Abo Bibliothek: Guest
ICHMT DL Home Aktuelles Jahr Archive Vorstand International Centre for Heat and Mass Transfer


DOI: 10.1615/ICHMT.2008.CHT.1070
20 pages

Marcos Vera
Departmento de Ingeniería Térmica y de Fluidos, Universidad Carlos III de Madrid, 28911 Leganés, Spain

Amable Linan
Dept. de Motopropulsión y Termofluidodinámica, E.T.S.I. Aeronáuticos, Universidad Politécnica de Madrid, 28040 Madrid, Spain


Multilayered counterflow parallel plate heat exchangers are analyzed numerically and theoretically. The analysis, carried out for constant property fluids, assumes that the Prandtl and Peclet numbers of the flow are both large compared to unity, as typically occurs for most non-metallic liquids in applications. For simplicity, a hydrodynamically developed laminar flow is considered, and longitudinal conduction is neglected both in the fluid and in the plates.
The theoretical model for the bulk fluid, based on an eigenfunction expansion procedure, is solved by means of standard symbolic algebra packages. This leads to analytic expressions for the eigenfunctions in terms of Whittaker functions, which can then be used to evaluate the eigenvalues numerically.
In a second step, we present an asymptotic analysis of the thermal entrance region that provides the temperature distribution near the inlet. According to the local, near-inlet, solution, the dimensionless temperature grows along the plate as ξj, where ξ is the dimensionless distance from the inlet section, and the exponent, 0 < j < 1/3, depends only on k = (A2/A1)1/312)1/3(k2/k1), a lumped parameter defined in terms of the ratios of the wall velocity gradients, Ai, thermal diffusivities, αi, and thermal conductivities, ki, of the fluids entering, i = 1, and exiting, i = 2, the heat exchanger. Closed-form analytical expressions for the exponent j are given, which, together with order of magnitude estimates, lead to accurate estimations of the maximum temperature gradient (and therefore thermal stress) experienced by the separating plate.
Fully numerical simulations performed using standard finite-difference methods show very good agreement with the analytical results obtained from the global and local analyses, both for the bulk fluid and plate temperatures. This suggests the possibility of using the analytical solutions presented here as a benchmark problem for computational heat transfer codes.

ICHMT Digital Library

Bow shocks on a jet-like solid body shape. Thermal Sciences 2004, 2004. Pulsed, supersonic fuel jets - their characteristics and potential for improved diesel engine injection. PULSED, SUPERSONIC FUEL JETS - THEIR CHARACTERISTICS AND POTENTIAL FOR IMPROVED DIESEL ENGINE INJECTION
View of engine compartment components (left). Plots of temperature distributions in centreplane, forward of engine (right). CHT-04 - Advances in Computational Heat Transfer III, 2004. Devel... DEVELOPMENT AND CURRENT STATUS OF INDUSTRIAL THERMOFLUIDS CFD ANALYSIS
Pratt & Whitney's F-135 Joint Strike Fighter Engine under test in Florida is a 3600F class jet engine. TURBINE-09, 2009. Turbine airfoil leading edge stagnation aerodynamics and heat transfe... TURBINE AIRFOIL LEADING EDGE STAGNATION AERODYNAMICS AND HEAT TRANSFER - A REVIEW
Refractive index reconstructed field. (a) Second iteration. (b) Fourth iteration. Radiative Transfer - VI, 2010. Theoretical development for refractive index reconstruction from a radiative ... THEORETICAL DEVELOPMENT FOR REFRACTIVE INDEX RECONSTRUCTION FROM A RADIATIVE TRANSFER EQUATION-BASED ALGORITHM
Two inclusion test, four collimated sources. Radiative Transfer - VI, 2010. New developments in frequency domain optical tomography. Part II. Application with a L-BFGS associated to an inexa... NEW DEVELOPMENTS IN FREQUENCY DOMAIN OPTICAL TOMOGRAPHY. PART II. APPLICATION WITH A L-BFGS ASSOCIATED TO AN INEXACT LINE SEARCH