N2 - The paper presents two analytical solutions namely for Fanning friction factor and for Nusselt number of fully developed laminar fluid flow in straight mini channels with rectangular cross-section. This type of channels is common in mini- and microchannel heat exchangers. Analytical formulae, both for velocity and temperature profiles, were obtained in the explicit form of two terms. The first term is an asymptotic solution of laminar flow between parallel plates. The second one is a rapidly convergent series. This series becomes zero as the cross-section aspect ratio goes to infinity. This clear mathematical form is also inherited by the formulae for friction factor and Nusselt number. As the boundary conditions for velocity and temperature profiles no-slip and peripherally constant temperature with axially constant heat flux were assumed (H1 type). The velocity profile is assumed to be independent of the temperature profile. The assumption of constant temperature at the channel’s perimeter is related to the asymptotic case of channel’s wall thermal resistance: infinite in the axial direction and zero in the peripheral one. It represents typical conditions in a minichannel heat exchanger made of metal.
L1 - http://www.journals.pan.pl/Content/94670/PDF/02_paper.pdf
L2 - http://www.journals.pan.pl/Content/94670
PY - 2014
IS - No 4 December
EP - 42
DO - 10.2478/aoter-2014-0031
KW - analytical solution
KW - heat transfer
KW - rectangular channel
KW - laminar flow fully developed
A1 - Mikielewicz, Jarosław
A1 - Rybiński, Witold
PB - The Committee of Thermodynamics and Combustion of the Polish Academy of Sciences and The Institute of Fluid-Flow Machinery Polish Academy of Sciences
DA - 2014
T1 - Analytical solutions of heat transfer for laminar flow in rectangular channels
SP - 29
UR - http://www.journals.pan.pl/dlibra/publication/edition/94670
T2 - Archives of Thermodynamics