Showing papers by "Chuck Wah Yu published in 2015"

Energy demand for hot water supply for indoor environments: Problems and perspectives

Abstract: Supply of hot water, including space heating and domestic hot water (DHW), is very important for the creation of indoor environment. Hot water is not only the most important source for space heating in winter, but also widely used for bathing, washing, swimming and so on. It is not exaggerated to say that human being cannot live without hot water. The building energy consumption contributes 30– 40% to the total energy consumption in developed countries, and about 15–25% in developing countries. 1 The energy consumption breakdown by end uses in developed countries is summarized in Table 1. 1,2 In residential sector, space heating uses 20–50% and DHW, 10–20% of the total building energy consumption. In commercial sector, space heating accounts for 15–50% and DHW, 5–10% of the total building energy consumption. The energy consumption ratio related to hot water can reach 40–60% for residential buildings and 20–60% for commercial buildings in developed countries. As for developing countries, using China as a representative, the energy consumption for heating and DHW is shown in Figure 1. 2 The energy consumption related to hot water supply in China can be categorized as: heating in northern urban areas, heating in central urban areas and DHW in urban areas. The energy consumption for heating in northern urban areas was doubled from 72 million ton of standard coal equivalent (Mtce) in 1996 to 153 Mtce in 2008, accounting for 23% of the total building energy consumption. Besides, heating in central urban areas contributes more than 2% and DHW in urban areas contributes slightly less than 2% of the total building energy consumption. As a result, the energy consumption related to hot water supply is currently about 27% of total building energy consumption in China. The energy consumption related to hot water in

Desiccation cracking of earthen sites in archaeology museum – a viewpoint of chemical potential difference of water content

Abstract: Unearthed relics and earthen sites are historical evidence of our cultural heritage. Many of them are referred to as immobile cultural relics since both the relics-in-itself and their surroundings are our historic heritage of past emperor’s burial with significant historical importance such that they cannot be moved into indoor-display museums. Researchers have studied the specific environmental specifications to establish the desired steady temperature, humidity and air quality for collections and visitors in indoor-display museums. However, due to the unique exhibition characteristics, the conservation of earthen sites is still a challenge to environmental scientists and technologists, and how to effectively protect these ancient sites has been a major concern globally. Archaeology museum is developing advanced techniques to prevent weathering of relics caused by the sun, wind and rain. The in-situ relics in archaeology museum are far from being well preserved because of the lack of understanding of site conservation and the impact of indoor micro-climatic conditions. Many of them are suffering deteriorations or even ruins due to improper preservation environment adopted for maintenance of relics. Among the hazards that unearthed relics are facing with, desiccation cracking is the most common and problematic. The drying layer of the earthen site in the Banpo museum (Xi’an, China) is thicker than 0.4m (see Figure 1(a)). The same phenomena are also found in the Emperor Qin’s Terra-Cotta Warriors and Horses Museum (see Figure 1(b)), the water content of the earthen site decreased from 15% to 22% in 1994 when it was excavated to less than 5% now, such that serous shrinkage and cracking occurred on the surface of the site. To upgrade the conservation of the relics in archaeology museums, great efforts have been made in recent years, e.g. maintenance of a high relative humidity (RH) and space division in the exhibiting hall have been implemented in archaeology museum as a part of the preservation regime. The underground exhibiting hall of Hanyangling Museum (Xi’an, China) is such a modern archaeology museum (see Figure 1(c)). It exhibits partially exposed pits containing pottery figurines in the co-burial grave of the fourth Emperor (188–141 B.C.) and Queen of Han Dynasty, China. The enclosed space for relics’ domain is being maintained at about 24 C in summer and 16 C in the winter. Moreover, the RH has been maintained at a level higher than 95% to prevent the drying of unearthed relics and sites. However, the water content of the earthen site in the exhibiting hall still decreased from over 15% when it was excavated in 2006 to around 4% in 2009. In addition to the desiccation cracking, gypsum was found to deposit on the surface of relics due to the transport mechanism by which the carbonates were diffused and migrated with moisture across the air-relic-topsoil complex interfaces. The carbonates would react with the penetrating SO2 from the ambient atmosphere to form sulphates (see Figure 1(d)). The reason why desiccation cracking occurs in high humidity environment is not entirely clear. The conservation protocol, i.e. space division and maintaining a high RH as a preservation regime, has been considered by archaeologists as an approved practice and therefore the protocol was applied to new archaeology museums; however, cracking still persists in the terracotta relics and earthen sites. The desiccation cracking of unearthed relics and excavated sites in these archaeology museums seems to be a spontaneous process even though the RH of the atmospheric environment was at approximately the ceiling value (100%). In order to clarify the mechanism of moisture migration behind the desiccation cracking phenomenon and to verify whether a high RH is adequate to prevent the desiccation cracking of unearthed in-situ relics, the chemical potential analysis

