Modeling of Hydrogen-Peroxide Films for Aseptic Processing Applications- A Parameter Study on Hydrogen-Peroxide Exposure to Internal Surfaces of mm-wide Slits
Ladda ner
Typ
Examensarbete för masterexamen
Program
Innovative and sustainable chemical engineering (MPISC), MSc
Publicerad
2019
Författare
Eriksson, Jesper
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Disinfection methods are used within many fields to keep equipment and environments
free from harmful biological agents such as fungi, bacteria, viruses and spore
forms. Within the food and drug industry, aseptic processing refers to a process
chain in which sterilized products are filled into sterilized containers. Aseptic processing
brings benefits such as improved quality and increased shelf life of a product,
which in turn leads to less waste due to the expiration of products. The benefits of
aseptic processing introduce a demand for the development of effective disinfection
methods.
A common chemical disinfection method is the usage of hydrogen-peroxide to kill
bacteria. One way to perform hydrogen-peroxide disinfection is to spray a vapor
containing air, water and hydrogen-peroxide which is allowed to condense on cold
surfaces forming a liquid film of water and hydrogen-peroxide which conducts the
desired bacteria killing. It is important that all surfaces have been exposed to a
hydrogen-peroxide film to ensure a rapid disinfection. This project aims to investigate
the process of hydrogen-peroxide film condensation to evaluate the degree
of liquid film coverage and gas hydrogen-peroxide exposure within mm-wide slits.
The investigation was carried out using Computational Fluid Dynamics (CFD). The
process of hydrogen-peroxide gas disinfection is well understood, but the process of
liquid film formation and dynamics is more complex and many challenges remain
within this field. In particular, there are no previous studies investigating film formation
within small slits.
A parameter study was performed to evaluate how the characteristic width of a slit
h and the external gas flow velocity v influence the degree of liquid film coverage
on the inside surfaces of a slit. The results suggest that the critical value of h as a
function of v to ensure full surface film coverage follow hcrit(v) = 6.44v−0.2838−1.84,
which is valid within the range v = [0.5, 2.0]. Expressed in terms of the dimensionless
mass transfer Péclet number Peh, the criteria for full surface film coverage is
according to the results Peh > 97. The results remove the need of having a high
spatial resolution around mm-narrow spaces. Instead the developed macro-scale
model can be used to predict the degree of hydrogen-peroxide exposure within the
slit only with the knowledge of gas velocity external to the slit.
Beskrivning
Ämne/nyckelord
hydrogen-peroxide, aseptic, disinfection, film, condensation, model, dropwise, CFD, slit