CFD Simulation of Innovative Roadvent Technology to Combat Airborne Pollution
Roadvent™ (www.roadvent.com) is a highly innovative system developed by Pollution Solution™ to directly address the critical health dangers of exhaust and brake particulate emissions, significantly improving air quality by removing the dirty air adjacent to these vehicles through slots and cleaning at the roadside.
To support development and provide independent validation of the system’s effectiveness, Wilde Analysis was commissioned to undertake an independent, impartial study using Computational Fluid Dynamics (CFD) simulation techniques. Applying Ansys Fluent CFD software with a novel modelling approach, our engineers were able to demonstrate the potential effectiveness of Roadvent™, predicting pollution concentrations to compare against UK, European and US standards and World Health Organisation (WHO) guidelines while also undertaking preliminary optimisation of the system.
Roadvent™ has subsequently been successfully tested at UTAC Millbrook Proving Ground, UK, with a live installation reducing roadside pollution levels by 91%.
The Environmental Problem
Slow moving and stationary fossil fuelled vehicles have been proven to have the highest negative impact of all vehicle usage on human health as a result of the emissions they produce. Alternative fuel vehicles (such as electric) have also been found to produce dangerously high levels of particulate matter from vehicle braking systems.
Both of the above issues have caused “hot-spot” pollution points around the world, mainly in towns and cities that have a high population of humans. As a result, millions of people are subjected, on a daily basis, to illegal and extremely harmful levels of toxic pollutants which have been found to cause numerous health issues, many of which result in terminal diseases. Studies have now proven that hundreds of thousands of humans die on a yearly basis as a result of road-based emissions.
A recent BBC Inside Out documentary, involving research by Coventry University, focused on “drive-thru” takeaways as an example. Here, vehicles often queue or move forward slowly, emitting dangerous fumes which the documentary suggested can concentrate near to serving staff, risking persistent exposure and inhalation.
The Pollution Solution
Formed in 2014, Pollution Solution has engineered the Roadvent™ solution to tackle such "hot-spot" zones by pulling in polluted air, removing the contaminants and pushing the clean air back into the atmosphere.
The system is comprised of channels embedded in the road where a fan draws air through the system from road level. Air is passed through filters to remove harmful gases and particulate matter before being released back into the environment. Designed to be positioned as close as possible to the vehicle's exhaust outlets, it seeks to achieve the highest potential pollutant capture rate.
Applying Computational Fluid Dynamics (CFD) to Validate and Accelerate Development
Physical testing of new technologies is often impractical and expensive at early concept stages, slowing down development and not providing the insight required for optimisation. This was the case for Pollution Solution™, where installation of their system in an actual drive-thru location was not possible.
In the absence of actual measurement, computer simulation, based on computational fluid dynamics (CFD), was identified as an ideal technique to assess the effectiveness of their proposed solution to dangerous emissions. Furthermore, Pollution Solution™ sought the independent input of Ansys Channel Partner and CFD specialist, Wilde Analysis, to conduct this modelling task and provide engineering support with preliminary optimisation of the Roadvent™ system, including channel design.
A Virtual Drive Thru
Creating a “virtual” Drive-Thru using Ansys SpaceClaim, Wilde developed a methodology using CFD to calculate likely concentrations of primary pollutants PM10, carbon monoxide and the oxides of nitrogen. The overset mesh capability in Ansys Fluent was used to enable cars to be simulated ‘driving’ through the Drive-Thru as a transient analysis, predicting the time-varying levels of pollution in the vicinity, including at open window locations where staff would be working.
To assess a range of scenarios, simulations included a mixture of typical diesel and petrol vehicles, some queuing and moving between the payment and serving hatches, others parked nearby. In reality, a number of customers will typically queue to order, pay and collect then drive off, resulting in a range of movement characteristics, speeds and vehicle numbers around the restaurant building that contribute to the changing pollution patterns. To efficiently recreate these conditions using CFD, nine simulated vehicles were included in the final models, comprising six moving and three stationary, which performed a cycle of acceleration, deceleration and idling behaviour informed by observation at several actual Drive-Thru locations throughout the UK.
Early Stage Analysis
Early stage CFD analysis helped established preferred channel configurations in the road to capture both exhaust emission and brake particulates. It predicted that potential levels of exhaust capture up to 97% in calm weather conditions may be achieved when the Roadvent™ system is activated.
The CFD results supported concerns that serving staff may be regularly exposed to high levels of airborne pollutants directly associated with exhaust emissions from vehicles using Drive-Thru restaurants. This included agreement with findings of the BBC documentary and suggested, as might be expected, that the close proximity of the serving hatches to queuing vehicles resulted in even higher exposure to pollutants at these locations than recorded at the vehicles parked nearby during their investigation.
Pollution Solution engaged with Wilde Analysis when Roadvent™ was still at the early concept stage and their enthusiasm for the project was infectious.
Both Dr Simon Leefe and Alex Jones worked tirelessly with Thomas and I in what proved to be many complicated simulations and scenarios. The end result was a series of professional, factual results and findings. Throughout the process many changes were implemented which resulted in some long drawn-out sessions via conference calls, these changes were carried without question and many of these were outside the original scope of work.
The Wilde Analysis team dedicated their time and vast knowledge to Roadvent™ and went above and beyond to accommodate our expectations. We would not hesitate in using Wilde Analysis in the future for product development or installation simulations.
Dave Lewis, Commercial and Construction Director, Pollution Solution Holdings
Demonstrating the Environmental Imperative
This CFD study conducted by Wilde Analysis successfully demonstrated the environmental imperative for pollution mitigation around Drive-Thrus and similar infrastructure and the effectiveness of Pollution Solution’s innovative design.
A further outcome was that results, presented as videos and images, formed a highly effective communication tool for public discussion and when engaging further investors.
Physical Tests at Millbrook Installation Site
Following the development of this proof-of-concept, Pollution Solution™ proceeded with the installation of a test site at Millbrook Proving Ground. In conjunction with a test partner, Roadvent™ was found to perform well.
This included also demonstrating the efficacy of the system to mitigate separate environmental concerns at school-drop off points, reducing roadside pollution levels by 91% when measured at the height of a child’s face.
Demonstrated the effectiveness of the Roadvent™ solution in addressing a major pollution issue.
Predicted current pollution concentration estimates around a representative Drive-Thru site, enabling comparison with NAAQS in the US and WHO guidelines that are embodied in air quality legislation across Europe.
Created communication material for Pollution Solution™ to support further engagement with prospective customers and investors.