There are limited studies on the impact of room temperature on sleep quality, particularly outside laboratories. Also, limited studies investigated the impact of thermal control on sleep quality and energy related matters, while heating and cooling are responsible for 40% of the energy use in buildings. This work investigated the impact of thermal comfort on the sleep quality, gender differences, ventilation mode and thermal control systems, which lead to differences in the energy use. Field test studies of thermal comfort were applied between 2010 and 2014. 13,728 datasets from 61 buildings and 135 participants were collected in participantsâ€™ bedrooms in Japan. The results indicated that female participants had lower comfort temperature, as compared to men, before sleep during the cold months. Otherwise, no significant difference was found between their comfort temperatures, which is in disagreement with the existing research. The sleep quality was improved when thermal sensation was between slightly cool and neutral; and the comfort temperature between 17-27ï‚°C. Natural ventilation had a consistent impact on the sleep quality, as compared to heating and cooling modes. Opening a window improved the sleep quality during the warm months; while reduced it during the cold months. This suggested extra care regarding the natural ventilation to improve the sleep quality and to reduce the energy demand of the building.
This work investigated thermal comfort and adaptive behaviour of older people in their houses as well as the related energy demand during the summer 2020 and the COVID-19 situation in India, Turkey and the UK. Older people are considered, as less sensitive and responsive towards the changes of the thermal environment. Thus, their health is at risk, particularly concerning the climate change and the recent increase in heat waves. The use of control systems and the related energy demand was of particular focus in this work. Field test studies of thermal comfort using both longitudinal and transverse approaches were applied in India, Turkey and the UK. Overall, were included in this work. The comfort temperature was respectively 30.12ï‚°C, 24.88ï‚°C and 22.49ï‚°C. The comfort level of the Indian respondents was significantly decreased by the increased humidity levels, particularly the female respondents. Otherwise, the comfort temperatures of women were found similar to men. In Turkey and the UK, mainly natural ventilation and heating were in use. However, a variety of thermal control systems were available in the Indian case studies. Natural ventilation and fan were constantly in use, while more energy intensive systems, such as air conditioner, was only in use when outdoor temperatures reached 30ï‚°C and over. The energy use of the Indian case studies was found slightly lower than the British case studies, despite the availability of various thermal control systems.
Solid oxide fuel cell systems operating with biogas can be considered an efficient solution for carbon-free energy conversion. Given the efficiency levels at small-scale, a 100 kW range cogenerative system for micro-grid applications was considered in this study. The challenge in employing biomass-derived fuel in solid oxide fuel cells is related to the performance fluctuations due to biomass intrinsic variability. Thus, the exact composition of the fuel may vary in unpredicted ways during the fuel cell lifetime. An uncertainty analysis combined with a design optimization study was conducted on the fuel cell system and it was demonstrated that the deviation in rate of return is statistically significant, and thus robust optimization is needed for designing a system fueled with highly variable biogas composition.
Microalgae cell adhesion plays an essential role in biofilm wastewater treatment, photobioreactor material selection, and surface biofouling control. The interaction energy between microalgae cells and solid substrate behind the cell adhesion phenomenon is the key to boost these issues. Surface properties, including surface potential and surface free energy components, have a significant influence on the adsorption capacity of algal cells on the substrate. According to the extended Derjaguin-Landau-Verwey-Overbeek (eDLVO) theory, the impact degree and trend of surface properties of cells and solid substrate on the total interaction energy were discussed via sensitivity analysis. The results revealed that when algae cells and solid substrate own same property charges, increasing the surface potential of solid substrate (Î¾s) or reducing the surface free energy electron donor components of solid substrate (Î³s-) is the most effective measure to promote cell adhesion. When algae cells and solid substrate own dissimilar property charges, reducing the surface potential of the algae cells (Î¾m) or enhancing the Î³s- is an effective way to prevent excessive algae cell adhesion. Overall, the research provides direction for the selection of surface-modified, solid substrate, and algal cells to control cell adhesion under different demands
Cocoa pod husk (CPH) has been investigated as a biofuel for use in a gasifier-electricity generator for cocoa farming communities in rural Ghana. CPH has embodied energy of approximately 17MJ/kg and so is a valuable energy source for bioenergy systems. A small-scale 5kWe CPH fueled gasifier-generator has been installed and its performance evaluated. At 4kWe, the system consumed approximately 11kg/h, supplying 27m3/h of gas for the engine. Over 50% of the energy in the fuel was converted into combustible gas and 7.5% was converted into electricity. The gas engine efficiency was 25%, comparable to similar systems reported elsewhere. High moisture content reduced conversion efficiencies, but this can be easily overcome by employing enhanced drying techniques. Waste heat could be utilised to improve overall performance, so that 40-50% of the energy in the CPH can be put to useful purpose.
