The build-up of deposits in exhaust systems is one of the problems affecting the performance of numerous combustion systems. Over time, these residues reduce the efficiency of heat exchangers, increase maintenance requirements and hinder the operation of the installations. Finding solutions capable of minimising this phenomenon, known as fouling, is one of the current challenges facing energy engineering.
With this aim in mind, Saúl Díaz Rodríguez carried out his doctoral thesis, Study of the use of ozone in the reduction of deposits in exhaust systems, at the Centre for Research in Technologies, Energy and Industrial Processes – CINTECX – at the University of Vigo, supervised by Eduardo Suárez Porto and Miguel Concheiro Castiñeira as part of the doctoral programme in Energy Efficiency and Sustainability in Engineering and Architecture.
The research analyses the use of ozone as an oxidising agent to reduce the deposits generated by the exhaust gases from combustion systems, an area that still has few experimental studies despite its potential to improve energy efficiency and reduce the costs associated with the operation of this equipment.
A new strategy for keeping exhaust systems clean
One of the main challenges of the work was to understand how ozone interacts with the deposits accumulated in exhaust systems. To this end, the research included the design, construction and validation of a new specific test bench that allowed the influence of variables such as ozone concentration, temperature, inlet flow rate or exposure time to be analysed.
The results enabled the development of a model capable of describing the reaction between ozone and fouling deposits, as well as identifying the most favourable conditions to maximise its effectiveness. Subsequently, the study progressed towards scenarios closer to real operating conditions, incorporating ozone injection during the very process of deposit formation.
The tests also included hydrocarbons characteristic of exhaust gases from internal combustion engines, with the aim of reproducing situations more representative of industrial operation. Even under these more complex conditions, ozone maintained its effectiveness.
The research found improvements in the thermal efficiency of the systems, reductions in the hydrocarbons present in the gas stream and significant changes in the characteristics of the deposits formed. The study’s conclusions position ozone as a promising alternative for combating deposit build-up in exhaust systems.