tailieunhanh - Heat Transfer Handbook part 53

Heat Transfer Handbook part 53. The Heat Transfer Handbook provides succinct hard data, formulas, and specifications for the critical aspects of heat transfer, offering a reliable, hands-on resource for solving day-to-day issues across a variety of applications. | 512 FORCED CONVECTION EXTERNAL FLOWS b - Re Uct Ref - v The parameter a is the aspect ratio. a s W where W is the strip width. Flush-mounted heat sources Section NU - 53 V kL V 0 s kfJ For the rectangular patch Nu - 2 pg x 2xs is 2 A 2 P 0 07 2xs J 2A J Here Nu is as defined for the two-dimensional strip _ U0 sx se Pec -------------- a A P is the source surface area perimeter ratio. The foregoing correlations are valid for 103 Pec 105 5 Xs s 2 150 Ws 5 - 4 is In the foregoing ws is the heat source height Pi its length and Pw its width. The channel width is W 12 mm and the height H can vary from 7 to 30 mm. The heat source dimensions covered in the experiments are Pf 12 mm Ph 4 8 and 12 mm H Ph 3 8 and 12 mm and Ps 12 mm. Isolated blocks Section Nu - 612 A -0 455 where Nu - h Pt k h is the average heat transfer coefficient aad As is the heat transfer area As - 2PhPw PP 2PhPt Ts is the average surface temperature and T is the stream temperature. The Reynolds number is denned as Re UDh v where U is the average channel SUMMARY OF HEAT TRANSFER CORRELATIONS 513 velocity upstream of the heat source DH is the channel hydraulic diameter at a section unobstructed by the heat source and v is the fluid air kinematic viscosity. The fraction of the channel open to flow is A 1 Pw W Ph H Equation is valid for 15QQ Re 1Q4 Pt W H Pt A realistic error bound is 5 . Block array Section Nup where the characteristic length for both Nu and Re is the streamwise length of the block Pt. Pin fin heat sinks Section Two correlations are given Nu x 10 C L 0 223 p 1 72 where in Ca PL3 Ap p is the dynamic viscosity of the air. Equation was derived from the data for 5 x 106 CAp x 108 Nu x 10-6C0 W2 0 205 j 0 89 where r P2 LPw CPW Ll3 covers a range of 1011 to 1013. Single round submerged jet impinging on an .