Piotr Tomasz Mitkowski

Extensional viscosity measurements of concentrated emulsions with the use of the opposed nozzles device

This paper presents results of experimental studies on the apparent extensional viscosity of emulsions. The apparent extensional viscosity measurements were carried out with the use of a customized rheometer which utilizes stagnation flow between two opposing nozzles. Apparent extensional viscosity was determined for emulsions containing 60, 70 and 74 vol.% of dispersed phase. The emulsions were produced using a homogenizer equipped with different dispersing endings that resulted in emulsions characterized by different droplet sizes. The experimental results show that the value of apparent extensional viscosity of the emulsion is significantly influenced by the droplet size and by the concentration of dispersed phase. Apparent extensional viscosity as well as shear viscosity of the emulsions increases with the increase of the dispersed phase concentration and with the decrease of the droplet diameter. It has also been observed that the decrease in the diameter of droplets increases the ratio of the apparent extensional viscosity to the shear viscosity, known as the Trouton ratio.

Hybrid process scheme for the synthesis of ethyl lactate: conceptual design and analysis

Hybrid processes have received increased attention in the field of chemical and biochemical engineering because of their ability to overcome certain obstacles related to thermodynamics of the separation task to be carried out. Usually, in a hybrid process two processes are coupled; either reaction with separation or two different separation processes. In the design of such hybrid systems, the performance of each constituent element has to be taken into account, while their optimisation must account for their interdependency. In this paper, the methodology presented by Mitkowski et al. (2009a) is applied to design and analyse a hybrid process scheme for the synthesis of ethyl lactate. Generated hybrid process schemes have been validated through computer-aided simulations.

Chemical Processing of Switchgrass ( Panicum virgatum ) and Grass Mixtures in Terms of Biogas Yield in Poland

Decomposition of waste biomass as a result of thermal, biological and chemical processing allows for the acquisition of energy and its carriers. Switchgrass (Panicum virgatum) and grass mixtures are a universal biological substrate for energy purposes. The digestibility of organic substrates in the fermentation process limits the presence of raw fiber. The aim of the work was to indicate the effectiveness of the method, which consists in pretreatment with the sodium hydroxide of the plant material. Processing conditions for low sodium concentrations (3.5 and 2% m/m) were determined. The study used the methodology of testing productivity of biogas in accordance with DIN 38414 p.8. Fresh vegetable substrate, slurry and inoculum were used to produce test mixtures. The results of the research have been developed statistically. Shapes of obtained characteristics of biogas productivity showed the correct course of the methane process. The total biogas productivity of switchgrass as a result of processing with sodium hydroxide gave better effect than with similarly processed grass mixtures. Cumulative biogas productivity of switchgrass mixtures as a result of chemical processing increased by about 10% v/v. Cumulative biogas productivity of grass mixtures, as a result of chemical processing, increased by approximately 17.5% v/v.