Design and analysis of Air purifier

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Design and analysis of Air purifier
Abhishek Mishra1, Ayush Kakani2 , Ayush Shah3, Lester Dsouza4 , Prof. Dhaval Birajdar1
1,2,3,4 UG Student, Dept. of Mechanical Engineering, Dwarkadas J. Sanghvi College of Engineering, Mumbai, India.
5 Assistant Professor, Dept. of Mechanical Engineering, Dwarkadas J. Sanghvi College of Engineering, Mumbai,
India
---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Air purifiers are increasingly used to improve
indoor air quality and promote healthy living and working
environments. In this study, we designed and analyzed an
air purifier for a standard office space using a combination
of literature survey, market research, software tools, and
simulation techniques. We conducted a comprehensive
search and screening of research papers related to various
aspects of air purification, ventilation, design of air filter
and narrowed down our focus to the specific domain of air
purifier design and analysis. We used Solidworks software to
design the air purifier and conducted CFD analysis using
ANSYS Fluent to gain a better understanding of the airflow,
removal, and capture of dust, pollen, and other airborne
contaminants. Our results showed that the designed air
purifier based on best possible filter selection was effective
in removing pollutants from indoor air, with a suggested
standard air purifier capacity for a standard office space
and residential bedrooms. The simulation results were
validated by comparison with analytical solutions. Our study
highlights the importance of air purifiers in maintaining
healthy indoor air and provides insights into their design
and analysis along with the filter design.
Key Words: Air purifier, Indoor air quality, Design,
analysis, Solidworks, CFD, ANSYS Fluent, Simulation,
pollutants, Office space, clean air delivery rate.
1.INTRODUCTION
Air purifiers are devices designed to improve the
quality of indoor air by removing pollutants, such as dust,
smoke, allergens, and other harmful particles. The air
quality in indoor spaces, such as homes, offices, schools,
and hospitals, can have a significant impact on the health
and well-being of the occupants. Poor indoor air quality
can lead to a range of health problems, including allergies,
asthma, respiratory illnesses, and even cancer.
Air purifiers have become increasingly popular in recent
years, as people become more aware of the importance of
maintaining healthy indoor air. With the rise of air
pollution levels, natural disasters, and pandemics, air
purifiers have become an essential tool in ensuring that
indoor air is safe and healthy.
The significance of air purifiers is particularly evident in
areas with high levels of outdoor pollution, such as cities
and industrial areas. In these areas, the use of air purifiers
can help to reduce the harmful effects of pollution on
human health, particularly among vulnerable populations
such as children, the elderly, and those with pre-existing
health conditions.
In addition, air purifiers are also important in workplaces,
where the quality of indoor air can have a significant
impact on productivity, absenteeism, and employee health.
For example, in office spaces, air purifiers can help to
reduce the spread of germs and viruses, particularly
during flu season.
2.PROPOSED METHODOLOGY:
1) The project was initiated with the selection of air-
purifiers as the topic of research.
2) A comprehensive search and screening of
research papers related to various aspects of air-
purification were conducted, including
performance evaluation, ventilation, applications,
and emerging technologies.
3) The analyzed research papers were discussed in
the research work.
4) The team narrowed down their focus to the
specific domain of air purifier design and analysis
to check effectiveness and suggest a standard air
purifier capacity with best possible filter selection
along with ventilation and heat treatment study
for a standard office space .
5) Solidworks software was utilized to design the air
purifier, taking into account market research and
available air purifier models.
6) CFD analysis was conducted using ANSYS Fluent
to gain a better understanding of the airflow,
removal, and capture of dust, pollen, and other
airborne contaminants.
7) The results obtained from the CFD simulations
were validated by comparison with analytical
solutions.
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 10 Issue: 04 | Apr 2023 www.irjet.net p-ISSN: 2395-0072

