ABSTRACT
This paper presents the experimental analysis of aluminum BPHX, with dimensions of 215 × 80 × 61 mm, having transversal offset strip fins with two pitches of 5 and 6.8 mm using liquid to liquid to measure the heat transfer and pressure drop performance in the Reynolds range of transitional to turbulent regime [103, 104]. Firstly, the heat exchangers were tested using water on both sides. A heat transfer and friction coefficients empirical correlations were determined, and the resulted functions were compared with two other models presented in the literature. Secondly, the heat exchangers were measured using water and engine oil as hot fluid.
Acknowledgments
This study was carried out with the help of Romanian Company of RAAL which supplied the BPHEs and testing facilities for this study. We also want to thank the University Politehnica of Timișoara for its documentation and know how support received.
Nomenclature
A – heat exchange surface (m2)
B – friction criterial equation coefficient
C – Nusselt criterial equation coefficient
Cmin, Cmax – heat capacity flow = ṁ cp (W/K)
cp – heat capacity of the stream (J/kgK)
Dh – hydraulic diameter (mm)
f – friction coefficient (Fanning)
Fp – pitch ratio
g – strip fin thickness (mm)
h – strip fin height (mm)
j – Colburn number
k – global heat transfer coefficient (W/m2K)
L – strip fin width (mm)
ṁ – mass flow (kg/s)
Nu – Nusselt number
NTU – number of thermal units
p – strip fin pitch (mm)
Pr – Prandtl number
Q̇ – heat transferred (W)
Q̇̅ – mean value
Re – Reynolds number
s – offset of the next strip (mm)
x – general variable in measurements
x̅ – mean value
α – convection coefficient (W/m2K)
ϵ – heat exchanger efficiency
λ – aluminum conductivity (W/mK)
μ – heat capacity flow ratio
σ – standard deviation of the population sample
σ’ – uncertainties in the measurement defined
Subscripts
c – cold stream
h – hot stream
i – index
min – minimum between two or more values
max – maximum between two or more values