| In information society, computers are used widely in every walk of life.Components of computer, which is designed to improve computers' performanceand application circumstance, are attached much importance by computermanufactures and users. With the improvements of computers' calculationcapabilities, the design of chip radiator has become a bottle-neck for thedevelopment of computer chips. Existing chip radiator systems get rid of heatfrom chip by fans, which force an air convection. The disadvantages of suchsystem are obvious. Firstly, radiating capacity is very limited. Secondly, the sizeof radiator is restricted by the inner configuration of computer. Finally the noiseof fan is loud. Aiming at this problem, the main computer manufactures andacademies propose many solutions.On the base of analyzing all kinds of solutions to radiators, this paper chosemacro-pipelined water-cooling system driven by piezoelectric (PZT) pump todesign water-cooling system. The creative point of this system is the design ofsingle antrum PZT pump, which has double diaphragms. The optimal workingfrequency of this pump is low. The system can run with the daily power supplywhose voltage is 220V and frequency is 50HZ, and it can provide a satisfyingresult. This paper is composed of four major pars.1, The test of existing radiators for computer chips.The earlier stage work of this paper is testing the existing radiators forcomputer chips. The experiments were done on the simulative radiatorwhich is maken by us. The tested products are the water cooler king ofAucma and fan -cooled radiator for Pentium 4, which are leading productsin market. In experiments, we found that water –cooled radiator can providebetter performance in average heat radiation time and temperature. Whenthe discharge of pump is more than 200ml, it has little influence on heatradiation capability of water–cooled system. The existing water –cooledradiators generally adopt immersion pump or centrifugal pump whosevolumes are big, so it has to be fixed outside the computer. However, thiskind of radiator is expensive, which hinders the generalization of it.2, An analysis of key factors which have an influence on the performanceof piezoelectric pump.PZT pump changes its antrum volume by inverse piezoelectric effect ofthe PZT diaphragm, and with the help of one way valve, fluid can bepumped toward one direction. Because of its characters of small bulk,silence, low energy consumption, and high output capability, PZT pump isselected as the driven component of computer water-cooling system. Thestudents and professors of Jilin University's PZT Lab have been engaged inthe development of PZT products, so they have rich experience. On the baseof their achievements, we build water-cooled system model by analyzingstructural parameters, which affect the system's performance. And theexperiments are done to analyze the factors that have an influence on PZTpump.Piezoelectric diaphragm, which can be produced by sticking PZT chipon a round copperplate, will produce mechanical deformation with theelectric signal. In this paper, the basic knowledge of pressure is introduced.The parameters and characteristics of piezoelectric diaphragm which is usedin experiments, is also presented. Different wave signals have differentinfluence on PZT diaphragm's deformation, so we do experiments withvarious signals. According to the distortion of PZT diaphragm's center, thecalculations of discharge and pressure in theory are explained.Valve is one of factors have impacts on the performance of PZT pump.In this paper, umbellate rubber valve is adopted, which has low criticalvoltage, good counter cut-off performance and fast response speed, so it canbe used in higher frequency. Based on hydrodynamics, the model of rubbervalve is established. At the same time, the expression of PZT pump'sdischarge and the equation of rubber valve's working state are introduced.The relationship between PZT diaphragm's distortion and valve's turn-onaltitude and delay is analyzed. The valve's configuration is meliorated toimprove PZT pump's performance.Because the change of it is so small, the antrum's cubage has a vitalinfluence on PZT pump. In experiments, it is found that a reasonableantrum's cubage can not only improve PZT pump's performance in lowerfrequency, but also enhance its own abilities of absorption and air bladderresist.Working in low frequency, PZT pump and liquid can produce resonance;while in high frequency, PZT diaphragm may be very noisy. Based on theanalysis of the reason why PZT pump make so much noise, a solution to itis proposed in this paper.The design of PZT pump's configuration.On the base of the work mentioned above, PZT pump of double antrum andsingle antrum PZT pump of double diaphragms is designed. Although PZT pumpof double antrum has larger discharge and more pressure, its optimal workingfrequency is relative high. So it must be equipped with special power supply,which not only needs larger space, but also increase cost. On the other hand,single antrum PZT pump of double diaphragm has smaller volume and compactconfiguration. What's more, its optimal working frequency is about 50Hz. Whenthe voltage is 220V, its output discharge is 560ml/min, and output pressure can upto 26KPa. So it is selected as driver of water-cooled system for computer chips.The test of water-cooled system for computer chipsBased on the sum-up of the theories and experiments, a compositive water-cooledsystem for computer chips is designed to accelerate the process of generalizingwater-cooled system which is driven by PZT pumps. In order to guarantee theperformance of the water-cooled system, we optimize the collocation of innercomponents, and do experiments with single antrum PZT pump of doublediaphragm. Working under the same circumstance, water-cooling system drivenby P ZT pump is much more efficient than fan-cooling system. When heatingpower is 60W and system reaches thermal steady state, the temperature ofsimulative heater cooled by water-cooling system is lower than that cooled byfan-cooling system by 13 ℃. And it takes water-cooling system less time toreach thermal steady state, this time difference is about 15 minutes.The size of water-cooling system is as much as that of CD-ROM, so it canbe fixed in computer. Single antrum PZT pump of double diaphragms, which isused as a driver for water-cooling system, has simple configuration and satisfyingoutput. The water-cooling system presented in this paper, is designed forcomputer chips. It is an effective, applied, and silent system, which has certainapplication value on market. |
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