• Energy Research

The synergistic effect of co-pyrolysis for the mixtures of sewage sludge (SS), rice straw (RS) and composite plastic wastes (PE&PP) has been investigated with the aim of high gas yields and hydrogen generation. In this context, the applicability of high temperature pyrolysis technology was evaluated at both rotary type batch reactor and rotating screw type continuous reactor operating under the industrially relevant conditions. Gas yields have been improved at increasing the operating temperatures up to 850 °C. The gas yield of 75.06 % with its H2 portion of 32.35 % has been achieved as the best results for continuous pyrolysis unit at pilot scale. Secondary reactions such as steam de-alkylation, steam cracking, water gas shift and so on were regarded as being responsible for the high gas yields when the primary products of pyrolysis, i.e. condensable vapors, were much exposed to the hot zones inside the reactor. The dehydration of organic components involving the loss of water may supply steam to create a reactive pyrolysis atmosphere. While the pyrolysis of sewage sludge and rice straw favors CO and CO2 formation due to the high oxygen contents of these feedstocks, more methane and light olefins were produced when the plastics were added to the feedstock blends. This was ascribed to the initially generated radicals from the decomposition of sewage sludge and/or rice straw that might promote the scission reactions of plastics towards volatiles. It was shown that high temperature pyrolysis can be applied to a variety of organic wastes such as rice straw, sewage sludge and waste plastics. Conversion of wastes to hydrogen fosters the circular economy by putting the disposal costs down and creates a new route on renewable hydrogen generation.

The synergistic effect of co-pyrolysis for the mixtures of sewage sludge (SS), rice straw (RS) and composite plastic wastes (PE&PP) has been investigated with the aim of high gas yields and hydrogen generation. In this context, the applicability of high temperature pyrolysis technology was evaluated at both rotary type batch reactor and rotating screw type continuous reactor operating under the industrially relevant conditions. Gas yields have been improved at increasing the operating temperatures up to 850 °C. The gas yield of 75.06 % with its H2 portion of 32.35 % has been achieved as the best results for continuous pyrolysis unit at pilot scale. Secondary reactions such as steam de-alkylation, steam cracking, water gas shift and so on were regarded as being responsible for the high gas yields when the primary products of pyrolysis, i.e. condensable vapors, were much exposed to the hot zones inside the reactor. The dehydration of organic components involving the loss of water may supply steam to create a reactive pyrolysis atmosphere. While the pyrolysis of sewage sludge and rice straw favors CO and CO2 formation due to the high oxygen contents of these feedstocks, more methane and light olefins were produced when the plastics were added to the feedstock blends. This was ascribed to the initially generated radicals from the decomposition of sewage sludge and/or rice straw that might promote the scission reactions of plastics towards volatiles. It was shown that high temperature pyrolysis can be applied to a variety of organic wastes such as rice straw, sewage sludge and waste plastics. Conversion of wastes to hydrogen fosters the circular economy by putting the disposal costs down and creates a new route on renewable hydrogen generation.

The aim of this study was to examine the risk of heavy metal, ammonia and sulfate transition from underground coal gasification (UCG) chars and process water of Malkara lignite to the groundwater around the UCG cavity. The residues were collected during laboratory-scale underground coal gasification studies of Malkara lignite in ex situ gasification simulator. In order to compare gasification with combustion in terms of water pollution, ash samples were obtained by combustion of Malkara lignite. To determine the leaching behavior of the char and ash samples, two leaching tests (EPA TCLP and EN 12457-2 methods) were applied. The concentration of heavy metals in char, ash and process water samples was determined by ICP-OES. Additionally, ammonia and sulfate analyses were conducted for process water. Based on the results of this study, it has been found that the concentration of some elements, such as B, Sb and Al in char and ash eluates exceeded the maximum level of drinking water standards. However, there is no landfill concern about char samples according to EU Landfill Directive. A significant increase in B concentration was observed in ash samples. Considering B and some other elements combustion residues were identified with much higher water contamination ability, compared to gasification residues. Ammonia concentration was observed extremely high in process water of the gasification tests. UCG technique may be more environmentally applicable technology compared to combustion for Malkara lignite reserves. However, further detailed studies are necessary in the early stage of the UCG field test design and application.

