Investigation on cross-flow three-fluid compact heat exchanger under flow non-uniformity: an experimental study with ANN prediction

ABSTRACT

Non-uniformity in flow is the veritable situation in the case of heat exchangers and a decisive aspect of the design of heat exchangers. The extensive experimental investigation is ushered for compact three-fluid heat exchanger with cross-flow configuration under three distinct flow non-uniformities at the inlet of central fluid. The maximum augmentation of 3.4% in cooling efficacy is marked for ${\mathrm{C}}_1$ and ${\mathrm{C}}_2$ configuration under $\mathrm{F}{\mathrm{N}}_3$ (flow non-uniformity type 3) condition. Artificial neural network (ANN) prognosis is perpetrated and the thermo-hydraulic efficacy is more accurately predicted by ANN configuration 3-4-4 under flow non-uniformity with an absolute fraction of variance almost equal to one.

KEYWORDS:

• Thermo-hydraulic performance three-fluid heat exchanger
• artificial neural network
• flow non-uniformity
• cross-flow
• steady-state
• experimental investigation

Nomenclature

A	=	Area, ${\mathrm{m}}^2$
${\mathit{\text{c}}}_{\mathit{\text{p}}}$	=	Specific heat at constant pressure, J/kgK
${\text{C}}_1,{\text{C}}_2,{\text{C}}_3{\text{and C}}_4$	=	Cross flow arrangements
${\mathit{\text{D}}}_{\mathit{\text{h}}}$	=	$\frac{4\mathrm{X}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{i}\mathrm{m}\mathrm{u}\mathrm{m}\mathrm{f}\mathrm{l}\mathrm{o}\mathrm{w}\mathrm{a}\mathrm{r}\mathrm{e}\mathrm{a}}{\mathrm{t}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}\mathrm{h}\mathrm{e}\mathrm{a}\mathrm{t}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{n}\mathrm{s}\mathrm{f}\mathrm{e}\mathrm{r}\mathrm{a}\mathrm{r}\mathrm{e}\mathrm{a}\mathrm{p}\mathrm{e}\mathrm{r}\mathrm{u}\mathrm{n}\mathrm{i}\mathrm{t}\mathrm{l}\mathrm{e}\mathrm{n}\mathrm{g}\mathrm{t}\mathrm{h}}$, Hydraulic diameter, m
$E_{ab}$	=	$\frac{{\left(\mathrm{m}\mathrm{c}\right)}_{\mathrm{a}}}{{\left(\mathrm{m}\mathrm{c}\right)}_{\mathrm{b}}}$
$E_{cb}$	=	$\frac{{\left(\mathrm{m}\mathrm{c}\right)}_{\mathrm{c}}}{{\left(\mathrm{m}\mathrm{c}\right)}_{\mathrm{b}}}$
H	=	Height of the fin, m
$h_f$	=	=H-${\mathrm{t}}_{\mathrm{f}}$, m
h	=	Average or uniform case heat transfer coefficient, W/${\mathrm{m}}^2$-K
L	=	Flow length, m
m	=	Mass flow rate, kg/s
${\mathit{\text{m}}}^{\mathit{\text{lpm}}}$	=	Volume flow rate, lpm
${\mathit{\text{n}}}_{\mathit{\text{f}}}$	=	Fin frequency, fins/m
NTU	=	$\frac{{\left(\mathrm{U}\mathrm{A}\right)}_{\mathrm{a}\mathrm{b}}}{{\mathrm{C}}_{\mathrm{m}\mathrm{i}\mathrm{n}}}$,Number of transfer units
$\mathrm{\Delta }\mathrm{P}$	=	Pressure drop, Pa
${\mathit{\text{R}}}_{\text{ab}}$	=	$\frac{{\left(\eta \mathrm{h}\mathrm{A}\right)}_{\mathrm{a}}}{{\left(\eta \mathrm{h}\mathrm{A}\right)}_{\mathrm{b}}}$, Conduction ratio between fluid ‘a’ and ‘b’
${\mathit{\text{R}}}_{\text{cb}}$	=	$\frac{{\left(\eta \mathrm{h}\mathrm{A}\right)}_{\mathrm{c}}}{{\left(\eta \mathrm{h}\mathrm{A}\right)}_{\mathrm{b}}}$, Conduction ratio between fluid ‘c’ and ‘b’
Re	=	Reynolds number
${\mathit{\text{s}}}_{\mathit{\text{f}}}$	=	1/${\mathrm{n}}_{\mathrm{f}}$ - ${\mathrm{t}}_{\mathrm{f}}$, m
T	=	Temperature, ℃
${\mathrm{t}}_{\mathrm{f}}$	=	Fin thickness, m
${\mathrm{U}}_{\mathrm{n}}$	=	Uncertainty
${\mathrm{V}}_{\mathrm{a},\mathrm{b},\mathrm{c}}$	=	$\frac{{\left({\mathrm{A}}_{\mathrm{c}}\mathrm{L}\rho \mathrm{c}\right)}_{\mathrm{a},\mathrm{b},\mathrm{c}}}{{\left(\mathrm{M}\mathrm{c}\right)}_{\mathrm{w}}}$, Capacitance ratio
Greek letters	=
η	=	Overall surface efficiency
$\mu$	=	Dynamic viscosity, Pa.s
$?$	=	Density, $\mathrm{k}\mathrm{g}/{\mathrm{m}}^3$
$t$	=	Deterioration factor
Abbreviations	=
ANN	=	Artificial neural network
FA	=	Flow arrangement
FN	=	Flow non-uniformity
MRE	=	Maximum relative error
MSE	=	Mean square error
RE	=	Relative error
SS	=	Stainless steel
3-FHE	=	Three fluid heat exchanger
3-FCHE	=	Three fluid compact heat exchanger
Subscripts	=
a,b and c	=	Fluid a, b and c
exp	=	Experimental
ff	=	Free flow area
HT	=	Heat transfer
in and ex	=	Inlet and exit
min and max	=	Minimum and maximum
prd	=	Predicted
w	=	wall
Superscripts	=
exp	=	Experimental
fp	=	Finned passage
lpm	=	Litre per minute
prd	=	Predicted
wfp	=	Without fin passage

Acknowledgments

The authors are grateful for the financial support from Science & Engineering Research Board, Department of Science & Technology, Government of India.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors have no funding to report.