Simulation study of a down-draft wood gasifier used to produce thermal energy for tea drying

A detailed computer model has been developed using the physical and chemical phenomena in gasification for a down-draft biomass gasifiers. The model has been used to investigate the effects of operational and design parameters on reactor performance in terms of the composition of the output gas and the hot gas efficiency. The results obtained from the simulation study are the effects of fuel moisture content, particle size, feed rate, reactor load and capacity on hot gas efficiency. The model has been validated using experimental data available in the open literature. The hot gas efficiency of a particular down-draft throated gasifier designed to generate thermal energy for tea drying is predicted to be approximately 86%

Computer simulation of a downdraft wood gasifier for tea drying

A gasifier has been fabricated in Sri Lanka for the tea industry, but there is a lack of knowledge of the effect of certain key operating parameters and design features on its performance. Experimental testing of the design under various conditions has produced data that has then been used to calibrate a computer program, developed to investigate the impact of those parameters and features on conversion efficiency. The program consists of two sub-models of the pyrolysis and gasification zones, respectively. The pyrolysis sub-model has been used to determine the maximum temperature and the composition of the gas entering the gasification zone. The gasification zone sub-model has been calibrated using data gathered from the experiments. It was found that a wood chip size of 3–5 cm with a moisture content below 15% (d.b.) should be used in this gasifier. Feed material with a fixed carbon content of higher than 30% and heat losses of more than 15% should be avoided. For the above parameters, the gasification zone should be 33 cm long to achieve an acceptable conversion efficiency

Pre-treatment with a novel synthetic TLR4 agonist prior to challenge with mouse-adapted H1N1 and H2N3 influenza strains reduced morbidity and mortality in BALB/c mice

Abstract According to the World Health Organization, influenza causes 3–5 million cases of severe illness and 250,000 – 500,000 deaths annually despite the availability of a seasonal vaccine. As an alternative therapy for use in high-risk groups and environments, we evaluated the efficacy of prophylactic treatment with a novel synthetic TLR4 agonist in BALB/c mice. Animals were anesthetized and treated with a TLR4 agonist intranasally (IN) 0 to 28 days prior to a lethal challenge with either H1N1 or H3N2 mouse-adapted human influenza. Animals were monitored daily for weight loss, decreased body temperature, body score, and mortality. Initial dose-response experiments demonstrated that mice treated with 50 μg or 10 μg of our novel TLR4 agonist in an aqueous formulation were similarly protected from H3N2 influenza challenge with respect to weight loss and survival. However, initial weight loss data demonstrated that 50 μg was not as well tolerated as 10 μg. The 10 μg dose was therefore selected as the lead dose in subsequent experiments. In a series of formulation comparison experiments, the lead formulation resulted in marked improvement in both percent weight loss and survival compared to initial TLR4 agonist formulations. Animals treated with all formulations of our novel synthetic TLR4 agonist 0, 7, or 14 days prior to infection resulted in 80–90% survival. The lead formulation also resulted 80–90% survival when given prophylactically 21 or 28 days prior to infection compared to 0–20% survival in untreated mice. Overall, our results show that pre-treatment with our novel synthetic TLR4 agonist prior to exposure to mouse-adapted H1N1 and H2N3 influenza strains reduced morbidity and mortality in infected mice for up to 28 days after treatment. This work was supported by NIH grant 5R44AI136081-03</jats:p

Performance prediction and validation of equilibrium modeling for gasification of cashew nut shell char

Cashew nut shell, a waste product obtained during deshelling of cashew kernels, had in the past been deemed unfit as a fuel for gasification owing to its high occluded oil content. The oil, a source of natural phenol, oozes upon gasification, thereby clogging the gasifier throat, downstream equipment and associated utilities with oil, resulting in ineffective gasification and premature failure of utilities due to its corrosive characteristics. To overcome this drawback, the cashew shells were de-oiled by charring in closed chambers and were subsequently gasified in an autothermal downdraft gasifier. Equilibrium modeling was carried out to predict the producer gas composition under varying performance influencing parameters, viz., equivalence ratio (ER), reaction temperature (RT) and moisture content (MC). The results were compared with the experimental output and are presented in this paper. The model is quite satisfactory with the experimental outcome at the ER applicable to gasification systems, i.e., 0.15 to 0.30. The results show that the mole fraction of (i) H2, CO and CH4 decreases while (N2 + H2O) and CO2 increases with ER, (ii) H2 and CO increases while CH4, (N2 + H2O) and CO2 decreases with reaction temperature, (iii) H2, CH4, CO2 and (N2 + H2O) increases while CO decreases with moisture content. However at an equivalence ratio less than 0.15, the model predicts an unrealistic composition and is observed to be non valid below this ER