Controlled Morphology and Its Effects on the Thermoelectric Properties of SnSe2 Thin Films

In the last few years, the thermoelectric properties of tin selenide (SnSe) have been explored in much detail due to its high efficiency and green nature, being free of Te and Pb. In the same chalcogenide family, SnSe2 is also a layered structured material, but its thermoelectric potential has not been widely explored experimentally. Since SnSe2 has the layered structure, its electrical transport properties may strongly be affected by its microstructure and morphology. Here, we report the effect of reaction time on the structure, phase, and morphology of the SnSe2 during solvothermal synthesis process. We have studied four SnSe2 samples with different reaction times. The sample obtained after 16 h of reaction time was named as M1, for 20 h M2, similarly for 24 h was M3 and for 48 hours’ time, the sample was named as M4. We investigated its thermoelectric properties and found that phase purity and morphology can affect the thermoelectric performance of the synthesized samples. The peak power factor (PF) value along the ab plane was (0.69 μWcm−1K−2) for the M4 sample at 575 K, which was the highest among all the measured samples. The comparatively larger PF value of sample M4 can be related to the increase in its electrical conductivity due to increase in phase purity and band gap reduction

Nonuniform current distribution within parallel-connected batteries

An imbalanced current distribution is often observed in cables of parallel batteries, which may limit the release of the energy and power in the battery pack. Hence, it is very important to analyze the homogeneous current distributions within parallel battery batteries and explore the effect on the state of charge and energy loss. Initially, it can be found that a battery near the load will experience a large local current under higher discharge rate. With the discharge, the current distribution will show a surge wave distribution, and the peak is gradually shifted backwards. As discharge continues, local current profile in segments will have different development trends, while current profile with lower initial current values increase, which leads to an entirely different form of current distribution with the initial stage of discharge. The current profile moves in a wavelike form transmission when the total discharge rate is low. The higher the current rate, the more divergent the current distribution. The state of charge distribution is also nonuniform, clearly indicating underutilization of active materials, which will further aggravate the nonuniformity of the local current distribution in the parallel battery pack

Investigation of the Effects of the Incident Flow Angle on Vibration Behavior in Heat Exchanger Tube Bundle

Experimental study of incident flow angle effects on vibration behavior has been carried out on aluminum tube in parallel triangular tube bundle with P/D ratio of 1.375. Fluid elastic instability is the most fatal mechanism from all of the vibration mechanisms and therefore must be dealt with a lot of attention. Experiments were performed on low speed water tunnel with the velocity of water ranges from 0.3 m/s to 0.7 m/s. The experiments were designed in a unique way to study the effects of incident flow angle on vibration behavior. The monitored tube was mounted flexibly in an array of rigid tubes. Experiments were conducted on a flexible tube for different velocities ranging from 0.3 m/s to 0.7 m/s with different array rotated angles (0 to 90 degrees). It was observed that the vibration level was significantly high at 75 degree configuration as compared to other rotated angle configurations. Also it was observed that the damping response is dispersed with all positive values, indicating that there is no instability in the tube