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Shell-and-Tube Heat Exchanger Design: Objectives and Background

DOI 10.1615/hedhme.a.000247

3.3.1 and 3.3.4 Shell-and-tube heat exchanger design: objectives and background

The basic design of shell-and-tube exchangers was introduced in the early 1900s to fill the needs in power plants for large heat exchanger surfaces as condensers and feedwater heaters capable of operating under relatively high pressures. Both of these original applications of shell-and-tube heat exchangers continue to be used, but the designs have become highly sophisticated and specialized, subject to various specific codes and practices.

The broad industrial use of shell-and-tube heat exchangers known today also started in the 1900s to accommodate the demands of the emerging oil industry. Oil heaters and coolers, reboilers, and condensers for a variety of crude oil fraction and related organic liquids were required for rugged outdoor service, often "dirty" fluids, and high temperatures and pressures. Ease of cleaning and field repairs was unconditionally required.

The most serious problems in these early stages of shell-and-tube heat exchanger development appeared not to be those of heat transfer (which was crudely estimated from practice) but rather of material strength calculations for the various components, especially tubesheets. A host of other problems in the area of manufacturing techniques and practices followed, such as tube-to-tubesheet joints, flange and nozzle welding, and so on, surprisingly many being still on the list of items of continued concern and development.

During the 1920s shell-and-tube manufacturing technology became fairly well developed, mainly because of the efforts of relatively few major manufacturers. Units up to 500 m2 (5,000 ft2), that is, approximately 750-mm diameter and 6-m length (3 ft by 16 ft), were manufactured for the rapidly growing oil industry. In the 1930s, the shell-and-tube heat exchanger designers established many sound design principles from intuition and data emerging on ideal tube banks. Water-water and water-steam exchangers were probably designed about as well as they are today, because of the predominant effects of fouling resistances. Viscous flow was one of the most difficult problems for shell-side flow and was poorly understood until the 1960s. Shell-side pressure drop is not even mentioned in the literature until the late 1940s. Condensers and reboilers were designed purely to experience-derived values, often tightly guarded secrets of the manufacturers.

The need for mechanical design standards was equally important for reasons of safety, uniformity of tolerances, quality control, and general orderliness in competition. The first such document is the TEMA Standards of 1941 (TEMA, 1941), presently in its sixth edition and considered a standard practice all over the world.

In the following sections, an and a method for sizing shell-and-tube heat exchangers will be presented. The former is an estimation method that can be used those occasions (e.g. assessment of plant cost, layout, and space requirements) when a good approximate size estimate of shell-and-tube heat exchangers is sufficient. This will provide a quicker answer than a detailed design. The detailed method (of intermediate complexity) includes a modified version of the Bell-Delaware method and the .

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