Experimental study on three-effect tubular solar still under vacuum and immersion cooling

Solar still is widely used for supplying fresh water to small communities in remote areas. One drawback of this technique lies in the low freshwater yield. Recent studies on stills of multi-effect and vacuum design proved their potential for high yield. However, such systems suffer from high electricity consumption and insufficient cooling. In this study, a novel system with a periodic pressure control scheme and water immersion cooling has been proposed to mitigate these defects. A prototype was constructed and associated with a 0.19-m2 solar panel. A 5-day outdoor experiment was conducted to evaluate the overall performance. Results indicated that the highest yield during the test was 9.8 kg/m2 at operating pressure of 40 kPa. A significant performance ratio of 1.87 was achieved with immersion cooling, i.e., 0.42 higher than that with air cooling. Thermal analysis showed that the heat transfer coefficient of water immersion cooling was 15–50 times higher than that of air cooling. Compared with previous vacuum-operated systems, the specific electricity consumption of maintaining vacuum was greatly reduced, i.e., from 21.6 kJ/kg to 1.7 kJ/kg for the case at 60 kPa. The forecast cost of the distilled water is $0.012/kg, representing an affordable desalination technique for off-grid communities

Experimental investigation on an energy-efficient floor heating system with intelligent control: A case study in Chengdu, China

The space heating system accounts for 20%~50% of building energy consumption, and may lead to energy waste due to unreasonable controls. In this study, an energy-efficient floor heating system with intelligent control was proposed to improve energy efficiency of the system. In order to validate the concept of the proposed intelligent control, an experimental system was designed and constructed in Chengdu, China. Temperature, control cycle and energy consumption were then studied under different control strategies. The result shows that a larger flow rate of supply water will result in a longer control cycle and a lower control frequency, i.e., the average control cycle at 7 L min−1 is 1.7 h during the test day, while it is 1.5 h at 5 L min−1. Moreover, adopting water with a higher temperature and flow rate could achieve a higher efficiency of the system. The energy consumptions in case 1 (5 L min−1, 50 °C), case 2 (5 L min−1, 55 °C), case 5 (7 L min−1, 55 °C) and case 6 (7 L min−1, 60 °C) are 4746 kJ, 3534 kJ, 3093 kJ and 3028 kJ, respectively. Based on the experimental data, the supply water temperature is suggested to set lower than 60 °C considering human comfort

Size-Specific Infrared Spectroscopic Study of the Reactions between Water Molecules and Neutral Vanadium Dimer: Evidence for Water Splitting

Investigation of the reactions between water molecules and neutral metal clusters is important in water splitting but is very challenging due to the inherent difficulty of size selection. Here, we report a size-specific infrared-vacuum ultraviolet spectroscopic study on the reactions of water with neutral vanadium dimer. The V2O3H4 and V2O4H6 products were characterized to have unexpected V2(μ2-OH)(μ2-H)(η1-OH)2 and V2(μ2-OH)2(η1-H)2(η1-OH)2 structures, indicative of a water decomposition. A combination of theory and experiment reveals that the water splitting by V2 is both thermodynamically exothermic and kinetically facile in the gas phase. The present system serves as a model for clarifying the pivotal roles played by neutral metal clusters in water decomposition and also opens new avenues toward systematic understanding of water splitting by a large variety of single-cluster catalysts

Size-Specific Infrared Spectroscopic Study of the Reactions between Water Molecules and Neutral Vanadium Dimer: Evidence for Water Splitting

Investigation of the reactions between water molecules and neutral metal clusters is important in water splitting but is very challenging due to the inherent difficulty of size selection. Here, we report a size-specific infrared-vacuum ultraviolet spectroscopic study on the reactions of water with neutral vanadium dimer. The V2O3H4 and V2O4H6 products were characterized to have unexpected V2(μ2-OH)(μ2-H)(η1-OH)2 and V2(μ2-OH)2(η1-H)2(η1-OH)2 structures, indicative of a water decomposition. A combination of theory and experiment reveals that the water splitting by V2 is both thermodynamically exothermic and kinetically facile in the gas phase. The present system serves as a model for clarifying the pivotal roles played by neutral metal clusters in water decomposition and also opens new avenues toward systematic understanding of water splitting by a large variety of single-cluster catalysts

Improvement of Symptoms and Quality of Life After Successful Percutaneous Coronary Intervention for Chronic Total Occlusion in Elderly Patients

Background Data regarding the impact of successful chronic total occlusion treated with percutaneous coronary intervention (CTO‐PCI) on symptoms and quality of life (QOL) in elderly patients (≥75 years) are unknown. This prospective study aimed to assess whether successful CTO‐PCI could improve the symptoms and QOL in elderly patients (≥75 years). Methods and Results Consecutive patients who underwent elective CTO‐PCI were prospectively enrolled and subdivided into 3 groups based on age: age<65 years, 65 years≤age<75 years, and age≥75 years. The primary outcomes included symptoms, as assessed with the New York Heart Association functional class and Seattle Angina Questionnaire, and QOL, as assessed with the 12‐Item Short‐Form Health Survey questionnaire, at baseline, 1 month, and 1 year after successful CTO‐PCI. Of 1076 patients with CTO, 101 were age≥75 years (9.39%). Hemoglobin, estimated glomerular filtration rate, and left ventricular ejection fraction levels all decreased with increasing age, and NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide) increased. The proportion of dyspnea and coronary lesions, including multivessel disease, multi‐CTO lesion, and calcification were higher in elderly patients. Procedural success rate, intraprocedural complications, and in‐hospital major adverse cardiac events were not statistically different in the 3 groups. Importantly, symptoms, including dyspnea and angina, were markedly improved regardless of age at 1‐month and 1‐year follow‐up (P<0.05). Likewise, successful CTO‐PCI significantly improved QOL at 1‐month and 1‐year follow‐up (P<0.01). Additionally, the incidence of major adverse cardiac events and all‐cause mortality at 1‐month and 1‐year follow‐up was not statistically different in the 3 groups. Conclusions Successful PCI was beneficial and feasible to improve symptoms and QOL in patients ≥75 years of age with CTO

NTIRE 2019 Image Dehazing Challenge Report

This paper reviews the second NTIRE challenge on image dehazing (restoration of rich details in hazy image) with focus on proposed solutions and results. The training data consists from 55 hazy images (with dense haze generated in an indoor or outdoor environment) and their corresponding ground truth (haze-free) images of the same scene. The dense haze has been produced using a professional haze/fog generator that imitates the real conditions of haze scenes. The evaluation consists from the comparison of the dehazed images with the ground truth images. The dehazing process was learnable through provided pairs of haze-free and hazy train images. There were 270 registered participants and 23 teams competed in the final testing phase. They gauge the state-of-the-art in image dehazing