This paper presents a humidification–dehumidification (HDH) desalination system with an air-cooling condenser. Seawater in copper tubes is usually used in a condenser, but it has shown the drawbacks of pipe erosion, high cost of the copper material, etc. If air could be used as the cooling medium, it could not only avoid the above drawbacks but also allow much more flexible structure design of condensers, although the challenge is whether the air-cooing condenser can provide as much cooling capability as water cooling condensers. There is no previous work that uses air as cooling medium in a condenser of a HDH desalination system to the best of our knowledge. In this paper we designed a unique air-cooling condenser that was composed of closely packed hollow polycarbonate (PC) boards. The structure was designed to create large surface area of 13.5 m² with the volume of only 0.1 m³. The 0.2 mm thin thickness of the material helped to reduce the thermal resistance between the warm humid air and cooling air. A fan was used to suck the ambient air in and out of the condenser as an open system to the environment. Results show that the air-cooling condenser could provide high cooling capability to produce fresh water efficiently. Meanwhile, cellulous pad material was used in the humidifier to enhance the evaporative process. A maximum productivity of 129 kg/day was achieved using the humidifier with a 0.0525 m³ cellulous pad with a water temperature of 49.5 °C. The maximum gained output ratio (GOR) was 0.53, and the maximum coefficient of performance (COP) was 20.7 for waste heat recovery. It was found that the system performance was compromised as the ambient temperature increased due to the increased temperature of cooling air; however, such an effect could be compensated by increasing the volume of the condenser.

Nanowires can potentially be used with low-cost flexible plastic substrates for applications such as large-area displays and sensor arrays. However, high temperature processing steps such as thermal annealing that are incompatible with plastic substrates are still a major hindrance. Laser annealing permits localized energy input without affecting the underlying substrate and can help overcome this problem. In this study, the excimer laser annealing of silicon nanowires is demonstrated to be an efficient means of activating implanted dopants. The optical absorption of the nanowires is discussed and the effect of parameters such as fluence and number of pulses is investigated.

Ultralarge-grained polycrystalline-silicon films have been formed from 50-nm-thick amorphous-silicon layers using double-laser crystallization (DLC). In situ images were captured to monitor the transient melting and solidification processes. Scanning electron microscope and plan-view transmission electron microscope analyses show that lateral grain dimensions up to 10μm can be achieved by this crystallization method. Prepatterning of the amorphous-silicon film prior to DLC provides a means for modifying the lateral temperature profile (hence grain structure) via edge cooling effects. Amorphous-silicon films as thin as 20 nm can be crystallized by DLC. Atomic force microscope images showed rms surface roughness less than 3 nm. High-performance n-channel thin-film transistors (TFTs) were fabricated in 50-nm-thick DLC films, with channel regions aligned to the large-grained regions, yielding electron field-effect mobilities as high as 124cm2∕Vs, threshold voltage as low as 0.2 V, and on-off current ratio as high as 108. The DLC poly-Si TFTs show substantially better performance than control devices fabricated via excimer laser crystallization.