Development of a gas/liquid phase change actuator for high temperatures

ROBOMECH Journal, Jan 2016

Gas/liquid phase changes produce large volume changes in working fluids. These volume changes are used as the driving power sources in actuators such as micro-pumps and valves. Most of these actuators are utilized in ordinary temperature environments. However, the temperature range in which the phase change actuator can operate depends on the characteristics of the working fluid. We hypothesized that proper selection of the working fluid and the structure of the actuator can enable such actuators to be applied not only in ordinary environments but also in high temperature environments. Consequently, in this paper, we discuss the design and fabrication of a new gas/liquid phase change actuator for use in high temperature environments. Our proposed actuator consists of a bellow body, spring, heater, and working fluid. We used the Inconel super alloy, which is highly heat and corrosion resistant, for the bellow and moving parts of the actuator. For the working fluid, we prepared triethylene glycol, which has a boiling point of 287.3 °C and very low vapor pressure at ordinary temperature. As a result, our proposed actuator can be utilized in high temperature environments up to 300.0 °C. The results of several experiments conducted confirm that our proposed actuator generates 1.67 mm maximum displacement in a 300.0 °C atmospheric environment. In addition, we confirmed that the operation of the actuator is stable in that environment. Our results confirm that a gas/liquid phase change actuator can be used in high temperature environments.

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Development of a gas/liquid phase change actuator for high temperatures

Matsuoka et al. Robomech J Development of a gas/liquid phase change actuator for high temperatures Hiroki Matsuoka 0 Koichi Suzumori Takefumi Kanda 0 0 Okayama University , 3-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530 , Japan Gas/liquid phase changes produce large volume changes in working fluids. These volume changes are used as the driving power sources in actuators such as micro-pumps and valves. Most of these actuators are utilized in ordinary temperature environments. However, the temperature range in which the phase change actuator can operate depends on the characteristics of the working fluid. We hypothesized that proper selection of the working fluid and the structure of the actuator can enable such actuators to be applied not only in ordinary environments but also in high temperature environments. Consequently, in this paper, we discuss the design and fabrication of a new gas/ liquid phase change actuator for use in high temperature environments. Our proposed actuator consists of a bellow body, spring, heater, and working fluid. We used the Inconel super alloy, which is highly heat and corrosion resistant, for the bellow and moving parts of the actuator. For the working fluid, we prepared triethylene glycol, which has a boiling point of 287.3 °C and very low vapor pressure at ordinary temperature. As a result, our proposed actuator can be utilized in high temperature environments up to 300.0 °C. The results of several experiments conducted confirm that our proposed actuator generates 1.67 mm maximum displacement in a 300.0 °C atmospheric environment. In addition, we confirmed that the operation of the actuator is stable in that environment. Our results confirm that a gas/liquid phase change actuator can be used in high temperature environments. Actuator; Gas/liquid phase change; High temperature; Triethylene glycol; Bellow - Background Phase changes in materials, resulting from temperature changes, produce huge volume changes, especially in liquid/gas phase changes. This attribute is utilized to provide a power source for micro-pumps and valves in combination with MEMS (micro-electromechanical system) heaters, micro-channels, diaphragms, and membranes [1–10]. Kato et  al. used this phenomenon to provide a power source for actuators and robots. They made a metal bellow actuator to control cutting equipment and a pipe inspection robot [11, 12]. Phase change is used not only in actuators but also in some kinds of pressure sources. For example, Kitagawa et  al. used the triple point of carbon dioxide as a mobile pressure source [13], and Shibuya et  al. developed a buoyancy control device for underwater robots using paraffin oil [14]. The actuators described above were developed for use in ordinary environments. In contrast, our aim is to utilize these phase change actuators in special environments. In particular, driving actuators in high temperature environments is a typical example of the special environments being considered. For example, in the hydrothermal synthesis method, which is one of the methods used to fabricate piezoelectric devices, the water solution inside the high temperature chamber needs to be agitated [15]. In one instance where this process was used, the water solution was agitated using an autoclave—an end-overend shaker with heat. Fabrication of the (Pb, La)(Zr, Ti) O3 (PLZT) film took 24  h. Not only the rotation condition but also the attitude of the sample will affect the quality of the fabrication. The actuators, which produce the inclination of the shaker, are predictably effective devices. Another example is the fabrication process for the ferric oxide crystal via the floating-zone melting method [16]. © 2016 Matsuoka et al. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. In this process, the partially melted sample is turned and pulled inside the chamber for growth. Both the processes require 8–24  h and a single directional drive in order to fabricate the tiny sample. We believe that an actuator that can realize linear motion in high temperature environments can rectify these quality problems. In previous work, we targeted these environments for utilization of actuators and proposed gas/liquid phase change actuators. We subsequently fabricated an actuator driven by the gas/liquid phase change of water. This actuator consisted of a cylinder as a vessel and actuation device, an external heater to excite the phase change, and a spring that controlled the speed of motion. Our proposed actuator was driven in a 180  °C environment. Thus, we realized directional motion with gas/liquid phase changes in a high temperature envi (...truncated)


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Hiroki Matsuoka, Koichi Suzumori, Takefumi Kanda. Development of a gas/liquid phase change actuator for high temperatures, ROBOMECH Journal, 2016, pp. 1, 3, DOI: 10.1186/s40648-016-0041-7