=Paper=
{{Paper
|id=Vol-2744/short36
|storemode=property
|title=Modeling of UV Disinfection Irradiation Installations Using Computer Graphics Programs (short paper)
|pdfUrl=https://ceur-ws.org/Vol-2744/short36.pdf
|volume=Vol-2744
|authors=Tatiana Meshkova,Vladimir Budak
}}
==Modeling of UV Disinfection Irradiation Installations Using Computer Graphics Programs (short paper)==
https://ceur-ws.org/Vol-2744/short36.pdf
Modeling of UV Disinfection Irradiation Installations
Using Computer Graphics Programs*
Tatiana Meshkova [0000-0003-1008-2161] and Vladimir Budak [0000-0003-4750-0160]
National Research University "Moscow Power Engineering Institute", Krasnokazarmen-
naya 14, Moscow, 111250 Russia
tvmesh@mail.ru, budakvp@gmail.com
Abstract. In connection with the appearance and spread of COVID-19, lighting
equipment manufacturers have prepared product lines and marketing programs
to promote irradiators for air disinfection for domestic and industrial needs. In
this regard, the CIE issued an official request for the use of ultraviolet radiation
to fight the spread of COVID-19. Nevertheless, the penetration force of ultravio-
let rays is small. The action of rays is limited only to the surface of the irradiated
object, and the method of calculating and simulating irradiators is based on ob-
taining normalized values of irradiation on the surface. However, the main goal
of designing bactericidal systems is to distribute UV radiation uniformly in all
directions of engineering designs, regardless of their type. However, now, there
is no computer graphics program allows you to get the values of normalized val-
ues at each point in space to check the effectiveness of the bactericidal system.
This article presents a new method for solving the problem of modeling irradia-
tion installations with the ability to analyze the normalized values at each point
of the volume of air being treated.
Keywords: UV-Radiation, Room Disinfection, Irradiation, Protection from
COVID-19.
1 Introduction
In connection with the appearance and spread of COVID-19, lighting equipment man-
ufacturers have prepared product lines and marketing programs to promote irradiators
for air disinfection for domestic and industrial needs. In this regard, the CIE issued an
official request for the use of ultraviolet radiation to fight the spread of COVID-19. [1]
According to the design, UV bactericidal irradiators can be divided into two groups:
open - type irradiators or closed-type recirculators. The main feature of bactericidal
irradiators of the open type is that the flow of ultraviolet radiation from it spreads
throughout the space where the light from the bactericidal lamp falls. This is the most
effective way to disinfect both the air and surfaces of the room, and even objects in the
room. Nevertheless, the penetration force of ultraviolet rays is small. Even a thin layer
Copyright c 2020 for this paper by its authors. Use permitted under Creative Commons License
Attribution 4.0 International (CC BY 4.0).
2 T. Meshkova, V. Budak
of glass is enough to prevent their passage. The action of the rays is limited only by the
surface of the irradiated object. In other words, UV radiation is effective if microorgan-
isms and dust particles are located in the same layer, but in a multi-layer arrangement,
the phenomenon of shielding occurs: the upper layers protect the lower layers.
The main goal of designing bactericidal systems is the uniform distribution of UV
radiation in all directions of engineering structures, regardless of their type. For exam-
ple, there are bactericidal systems with built-in fans to improve air mixing, which sig-
nificantly increases the overall efficiency of the systems. However, now there is no
computer graphics program allows you to get the values of normalized values at each
point in space to verify the effectiveness of the bactericidal system.
The method of calculating and modeling irradiators is based on obtaining normalized
values of irradiation on the surface, while for the above reasons, for high-quality disin-
fection, it is necessary to calculate the irradiation of the treated air in volume.
The basis of both computer graphics and calculation of the irradiation system in
lighting engineering is the equation of global illumination (GI), obtained in 1986 by J.
Kajia [2]
By modeling GI equation, we get a spatial-angular distribution of brightness, i.e.
visualization of 3M scenes. The equation is an integral equation of the second kind,
and, accordingly, it does not have an analytical solution in general (except for some
special cases that can be applied to evaluate a particular numerical method. Currently,
there are a number of numerical methods for solving GI equation, but all of them have
a number of assumptions that ultimately affect the reliability of the calculation. The
most common computer programs for designing lighting installations, such as DIALux
[3] and Relux [4], are based on the method of radiosity and, accordingly, do not get the
ability to calculate the spatial-angular distribution of brightness.
