Heat Transfer Enhancement Through Pcm Thermal Storage By Use of Copper Fins

Enhancement of heat transfer over a cylinder shaped thermal energy storage filled by paraffin E53 by use of longitudinal rectangular copper fins was analyzed. The thermo-physical features of the storage material are determined in separate experiments and implemented to FLUENT software over user defined function. Advanced thermal storage geometry comprehension and optimization required introduction of a parameter suitable for the analysis of heat transfer enhancement, so the ratio of heat transfer surfaces as a factor was proposed and applied. It is revealed that increase of the ratio of heat transfer surfaces leads to the decrease of melting time and vice versa. Numerical analysis, employing the 3-D model built in Ansys software, observed storage reservoir geometries with variable number of longitudinal fins. The adjusted set of boundary conditions was carried out and both written in C language and implemented over user defined function in order to define variable heat flux along the height of the heater. The comparison of acquired numerical and experimental results showed a strong correlation. Experimental validation of numerical results was done on the real thermal energy storage apparatus

Kinetic Parameters Identification of Conductive Enhanced Hot Air Drying Process of Food Waste

The efficient utilization of waste from food industry is possible after thermal treatment of the material. This treatment should be economically feasible and compromise the energy efficient drying process. The main goal of this investigation is to determine drying characteristics of nectarine pomace as a waste from food industry. The measurements were performed in an experimental dryer by combined conductive-convective drying method with disk-shaped samples of 5, 7, and 10 mm thickness and 100 mm in diameter at the air temperatures of 30, 40, 50, 60, and 70°C, hot plate temperatures of 50, 60, and 70°C and air velocity of 1.5 m/s. The drying curves were compared to a few semi-theoretical mathematical models. The Logarithmic model showed the best correlation. On the basis of experiments, it is determined that the drying process takes place in a falling rate period and it is accepted that the main mechanism of moisture removal is diffusion. The effective coefficient of diffusion was determined using experimental results by calculating the slope of the drying curves. Drying time and equilibrium moisture are determined for each experiment. Analysis of drying curves showed that the conductive-enhanced drying method reduces drying times and increases the diffusivity coefficient. The character of drying rate curves for conductiveenhanced drying was analysed and compared with pure convective drying of nectarine pomace

Applicability of Construction and Demolition Waste in Geopolymers – A Screening Test

In this study, the applicability of construction and demolition waste (C&DW) in geopolymerization technology was investigated. The C&DW components, concrete and solid bricks, were collected from demolition sites in Belgrade, Republic of Serbia. The concrete sample came from a demolished fifty-year-old construction road, while the remains of solid bricks originated from a 1930s building. Prior to mechanical testing, the C&DW components were characterized by XRD analysis for their mineralogical composition. The results showed that the concrete waste consisted mainly of quartz (SiO2) and calcite (CaCO3), while the brick waste sample contained anorthite from the feldspar group (CaAl2Si2O8), wollastonite (Ca0.957Fe0.043O3Si) and mullite (Al2.4O4.8SiO6). The mechanical properties were examined using the screening method on three geopolymer mixtures, one of each mixture of concrete and brick powders and a mixture of both C&DW components. According to the standard SRPS EN 12390-3:2010 for cubic samples, the geopolymer samples were prepared with alkaline activators for testing the compressive strength as the dominant parameter in the mortar and concrete evaluation. The compressive strength values increased in the range of 2.4 MPa for concrete, 10.2 MPa for brick, and 10.8 MPa for the mixed geopolymer sample. The low compressive strength result of the concrete sample was the consequence of the mineral composition, i.e., the absence of aluminosilicate. However, the brick and the sample with a combination of both types of waste showed moderately satisfactory compressive strength, which could be the starting point for further investigations