The aim of this study was to examine the risk of heavy metal, ammonia and sulfate transition from underground coal gasification (UCG) chars and process water of Malkara lignite to the groundwater around the UCG cavity. The residues were collected during laboratory-scale underground coal gasification studies of Malkara lignite in ex situ gasification simulator. In order to compare gasification with combustion in terms of water pollution, ash samples were obtained by combustion of Malkara lignite. To determine the leaching behavior of the char and ash samples, two leaching tests (EPA TCLP and EN 12457-2 methods) were applied. The concentration of heavy metals in char, ash and process water samples was determined by ICP-OES. Additionally, ammonia and sulfate analyses were conducted for process water. Based on the results of this study, it has been found that the concentration of some elements, such as B, Sb and Al in char and ash eluates exceeded the maximum level of drinking water standards. However, there is no landfill concern about char samples according to EU Landfill Directive. A significant increase in B concentration was observed in ash samples. Considering B and some other elements combustion residues were identified with much higher water contamination ability, compared to gasification residues. Ammonia concentration was observed extremely high in process water of the gasification tests. UCG technique may be more environmentally applicable technology compared to combustion for Malkara lignite reserves. However, further detailed studies are necessary in the early stage of the UCG field test design and application.

Abstract High-chain fatty acid esters have not been investigated for their thermal properties as phase change materials (PCMs) in thermal energy storage. A series of high-chain fatty acid esters of myristyl alcohol (1-tetradecanol) were synthesized via esterification of lauric, myristic, palmitic, stearic and arachidic acids under vacuum and in the absence of any catalyst. The esterification reactions were studied by FT-IR spectroscopy. A differential scanning calorimeter (DSC) and a thermo-gravimetric analyzer (TGA) were intensively used to determine the thermal properties of the introduced thermal storage materials. The thermal properties were given in terms of phase change temperature, enthalpy, specific heat (Cp) and thermal decomposition temperature with related statistical data. The thermal reliability of the novel organic PCMs was investigated by thermal cycling with 1000 thermal cycles with respect to the thermal properties of the original synthesized PCMs. In addition to the synthesized esters, one commercial product was also investigated. The DSC analyses indicated that the melting points of the novel organic PCMs were between 38 and 53 °C with phase change enthalpy above 200 kJ/kg. The effect of chemical structure of the materials on thermal properties was also discussed. The results showed that these materials were favorable for low temperature heat transfer applications with superior thermal properties and reliability.

Abstract High-chain fatty acid esters have not been investigated for their thermal properties as phase change materials (PCMs) in thermal energy storage. A series of high-chain fatty acid esters of myristyl alcohol (1-tetradecanol) were synthesized via esterification of lauric, myristic, palmitic, stearic and arachidic acids under vacuum and in the absence of any catalyst. The esterification reactions were studied by FT-IR spectroscopy. A differential scanning calorimeter (DSC) and a thermo-gravimetric analyzer (TGA) were intensively used to determine the thermal properties of the introduced thermal storage materials. The thermal properties were given in terms of phase change temperature, enthalpy, specific heat (Cp) and thermal decomposition temperature with related statistical data. The thermal reliability of the novel organic PCMs was investigated by thermal cycling with 1000 thermal cycles with respect to the thermal properties of the original synthesized PCMs. In addition to the synthesized esters, one commercial product was also investigated. The DSC analyses indicated that the melting points of the novel organic PCMs were between 38 and 53 °C with phase change enthalpy above 200 kJ/kg. The effect of chemical structure of the materials on thermal properties was also discussed. The results showed that these materials were favorable for low temperature heat transfer applications with superior thermal properties and reliability.

We present the results of a dispersion-modelling study of SO2 concentrations in Gebze, Turkey. Point and area sources were investigated and SO2 emissions were compiled. Emissions, meteorological and topographical data were loaded on the USEPA-approved ISCLT model to predict winter average SO2 contributions to the air quality over Gebze. The effects of fuel-change options on these contributions were investigated.