility.
Naming the Relevant Parts of a Shell and Tube Heat Exchanger
The tube array is typically formed in U-sections, with the input pumping fluid through the input plenum. A plenum is simply the terminating port on the exterior of the shell, the point where the tube array penetrates the header and attaches to the exterior flow pipes. In the case of U-section tube arrays, the output plenum is located on the header with the input side located nearby. Straight tube models place the plenum ports at opposite sides of the shell.
There's little else to explain at this basic level other than energy constraints and pressure ratings. The baffles hold the tube array in place, with design specifications allowing room for expansion and contraction due to temperature variances. The shell must be rated for high pressure applications, especially when the device is used in chemical facilities and oil refineries. These industrial applications use both single-state and two-state profiles. The single phase version uses two fluid in the same state. Two hot liquids are common in this configuration. A two-state model occupies loftier engineering principles. It's here that liquids flow through the tube or shell side while a highly pressurized gas is pumped through the other side of the system.
Due to pressure and conductance considerations, copper and steel alloys are commonly used in the manufacturing of shell and tube heat exchangers.
Fusion - Weld Engineering Pty Ltd
ABN 98 068 987619
1865 Frankston Flinders Road,
Hastings, VIC 3915
Ph: (03) 5909 8218
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