3.CONSTRUCTION AND PERFORMANCE OF AIR
PURIFIER
Fig -1: HEPA Filter
Air Purifier's function is to reduce, remove or prevent
the Contaminants present in air. Hence, all these functions
are performed by filter. Hence, Filter is the most essential
component of AP. There has been evolution in the filters
and hence the classification of filter is discussed. To
improve the performance of Air purifier we need to be
keen on the selection of the filter and filtration process,
i.e., air purification technique.
3.1.Types Of Inside Air Filtration Technique-
Capture type is based on separation, prevention, removal
of contaminants present in air and Reactive type includes
reaction which involves some kind of transformation to
the contaminants of air, i.e., ionization, catalysis
, oxidation etc.
Normally, reactive types of Air Purifiers can cause some
problem of smell, odor due to chemical reaction & hence
causes unnecessary pollution. Therefore, Capture type of
Air Purifiers are preferred over reactive type Air Purifiers .
3.2.Types Of Capture Filters-
1. Mechanical filter (HEPA - high efficiency
particulate air)
2. Electrostatic Precipitator (ESP ionizer)
3. Hybrid
Mechanical filter consists of prefilter, fan & casing and
the purification process is diffusion. Its efficiency is
affected by fan speed, filter material characteristic and
structure of Air purifier i.e., coverage area etc. Mainly
porous fibrous material is preferred as filter.
ESP uses high voltage electrode & Collecting electrode and
electricity is generated, by creating electrostatic field. In
the presence of electrostatic fields contaminants are
ionized and with collision, they continue the chain of
ionization. Due to influence of electric field forces, charged
particles flow in direction of electric field & are collected
on collecting electrode. Hence electrodes need to be
charged or maintained to improve functionality. However,
this process generate smell with ozone generation that
process may hamper IAQ.
Hybrid AP combines static electricity with filtration. In
which, ESP removes gases contaminants and Mechanical
filter removes other contaminants. HEPA filter, a fibrous
material with ionizer has been taken in the purification
system that we have taken for analysis. The efficiency for
good HEPA is about 99.97%. Along with these 2 filters, two
Pre-filters are placed at front & back as they remove
Contaminants > PM 2.5 easily and can be replaced at low
cost or can be maintained or cleaned very easily.
4.DESIGN AND CAD:
4.1.Objective Of Design :
The main objective of using design or CAD software in the
research paper on air purifiers is to create a prototype
that meets the desired specifications and is capable of
efficiently removing airborne contaminants. CAD software
is used to design the air purifier, considering market
research and available air purifier models.
4.2.Selection Of Software:
In this project, Solidworks software was chosen for
designing the air purifier due to its versatility and user-
friendliness. Solidworks offers a wide range of design tools
that allow for efficient creation and modification of 3D
models. It also offers advanced simulation capabilities that
enable the researchers to evaluate the design and make
informed decisions. The availability of a vast library of
pre-built parts and models in Solidworks reduces design
time and increases productivity. Additionally, Solidworks
is widely used in various industries, making it an ideal
choice for designing an air purifier that can be
manufactured at scale.
4.3.Components Of Air Purifier:
The following are the components of air purifier.
1) Casing
2) Set of 4 Filter
(i) pre–Air Filter
(ii) 2 x HEPA Filter
(iii) Activated Carbon Air Filter

4.3.1. Casing
Fig -2: Volume of Body casing with inlet and outlet pipe
4.3.2. 4x Filter
Fig -3: Isometric view of filter
4.3.3. Final Assembly of Air Purifier
Fig -4: Isometric view of air purifier
5.SIMULATION:
5.1.Objective Of The Simulation :-
The design of the air purifier is done using American
Micronic air purifier , the required dimensions for the
purpose of design are obtained based on referring to it .
Also, parameters of the air flow are determined using the
analytical method. To compare the results, we require a
software CAD model which will imitate the process of air
flow and the capture of dust particles by the filter.
5.2.Selection Of Software :-
There are a number of software available in the market
which allow the simulation of the airflow . Namely ,
Autodesk CFD , Simscale , Ansys Fluent , Open FOAM ,
Simcenter , Paraview etc. Among all these software we
used Ansys fluent . The main reason for selection of Ansys
Fluent was the amount of community help and tutorials
available in the market about the same.
5.3.Process Of Simulation :-
The simulation of the air purifier has to be done in number
of stages :-
a. Importing the geometry:
Fig -5: Modelling of air purifier in Ansys Fluent
The geometry which is created using the Solidworks
software is imported in order to conduct further analysis
on it.
b. Meshing of the Air Purifier:
Fig -6: Meshing of model

In this step the geometry is divided into finite numbers of
elements in order to obtain an approximate solution.
c. Setting up of the boundary conditions:
Fig -7: Boundary condition of Air purifier
The following assumptions of boundary conditions are
made –
 Laminar viscous flow
 Suitable values of viscous resistance for the
porous filter material
 inlet velocity magnitude
 outlet intensity and hydraulic diameter
d. Solution:
For the above boundary conditions the solution is
obtained for 1000 iterations.
Fig -8: Initial condition before running iteration
Fig -9: After running iteration
e. Obtaining the results :- The results in the form of a
graph obtained are –
● Continuity
● Outlet air flow rate
● Outlet Mass flow rate
● Outlet Volume flow rate
● Permeability
Fig -10: Plot of results
6.ANALYTICAL CALCULATION:
Fig -11: Multistage air filtration
6.1.Specifications:
1. Coverage area(CA): 300 sq.ft
2. Ceiling height(h): 10 ft
Normally, residential buildings have ceiling height of 9 to
11 ft in Mumbai.

