7.1 Introduction

In the Stream Analysis method a hydraulic model is used to calculate the pressure drop and flow rates of the cross flow, leakage and bypass streams in the shell of a shell-and-tube exchanger. These flow rates are then used to calculate the shell-side heat-transfer coefficient. This approach, although still highly empirical, is considered more fundamental than that of the Delaware method because it is based on sound hydraulic principles that properly account for interactions among the shell-side streams. The method was conceived by Tinker [1 3] and further developed by others, notably Palen and Taborek [4] at Heat Transfer Research, Inc. (HTRI). By computerizing the model and fitting it to HTRI's extensive experimental database on industrial-size exchangers, the latter workers produced a powerful tool for design and analysis of shell-and-tube exchangers.

Although the basic ideas and equations involved in the Stream Analysis method have been published, values of the many empirical parameters required for its implementation remain proprietary. Therefore, commercial software is required in order to use the method, with one exception. Wills and Johnston [5] published a simplified, but complete, version that can be used to calculate shell-side pressure drop. The HTRI version is presented below, followed by the Wills Johnston version.

7.2 The Equivalent Hydraulic Network

The shell-side flow is represented by an equivalent hydraulic network as shown in Figure 7.1. The streams are defined as follows:

Figure 7.1: Equivalent hydraulic network for shell-side flow (Source: Ref [4])

A = tube-to-baffle leakage

B = Cross flow