Numerical methods for solving complex heat exchanger models in transient operation
Heat exchangers are important in many industrial systems. In order to maximize
heat transfer while fulfilling requirements to size and weight, it is crucial to have
good numerical tools available. Sintef has developed a modelling framework for
solving a variety of different heat exchangers in steady-state. This thesis contains
the work done to extend the framework with a transient solver. Dynamical aspects
of heat exchangers can not be investigated by steady-state solvers, and a transient
formulation is needed to explore these phenomena.
The transient formulation that has been attempted has proven to form a set of stiff
equations. The stiffness is related to the size of the control volumes used by the
solver. Furthermore, the transient solver is unable to solve a base case for the
reference heat exchanger that has been investigated. In order for the solution to
converge, the tube diameters need to be multiplied by a factor of 30. Increasing the
tube diameters does not only violate potential size requirements, but it also results
in a lower heat transfer. Thus, the transient formulation that is implemented is
not robust enough to solve compact heat exchangers.
Place, publisher, year, edition, pages
Institutt for fysikk , 2014. , 71 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-26980Local ID: ntnudaim:10996OAI: oai:DiVA.org:ntnu-26980DiVA: diva2:754708
Hansen, Alex, ProfessorSkaugen, Geir