Heat transfer enhancement through PCM thermal storage by use of copper fins

Enhancement of heat transfer over a cylinder shaped thermal energy storage filled by paraffin E53 by use of radial rectangular copper fins was analyzed. The thermo-physical features of the storage material are determined in separate experiments and implemented to Fluent software over UDF. Advanced thermal storage geometry comprehension and optimization required introduction of a parameter suitable for the analysis of heat transfer enhancement, so the ratio of heat transfer surfaces as a factor was proposed and applied. It is revealed that increase of the ratio of heat transfer surfaces leads to the decrease of melting time and vice versa. Numerical analysis, employing the 3D model built in Ansys software, observed storage reservoir geometries with variable number of longitudinal radial fins. The adjusted set of boundary conditions was carried out and both written in C language and implemented over UDF in order to define variable heat flux along the height of the heater. The comparison of acquired numerical and experimental results showed a strong correlation. Experimental validation of numerical results was done on the real TES apparatus. [Projekat Ministarstva nauke Republike Srbije, br. III42011, TR 33042 i OI 176006

Numerical simulation of latent heat storage with conductance enhancing fins

Precise understanding of heat transfer processes inside the latent thermal energy storage exposed to different initial and boundary conditions is crucial for development of optimized design and operating features of similar devices. The paper presents 3D numerical study of phase change material heat storage in the shape of vertical cylinder reservoir with axially placed heat source/sink equipped with variable number of conductance enhancing longitudinal rectangular fins. As the principally important observed is the case of vertically variable heat flux supplied to the phase change material during the melting process. The numerical modeling is based on the physical model of the process and is being carried out by Fluent software that uses finite volume method for solving continuity, momentum and energy equations. The coupling between pressure and velocity is based on the Semi- Implicit Pressure- Linked Equation (SIMPLE) algorithm. The results of numerical simulations are verified through the comparison with the own experimental results. Exemplary results for characteristic heat storage geometries and boundary conditions are presented and analyzed in the paper.15th International Scientific Conference on Renewable Energy and Innovative Technologies, Jun 10-11, 2016, Tech Coll Smolyan, Smolyan, Bulgari

Diesel production by fast pyrolysis of Miscanthus giganteus, well-to-pump analysis using the greet model

In this paper “well-to-pump” environmental analysis of pyrolytic diesel from Miscanthus gigantheus is performed. The average annual yield of Miscanthus from III-V year of cultivation on 1 ha of chernozem soil in Serbia (23.5 t) is considered as an input for the process. Two pyrolytic diesel pathways are considered: distributed pyrolytic pathway with external hydrogen production (from natural gas) and integrated pyrolytic pathway with internal hydrogen production (from pyrolytic oil). and are compared to a conventionally produced diesel pathway. The results of the analysis reveal that integrated-internal pyrolytic diesel pathway has lowest resources consumption and lowest pollutant emissions. Compared to conventionally produced diesel, integrated-internal pyrolysis pathway consumes 80% less of fossil fuels, and 92% more of renewables, has 90% lower global warming potential, 30% lower terrestrial acidification potential but 38% higher particulate matter formation potential. Compared to the distributed-external pathway, 88% less fossil fuels, and 36% less renewables are consumed in the integrated-internal pathway, global warming potential is 97% lower, terrestrial acidification is 20% lower, and particulate matter formation is 49% lower. Nevertheless, this pathway has high coal and hydroelectrical power consumption due to electricity production and high emissions of particulate matter, CO2, SOx, and N2O. Another drawback of this production pathway is the low yield of diesel obtained (38% lower than in distributed-external pathway). With this regard, it is still hard to designate production of diesel from fast pyrolysis of Miscanthus as a more environmentally friendly replacement of the conventional production diesel pathway

Radionuclide Immobilization by Sorption onto Waste Concrete and Bricks—Experimental Design Methodology

The utilization of construction and demolition waste materials for the radionuclide immobilization by sorption processes was investigated. Given that the liquid radioactive waste usually has a complex composition and that effects of competition may significantly influence the efficiency of the treatment, the Simplex Centroid experimental design was used to explore ions sorption from multi-component solutions. For the purpose of this study, the common components of construction and demolition waste, such as pathway concrete and different bricks samples, were used along with the multi-component Sr2+, Co2+, and Ni2+ ions solutions. The equations for the prediction of metal ions sorption capacities were derived. The coefficients that correspond to the linear and interaction terms were obtained using a special cubic model. Likewise, by analysis of variance, statistically significant terms of the obtained polynomial were defined. The investigation has shown that the most effective sorption was onto the pathway concrete for all three cations, while the highest sorption capacity was found for Co2+ ions. Also, it has been determined that concerning Sr2+ ion removal there was a competition with coexisting Co2+ and Ni2+ ions, reducing its sorption capacity, while sorption of Co2+ and Ni2+ occurred more independently on other cations in multi-component solutions. Based on the obtained results, the applied experimental design can be efficiently used for the description of competitive sorption process and could be a powerful tool for the prediction of cation immobilization in liquid radioactive waste treatment

