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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 [Fi r s [10 2 Lin e 6.2 5 —— No r m * PgE [10 2 CHAPTER 14 HeatTransfer Enhancement R. M. MANGLIK Thermal-Fluids and Thermal Processing Laboratory Department of Mechanical, Industrial and Nuclear Engineering University of Cincinnati, Cincinnati, Ohio 14.1 Introduction 14.1.1 Classi±cation of enhancement techniques 14.1.2 Performance evaluation criteria 14.2 Treated surfaces 14.2.1 Boiling 14.2.2 Condensing 14.3 Rough surfaces 14.3.1 Single-phase flow 14.3.2 Boiling 14.3.3 Condensing 14.4 Extended surfaces 14.4.1 Single-phase flow 14.4.2 Boiling 14.4.3 Condensing 14.5 Displaced enhancement devices 14.5.1 Single-phase flow 14.5.2 Boiling 14.5.3 Condensing 14.6 Swirl flow devices 14.6.1 Single-phase flow 14.6.2 Boiling 14.6.3 Condensing 14.7 Coiled tubes 14.7.1 Single-phase flow 14.7.2 Boiling 14.7.3 Condensing 14.8 Additives for liquids 14.8.1 Single-phase flow 14.8.2 Boiling 14.9 Active techniques 14.10 Compound enhancement Nomenclature References 1029
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1030 HEAT TRANSFER ENHANCEMENT 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 [103 0 Lin e 0.0 p —— Nor m PgE n [103 0 14.1 INTRODUCTION The conversion, utilization, and recovery of energy in every industrial, commercial, and domestic application involve a heat exchange process. Some common examples are steam generation and condensation in power and cogeneration plants; sensible heating and cooling of viscous media in thermal processing of chemical, pharma- ceutical, and agricultural products; refrigerant evaporation and condensation in air conditioning and refrigeration; gas flow heating in manufacturing and waste-heat re- covery; air and liquid cooling of engine and turbomachinery systems; and cooling of electrical machines and electronic devices. Improved heat exchange, over and above that in the usual or standard practice, can signiFcantly improve the thermal efFciency in such applications as well as the economics of their design and operation. The engineering cognizance of the need to increase the thermal performance of heat exchangers, thereby effecting energy, material, and cost savings as well as a con- sequential mitigation of environmental degradation had led to the development and use of many heat transfer enhancement techniques. These methods have in the past been referred to variously as augmentation and intensiFcation, among other terms. There is an enormous database of technical literature on the subject, now estimated at over 8000 technical papers and reports, which has been disseminated periodically in numerous bibliographic reports (Bergles et al., 1983, 1991, 1995; Jensen and Shome, 1994), reviews (Webb and Bergles, 1983a; Webb, 1987; Shatto and Peterson, 1996; Bergles, 1998, 1999; Manglik and Bergles, 2002a), and monographs and edited texts (Thome, 1990; Webb, 1994; Manglik and Kraus, 1996; Kakac ¸ et al., 1999). This information growth, represented by the typical yearly distribution of technical pub- lications depicted in ±ig. 14.1, urgently warrants that a digital library of enhanced heat and mass transfer be established (Bhatnagar and Manglik, 2002). This literature
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