Numerical simulation of unsteady-state particle dispersion in ferroalloy workshop:

Abstract: Fluent software was used to simulate the unsteady-state two-phase flow of particle dispersion during tapping in a workshop with a ferroalloy furnace. The gas phase was studied using the Euler coordinate system, and the motion of every solid particle was described using the Lagrange system with a discrete phase model. The concentration distribution and residence time of the particles was obtained by simulation under different conditions. The results showed that particles spread to every corner of the workshop with no wind. Ventilation can significantly reduce the particle content of the workshop. When tapping lasts for at least 720 s, the particle content of the workshop with no wind was 3.8 times more than that under north wind conditions (with a speed of 0.2 m/s). The north wind condition can be more effective to remove the particles than the south wind. The maximum residence time of a particle was only 780 s when the speed of the north wind was more than 2 m/s. A greater wind velocity would provide a be...

From Dust Devil to Sustainable Swirling Wind Energy

Abstract: Dust devils are common but meteorologically unique phenomena on Earth and on Mars. The phenomenon produces a vertical vortex motion in the atmosphere boundary layer and often occurs in hot desert regions, especially in the afternoons from late spring to early summer. Dust devils usually contain abundant wind energy, for example, a maximum swirling wind velocity of up to 25 m/s, with a 15 m/s maximum vertical velocity and 5 m/s maximum near-surface horizontal velocity can be formed. The occurrences of dust devils cannot be used for energy generation because these are generally random and short-lived. Here, a concept of sustained dust-devil-like whirlwind is proposed for the energy generation. A prototype of a circular shed with pre-rotation vanes has been devised to generate the whirlwind flow by heating the air inflow into the circular shed. The pre-rotation vanes can provide the air inflow with angular momentum. The results of numerical simulations and experiment illustrate a promising potential of the circular shed for generating swirling wind energy via the collection of low-temperature solar energy.

Update on IBE and 2014 papers of the year

Abstract: I begin this editorial by referring you to the editorial of 19(2), 2010, ‘A gate keeper of knowledge transfer’. I have now served the readers and SAGE as the editor of the journal for over six years. I was appointed as the editor in February 2009 and officially, in April 2009. I believe the journal has advanced in all aspects since I have become the editor. The journal has become more popular; the submission rate, the download rate of papers and the impact factor of the journal have all been improved. The journal is now widely accepted by most of our readers as one of the leading journals on indoor environmental quality, environmental/architectural engineering and sustainable built environment. We should all rejoice by the fact that there is now a journal of internationally recognized quality with a rapid improvement on the impact value in academic research, national and international standard developments and guidelines for design/planning applications. As I have explained in the editorial of 23(4), 2014 that the rapid rise in our impact value can be explained by the high level of global concern in the sustainable development of built environments, on social, pollution and environmental health issues in relation to urban developments, ageing communities, energy efficiency and resource management. I believe our published papers are serving this research demand pertaining to the quality of future sustainable built environments and well-being of our communities. We have established our niche area in publishing original research papers on the performance and functioning of various forms of built environments leading to developments of standards and guidelines relating to environmental quality in buildings and urban environments. However, the rapid rise in popularity of our journal has generated a surge in citation of our journal papers especially by other authors of the same journal (i.e. self-citations). This led to our suspension in the 2012 JCR (Journal Citation Report) published by Thomson Reuters. The published papers in our journal before I became the editor and during my first two years as the editor really did not receive many citations whether from internal or external sources. As the journal has been attracting loyalty and interest from authors worldwide, especially from the Far East, and also due to our unique niche subject areas, therefore our published papers are naturally attracting citations from authors who use the journal, especially from the special issue papers. I have checked and compared our journal with other journals of similar subject areas and found that the number of so-called self-citations in our journal is really less than the other comparable journals but because Indoor and Built Environment has a comparatively smaller volume, the ‘self-citation’ rate was higher. Therefore, the rapid rise in popularity of the journal has a higher impact on the ‘self-citation’ rate.