Review of passive heat transfer augmentation techniques

Abstract

Heat transfer augmentation techniques (passive, active or a combination of passive and active methods) are commonly used in areas such as process industries, heating and cooling in evaporators, thermal power plants, air-conditioning equipment, refrigerators, radiators for space vehicles, automobiles, etc. Passive techniques, where inserts are used in the flow passage to augment the heat transfer rate, are advantageous compared with active techniques, because the insert manufacturing process is simple and these techniques can be easily employed in an existing heat exchanger. In design of compact heat exchangers, passive techniques of heat transfer augmentation can play an important role if a proper passive insert configuration can be selected according to the heat exchanger working condition (both flow and heat transfer conditions). In the past decade, several studies on the passive techniques of heat transfer augmentation have been reported. The present paper is a review on progress with the passive augmentation techniques in the recent past and will be useful to designers implementing passive augmentation techniques in heat exchange. Twisted tapes, wire coils, ribs, fins, dimples, etc., are the most commonly used passive heat transfer augmentation tools. In the present paper, emphasis is given to works dealing with twisted tapes and wire coils because, according to recent studies, these are known to be economic heat transfer augmentation tools. The former insert is found to be suitable in a laminar flow regime and the latter is suitable for turbulent flow. The thermohydraulic behaviour of an insert mainly depends on the flow conditions (laminar or turbulent) apart from the insert configurations. The present review is organized in five different sections: twisted tape in laminar flow; twisted tape in turbulent flow; wire coil in laminar flow; wire coil in turbulent flow; other inserts such as ribs, fins, dimples, etc.

Numerical investigation of heat transfer and fluid flow of water through a circular tube induced with divers' tape inserts

“…These benefits are its easy installation, low cost and low maintenance [4,8]. The resistance to heat flow in a heat exchanger is broken by the disturbance introduced to the flow by the twisted-tape and therefore allow more heat to be transferred [3,9,10].…”

Heat Transfer Enhancement for Tube in Tube Heat Exchanger Using Twisted Tape Inserts

“…A Dewan et.al. [9]have shown that heat transfer passive augmentation are advantageous compared with active techniques, because the insert manufacturing process is simple and these techniques can be easily employed in an existing heat exchanger. In design of compact heat exchangers, passive techniques of heat transfer augmentation can play an important role if a proper passive insert configuration can be selected according to the heat exchanger working condition (both flow and heat transfer conditions).…”

Heat Augmentation Using Non-metallic Flow Divider Type Inserts in Forced Convection

“…Compound methods are hybrid methods in which both active and passive methods are used in combination. Passive and active techniques that are used for heat augmentation of laminar flow have been discussed in detail by Bargles [1].These are effective but involve complicated design and hence have limited applications [1][2][3]. Heat augmentation can further increased by perforating the twisted tape with different shapes with different arrangement [3].…”