25 Environmental and Economic Impacts of Biofouling on Marine …
395
Category 7: Heat exchanger design modifications due to biofouling
As biofouling is a major unresolved problem to the heat exchanger end-users, the heat
exchanger manufacturing companies try to improve the heat exchanger resistance
towards biofouling by improving their product design.
A generally referenced source for deciding fouling factors during the design
of heat exchangers is TEMA (The Tubular Exchanger Manufacturers Association)
(Diaz-Bejarano et al. 2017; Ross et al. 2015). One common method followed is to
increase or oversize the heat exchanger heat transfer area to account for diminished
performance due to biofouling (Diaz-Bejarano et al. 2017; Ross et al. 2015).
Design modifications are also done based on the type of heat exchanger. For
example, for a shell and tube heat exchanger, a common solution is to increase the
heat exchanger tube side velocities (Coletti et al. 2015). This increases the wall shear
stress, and thereby less fouling material is deposited on tube surfaces (Coletti et al.
2015). In the same way, to prevent biofouling in a plate heat exchanger, one might
undersize the unit to keep the turbulence high in the heat transfer channels.
Another common practice is to add effective surface coatings to mitigate
biofouling related issues in marine heat exchangers (Santos et al. 2017). Siliconebased coatings and Polymer coatings based on the sol-gel process are widely used
to resist fouling (Hjalmars 2014). More advanced fouling resistant coatings like
Carbon nanotube-polytetrafluoroethylene, Nano-hybrid sol-gel coatings, Diamondlike carbon (DLC) coatings, among others, are formulated through research and
development (Hjalmars 2014). All these design alterations will help to reduce
biofouling, but will also increase the heat exchanger product cost in the market.
25.4 Discussion
The global energy requirement is increasing year by year. As heat exchangers are
one of the most efficient means of heat transfer, the heat exchanger market is also
growing, and the increase in the number of heat exchangers will cause a proportional
increase in the environmental and economic impacts associated with heat exchanger
biofouling. Thus, it is necessary to implement effective methods to reduce biofouling.
Currently, there are various techniques adopted for biofouling prevention in marine
heat exchangers. Primarily, the heat exchanger manufacturers would prefer to mitigate biofouling through the proper design of heat exchangers and then, the most
adopted method is the use of online mitigation techniques (Müller-Steinhagen et al.
2011). Online methods are more preferred when compared to offline techniques as
it will not affect the equipment availability.
Among different online mitigation techniques, the most common method is the
use of chemical agents (Müller-Steinhagen et al. 2009). But, the presence of toxic
substances in these chemical agents could greatly outweigh, from an environmental
point of view, the benefits of fouling mitigation. Hence, it is significant to adopt more
395
Category 7: Heat exchanger design modifications due to biofouling
As biofouling is a major unresolved problem to the heat exchanger end-users, the heat
exchanger manufacturing companies try to improve the heat exchanger resistance
towards biofouling by improving their product design.
A generally referenced source for deciding fouling factors during the design
of heat exchangers is TEMA (The Tubular Exchanger Manufacturers Association)
(Diaz-Bejarano et al. 2017; Ross et al. 2015). One common method followed is to
increase or oversize the heat exchanger heat transfer area to account for diminished
performance due to biofouling (Diaz-Bejarano et al. 2017; Ross et al. 2015).
Design modifications are also done based on the type of heat exchanger. For
example, for a shell and tube heat exchanger, a common solution is to increase the
heat exchanger tube side velocities (Coletti et al. 2015). This increases the wall shear
stress, and thereby less fouling material is deposited on tube surfaces (Coletti et al.
2015). In the same way, to prevent biofouling in a plate heat exchanger, one might
undersize the unit to keep the turbulence high in the heat transfer channels.
Another common practice is to add effective surface coatings to mitigate
biofouling related issues in marine heat exchangers (Santos et al. 2017). Siliconebased coatings and Polymer coatings based on the sol-gel process are widely used
to resist fouling (Hjalmars 2014). More advanced fouling resistant coatings like
Carbon nanotube-polytetrafluoroethylene, Nano-hybrid sol-gel coatings, Diamondlike carbon (DLC) coatings, among others, are formulated through research and
development (Hjalmars 2014). All these design alterations will help to reduce
biofouling, but will also increase the heat exchanger product cost in the market.
25.4 Discussion
The global energy requirement is increasing year by year. As heat exchangers are
one of the most efficient means of heat transfer, the heat exchanger market is also
growing, and the increase in the number of heat exchangers will cause a proportional
increase in the environmental and economic impacts associated with heat exchanger
biofouling. Thus, it is necessary to implement effective methods to reduce biofouling.
Currently, there are various techniques adopted for biofouling prevention in marine
heat exchangers. Primarily, the heat exchanger manufacturers would prefer to mitigate biofouling through the proper design of heat exchangers and then, the most
adopted method is the use of online mitigation techniques (Müller-Steinhagen et al.
2011). Online methods are more preferred when compared to offline techniques as
it will not affect the equipment availability.
Among different online mitigation techniques, the most common method is the
use of chemical agents (Müller-Steinhagen et al. 2009). But, the presence of toxic
substances in these chemical agents could greatly outweigh, from an environmental
point of view, the benefits of fouling mitigation. Hence, it is significant to adopt more