U-tube heat exchangers

Effective Tube Length for U-Tube Heat Exchangers... 

One challenge in the design of U-tube heat exchangers is to determine the effective length of the tubes. For example, when U-tube bundles are fabricated from 12-ft tubes, the maximum length tube in the bundle is 12 ft which is in the outside tube row. The inside tube is the shortest and is less than 12 ft long. 

Determine the 197 1 module cost of a 5,000 ft2 U-tube heat exchanger constructed of carbon steel shell and monel tubes and rated at 500 psi. 

Cooldown heat exchanger 22 million Btu/hr, U-tube heat exchanger... 

U-tube heat exchangers are commonly used in steam heating applications, or heating and cooling applications that handle chemical fluids as opposed to water. 

U-tube heat exchanger with 1-in. tubes x 1-in. square pitch and 16-ft bundles operating at 150 psi. 

U-Tube Heat Exchanger (Fig. 11 -36d) The tube bundle consists of a stationary tube sheet, U tubes (or hairpin tubes), baffles or support plates, and appropriate tie rods and spacers. The tube bundle can be removed from the heat-exchanger shell. A tube-side header (stationary head) and a shell with integral shell cover, which is welded to the shell, are provided. Each tube is free to expand or contract without any limitation being placed upon it by the other tubes. 

From Figures 5.22 and 5.23, it is seen that there is room to accommodate the thermal expansion of the tubes. In the case of the finned heat exchanger, the tubes can expand in an expandable shell, whereas in the case of the U-tube heat exchanger, expansion room is provided because of the existence of free fixed tubes in a firm shell. 

FIG. 11 -36 (Continued) Heat-exchanger-component nomenclature, (c) Outside-packed floating-head exchanger. Type AER (d) U-tube heat exchanger. Type CFU. (e) Kettle-type floating-head reboiler. Type AKT. (Standard of Tubular Exchanger Manufacturers Association, 6th ed., 1978.)... 

Assumed the established model use single U-tube heat exchanger, because of the small pitch in two pipes, will interfere each other, could cause heat change different of the outside pipe and concrete. To simplify the calculation, instead the two pipe of U-tube of an equivalence pipe. Its equivalent diameter D =->j2D (Bose JE,1993), D is the diameter of one of the U-tube. Consider that the heat change of equivalence pipe wall and concrete is uniform ... 

It is improbable that these clearances will all accumulate to either the positive or negative side, so it is customary to compute heat transfer relationships on the basis of average clearances. Refer to Plate and Frame Heat Exchanger, Spiral Plate Heat Exchanger, and U-Tube Heat Exchanger. (Source N. P. Cheremisinoff, Handbook of Chemical Processing Equipment, Butterworth-Heinemann Publishers, U.K., 2000). 

U-tube heat-exchanger bundles will have residual bending stresses. The bend may be vulnerable to chloride-induced stress-corrosion cracking unless the tubes are annealed to relieve the stresses. Type 304 stainless steel is also subject to stress-corrosion cracking when exposed to caustic solutions. 

A typical heat exchanger, or steam generator, for a PWR is illustrated in Fig. 6.16. The generator is divided into a lower and an upper section, known as the evaporator and the steam drum. The former consists of a U-tube heat exchanger and the latter houses moisture-separating equipment. Each of the U tubes is welded to a tubesheet the space under the tubesheet is divided in two by a vertical divider plate which separates the inlet from the outlet flow. The high-temperature primary coolant enters by the primary inlet, flows through the U tubes, and leaves by the primary outlet. 

The steam generators are divided into two sections, the evaporator below and the steam drum above. The evaporator consists of a U-tube heat exchanger. Water of the primary coolant, at a temperature of 321 C, flows through the tubes, which are made from Inconel. The flow in the secondary circuit is upward through the tube bundle, the steam-water mixture passing... 

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