product. innovation. construction
Low-cost air purification device for public transport and housing
Finalists for 2022
Project Collaborator : Noelle Pan
IS CLEAN AIR A PRIVILEGE OR A BASIC RIGHT THAT MANY ARE DENIED?
Several Indian states are affected by air pollution where atleast 660 million Indians lose 3 years of their life from breathing the air. While Delhi is infamous for leading the pack, rapis urbanisation producing more construction waste have polluted the air for states such as Ahmedabad. The worst hit are urban slum dwellers who are forced to breathe this toxic air with no affordable solution in the market.
"Ahmedabad continues to be one of the most polluted cities of India"
- Times of India
HOW DOES IT FEEL TO WRAP IN THE SHACKLES OF CONFINEMENT?
Urban slums are defined as densely packed residential neighbourhood with lack of proper housing construction. Their homes are one of the significant contributors to exacerbating the air quality since they are made of poor materials emitting toxins and lack of ventilation to clear these toxins indoors and outdoors.
RESEARCH INTO EXISTING TECHNOLOGY
After visiting the slums in Ahmedabad, the design solution needs to be affordable, low-tech with low maintenance, and retrofitted to their existing architecture. Along with air purification, it also needs to offer a stable construction, primarily roofs which are the most deteriorated in these homes. No such solution currently exists in the market for dust separators and air purification systems.
HEPA - Activated Carbon filter
Industrial Dust Separator - Cyclones
Industrial Dust Separator - Swirl Separators
Air purifying paints using titanium dioxide
Ionizers and Ozone treatment
slit for separation
Clean air exit
Dirty air inlet
Dirty air inlet
Increased air velocity
Clean air exit
Corrugated Roof Panel
Galvanised Iron Top Panel
Air inlet holes
Dust separation module top half
Straw composite for separator
Straw composite for entire panel
Galvanised Iron Bottom Sheet
Dust separation module bottom half
Entry Exit Grill Vent
Air inlet holes
Dust Collection Hopper
Straw Insulation in Honeycomb geometry
Dust Collection Chamber with vacuum outlet
Slopping guides to direct dust particles
Dust Entry Inlet
From the CFD, the most optimum geometry and dimensioning of the separator design were identified. The key engineering considerations were maximum separation efficiency for low velocity of inlet air and low pressure drop across the system. As this is going inside the structural component of the house susceptible to wind loads, the weight should also be moderated.
PANEL DESIGN - EXPLODED VIEW
The roof panel uses a simple geometry of stacked cuboids to form the shell inside to form an insulated sandwich roof panel. Galvanised iron(GI) is chosen as the material of the shell and insulation is provided through agricultural waste such as straw. For fire protection it is contained inside a GIcasing. The straw around the separators acts to hold them in place and maintain temperature fluctuation of incoming air.
CAN ROOFS BE THE NEXT AIR PURIFIERS?
Looking at various technologies, what suits the requirement of low-cost, low-tech, and low maintenance was the operation of swirl separators. These swirl the air through a guide vane which allows the dust to separate as it travels inside a slit causing the separation. Different iterations were developed after performing computational fluid dynamics (CFD) studies. These separators are designed to be slotted into the roof panel.
SHELCO - AIR PURIFICATION PANEL : INTERNAL OPERATION
Shelco was developed after months of iteration on the dust separator design. Shown below is the array of separators that have multiple air inlets and a single outlet for cleaner air outlets and dust collection. The collected dust is periodically vacuumed from these slots.
After testing several composites of straw of materials such as casein glue, cascamite, corn starch, etc. straw insulation is competitively good to current insulation. It is a cheap raw material which can be sourced from farmers all across the state.
The system efficiently cleans PM2.5 with 85% efficiency and PM10 with 90% efficiency. With insulation and better construction of materials, this impact is far higher. The panels use a microfinance model to make the panels more affordable for slum dwellers.
DESIGN VARIATIONS - VERSATILE CONSTRUCTION AND PRODUCTION
REDESIGNING THEM FOR TRANSPORTATION?
Testing the prototype showed more efficiency when air entered at a higher speed. One such scenario is on the buses where air can naturally enter the block at higher speeds and get effectively cleaned. However, to match the construction of buses several design changes were made.
REIMAGINE CLEAN AIR WITH SHELCO PANELS ON BUSES
Fins are placed on the sides of the panels to direct more air. I imagine this to be a promising product for developing countries in need of clean air.
The design is changed to follow aerodynamics on the bus. The hopper is a removable fixture for easy maintenance. The dust is periodically vacuumed from the slots provided. For maintaining aerodynamics, a honeycomb structure is used to hold the separators in place and provide temperature control for incoming air.