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Nanotechnology and Performance Development of Cutting Fluids
Published in Girma Biresaw, K.L. Mittal, Surfactants in Tribology, 2017
Nadia G. Kandile, David R. K. Harding, Girma Biresaw, K.L. Mittal
A comparator is a device that compares two voltages or currents and produces a signal indicating which is larger. The concept is based on a single point of contact with the sample being assessed for its thermal conductivity. The transfer of heat from the hot material to the cold is very quickly measured by such a device. The temperature difference between the probe tip and a reference in the heated probe is measured with a thermocouple. The probe (Figure 6.16a) is copper. The heater compensates for heat loss from the probe and allows for a constant temperature difference between sample and probe. The probe and sample material are connected by a constantan thermocouple. The constantan wire is made from a copper–nickel alloy usually consisting of 55% copper and 45% nickel and has constant resistivity over a wide range of temperatures.
Nanotubes, Nanowires, and Nanofibers
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Recently, the fabrication of foil strain gauge comprising of CNT yarns was reported [159,160]. Metallic foil strain gauge sensors comprise of a piezoresistive membrane layer attached to a flexible substrate. The commonly used metallic component is constantan, an alloy of Cu (55%–60%) and Ni (45%–40%). Constantan has a low temperature coefficient suitable for resistance coils and a constant resistivity over a wide range of temperature. They are highly piezoresistive. The flexible substrate acts as a compliant structure that translates an input force into localized strain in the piezoresistive layer so that changes in electrical resistivity can be monitored and correlated to strain using the piezoresistivity effect. The strain in the piezoresistive layer can be electrically transduced by connecting to a Wheatstone bridge to improve the sensors’ sensitivity and compensate undesirable temperature effects. Metallic foil strain gauges can capture very low fluctuations of strain with a maximum range of about 5% [15,18] while semiconductor strain gauges have higher gauge factors than metallic strain gauges. However, semiconductor strain gauges are sensitive to temperature limiting their efficiency. These piezoresistive strain gauges cannot detect initiating damage in composite materials with high compaction or multifaceted construction. There is also a form factor where these strain gauges can only be applied either on the surface or lack the aspect ratio to be integrated into complex structural components. More critically, they fail to achieve damage detection without altering the microstructure of the composite material.
Foundations of Heat Transfer
Published in Sadık Kakaç, Yaman Yener, Carolina P. Naveira-Cotta, Heat Conduction, 2018
Sadık Kakaç, Yaman Yener, Carolina P. Naveira-Cotta
For pure crystalline metals, the ratio of the thermal conductivity k to electrical conductivity ke is found to be nearly proportional to the absolute temperature. A modified Lorenz equation expressing this relation is k/ke = 783 × 10–9T, where T is in°R [14]. This equation does not hold for amorphous materials or alloys of metals. Thermal conductivities of alloys may be less than that of any constituent; for example, constantan is an alloy of 55% copper (Cu) and 45% nickel (Ni) and has k = 23 W/(m·K), while for pure copper k = 401 W/(m·K) and for nickel k = 90.7 W/(m·K). Thermal conductivities of selected typical solids are given in Appendix A.
A flow-rate-controlled double-nozzles approach for electrochemical additive manufacturing
Published in Virtual and Physical Prototyping, 2022
Yawen Guo, Pengpeng Liu, Pengfei Jiang, Yongshuai Hua, Kaiyuan Shi, Hui Zheng, Yabin Yang
For a standard Cu-Constantan thermocouple, the copper and nickel compositions in the CuNi alloy leg are 55% Cu and 45% Ni. Hence for the proposed double-nozzles ECAM system, we first analyzed how the compositions of the copper and nickel in the codeposited CuNi alloy vary with the applied potential. The weight percent (wt.%) of the copper and nickel in the deposited alloy as a function of the applied potential and corresponding current density are plotted in Figure 13(a). It is found that when the applied potential is higher than −2 V, no nickel is deposited and 100% pure copper is obtained. When the potential is lower than −2 V, with the decreasing potential more nickel is deposited with less copper. When the potential is −8 V, the mass fraction ratio of Ni: Cu reaches 7:3. Figure 13(b) shows the printed CuNi alloy line under the potential of −8 V. The corresponding current density is ∼20.5 A/dm2. The presence of copper and nickel was further confirmed by using the Energy-dispersive X-ray spectroscopy (EDX) element mapping testing a small region of the printed line. Even distribution of the elements of copper and nickel can be observed in Figure 13(c, d). The hardness of the printed CuNi alloy was also measured using the nanoindentation, and the hardness is ∼3.7 GPa. Typical force-displacement curve of the nanoindentation for the printed copper and CuNi alloy are shown in Fig. S14 in the supplementary information (Section 6.2).
Dynamic Simulation and Operating Characteristics of Ground-Coupled Heat Pump with Solar Seasonal Heat Storage System
Published in Heat Transfer Engineering, 2020
Chao Lyu, Wey H. Leong, Maoyu Zheng, Ping Jiang, Feng Yu, Yueqin Liu
References [10,11] had detailedly introduced a demonstration project of GCHP with the SSHS system for heating and cooling in the severe cold zone. Figure 1 shows the schematic diagram of the system. It had operated successfully for many years, and field data of 3 years were collected and analyzed, including annual cycles of heat storage, heating, and cooling. The system was built in Harbin (45°45′N, 126°39′E), China. The total heating/cooling area is 500 m2. The annual heating and cooling load are 142.11 and 4.43 GJ, respectively. The heat loss index of the house is 19.9 W/m2. The house is used as a residence, so the people and equipment are few, as well as the heat. Radiant floors were used as heating and cooling terminals. The rated input power of the heat pump (HP) is 3.7 kW. High-efficiency flat plate solar thermal collectors were used, with a total area of 50 m2. The VGHE consists of 12 vertical single U-tubes. They are installed below the house with a length of 50 m each and are located about 4.2 m apart from each other. The 12 U-tubes are divided into two groups of six U-tubes each. In the summer, one group (VGHE1) is used to store solar heat, while another group (VGHE2) cools the house. The soil’s density is 2350 kg/m3, thermal conductivity is 1.82 W/(m K), and specific heat is 949 J/(kg K). The copper-constantan thermocouple was used for the temperature measurement, and the accuracy of the calibration temperature is ± 0.1 °C.
Moisture transfer and stress development during high-temperature drying of Chinese fir
Published in Drying Technology, 2020
Fan Zhou, Zongying Fu, Yongdong Zhou, Jingyao Zhao, Xin Gao, Jinghui Jiang
The MC was determined using the oven-dry method. After drying to the pre-estimated MC of 40–30%, 30–20%, 20–10% and 10–0%, the sample boards were taken out from the kiln and sawed for three moisture determination slices in longitudinal direction. Out of these, one with 10 mm in thickness was used for determining the MC of the sample board and two with 15 mm in thickness were used for evaluating the MC at different layers and for NMR test. The drying temperature in the sample board was monitored using six T-type temperature sensors (thermocouple copper/constantan). Out of these, one was placed on the surface of the sample board to determine the wood surface temperature and five were placed in the inner parts of the sample board to determine the drying temperatures along the thickness direction. The schematic diagram of the temperature sensor arrangement is shown in Figure 1.