In addition, the work of bactericidal irradiators, sufficient for surface disinfection, is
ineffective in the case of air disinfection. Although it is worth noting that properly de-
signed bactericidal systems are able to process both air and surfaces simultaneously.
You can improve system performance by improving the overall reflectivity of the in-
ternal surfaces of air ducts or supply units. This results in the reflection of UV radiation
into the irradiation zone and an increase in the UV dose.
This article presents a new method for solving the problem of simulating irradiation
installations with the possibility of analyzing the normalized values at each point of the
volume of air being treated.
2 Simulation of Irradiation Facilities
Currently, Russia has General recommendations and rules for the use of UV radiation
for disinfection of premises. The main of them are the following:
* Manual P 3.1.683-98 “Use of ultraviolet, bactericidal radiation for disinfection of
air and surfaces in premises”;
* Guidelines MU 2.3.975-00 “application of ultraviolet bactericidal radiation for air
disinfection of premises of organizations of the food industry, public catering and food
trade”;
Modeling of UV Disinfection Irradiation Installations Using Computer Graphics Programs 3
* Guidelines for the use of bactericidal lamps for disinfection of air and surfaces in
premises. Order no. 11-16 / 03-06 February 28, 1995;
* Resolution of the Chief state sanitary doctor of the Russian Federation of Novem-
ber 18, 2013 N 63 Moscow “on approval of sanitary and epidemiological rules SP
3.1.2.3117-13 “Prevention of influenza and other acute respiratory viral infections”.
The main restrictions on the use of irradiation installations for disinfection purposes
can be presented in the Table 1.
Table 1. Restrictions on the use of UV radiation to disinfect the premises
Type of room Irradiation time, hour / day Irradiance, (erythe- Recommended
mal) recommended*, erythemal
W∙m-2 dose**, J∙m-2
Working areas of in-
dustrial and public 8 5.0 40/144
buildings
Group rooms of chil-
dren's institutions,
classes and offices of
4-6 5.0 20-30/72-108
schools, wards of
hospitals, sanatori-
ums
* In the horizontal surface at the level of 1 m from the floor, in children's institutions-at the level
of 0.8 from the floor.
** For a different duration of exposure, the UV irradiation is calculated taking into account the
need to comply with the established dose.
The normalized fluence values are used for modeling the irradiation system and de-
veloping the irradiator itself (Table. 1). Usually, the fluence or surface radiation dose
values for some viruses are determined at a wavelength of 254 Nm, and the inactivation
efficiency is determined by 4 orders of magnitude (99.99 %).
The bactericidal dose (fluence) D is determined by the expression
D = ∫∫ E (λ ,t)S(λ )dλ dt, (1)
where E (λ, t) – time dependence of the spectral density of bactericidal irradiance. The
value of D, required for a tenfold reduction №, depends on the type of microorganism
and for many bacteria and viruses is 2–20 mJ/cm2.
Note that irradiance, as well as illuminance. – is a parameter determined relative to
the surface of the room.
The practical programs DIALux and Relux, commonly used in the design of lighting
installations, simulate the distribution of light in a diffuse approximation. The algorithm
for calculating these programs uses the radiation equation [6], which is solved by the
finite element method and is a consequence of the global illumination equation [7] in
the diffuse approximation (2).
4 T. Meshkova, V. Budak
𝜎(r)
𝑀(r) = 𝑀0 (r) +
𝜋
∫Σ 𝑀(r ′ )𝐹(r, r ′ )Θ(r, r ′ )𝑑 2 r ′, (2)
where M(r) – luminous exitance at a point on a surface r, M0(r) – first luminous exitance
at a point on a surface r directly from light sources in the approximation of a single
reflection, (r, r) – the visibility function of a point r from point r (1 if visible и 0 if
not), F (r, r) – elementary form factor [8], (r) – reflection coefficient.
