Table 2.

Optimal combination of plasmonic nanoparticles for the desired spectral absorption coefficient of the nanofluid.

Particle type Index	Property	Uniform distribution	Solar-spectrum-like distribution	Step-function-like distribution
#1	Material	Silver	Gold	Silver
	Type	Core-shell	Core-shell	Core-shell
	Design	(73, 14)	(15, 11)	(86, 8)
	$f_i\times {10}^6$	1.053	0.544	3.870
	Peak [nm]	580	550	720
#2	Material	Silver	Silver	Silver
	Type	Core-shell	Nano-rod	Core-shell
	Design	(80, 9)	(16, 120)	(87, 5)
	$f_i\times {10}^6$	3.602	0.187	1.547
	Peak [nm]	670	380, 810	850
#3	Material	Gold	Silver	Gold
	Type	Nano-rod	Core-shell	Core-shell
	Design	(28, 181)	(49, 13)	(86, 6)
	$f_i\times {10}^6$	0.605	4.224	0.036
	Peak [nm]	510, 890	500, 690	810
#4	Material	Gold	Silver	Silver
	Type	Core-shell	Core-shell	Core-shell
	Design	(52, 12)	(88, 10)	(89, 7)
	$f_i\times {10}^6$	3.116	2.642	1.933
	Peak [nm]	610, 740	680	760
#5	Material	Gold	Silver	Gold
	Type	Core-shell	Core-shell	Core-shell
	Design	(83, 6)	(53, 7)	(46, 5)
	$f_i\times {10}^6$	1.298	0.970	0.599
	Peak [nm]	800, 1080	610, 820	860
#6	Material	Gold	Gold	Silver
	Type	Core-shell	Core-shell	Core-shell
	Design	(88, 5)	(87, 5)	(15, 70)
	$f_i\times {10}^6$	1.434	1.909	0.003
	Peak [nm]	860	860	400

The design variables are r for the nano-sphere, (r_c, t_s) for the core-shell, and (r_r, l_r) for the nano-rod.