ISO 23152:2021

INTERNATIONAL ISO
STANDARD 23152
First edition
2021-07
Ships and marine technology —
Ballast water management systems
(BWMS) — Computational physical
modelling and calculations on scaling
of UV reactors
Navires et technologie maritime — Systèmes de gestion de l'eau de
ballast (BWMS) — Modélisation physique computationnelle et calculs
concernant les réacteurs UV
Reference number
©
ISO 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General requirements . 6
4.1 General principle . 6
4.2 Modelling best practices . 6
5 Modelling and calculations . 6
5.1 General . 6
5.2 Geometric model . 7
5.3 Turbulence model . 7
5.4 Radiation model . 7
5.5 Calculation of the UV dose . 8
5.5.1 General. 8
5.5.2 Lagrangian particle tracking . 8
5.5.3 Eulerian reacting tracer . 8
5.6 Scaling procedure . 8
5.6.1 Main steps . 8
6 Scaling metrics.12
6.1 General principles .12
Annex A (informative) RED calculation .13
Annex B (normative) Verification of model using empirical data .16
Bibliography .18
Foreword
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iv © ISO 2021 – All rights reserved

Introduction
Ballast water management systems (BWMS) are intended to treat ships' ballast water discharges to
comply with applicable standards (Reference [14]). Disinfection using ultraviolet (UV) light is common
to many BWMS. A key specification for a given model of a BWMS is its treatment rated capacity (TRC),
which indicates the unit’s rated volumetric flow rate during treatment of ballast water. A base system
(with a low range TRC) is empirically validated through land-based testing, while a unit with a larger
TRC (ideally at the highest rating) is validated through shipboard testing. The remaining models that
are not empirically tested can be validated through scaling, using a verified numerical approach to
predict performance at untested TRCs.
Effective 13 October 2019, the type approval of BWMS (both UV and other technologies) requires
[11]
testing in accordance with the BWMS Code (MEPC 72/17/Add.1 Annex 5) , adopted as an amendment
to the IMO International Convention for the Control and Management of Ships’ Ballast Water and
[14]
Sediments, 2004 . The BWMS Code specifies that a manufacturer of BWMS must provide technical
specifications for any scaling of TRC. Guidance on scaling is provided by the IMO through its ‘Guidance
[12]
on Scaling of Ballast Water Management Systems’ (BWM.2/Circ. 33/Rev. 1) . One of the requirements
is for validation of the modelling and calculations through comparison of predicted performance to
land-based, shipboard, or laboratory test data as appropriate. In scaled models, parameters affecting
performance must demonstrate equivalence to the base model, identify system design limitations
(SDL) for each scaled model, and conduct shipboard testing of the most vulnerable model as determined
through scaling.
This document is focused on the modelling of UV reactors for scaling purposes, i.e. justifying the
applicability of a UV reactor design across a range of TRCs, through the use of validated numerical
models and calculations. Numerical models are used to solve equations governing physical
characteristics of a computational domain that represents a model of the physical object (i.e. the UV
reactor). This requires numerical representation of the geometry of this system, a discretization of the
representation into volumetric sub-elements (meshing), and solving for parameters for various scales.
Results are submitted to an Administration to justify the type approval of UV reactors having TRC
ratings that have not been validated through type approval testing.
INTERNATIONAL STANDARD ISO 23152:2021(E)
Ships and marine technology — Ballast water management
systems (BWMS) — Computational physical modelling and
calculations on scaling of UV reactors
1 Scope
This document specifies the methodology to conduct computational modelling of ultraviolet (UV)
reactor designs for ballast water management systems (BWMS) that incorporate ultraviolet
disinfection technology (UVBWMS). The computational modelling is used to calculate the UV reduction
equivalent dose (RED) and to compare calculated REDs of the scaled reactor to its base reactor. REDs
are determined using organisms with a given dose response.
NOTE The IMO requires validation of the computational model.
The simulation of a physical UV reactor using a computational model requires that the model be
validated (i.e. it performs as intended and reflects the correct physical constraints) and verified (i.e.
produces outputs consistent with empirical data). A model developed according to this document
is intended to validate the performance of simulated but untested, scaled UV reactors, where the
simulation has been verified with test data from base model UV reactors within the product line. As a
complete UV BWMS typically incorporates other treatment methodologies such as filters, the impact of
changes to external subsystem performance on the overall BWMS is not considered in this document.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
American Type Culture Collection
ATCC
repository of cell lines and cultured organisms used for research
3.2
base model
ultraviolet ballast water management system (UVBWMS) (3.30) model that has successfully completed
land-based testing as defined in the BWMS Code
Note 1 to entry: Typically, a base model is with low range TRC (3.28).
3.3
base reactor
UV reactor (3.41) of the base model (3.2)
3.4
biodosimetry
measurement of biological response as a proxy for UV dose (3.34)
3.5
computational fluid dynamics
CFD
numerical methods and algorithms to solve and analyse problems that involve fluid flows
3.6
detached eddy simulation
DES
computational simulation used to numerically solve the Navier-Stokes equations (3.17), using RANS
modelling (3.23) to solve small length scales
3.7
discrete ordinates modelling
DO modelling
development and use of mathematical models to numerically solve the radiative transfer equation (3.18)
by discretizing the volume domain and directional vectors
3.8
direct numerical simulation
DNS
computational simulation used to numerically solve the Navier-Stokes equations (3.17) at all length
scales
3.9
emission spectrum
relative power emitted by a lamp at different wavelengths
3.10
germicidal range
range of UV wavelengths responsible for microbial inactivation in water (200 nm to 300 nm)
3.11
large eddy simulation
LES
computational simulation used to numerically solve the Navier-Stokes equations (3.17), excluding small
length scales
3.12
low pressure UV lamp
LP
discharge lamp of the mercury vapour type, without a coating of phosphors, in which the partial
pressure of the vapour does not exceed 100 Pa during operation and which mainly produces ultraviolet
radiation of 253,7 nm
3.13
medium pressure UV lamp
MP
medium pressure mercury arc lamp having a polychromatic emission spectrum (3.9) between 200 nm
and
...