Coal and coal-shale both tend to undergo spontaneous combustion under favourable atmospheric conditions. The Wits-Ehac index has been developed in South Africa since the late 1980's to test the spontaneous combust...Coal and coal-shale both tend to undergo spontaneous combustion under favourable atmospheric conditions. The Wits-Ehac index has been developed in South Africa since the late 1980's to test the spontaneous combustion liability of coal. However, in some cases, the Wits-Ehac index fails to produce tangible results when testing coal-shales. To overcome this problem, a new apparatus has been developed to test carbonaceous materials such as coal and coal-shale under chemical reactions with oxygen and an index has been obtained. This index is called the Wits-CT index. The equipment emulates the influence of oxygen adsorption on carbonaceous material for a period of 24 h without a heating system.The Wits-CT index uses the total carbon content of the sample and the temperature variations obtained from the samples during reaction with oxygen to predict the spontaneous combustion liability. Eighteen samples have been analyzed using both indices and the results are in-line. It was found that coals and coal-shales with higher values of the Wits-CT index are more liable to spontaneous combustion.Further research on different coal-shales is underway in order to establish an extensive database for coal and coal-shales, together with known incidences of self-heating.展开更多
In this article,the effect of using water/zinc oxide nanofluid as a working fluid on the performance of solar collector is investigated experimentally.The volumetric concentration of nanoparticles is 0.4%,and the part...In this article,the effect of using water/zinc oxide nanofluid as a working fluid on the performance of solar collector is investigated experimentally.The volumetric concentration of nanoparticles is 0.4%,and the particle size is 40 nm,and the mass flow rate of the fluid varies from 1 to 3 kg/min.For this experiment,a device has been prepared with appropriate measuring instruments whose energy source is solar radiation.The solar energy absorbed by the flat plate collector is absorbed by the nanofluid of water/zinc oxide.The nanofluid is pumped to the consumer,a heat exchanger,where it heats the water.The temperature,radiation level,flow rate,and pressure in different parts of the device were measured.The pressure drop and the heat transferred are the most important results of this experimental work.The ASHRAE standard is used to calculate efficiency.The results showed that the use of water/zinc oxide nanofluid increases the collector performance compared to water.For 1 kg/min of mass flow rate,the nanofluids have a 16% increase in efficiency compared to water.From the results,it can be concluded that the choice of optimum mass flow rate in both water and nanofluid cases increases efficiency.展开更多
The M/USY/Al2O3/kaolinite sulfur reduction additive systems containing vanadium were prepared by different methods. The influence of the preparation methods, the active constituent forerunners, the vanadium content an...The M/USY/Al2O3/kaolinite sulfur reduction additive systems containing vanadium were prepared by different methods. The influence of the preparation methods, the active constituent forerunners, the vanadium content and the type of molecular sieves on sulfur reduction of fluid catalytic cracking （FCC） gasoline were studied by a small fixed bed. The results showed that when FCC catalyst was blended with the sulfur reduction additives prepared by the special method at the ratio of 95：5, the relative sulfur reduction rate reached 35% and there was little influence on distribution of the products and quality of the gasoline. The XRD analysis indicated that the Y molecular sieve crystal structure in the additives prepared by the specific method retained integrity.展开更多
基金conducted in the context of coal-shale spontaneous combustion in the eMalahleni coalfields, South Africa was financially sponsored by Coaltech
文摘Coal and coal-shale both tend to undergo spontaneous combustion under favourable atmospheric conditions. The Wits-Ehac index has been developed in South Africa since the late 1980's to test the spontaneous combustion liability of coal. However, in some cases, the Wits-Ehac index fails to produce tangible results when testing coal-shales. To overcome this problem, a new apparatus has been developed to test carbonaceous materials such as coal and coal-shale under chemical reactions with oxygen and an index has been obtained. This index is called the Wits-CT index. The equipment emulates the influence of oxygen adsorption on carbonaceous material for a period of 24 h without a heating system.The Wits-CT index uses the total carbon content of the sample and the temperature variations obtained from the samples during reaction with oxygen to predict the spontaneous combustion liability. Eighteen samples have been analyzed using both indices and the results are in-line. It was found that coals and coal-shales with higher values of the Wits-CT index are more liable to spontaneous combustion.Further research on different coal-shales is underway in order to establish an extensive database for coal and coal-shales, together with known incidences of self-heating.
文摘In this article,the effect of using water/zinc oxide nanofluid as a working fluid on the performance of solar collector is investigated experimentally.The volumetric concentration of nanoparticles is 0.4%,and the particle size is 40 nm,and the mass flow rate of the fluid varies from 1 to 3 kg/min.For this experiment,a device has been prepared with appropriate measuring instruments whose energy source is solar radiation.The solar energy absorbed by the flat plate collector is absorbed by the nanofluid of water/zinc oxide.The nanofluid is pumped to the consumer,a heat exchanger,where it heats the water.The temperature,radiation level,flow rate,and pressure in different parts of the device were measured.The pressure drop and the heat transferred are the most important results of this experimental work.The ASHRAE standard is used to calculate efficiency.The results showed that the use of water/zinc oxide nanofluid increases the collector performance compared to water.For 1 kg/min of mass flow rate,the nanofluids have a 16% increase in efficiency compared to water.From the results,it can be concluded that the choice of optimum mass flow rate in both water and nanofluid cases increases efficiency.
文摘The M/USY/Al2O3/kaolinite sulfur reduction additive systems containing vanadium were prepared by different methods. The influence of the preparation methods, the active constituent forerunners, the vanadium content and the type of molecular sieves on sulfur reduction of fluid catalytic cracking （FCC） gasoline were studied by a small fixed bed. The results showed that when FCC catalyst was blended with the sulfur reduction additives prepared by the special method at the ratio of 95：5, the relative sulfur reduction rate reached 35% and there was little influence on distribution of the products and quality of the gasoline. The XRD analysis indicated that the Y molecular sieve crystal structure in the additives prepared by the specific method retained integrity.
