The capric acid (CA)/diatomite (DT)/carbon nanotube (CNT) ternary system was investigated to develop a shape-stabilized composite phase change material for thermal energy storage via the direct impregnation method. DT was used as the supporting material to absorb CA and prevent its leakage. It was found that good form stability could be obtained when the loading of capric acid in the CA/DT composite reached about 54%. Furthermore, CNTs were added into the CA/DT form-stable phase change material (FSPCM) to enhance the thermal conductivity of the binary system. Moreover, the X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy analyses were carried out to characterize the microstructure and chemical properties of the composite PCM. The thermal properties of the prepared form-stable phase change materials (FSPCMs) were determined using differential scanning calorimetry (DSC) and thermogravimetric analyses. The analysis results showed that the components of the FSPCMs were in good compatibility and CA is well-infiltrated into the structure of the DT/CNT matrix. DSC analysis indicated that the latent heat of fusion of the ternary system was 79.09 J g^–1 with a peak melting temperature of 31.38 °C. The thermal conductivity of the CA/DT/CNTs increased from 0.15 to 0.48 W m^–1 K^–1, with only 7 wt % of CNTs. It is shown that the thermal conductivity of the ternary system was greatly enhanced by the addition of CNTs. The thermal conductivity increased by 1.56 times compared to that of the binary system. Moreover, the enhancing mechanisms of heat conduction transfer by CNTs were revealed by taking advantage of energy wave theory.

Capric acid (CA) is one of the most promising phase change materials to be used in reducing the energy consumption of buildings due to its suitable phase change temperature and high latent heat. In this paper, a novel shape-stabilized phase change material (SSPCM) is fabricated by “hazardous waste” fly ash (FA) via simple impregnation method along with CA and carbon nanotubes (CNTs). In this composite, raw FA without any modification serves as the carrier matrix to improve structural strength and overcome the drawback of the leakage of liquid CA. Simultaneously, CNTs act as an additive to increase the thermal conductivity of composites. The results of leakage tests indicate that CA was successfully confined as 20 wt % in the composite. Then, various characterization techniques were adopted to investigate the structure and properties of the prepared SSPCM of CA/FA/CNT. Scanning electron microscopy and Fourier transform infrared spectroscopy results showed that CA was well adsorbed into the microstructure of FA, and there was no chemical interaction between the components of the composites. Thermogravimetric analysis results demonstrated that the SSPCM presented good thermal stability. Differential scanning calorimetry results indicated that the melting temperature and freezing temperature of CA/FA/CNT were 31.08 and 27.88 °C, respectively, and the latent heats of CA/FA/CNT during the melting and freezing processes were 20.54 and 20.19 J g^–1, respectively. Moreover, compared to the CA and CA/FA, the heat transfer efficiency of CA/FA/CNT was significantly improved by doping 1, 3, 5, and 7 wt % of CNT. All of the results suggest that CA/FA/CNT possessed comfortable melting and freezing temperatures, excellent thermal stability, high latent heat value, and favorable thermal conductivity, and therefore, it is a suitable thermal storage material for building applications. Simultaneously, CA/FA/CNT can improve the comprehensive utilization level of FA.

The inverse kinematics of redundant manipulators is one of the most important and complicated problems in robotics. Simultaneously, it is also the basis for motion control, trajectory planning, and dynamics analysis of redundant manipulators. Taking the minimum pose error of the end-effector as the optimization objective, a fitness function was constructed. Thus, the inverse kinematics problem of the redundant manipulator can be transformed into an equivalent optimization problem, and it can be solved using a swarm intelligence optimization algorithm. Therefore, an improved fruit fly optimization algorithm, namely, the hybrid mutation fruit fly optimization algorithm (HMFOA), was presented in this work for solving the inverse kinematics of a redundant robot manipulator. An olfactory search based on multiple mutation strategies and a visual search based on the dynamic real-time updates were adopted in HMFOA. The former has a good balance between exploration and exploitation, which can effectively solve the premature convergence problem of the fruit fly optimization algorithm (FOA). The latter makes full use of the successful search experience of each fruit fly and can improve the convergence speed of the algorithm. The feasibility and effectiveness of HMFOA were verified by using 8 benchmark functions. Finally, the HMFOA was tested on a 7-degree-of-freedom (7-DOF) manipulator. Then the results were compared with other algorithms such as FOA, LGMS-FOA, AE-LGMS-FOA, IFOA, and SFOA. The pose error of end-effector corresponding to the optimal inverse solution of HMFOA is 10−14 mm, while the pose errors obtained by FOA, LGMS-FOA, AE-LGMS-FOA, IFOA, and SFOA are 102 mm, 10−1 mm, 10−2 mm, 102 mm, and 102 mm, respectively. The experimental results show that HMFOA can be used to solve the inverse kinematics problem of redundant manipulators effectively.

In this paper, mullite was adopted in order to absorb Palmitic Acid (PA) via a direct impregnation method. The prepared PA/mullite form-stable phase change materials (FSPCM) were systematically characterized by the Leakage Test (LT), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimeter (DSC), Thermogravimetry (TG) and Cooling Curve Method (CCM). The results indicated that, among these composites with different mass fractions of PA, the sample with the 32 wt % Palmitic Acid has the best properties without any leakage. The enthalpy of 32%PA/68%mullite FSPCM is 50.8 J/g for melting process, and 58.3 J/g for solidifying process. The phase change point of 32%PA/68%mullite FSPCM is 64.1 °C for melting and 58.7 °C for solidifying. The heat storage efficiency of the PA/mullite FSPCM was enhanced considerably by adding mullite. The leakage and thermal properties of PA/mullite FSPCM were discussed and the performance of the FSPCM has been apparently improved.