Performance of a double pipe heat exchangers can be quite improved by a number of augmentation techniques. These techniques can be classified as active techniques and passive techniques. Active techniques are (i). vibration of heated surfaces, (ii). fluid vibration, (iii). application of electrostatic field etc, Passive techniques are (i). surface promoters providing roughness, (ii). displaced promoters, eg. rings, discs, mesh etc, (iii). swirl flow generators etc.
In general for high performance and high enhancement of heat transfer in a double pipe heat exchanger, which augmentation technique can be used?
Thank you Miaden Bosnjakovic with your answer. When considering augmentation in double pipe heat exchanger under forced convection, the best technique used to enhance heat transfer is by means of passive technique of which swirl flow generators (twisted tape) is reliable. Several empirical correlations are existing in literature to derive the same. However, what could be the other augmentation techniques in order?
Answers and technical discussions on best augmentation technique in double pipe heat exchangers are invited.
Even though several techniques are used for augmentation of heat transfer, twisted tape inserts (passive technique) could be the best used for enhancement of heat transfer.
Augmentation is enhancing heat transfer. In a double pipe heat exchanger, passive technique is best suitable for effective exchange of heat transfer between two fluids. Since the fluid may not occupy the whole diameter inside the tube, hence effective heat transfer can be got by putting spiral inserts, brush inserts, twisted tapes etc. All are best techniques and any one of them can be used for specific application.
The best enhancement technique to be used in double pipe heat exchangers is got by insertion of twisted tape inside a tube which is a passive technique.
Out of all the techniques used for enhancing heat transfer, in double pipe heat exchanger, twisted tape inserts- a passive technique is the best as far as I know.
In double pipe heat exchangers, several techniques are used for enhancing heat transfer, one is active technique and other passive technique. In passive technique, twisted tape inserts prove to be the most promising and easier to be used for augmenting heat transfer.
Augmentation or enhancement of heat transfer can be done by two methods one is active technique and other passive technique. Active technique is rarely used and in passive technique, twisted tape inserts are the one which are used and mostly dependent upon for enhancement of heat transfer.
Methods to increase heat transfer in a safe and easy way from fluid to fluid are gaining importance. Hence, the transfer of heat is preferred by using a passive technique of which twisted tape inserts are preferred.
All heat exchanger equipments uses different techniques for exchange of heat. They are classified as active and passive techniques. In passive techniques, inserting twisted tape inserts gives heat transfer enhancement which found easier, reliable and best.
Forced convection heat transfer is considered in double pipe heat exchangers since the heat is exchanged to fluids at higher rates than natural convection. In order to further increase in heat exchange and also if the fluid is not fully flowing, twisted tapes insertion, a passive augmentation technique is used for enhancing heat transfer.
Providing fins outside the tube side of the heat exchanger (making sure that it does not obstruct the flow on the shell side) will result in increased surface area for heat transfer. This would also increase the turbulence and effective Reynolds number. This assumes that the fluid that flows over the fins is non-toxic and would not leave any deposits creating maintenance problems.
The development of high performance thermal systems has stimulated interest in methods to augment heat transfer rate. Among the passive and active techniques investigated for augmentation of heat transfer rates, a wide variety of twisted tape inserts are found reliable. The swirl flow induced by twisted tape inserts improves heat transfer to normal and viscous fluids and this has become a effective tool.
Use pipe of copper material with much thickness to promote heat transfer from surface rapidly
In surrounding cold liquid pipes may be employed i.e. liquid nitrogen or oxygen
In heat exchangers, forced convection is used to augment or enhance heat transfer between fluids. Out of all described above, use of twisted tape inserts, material of high thermal conductivity, may not only cover the entire tube, also make the fluid to interact on to the walls and happens to create a swirl flow. In this process, overall heat transfer coefficient and effectiveness is increased.
In heat exchangers, of all the devices used for augmentation or enhancement of heat transfer, swirl flow generators i.e. twisted tape inserts are used. This induces swirl flow, which createsturbulence and gives out heat transfer at faster rate.
Augmentation technique like twisted tape inserts for removal of heat is considered in heat exchanger from hot fluid towards cold fluid. This gives a swirl flow and effective heat exchange takes place.
Effective heat exchange between two fluids in a double pipe heat exchanger is purely by forced convection and out of several techniques considered, swirl flow generators appears to be promising. The cost wise as well as manufacturing of twisted tape (swirl flow generators) is easier, reliable and efficient.
Several augmentation techniques are studied in forced convection heat transfer. In double pipe heat exchanger, out of the two techniques, passive technique, in which swirl flow generators and in it twisted tapes are the one which can be and more frequently used and proved to be the best augmentation technique.
For augmenting or for enhancing heat transfer in a double pipe heat exchanger, twisted tapes are used since this develops swirl and it has contact to walls of tube thereby fluid will be flowing at a velocity in contact.
Many augmentation techniques are studied especially in double pipe heat exchangers as active and passive techniques. Our of which swirl flow generators in which twisted tape inserts are found suitable, since this not only augments heat transfer but also gives swirl flow which in turn increases heat transfer.
In forced convection that too in double pipe heat exchangers, twisted tape insert (passive technique and classified as swirl flow generator) is found to be the best heat transfer enhancement device.
Heat exchangers are devices which makes heat to exchange from hot fluid to cold fluid. If the fluid flow is less on hot fluid side, augmentation technique is applied for enhancing heat transfer. In this aspect, swirl flow generators are proven to be conventional and most preferable since when kept this induces swirl flow as well as creates turbulence which is very much necessary for enhancing heat transfer.
In forced convection and in double pipe heat exchanger, twisted tape inserts are used for enhancing heat transfer. This not only induces swirl flow but gives high effectiveness.
In double pipe heat exchangers, there are two techniques which can be applied. One is active and other is passive technique. In the passive technique, for better augmentation of heat transfer, swirl flow generators looks promising and widely used.
Swirl flow generators as a part of passive technique is the best augmentation device used to enhance heat transfer in double pipe heat exchanger.
In double pipe heat exchangers, swirl flow generators as a part of passive technique is preferred, since swirl flow generators create turbulence, thereby enhances heat transfer.
For heat exchangers subjected to forced convection, swirl flow generators are the best augmentation device used for enhancement of heat transfer under passive technique. This not only creates swirl flow but also dissipates heay to the surface of the tubes.
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