3. Air changes per hour (ACH) : 3.5
ASHRAE recommends selecting ACH of 3 to 4, hence
selecting the average value.
4. This AP efficiency is 99.97% as it filters 99.97% of
dust, bacteria, odor & contaminants.
5. Multistage filtration is installed in the system
consisting of Pre-filter, HEPA, ionizer and
activated charcoal filter.
6. Power: 30W
7. Weight: 2.9 kg
8. Clean air delivery rate(CADR): 275 m^3/h
9. Dimensions: D25.5 x W25.5 x H36 cubic
centimeters
Material: ABS
10. Efficiency: 99.97%
11. Color: Ivory & Grey
12. Control method: Touch
13. Model: AMI-AP2-30Dx
6.2.Calculations:
Dimension of bedroom: 20 x 15 x 10 cubic ft.
CADR is clean air delivery rate i.e., since the purifier filters
the contaminants and impurities present in air and air at
outlet or discharge is pure and clean. Hence the term
CADR is used as a parameter to measure performance of
the purification system.
CADR = (ACH x CA x H)/60
= (3.5 x 300 x 10)/60
= 175 cubic ft/min (1 ft is equivalent to 0.305 m
)
= 175 x (0.305^3) x 60
= 274.3466 cubic m/h
CADR = Area at outlet x Velocity at outlet ( diameter at
outlet is 0.11m, outlet is circular in shape, V is velocity at
outlet )
CADR = (3.142x d x d)/4 x V
274.3466 = (3.142 x 0.11 x 0.11)/4 x V
V = 8.019 m/s
The value of V is in range with the simulation results.
Hence results are verified. Since the results are verified,
we also need to define the accuracy of the solution and for
that purpose we need to calculate the percentage error. If
the percentage error is less than 5% i.e., 5% deflection
from the actual values then the results will be accurate.
% error = (Actual - Calculated)/Actual x 100
Here, calculated value of CADR IS 274.3466 m^3/h and
actual value is 275 m^3/h (specifications)
% error = (275-274.3466)/275 x 100
= 0.237596 %
The percentage error is under control i.e., <5%. Hence
results are satisfactory.
7.VENTILATION AND HEAT TREATMENT
7.1.External Factors Affecting Air Purifier
Performance :
Since the purpose of installation of Air Purifier is to free
the air from contaminants or to keep the system free from
contaminated air. Ventilation is the process of exchange of
air in which fresh air is brought inside the system and
expelling the contaminated air outside. Doing ventilation
at regular intervals ensures the proper working and
efficiency of the Air Purifier. This also leads to increase of
intervals of maintenance and removal of filters and thus
reducing the overall cost. Improving ventilation efficiency
and performance further improves the performance and
efficiency of Air Purifier. Hence, natural ventilation and
PAC (Portable air conditioners) combined yields better
results than the individual Air Purifier installation.
Another thing which came to our notice with regards to
Air Purification is the presence of harmful contaminants in
air. It's very similar to polluted or contaminated water
problem which is solved by boiling the water as the
contaminants lose their functionality at the high
temperature. The thing which brought this to our
attention was that air as well as water both are very
essential for human life to sustain. Hence, we studied and
analyzed the feasibility and process of heat treatment of
air and its limitations.
7.2.Proposed Solution-
Presence of contaminants like dust, pollen, and bacteria
are the prime reasons for poor air quality. As we all know,
these contaminants cannot survive when temperature is
higher than 100°C as in the case of boiling water. Hence,
air heat treatment is also an air disinfection approach. As
mentioned in the calculations below, the same heat
required for air and water to 100°C makes this method
considerable. Sometimes, heating may require too much
energy which results in an increase in expenditure.
Continuous heat recovery from air already heated during
the disinfection process hence energy & cost efficient. The
process involves inactivation i.e., losing functionality of
contaminants. Hence using kinetics equation of half-life.
The inactivation rate of virus in aerosol follows equation:
C=C0 .
Where ,
k α T
k α UV radiation
C – concentration of active virus at time t
C0 – initial concentration of virus at time t=0
K – inactivation rate factor (min-1)
n – decay rate (0.5)

