• Journal of Hydrogen and New Energy
• /
• v.28 no.4
• /
• pp.426-432
• /
• 2017

Hydrothermal carbonization (HTC) is an effective and environment friendly technique; it possesses extensive potential towards producing high-energy density solid fuels. it is a carbonization method of thermochemical process at a relatively low temperature ($180-250^{\circ}C$). It is reacted by water containing raw material. However, the production and quality of solid fuels from HTC depends upon several parameters; temperature, residence time, and pressure. This study investigates the influence of operating parameters on solid fuel production during HTC. Especially, when food waste was reacted for 2 hours, 4 hours, and 8 hours at $200^{\circ}C$ and 2.0-2.5 MPa, Data including heating value, proximate analysis and water content was consequently collected and analyzed. It was found that reaction temperature, residence time are the primary factors that influence the HTC process.

• New & Renewable Energy
• /
• v.10 no.2
• /
• pp.12-18
• /
• 2014

The objective of this work is to produce solid biofuel from sawdust using the HTC (Hydrothermal carbonization) process. The HTC process of feedstock involves the raw material coming into contact with high temperature and pressurized water. The HTC process could produce gaseous, liquefied and solid products, but this study focused on solid product only as an alternative to coal. In this study, sawdust used for a feedstock and its moisture content was under 5%. Water was added with the feedstock to raise moisture content to 80% and also used catalysts. The HTC process was performed at temperature range from 200 to $270^{\circ}C$ and reaction time was 15 to 120 min. Rising temperature resulted in increasing the higher heating value (HHV) of HTC product. In case of adding catalyst, HHV of solid biofuel was higher and reaction occurred at lower temperature and pressure. Also, HTC solid product had been characterized and found to be hydrophobic, increased HHV (over 40%), and pelletized easily compared to raw material.

• Journal of Soil and Groundwater Environment
• /
• v.19 no.5
• /
• pp.45-52
• /
• 2014

Torrefaction and hydrothermal carbonization (HTC) are productive methods to reclaim energy from lignocellulosic biomass. The hydrophobic, homogenized, energy dense and carbon rich solid fuel can be obtain from torrefaction and hydrothermal carbonization. Dead leaves were carbonized in a stainless steel reactor of volume 200 ml with torrefaction ($250-270^{\circ}C$) for 120 minutes and hydrothermal carbonization ($200-250^{\circ}C$) for 30 minutes, with mass yield solid fuel ranging from 57-70% and energy content from 16.81MJ/kg to 22.01 MJ/kg compare to the biomass. The char produced from torrefaction process possess high energy content than hydrothermal carbonization. The highest energy yield of 89.96% was obtained by torrefaction at $250^{\circ}C$. The energy densification ratio fluctuated in between 1.15 to 1.30. On the basis of pore size distribution of the chars, the definition of the International Union of Pure and Applied Chemistry (IUPAC) was used as a classification standard. The pore diameter was ranging within 11.09-19 nm which play important role in water holding capacity in soil. Larger pores can hold water and provide passage for small pores. Therefore, it can be concluded that high pore size char can be obtained my HTC process and high energy content char of 22.01 MJ/Kg with 34.04% increase in energy can be obtain by torrefaction process.

• Journal of the Korean Society for Heat Treatment
• /
• v.28 no.6
• /
• pp.300-309
• /
• 2015

The aim of the present study was to predict the variations in microstructure and deformation occurring during gas carburizing and quenching processes of a SCM420H planetary gear in a real production environment using the finite element method (FEM). The motivation for the present study came from the fact that previous FEM simulations have a limitation of the application to the real heat treatment process because they were performed with material properties provided by commercial programs and heat transfer coefficients (HTC) measured from laboratory conditions. Therefore, for the present simulation, many experimentally measured material properties were employed; phase transformation kinetics, thermal expansion coefficients, heat capacity, heat conductivity and HTC. Particularly, the HTCs were obtained by converting the cooling curves measured with a STS304 gear without phase transformations using an oil bath with an agitator in a real heat treatment factory. The FEM simulation was successfully conducted using the aforementioned material properties and HTC, and then the predicted results were well verified with experimental data, such as the cooling rate, microstructure, hardness profile and distortion.

• Applied Chemistry for Engineering
• /
• v.33 no.1
• /
• pp.28-37
• /
• 2022

The lignite and bituminous coal are mainly used in thermal power plant. They exhaust green house gas (GHG) such as CO₂, and become deplete, thus require alternative energy resources. To solve the problem, the hydrochar production from biomass is suggested. In this study, both hydrothermal carbonization (HTC) and solvothermal carbonization (STC) were used to produce high quality hydrochar. To improve the reactivity of water solvent process in HTC, STC process was conducted using ethanol solution. The experiments were carried out by varying the solid-liquid ratio (1:4, 1:8, 1:12), reaction temperature (150~300 ℃) and retention time (15~120 min) using kenaf. The characteristic of hydrochar was analyzed by EA, FT-IR, TGA and SEM. The carbon content of hydrochar increased up to 48.11%, while the volatile matter decreased up to 39.34%. Additionally, the fuel characteristic of hydrochar was enhanced by reaction temperature. The results showed that the kenaf converted to a fuel by HTC and STC process, which can be used as an alternative energy source of coal.

