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首页> 外文期刊>Proceedings of the Royal Society. Mathematical, physical and engineering sciences >Measuring bubble nucleation temperature on the surface of a rapidly heated thermal ink-jet heater immersed in a pool of water
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Measuring bubble nucleation temperature on the surface of a rapidly heated thermal ink-jet heater immersed in a pool of water

机译：测量浸入水池中的快速加热的热喷墨加热器表面上的气泡成核温度

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摘要

We describe a method for measuring the average surface temperature of a small square thin metallic film deposited on a silicon substrate and immersed in subcooled water during a voltage pulse of short duration. The thin film studied is a material used in the current generation of commercial 'desk-jet' printers and comprises a mixture of tantalum and aluminium 65 #mu#m wide and 0.2 #mu#m thick. The experiment uses a bridge circuit with a dynamic amplifier design to measure the evolution of electrical resistance, coupled with a separate calibration of the thin film resistor element with temperature to determine average surface temperature. Voltage pulses of 5 #mu#s typical duration are applied to the thin films. An 'inflection' point in the resulting evolution of heater surface temperature identifies bubble nucleation. The calibration of the heater resistance with temperature showed a hysteresis effect that required a burn-in process to stabilize the electrical resistance. With the calibration curve obtained, resistance was converted to temperature and the results analysed. For low power input the average surface temperature exhibited an oscillatory behaviour which indicated a cyclic growth/collapse process often found in nucleate boiling. At higher powers, the oscillatory behaviour disappeared and gave way to an exponential variation of temperature with time similar to a lumped capacitance behaviour of a thermal system. An inflection point in the evolution of surface temperature was found that signified bubble nucleation. The largest heating rate and highest nucleation temperature measured were 0.25 * 10~9 deg C s~(-1) and 556 K, respectively. This temperature is in good agreement with homogeneous nucleation theory as applied to a surface. The contact angles needed for measured nucleation temperatures to agree with predictions are within the range that is typical for water on metallic surfaces.
机译：我们描述了一种测量短时电压脉冲期间沉积在硅基板上并浸入过冷水中的小方形金属薄膜的平均表面温度的方法。研究的薄膜是当前一代商用“台式喷墨”打印机中使用的材料，它包含钽和铝的混合物，铝和铝的混合物为65＃mu＃m宽和0.2＃mu＃m厚。该实验使用具有动态放大器设计的桥式电路来测量电阻的演变，并通过温度对薄膜电阻器元件进行单独校准，以确定平均表面温度。将典型持续时间为5＃μs的电压脉冲施加到薄膜上。加热器表面温度的最终变化中的“拐点”表明气泡成核。加热器电阻随温度的校准显示出滞后效应，需要进行老化过程才能稳定电阻。根据获得的校准曲线，将电阻转换为温度并分析结果。对于低功率输入，平均表面温度表现出振荡行为，这表明经常在成核沸腾中发现周期性的生长/塌陷过程。在更高的功率下，振荡行为消失了，并让温度随时间呈指数变化，这类似于热系统的集总电容行为。发现表面温度演变中的拐点表明气泡成核。测得的最大加热速率和最高成核温度分别为0.25 * 10〜9℃s〜（-1）和556K。该温度与应用于表面的均相成核理论高度吻合。测得的成核温度与预测值所需的接触角在金属表面水的典型范围内。

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