Experimentally at 20°C and 50%RH, half-life is 274 for the
virus and Relative Humidity (RH) depends on the virus.
The proposed solution is to heat above 50°C, where
viruses lose their functionality.
Different methods of air purification / disinfestation are:
o UV radiation
o filtration
o ventilation
o photocatalysis
7.3.What Makes The Heating Feasible?
Human consumption of air (daily basis) = 14 kg
Human consumption of water (daily basis) = 3 kg
Energy required to heat to 100°C
For water,
Q = Cwater Mwater ∆T
= 4.20×3×(100-20) = 1008 KJ
For air,
Q = Cair Mair ∆T
= 1×14×(100-20) = 1120 KJ
Where,
C -Specific heat (KJ/KgK)
M -mass (kg)
T – temp difference (k)
Q - required for air and water is almost equal hence it is
feasible to heat
7.4.How To Make Heat Treatment More
Economic:-
It is required to set up a continuous heat recovery system
due to:
o Reduce the cost of energy input
o Outlet air temperature reduction from system
Cost of thermal disinfection of air:-
Cost = R×0.31110.9
Where
R – cost of electric energy per KWh
0.9 - efficiency of conversion electrical to thermal energy
0.311 - equivalent of 1120 KJ
Out considering cost & efficiency of conversion, cost can
be reduced by cheaper heat source (heat recovery used)
i.e., heat exchanger(HE). Efficiency(h) of HE depends on:-
Maximum heating temperature and the Exposure time.
However, heat treatment of air disinfestation cannot solve
the problem of smell and odor in air and also it makes the
air purification system bulky due to use of heat exchanger .
Hence before adoption of this method we need to do more
research and improve this method. However, this is an
excellent area to be focused in future for the purpose of
innovating the air purification process.
8. RESULTS AND DISCUSSIONS:
Table -1: Comparison of results
The present study was conducted to design and analyse an
air purifier for a standard office space using a combination
of literature survey, market research, software tools, and
simulation techniques. The air purifier was designed using
Solidworks software, taking into account market research
and available air purifier models. Capture filters were used
for filtration, and the velocity of the air purifier was found
to be in the range of 8-9 m/s.
To validate the simulation results, we compared them with
analytical solutions. The results of the simulation and
analytical solutions matched well, indicating the accuracy
of the simulation technique. The clean air delivery rate
(CADR) of the air purifier was found to be in the range of
250-300 m³/h, which is within the acceptable range for an
air purifier to be effective.
Our study also highlighted the importance of natural
ventilation and portable air conditioners (PAC) for
maintaining healthy indoor air quality. The recommended
ventilation should allow for the natural flow of air into the
space and should be combined with PAC to provide
optimal filtration. Additionally, our study showed that heat
treatment above 50°C is necessary to remove all airborne
contaminants effectively.
In conclusion, our designed air purifier based on the best
possible filter selection was effective in removing
pollutants from indoor air, with a suggested standard air
purifier capacity for a standard office space and residential
bedrooms. Our study provides insights into the design and
analysis of air purifiers, including filter design and
recommendations for natural ventilation and heat
treatment, to maintain healthy indoor air.
9. CONCLUSIONS:
This study highlights the importance of air purifiers in
maintaining healthy indoor air quality. The designed air
purifier is based on the best possible filter selection which
Sr.
no.
Parameter Analyt
ical
values
CFD simulation
values or
specification value
1 CADR (clean air
delivery rate )
274.34
m^3/h
275 m^3/h
2 Velocity at
outlet
8.019
m/s
9.29s m/s

was effective in removing pollutants from indoor air,
capacity selection , ventilation and heat treatment
suggestions . The insights gained from this study can be
useful for designing and implementing effective air
purifiers in indoor environments to promote healthy living
and working environments.
REFERENCES
[1] G.S.N.V.K.S.N. Swamy (2021) , Development of an
indoor air purification system to improve ventilation
and air quality ,
https://doi.org/10.1016/j.heliyon.2021.e08153
[2] Haiguo Yina, Zhuohang Li , Xinping Zhai , Yuxuan
Ninga, Le Gaoa, Haihang Cui ,Zhenjun Mae, Angui Li
,(2022) , Field measurement of the impact of natural
ventilation and portable air
cleaners on indoor air quality in three occupant states
, https://doi.org/10.1016/j.enbenv.2022.05.004
[3] Stuti Dubey , Himanshi Rohra , Ajay Taneja (2021).
Assessing effectiveness of air purifiers (HEPA) for
controlling indoor particulate pollution ,
https://doi.org/10.1016/j.heliyon.2021.e07976.
[4] Aditya Roy , Chetan Mishra, Naveen Solanki (2018). A
review of general and modern methods of air
purification , DOI:10.18186/thermal.529054
[5] Deng, Zhihui, Zhang, Xiliang (2018). Performance Test
and Structural Analysis of Indoor Air Purifier ,
https://doi.org/10.3303/CET1871137

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