Heat Transfer Handbook part 102. 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. | 1006 HEAT TRANSFER IN ELECTRONIC EQUIPMENT In all 12 heat sinks studied the vertical-vertical orientation that is a vertically oriented base with vertical fins and channels yielded the highest heat transfer coefficients most often. However in a relatively large number of situations the thermal performance of the vertical-vertical arrays was indistinguishable from that attained by a vertical base plate with fins rotated 30 from the axis a horizontal base plate and a base plate inclined 60 from the horizontal with unrotated fins. On the other hand vetical-horizontal orientation that is the base plate vertical and the fins rotated 90 from the axis led to the lowest heat dissipation rates. For the unrotated fins the lowest heat transfer coefficients were almost always found to occur at a base plate angle of 30 from the horizontal. The use of smoke revealed a relatively complex threedimensional flow pattern around the heat sinks with very substantial inflow from the direction of the fin tips when the base plate was strongly inclined and when the heat sinks were in the vertical base-horizontal fins orientation. The influence of the spacing z between the fins for short and tong base plates was examined by comparing pairs of heat sinks that differed only in geometric parameters z fin arrays 1 and 4 2 and 5 3 and 6 7 and 10 8 and 11 and 9 and 12 in Table . Bilitzky 1986 observed that in nearly all the configurations and operating conditions examined the highest heat transfer coefficients were attained with the larger fin spacing. However the improvement in the heat transfer coefficient was not always sufficient to compensate for the loss of wetted fin surface area. Moreover for the horizontal base plate configurations as well as for the vertical base with horizontal fins the total array dissipation appeared not to depend on this parameter. PHASE-CHANGE PHENOMENA Heat Pipes and Vapor Chambers Among the various available cooling techniques the use of heat .
