The innovative design of air caps for improving the thermal efficiency of CFB boilers.

Air caps are an effective way of ensuring uniformity of air flow in Circulating Fluidized Bed (CFB) boilers. Published literature on the design and configuration of these air caps is severely limited. In this study, extensive theoretical as well as experimental investigations have been carried out to design novel air caps in order to improve efficiency of CFB boilers. A small-scale test bench of 220 t/h CFB boiler has been developed, integrated with novel air caps. It has been observed that inhomogeneity in air flow velocity decreases from 65.79% to 21.25%, while the pressure drop decreases by 20%. A mathematic model of air caps has been derived and its accuracy verified through cold tests. Two empirical correlations for calculating the pressure drop and the air jet penetration length of the novel air caps have been obtained and verified. Finally, in order to validate the innovative design of air caps, this methodology has been implemented to a full-scale 220 t/h CFB boiler. The hot test results depict that the thermal efficiency of the boiler has increased from 86.4% to 91.8% when tested with the novel air caps in-place, which is equivalent to a saving of 6000 tons of coal per year

Constructing tissue-like complex structures using cell-laden DNA hydrogel bricks

Tissue engineering has long been a challenge because of the difficulty of addressing the requirements that such an engineered tissue must meet. In this paper, we developed a new "brick-to-wall" based on unique properties of DNA supramolecular hydrogels to fabricate three-dimensional (3D) tissuelike structures: different cell types are encapsulated in DNA hydrogel bricks which are then combined to build 3D structures. Signal responsiveness of cells through the DNA gels was evaluated and it was discovered that the gel permits cell migration in 3D. The results demonstrated that this technology is convenient, effective and reliable for cell manipulation, and we believe that it will benefit artificial tissue fabrication and future large-scale production

Study of Baryon Number Transport Dynamics and Strangeness Conservation Effects Using Ω\Omega-hadron Correlations

In nuclear collisions at RHIC energies, an excess of $\Omega$ hyperons over $\overline{\Omega}$ is observed, indicating that $\Omega$ carries a net baryon number despite $s$ and $\bar{s}$ quarks being produced in pairs. The baryon number in $\Omega$ could have been transported from the incident nuclei and/or acquired and balanced in baryon pair productions associated with other types of anti-hyperons, such as $\overline{\Xi}$. To investigate these two scenarios, we propose to measure correlations between $\Omega$ and $K$, as well as between $\Omega$ and anti-hyperons. We will use two versions, the default and string-melting, of a multiphase transport (AMPT) model to illustrate the correlation method. We will present the $\Omega$-hadron correlations from simulated Au+Au collisions at $\sqrt{s_{NN}} = 7.7$ and 14.6 GeV, and discuss the dependence on collision energy and on the hadronization scheme in these two AMPT versions. These correlations from the AMPT model provide a baseline for experimental exploration of the dynamics of baryon number transport and the effects of baryon number and strangeness conservation in nuclear collisions

Development of a novel methodology for calculating the thermal efficiency of clean fuel boilers based on error analysis method.

Clean fuel boilers often use natural gas and wood pellets as their primary fuel, which result in reduced emissions from the boiler. Accurate determination of the thermal efficiency of these boilers plays a vital role in appropriately controlling the process parameters for enhanced thermal performance of the boilers. The traditional methods for calculating the thermal efficiency of clean fuel boilers require a number of input parameters, which is not suitable for fast calculation of the thermal efficiency. Moreover, the conventional methods are often significantly inaccurate in the determination of the thermal efficiency of boilers. Thus, a novel method for rapid and accurate determination of boiler’s thermal efficiency is required. Therefore, using error analysis method, this study presents a novel mathematical model to calculate the thermal efficiency of an industrial boiler, fueled with natural gas and wood pellets. The main factors that affect the thermal efficiency of clean fuel industrial boilers are obtained based on the results of the thermal efficiency error analysis. A novel mathematical model to calculate the thermal efficiency of the boilers is developed as a function of these major factors. Finally, the calculated results, based on the model, are compared with the test values provided by Guangdong Special Equipment Inspection and Research Institute. The maximum deviation in comparative results has been observed to be within ±3%, indicating the appropriateness and commercial viability of the novel methodology proposed in this study

Experimental investigations on a grate incinerator of L-shaped flame fuelled by rural solid waste.

In this article, investigations on the structural parameters and aerodynamic characteristics of the furnace arches of a small scale L-shaped flame incinerator for the disposal of rural solid waste are carried out. A novel configuration of furnace arches for the incinerator of L-shaped flame is developed. Eight different test conditions are determined by using orthogonal experimental design method. Cold test with full coverage arch and sub-warehouse air supply are analyzed under eight different test conditions. Experimental results show that a stable combustion can be obtained by using L-shaped flame technology and the optimum air supply ratio between the front arch and the rear arch is discovered to be 3:7. It is found that the maximum turbulence intensity along the length of grate can reach 10%, and the burning exuberant zone is approximately 40%~75% of the whole relative length of the grate. The optimum dimensionless structural parameters of the furnace arch are: H/L = 0.333 and h/L = 0 .12 with the front arch angle of 45º. The effectiveness of configuration of arches as well as combustion air supply ratio for the L-shaped flame grate incinerator fueled by rural solid waste is verified by hot test

Performance improvement of a circulating fluidized bed boiler through flow modifications in primary air supply system.

The primary air supply system is a key component of a Circulating Fluidized Bed (CFB) boiler. The uniformity of air flow through the primary air supply system is important for highly efficient operation of the CFB boiler. Non-uniform air flow distribution within the primary air supply system can affect the boiler's combustion adversely, resulting in higher energy consumptions. An effective measure to solve this problem is to install an air flow modifier in the primary air supply system. Thus, extensive numerical investigations have been carried out to design a suitable air flow modifier in order to improve operational efficiency of the CFB boiler. It has been shown that inhomogeneity in the air flow velocity, at a control cross-section of the wind-box, reduces from 65.79% to 21.25% when flow modifier is used. In order to validate the numerical results, visual and velocity distribution uniformity experiments have been conducted under five different test conditions. For this purpose, a small-scale model of a 220t/hr CFB boiler has been used. The experimental results substantiate the numerical predictions. Moreover, the same methodology has been implemented to a full-scale 220t/hr CFB boiler. The hot test results depict that the thermal efficiency of the boiler has increased from 85.71% to 88.34% when tested with an air flow modifier in place, which is equivalent to a saving of 5,000 tons of coal per year. The economic benefits of this energy-saving technology have been shown to be very significant, clearly demonstrating the effectiveness of the air flow modifier