In this study experimental tests are conducted to investigate an improved CPL design for high power density CPU cooling. The evaporator of the CPL is improved by using pin fins to form the grooved channels, heat spreader, and roughing the vertical and bottom surfaces of the grooved channels. The effects of the liquid inventory and the relative height between the condenser and evaporator on the performance of the CPL with the improved designs for its evaporator have been examined in detail. The major results obtained here can be briefly summarized as follows:
(1) An optimal liquid inventory exists at which Qe,max is the highest and Rth is the lowest for a given relative condenser-evaporator height for the CPL with a given evaporator design. Moreover, increasing or decreasing the liquid inventory from this optimal value causes a reduction in Qe,max and a raise in Rth.
(2) An increase in the relative height between the condenser and evaporator results in a significant improvement in the CPL performance with a much higher Qe,max and a much lower Rth.
(3) There is no noticeable enhancement in the heat transfer performance of CPL by using a pin fin block to form the grooved channels.
(4) The use of a large heat spreader in the evaporator can greatly enhance the heat transfer performance of the CPL. The maximum enhancement is nearly 100% in the tested conditions.
(5) Roughing the vertical and bottom surfaces of the grooved channels can also noticeably enhance the heat transfer performance of the CPL.
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