ABSTRACT

Chapter 7 through Chapter 9 address techniques to enhance the heat transfer coefficient inside a tube for single-phase flow. Hence, these three chapters discuss three different approaches to enhancement of tube-side convective heat transfer. Insert devices involve various geometric forms that are inserted in a smooth, circular tube. These devices are in competition with internal fins (Chapter 8) and integral roughness (Chapter 9). Which of the three methods is preferred depends on two factors—performance and initial cost. Integral internal fins and roughness require deformation of the material on the inside surface of a long tube. Cost-effective manufacturing technology to deform the inner surface of a tube has only recently been developed. Insert devices represent an early approach to tube side enhancement, which allowed use of a plain tube. Anticipating the material to be discussed in Chapters 7 through 9, this chapter shows that insert devices are generally not competitive with the current performance and cost of internal roughness for turbulent flow. Only in laminar flow are insert devices an effective solution. However, insert devices may be used to upgrade the performance of an existing heat exchanger.