Utilization of waste ceramics and roof tiles for radionuclide sorption

The possible utilization of waste ceramic (CT) and roof tiles (RT), as sorbents for liquid radioactive waste (LRW) treatment, was investigated. Following the European directives on waste and politics of saving natural raw materials, it is reasonable and desirable to explore potential applicability of such construction wastes. These materials are lowcost and locally available in high quantities, yet, their sorption characteristics were not evaluated to this point. In the present study, detailed physicochemical characterization of waste CT and RT included determination of mineral composition, surface functional groups, radioactivity, as well as the stability in aqueous media. The batch sorption study of Sr2+, Co2+ and Ni2+ ions from single- and multi-component solutions was performed, as their radioactive isotopes are common constituents in LRW. Sorption equilibrium was best described by Freundlich isotherm model, regardless of the sorbent and the sorbate type. Sorption capacities of CT, defined in single element solutions, increased in the order 0.035 mmol Sr/g LT 0.12 mmol Ni/g LT 0.17 mmol Co/g, while the affinity of RT was generally lower (0.030 mmol Sr/g LT 0.065 mmol Co/g LT 0.10 mmolNi/g). The study of competitive cation sorption was performed following a simplex centroid experimental design matrix. The equations for the prediction of metal sorption capacities from multi-component solution were derived. Utilization of CT and RT might be an efficient way for waste water purification, with simultaneous reduction in construction waste amount on municipal landfills. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved

The applicability of construction and demolition waste components for radionuclide sorption

Following the guiding 3R principle of sustainable development (Reduce, Reuse and Recycle), the potential applicability concerning various components of construction and demolition waste (C and DW) was investigated for radionuclide sorption (Sr, Co, Ni). Collected samples of waste concrete, facade, bricks and asphalt were characterized in respect to mineralogical and surface composition, pH and radioactivity, while their sorption capacities were determined in batch conditions. Selectivity of potential sorbents differed in respect to Co2+ and Ni2+ ions, whereas sorption of Sr2+ was generally low. Concrete and facade have demonstrated both: the highest sorption capacities and the strongest interaction with the investigated cations, as revealed by sequential extraction analysis of loaded sorbents. Taking into account chemical compatibility with mixtures, commonly used for the solidification of radioactive waste, and expressed high affinity for studied cations, waste cement materials and debris are promising matrices for radionuclide immobilization. (C) 2017 Elsevier Ltd. All rights reserved

Generation and management of medical waste in Serbia: A review

This study presents generation, quantities and medical waste (MW) management in Serbia. It represents assessment methods and total annual MW generation by categories. It was concluded that pharmaceutical (64%) and infectious (32%) MW production is the largest. According to available data, MW management in Serbia is currently at low level, except when it comes to infectious waste. Research proposed simpler treatment methods in existing autoclaves and complex methods (incineration and plasma-pyrolysis), as well as short-term and long-term solutions. Predicted MW growing amount requires existing capacity increase for processing and new solutions application. Installed autoclaves capacity could be increased by increasing working time, in order to avoid additional investment. However, treatment in autoclave is only suitable for infectious MW. For other medical waste, which main fractions are pharmaceutical and chemical waste, there is no infrastructure. As temporary solution, pharmaceutical waste is treated abroad which in longer period is not financially feasible. Considering that MW treatment in Serbia currently is based on health facilities network equipped with autoclaves, as central (CTF) and local (LTF) treatments facilities for infectious waste treatment, it is recommended additional capacity implementation for treatment of non-infectious waste to this network, with simultaneous management level optimization of whole MW