A Review of Comparative Study of Heat Transfer by Experimentation and CFD for Helical Coiled Heat Exchangers

Abstract

Heat Exchangers are of utmost industrial importance in the field of Power generation, Refrigeration, Air
Conditioning, Nuclear energy and numerous other applications. However it is required to utilize the heat energy of the
hot fluid to the optimum extent in order to come up with much more efficient energy systems. The classic design of a heat
exchangers mainly consists of a shell and tube. The tube is enclosed within the shell and generally caries the hot fluid.
The shell carries the cold fluid. There are various flow arrangements that can facilitate enhanced heat transfer. However
by continuous research, it was found that straight tube heat exchangers were not providing the required cooling effect
to the desired e x t e n t . This has led to the development of Helical coil Heat exchangers in which, instead of a
straight tube, a helical tube is used. The heat transfer analysis in helical coil heat exchangers is the next step towards
performance evaluation and optimization of the system. This can be accomplished in two ways. One being
experimentation and the other being numerical estimation by means of Computational Fluid Dynamics (CFD). This
work elaborates the methodology undertaken in experimentation as well as the analysis done by means of CFD
considering three cases. The experimental procedure comprises of making the fluid to flow at various mass flow rates and
obtaining the heat transfer characteristics. However the experimental results are prone to a certain external factors that
can affect the results. This limitation can be overcome by using CFD where everything is pre-programmed and
solutions totally depend on the mathematical models and equations. Further the same model is developed using
suitable software and the fluid flow simulation is carried out. Various boundary conditions like temperature, heat flux
and other temperature dependent thermal and transport properties are well defined during the pre processing
stage. Solutions are carried out to obtain the results of simulation. The chief objective is to establish a correlation
between the experimental results and the CFD results. On obtaining the results, critical comparison is done with regards
to the corresponding results obtained from experimentation and CFD. Thus we can look at CFD as an excellent tool to
analyze fluid flow systems with lesser investment as compared to experimentation. Since the fluid flow through the
Helical coil Heat exchangers has got complex flow characteristics, there may be certain areas where CFD can provide
results that have got much more realistic values. At the end a conclusion is drawn as to which method of analysis can
prove to be handy as well as reliable since the areas in which Helical Coil heat exchangers are used now a days are of
extreme technical importance.