As part of this work, local estimation algorithms were applied to the solution of the
global illumination equation [7]:
1
𝐿(𝑟, 𝑙̂) = 𝐿0 (𝑟, 𝑙̂) + 𝜋 ∫ 𝐿(𝑟 ′ , 𝑙̂′ )𝜎(𝑟; 𝑙̂′ , 𝑙̂)|𝐺(𝑁
̂ , 𝑙̂′ )|𝑑𝑙̂′, (3)
𝑁
1 1 𝐿0 (𝑟1𝑖 , 𝑙̂1𝑖 ) 𝜎(𝑟; 𝑙̂1𝑖 , 𝑙̂)𝐺(𝑟1 , 𝑟)
𝐿(𝑟, 𝑙̂) = 𝐿0 (𝑟, 𝑙̂) + ∑( +
𝑁 𝜋 𝑝1 (𝑟1𝑖 , 𝑙̂1𝑖 ) 𝑝2 (𝑟1𝑖 , 𝑙̂1𝑖 → 𝑟, 𝑙̂)
𝑖=1
1 𝐿 (𝑟 ,𝑙̂ ) 𝜎(𝑟2𝑖;𝑙̂1𝑖 ,𝑙̂2𝑖 )𝐺(𝑟1𝑖,𝑟2𝑖) 𝜎(𝑟;𝑙̂2𝑖 ,𝑙̂)𝐺(𝑟2𝑖,𝑟)
+ 𝜋2 𝑝0 (𝑟1𝑖 ,𝑙̂1𝑖 ) + ⋯ ). (4)
1 1𝑖 1𝑖 𝑝2 (𝑟1𝑖,𝑙̂1𝑖→𝑟2𝑖,𝑙̂2𝑖 ) 𝑝2 (𝑟2𝑖,𝑙̂2𝑖 →𝑟,𝑙̂)
Using these transformations, you can get the luminance value at each point in space.
However, in our case, fluence rate is important for estimating UV radiation at each
point in the volume of air being treated, so we can use the local estimation method to
solve the global illumination equation, as follows:
1
𝐸(𝑟, 𝑙̂) = 𝐸0 (𝑟, 𝑙̂) + 𝜋 ∫ 𝐸(𝑟 ′ , 𝑙̂′ )𝜎(𝑟; 𝑙̂′ , 𝑙̂)𝐺(𝑟 ′, 𝑟)𝑑 3 𝑟 ′ . (5)
Especially when modeling irradiation installations, it is necessary to pay attention to
the fact that the reflection and transmission of substances in the UV field of the spec-
trum differ from those existing in the visible field. A characteristic peculiarity here is a
decrease in transparency (an increase in the absorption coefficient) of most bodies that
are transparent in the visible field. For example, ordinary glass is opaque at λ < 320 nm,
and boron-silicate UV transparent quartz glass, quartz, etc. Moreover, the air is opaque
at λ < 200-190 nm, primarily due to the absorption of oxygen and water vapor. For
high-quality disinfection of the room using UV irradiation, it is necessary to consider
this.
Since the method is designed to calculate light values, the conversion coefficients
can be used to convert the resulting value to energy, photon, or conversely.
Coefficient of conversion of energy values to light values, lm/W:
700
𝐾𝑚 ∫400 𝜑(𝜆)∙𝑉(𝜆)∙𝑑𝜆
𝐾= 700 , (6)
∫400 𝜑(𝜆)∙𝑑𝜆
Coefficient of conversion of energy values to photons, mol/J:
700 𝜆
𝐾𝑚 ∫400 𝜑(𝜆)∙ ∙𝑑𝜆
ℎ∙𝑐∙𝑁 𝐴
𝐾= 700 , (7)
∫400 𝜑(𝜆)∙𝑑𝜆
Conversion coefficient of light values to photons, mol/s∙lm (8).
Modeling of UV Disinfection Irradiation Installations Using Computer Graphics Programs 5
700 𝜆
𝐾𝑚 ∫400 𝜑(𝜆)∙ ∙𝑑𝜆
ℎ∙𝑐∙𝑁𝐴
𝐾= 700 , (8)
∫400 𝜑(𝜆)∙𝑉(𝜆)∙𝑑𝜆
where h = 6,626 10–34 J·Hz-1 – Planck constant; с = 3·1017 nm/s – the speed of light in
vacuum; NA = 6,022·1023 mol-1; Km – the multiplier for day vision is equal to 683
lm/W; V(λ) – spectral luminous efficiency.
Thus, it becomes possible to estimate the radiation dose in volume when designing
irradiation installations.
3 Irradiation Installations
Ultraviolet radiation is known to have a wide range of effects on microorganisms,
including bacteria, viruses, spores and fungi.
