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Fig. 6. Dependency of the combined thermal geometrical parameter

A

on finning

paramemeters at

β

= 30

and Bi = 0.04 (see legends in Fig. 5)

Fig. 7. Dependency of the convective component of the efficiency criterion

K

Q

0

on

the flow mode for various fins crossing angles:

β

= 20

; —

β

= 30

;

N

β

= 45

cross finning. Within this framework, the energy efficiency of CC for LRE

chamber cooling was estimated, both numerically and analytically.

The coplanar channel efficiency with regard to the convective component

K

Q

0

(at

β >

30

, Fig. 7) reaches considerable values (from 1.5 to 4 and

more), with the thermal geometric parameter

A

being no lower than unity

within the investigated range, this can mean that the coplanar flow has a

positive cooling effect in the whole recommended range of Re numbers.

However, there is no efficiency at

β <

30

.

The final results of the efficiency estimation by the criterion

K

Q

confirm

these expectations. It was also found out that the decisive factor for the

efficiency is determined by the fins crossing angle

β

and the finning Biot

number. Thus, when the angle

β

increases from 30

to 40

,

K

Q

increases

ISSN 0236-3941. HERALD of the BMSTU. Series Mechanical Engineering. 2015. No. 2 51