• Carbon letters
• /
• v.25
• /
• pp.103-112
• /
• 2018

Hierarchically porous, chemically activated carbon materials are readily derived from biomass using hydrothermal carbonization (HTC) and chemical activation processes. In this study, empty fruit bunches (EFB) were chosen as the carbon source due to their sustainability, high lignin-content, abundance, and low cost. The lignin content in the EFB was condensed and carbonized into a bulk non-porous solid via the HTC process, and then transformed into a hierarchical porous structure consisting of macro- and micropores by chemical activation. As confirmed by various characterization results, the optimum activation temperature for supercapacitor applications was determined to be $700^{\circ}C$. The enhanced capacitive performance is attributed to the textural property of the extremely high specific surface area of $2861.4m^2\;g^{-1}$. The prepared material exhibited hierarchical porosity and surface features with oxygen functionalities, such as carboxyl and hydroxyl groups, suitable for pseudocapacitance. Finally, the as-optimized nanoporous carbons exhibited remarkable capacitive performance, with a specific capacitance of $402.3F\;g^{-1}$ at $0.5A\;g^{-1}$, a good rate capability of 79.8% at current densities from $0.5A\;g^{-1}$ to $10A\;g^{-1}$, and excellent life cycle behavior of 10,000 cycles with 96.5% capacitance retention at $20A\;g^{-1}$.

• Journal of Soil and Groundwater Environment
• /
• v.21 no.1
• /
• pp.22-27
• /
• 2016

Hydrothermal carbonization (HTC) is a carbonization method of thermochemical process at a relatively low temperature (180-250℃). It is reacted by water containing raw material. In this study, it was selected for effective disposal method of food waste because food waste in Korea has large amount water. 5 kg, 10 kg, 15 kg of food waste were reacted for 6 hours at 200℃ for selecting the optimum amount of raw material. Since the derived optimum amount, food waste was reacted for 2 hours, 4 hours and 6 hours at 200℃ and 1.5 MPa. After carbonization, it was analyzed to evaluated the properties by ultimate analysis, iodine adsorption, BET surface area and SEM. After analyzing the characteristics, it can be utilized as a basic data for applied.

• Journal of Appropriate Technology
• /
• v.7 no.1
• /
• pp.59-71
• /
• 2021

Hybrid hydrothermal carbonization (Hybrid HTC) technology is a proprietary thermochemical process for two or more organic wastes.The reaction time is less than two hours with temperature range 180~250℃ and pressure range 20~40bar. Thanks to accumulation of the carbon of the waste during Hybrid HTC process, the energy value of the solid fuel increases significantly with comparatively low energy consumption. It has also a great volume reduction with odor removal effect so that it is evaluated as the best solid fuel conversion technology for various organic wastes. In this study of the hybrid hydrothermal carbonization, the effect on the calorific value and yield of Cambodian mango waste were evaluated according to changes in temperature and reaction time. Through the study, parameter optimization has been sought with improving energy efficiency of the whole plant. It is decomposed in the Hydro-Carbonation Technology to Generate Gas. At this time, it is possible to develop manufacturing and production technologies such as hydrogen (H₂) and methane (CH₄). Based on the results of the study, a pilot plant (2t/day) has been proposed for future commercialization purpose along cost analysis, mass balance and energy balance calculations.

• Journal of Soil and Groundwater Environment
• /
• v.19 no.1
• /
• pp.1-7
• /
• 2014

When processing the biomass by Hydrothermal carbonization (HTC), a slow pyrolysis process, it produces bio-gas, biooil, and biochar. Among these end products, biochar is known for isolating or storing carbon and being used as a soil amendment. In this study, the characteristics of biochar generated by HTC at $250^{\circ}C$ for 1 hour, 2 hours, 3 hours, and 20 hours with synthetic food wastes and wood wastes were analyzed for potential uses in soil contaminated with heavy metals. The yield of biochar (weight %) increased when the ratio of wood wastes increased and showed a decreasing tendency as reaction time increased. Elemental analysis of biochar based on various conditions showed a maximum of 70% carbon (C) content. The carbon content showed an increasing tendency with the increase of wood wastes. Iodine adsorption test was peformed to determine the optimum reaction condition, which was 15% wood waste for mixing ratio and 2 hours for reaction time. Using biochar generated at the optimum condition, its capability of adsorbing heavy metals (Cd, Cu, Pb, Zn, Ni) was evaluated. It was concluded that lead (Pb) was removed efficiently while zinc (Zn) and nickel (Ni) were hardly adsorbed by biochar.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.14 no.1
• /
• pp.19-27
• /
• 2006

The characteristics of heat transfer and pressure drop have been investigated experimentally during gas-cooling process of carbon dioxide. The results of this study are useful information in the design of a heat exchanger of $CO_2$ refrigerator. The test section consists of 6 series of copper tube, 4.15 and 2.18mm ID, respectively. The inlet temperature, the operating pressure, and the mass flux are varied in the range of $80{\sim}120^{\circ}C,\;{7\sim}10MPa,\;and\;400{\sim}1,900kg/m^2s$, respectively. The heat transfer coefficient of $CO_2$ is affected by temperature, inlet pressure, and mass flux of $CO_2$. At the maximum HTC, the temperature of $CO_2$ nearly accords with the psuedocritical temperature. It is found that the pressure drop is substantially affected by mass flux and inlet pressure of $CO_2$ . The results have been compared with those of previous work. The heat transfer correlation at the gas-cooling process has been also suggested which predicts within the error of 20%.