UV radiation (UVR) is electromagnetic radiation that occupies the range between
visible and roentgen radiation, with a wavelength of λ from 400 to 10 nm. UVR is
divided into near (λ = 400-200 nm) and far, or vacuum 1, (λ = 200-10 nm) UVR. Ac-
cording to the biological effect, there are three sections of the near-UV spectrum: UV-
A-λ = 315-400 nm, UV-B-280-315 nm, and UV – C-200-280 nm. The biological effect
of UVR on λ = 315-390 nm is mainly tanning. UVR at λ = 280-400 nm in certain doses
is useful for the human body, animals and birds, having a so-called "vital" effect. UVR
in the UV-B range (280-315 nm) has an antimicrobial effect, and UVR in the UV-C
range (200-315 nm) is able to inactivate microorganisms. UVR at λ = 205-315 nm al-
ways produces a bactericidal effect, which consists in the absorption of UV photons by
DNA and RNA molecules. UV-C is often called bactericidal because of its effective-
ness against bacteria and viruses. [9]
Indoor air disinfection can be achieved by various methods, the most widely used of
which disinfection with bactericidal ultraviolet radiation (UVR) is using bactericidal
lamps. If the ventilation and air conditioning system has design or operational deficien-
cies, it can itself be a source of infection. Such irradiators are divided into two groups.
The first group includes the UV irradiators of open type, and the ultraviolet radiation
directly disinfects the air inside the room. Such irradiators are used in the absence of
people. The second group is a type of recirculation, in which ultraviolet radiation is
concentrated inside the chamber, through which a fan pumps the internal air, and the
purified air is injected back into the room. Bactericidal irradiators are integrated into
systems with forced ventilation and dust filters and as such belong to the second group
[9]. Open-type irradiation requires periodic rest of the room to be sanitized, or its use
during non-working hours (most often at night) [10].
Ceiling recirculators can be used for decontamination of premises. Ceiling recircu-
lators with germicidal lamps located perpendicular to the airflow have better technical,
microbiological and economic indicators than wall recirculators with germicidal lamps
located parallel to the airflow. For indoor air disinfection in the presence of people it
opens up prospects for creating more efficient industrial models of recirculators [11].
Traditionally produced in Russia, open irradiators are focused on the disinfection of
air and surfaces with the sanitary indicator microorganism Staphylococcus aureus. To
achieve a 99.9% degree of disinfection, therefore, the sanitary indicator microorganism
6 T. Meshkova, V. Budak
requires a dose of 6.9 MJ/cm2 bactericidal UV irradiation. To achieve the same degree
of disinfection (99.9 %) for other microorganisms, significantly higher doses of UV
radiation may be required [9].
However, it should be noted that the selection and effective use of UV recirculators
is a separate technological task. A simple example is a doctor's office, the volume of
the room is 50 m3, a recirculator with a capacity of 50 m3/h is installed, but not earlier
than an hour later, you can process all the air in the office, while in real life, 3-4 patients
can visit the office during this time. The multiplicity of air exchange with purified air
is a determining factor in achieving the necessary degree of disinfection [9]. Thus, the
main task facing developers of a powerful UV radiation source is to increase efficiency
in a given spectral range and increase it’s lifetime. The first problem is solved by se-
lecting the optimal filling and maintaining a certain thermal mode of operation of the
source; the second depends on the materials used in the source: their purity, heat re-
sistance, reliability, etc. At the first stage, the type and discharge conditions of the de-
veloped radiation sources are selected, then the optimal ratio of the source parameters
is selected depending on the requirements and operating conditions [12, 13].
Therefore, when modeling an effective bactericidal system, one of the important fac-
tors is also the correct calculation of air exchange in the volume to be cleaned.
4 Conclusion
In modern Domestic literature and regulatory documents on the use of bactericidal
radiation, some simplifications are allowed, which in some cases lead to significant
errors in the calculations of installations.
In an unmixed medium with a very high UV absorption coefficient (when bacteri-
cidal radiation is absorbed in the surface layer of the medium), the surface components
of the medium (including bacteria) will receive "excess" radiation, and the components
in the depth of the layer will receive a dose close to zero.
Unirradiated (optically removed from the radiation source) surfaces eventually be-
come infected and infect the treated masses.
At the same time, the design of irradiation plants is mainly focused on the imple-
mentation of standard values on the surface, while disinfection is important in the vol-
ume of air. Moreover, modern computer graphics programs do not allow you to calcu-
late the necessary parameters at each point in space.
However, due to the application of the local estimation method to the solution of the
global illumination equation, it became possible to obtain and analyze photon fluence
rate when modeling bactericidal systems.
It is also necessary to note the important role of air exchange in the cleaned volume
when modeling an effective irradiation system.
A similar approach can also be used to estimate greenhouse irradiation within the
plant layer.
Modeling of UV Disinfection Irradiation Installations Using Computer Graphics Programs 7
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