Turbulent jet ignition (TJI) shows great potentials of achieving lean combustion. In this work, a turbulent jet ignitor was designed and made, and the engine performance, combustion characteristics, pollutant emissions and knock characteristics were detailed studied in a single-cylinder engine. The results show that the lean burn limit is greatly extended through TJI combustion, and the indicated specific fuel consumption is apparently lower than that of spark ignition (SI) combustion under part load conditions. In TJI combustion, the flame jet leads to a fast burning rate at the beginning of the combustion; and with the fuel-air mixture becomes leaner, the burning rate gradually decreases while the spark timing needs to be advanced to keep appropriate combustion phase. The NOx emission in lean burn condition is extremely low, which decreases by 95%-99% under part load conditions compared with SI combustion. Furthermore, pressure oscillations were both observed in TJI and SI combustions, in which the pressure oscillation of TJI is caused by the fast burning rate after the flame ejection, while that of SI is caused by the end-side auto-ignition. The spectrum analysis on knock frequency shows that the pressure oscillation modes of TJI and SI are different in the combustion chamber.
Great attention has been focused on the production of non-polluting gas fuel (hydrogen) from water electrolysis combined with renewable resources. However, the H2 bubble removal during water electrolysis is still challenging, which is a critical factor to improve the electrode performance of hydrogen evolution reaction (HER). Herein, a gradient porous electrode with decreasing pore size from the middle of the electrode to the two sides (SML-LMS-HE) was developed to accelerate H2 bubble removal rate by optimizing the pore size distribution of HER electrode. This electrode was prepared by using composite Ni foams with gradient porous structure as the conductive substrate, then being decorated with MoS2/Ni3S2 heteronanorods. The as-prepared electrode exhibited a much higher H2 bubble removal rate as compared with that of homogeneous porous HER electrode (MMM-MMM-HE) and gradient porous HER electrode with increasing pore size from the middle of the electrode to the two sides (LMS-SML-HE), conducive to the sufficient exposure of the active sites and the effective improvement of the electrode performance. As a result, SML-LMS-HE demonstrated a considerably low overpotential of 83 mV at the current density of 10 mA cm-2 as compared with MMM-MMM-HE and LMS-SML-HE.
The new carbon emission reduction target proposed by the Chinese government is an important process for the international community to deal with climate change. Beijing-Tianjin-Hebei region is the representative region of the advanced region of China and it is important to analyze the low carbon transition in Beijing-Tianjin-Hebei region. This paper used a provincial China TIMES model to analyze the carbon emission, energy use and electricity transmission under low carbon scenarios. This paper established 3 scenarios which include reference scenario (REF), NDC (Nationally Determined Contribution) scenario which achieves Chinaâ€™s carbon emission peaking target in 2030 and a carbon neutrality scenario which achieves Chinaâ€™s carbon neutrality target in 2060. The results show that the carbon emission in Beijing-Tianjin-Hebei region will peak at 2035 and 2030 in the NDC_PEAK30 and CN60 scenario. In the low carbon scenarios, the proportion of electricity in the final energy consumption will continuously increase to achieve the low carbon transition target. The power sector will have negative emission in the carbon neutrality scenario and the Biomass Electricity plant with Carbon Capture and Storage (BECCS) will play an important role in carbon neutrality. The carbon neutrality is a big challenge to China especially in Beijing-Tianjin-Hebei region. It needs more effort in transport and building sector.
In this study, a mixed combustion system in a fixed bed is proposed to deal with electrolytic aluminum waste. The feasibility of the laboratory-scale fixed bed burner system is verified. The effect of different mixing proportions, temperatures (i.e. 900, 980 and 1050 Â°C) and the addition of limestone on the products of combustion and pollutant emission is investigated through SEM and XRD analysis. The results show that the combustion process and the physical characteristics of the product are exhibited by mixing with 7:3 (coal: waste) ratio at 900 Â°C. Adding limestone meets the requirements of using circulating fluidized bed boilers for mixed burning of electrolytic aluminum waste. This study provides a theoretical basis for commercialization.
In order to study the effect of catalytic conversion of biomass gasification tar model compound (toluene) by oak char, a fixed bed test system was used to test the conversion efficiency of toluene, the liquid phase composition was detected by GC-MS. The results show that the conversion efficiency of toluene does not exceed 57.27% at 600 and 700 Â°C, but it increases significantly at 800 Â°C, up to 93.07% of KMnO4 modified char. The content of the liquid phase product of the catalytic conversion of toluene is related to the temperature and whether the char is modified. Moreover, most of liquid phase product are aromatic compounds. Among them, bibenzyl is an important intermediate product in the catalytic conversion of toluene.