Abstract: In this study a direct-mode fuel cell in which the fuel and electrolyte are mixed with each other is tested. An alkaline electrolyte is used. The direct-mode fuel cell is exposed to an externally generated electromagnetic field between electrodes to cause both the splitting of the fuel molecule into smaller units (i.e. electrochemical reforming) and an increase in the activity of catalyst materials on the fuel before electrochemical oxidation. The target is to create a fuel cell with a capacity range of a few mW cm−2 with glucose as a fuel. In the selected fuel cell type with glucose as the fuel, a maximum current density of 13 mA cm−2 was obtained. On the basis of the tests it seems to be possible to use the glucose-fuelled cell in small-scale applications, e.g. in small electronic devices.
Abstract: In this study a direct-mode fuel cell in which the fuel and electrolyte are mixed with each other is tested. An alkaline electrolyte is used. The aim was to develop a fuel cell which operates directly by mixing the fuel with the electrolyte. The target is to create a fuel cell with a capacity of a few mW cm−2 with starch as a fuel source. Starch, glucose, and sorbitol were tested as fuels for the fuel cell. With the selected fuel cell type and with glucose as the fuel, a maximum current density of 8 mA cm−2 with a voltage of 0.5 V was obtained.
Abstract: In this study a test of the direct-mode bioorganic fuel cell (DMBFC) in which the fuel and the alkaline electrolyte are mixed with each other at two temperatures of 20 and 35 oC are carried out. The direct-mode bioorganic fuel cell is exposed to an externally generated electromagnetic field with simultaneous discharging in order to split the fuel molecule before the electrochemical oxidation at the two operation temperatures. The current-voltage characteristics are measured and analyzed. The liquid phase of the fuel-electrolyte concentration of the glucose was analysed both before and after the electrochemical tests at the operation temperature 20 oC. The aim is to continue with the development of the direct-mode glucose fuel cell by increasing the power density range by several mWcm-2. This type of the fuel cell with glucose as a fuel has increased to the specific capacity levels of 120.8 and 132.7 Ah / kg glucose at the temperatures of 20 oC and 35 oC, respectively.
Abstract: The use of glucose, which is produced from the acid hydrolysis of starch and cellulose, is studied as a fuel in a low-temperature direct-mode fuel cell (LTDMFC) with an alkaline electrolyte. Glucose is regarded as being as good a fuel as bioethanol, because both the fuels give 2 electrons per molecule in the fuel cell without carbonisation problems. However, glucose can be produced with fewer processing stages from starch and cellulose than can bioethanol. In the LTDMFC the fuel and the electrolyte are mixed with each other and the fuel cell is equipped only with metal catalysts. Cellulose as a fuel is of great importance because the fuel for the energy production is not taken from food production. A description of an acid hydrolysis method for starch and cellulose is presented. Values for glucose concentrations in each hydrolysate are analysed by means of a chromatographic method. Each glucose hydrolysate was made alkaline by adding of potassium hydroxide before feed in the fuel cell. Polarisation curves were measured, and they were found to produce lower current density values when compared to earlier tests with pure glucose. The Coulombic efficiency of pure glucose electrochemical oxidation in LTDMFC, which was calculated from a ratio of detected current capacity (As) to the maximum current capacity with the release of two electrons per molecule, was also found to be very low. Concerning the hydrolysates, the glucose concentrations were found to have values that were too low when compared to the earlier tests with pure glucose in a concentration of 1 M. The further development demands for the system under consideration are indicated. The concentration of glucose in the hydrolysate is essential to achieve high enough current density values in the LTDMFC.
Abstract: This paper deals with the kind of the bioorganic fuel cells that are equipped with or without ion exchange membranes. The bioorganic materials of interest are alcohols (methanol, ethanol) and glucose, which are obtained from renewable energy sources such as biomass. The operation temperatures of the direct fuel cells cover from room temperature up to 150 °C. The direct bioorganic fuel cells belong to the subject area of ‘Advanced fuel cells’ of the Working group 4 in the EU COST Action 543 among the collaborating Universities and Institutes. Bioorganic fuel cells are suitable for application in small portable power sources, such as backups, battery chargers and in electronic devices. A number of current and earlier works are summarised and advances are highlighted in this area with special emphasis on glucose as a fuel.
Abstract: In the present study, a direct-mode glucose fuel cell with a neutral-state and near-neutral-state aqueous electrolytes is studied. The near-neutral state electrolytes are important for two reasons. Firstly, the pH of the electrolytes would be near the pH of liquid in living cells. Secondly, the neutral electrolyte would enable good corrosion resistance of catalyst materials. Three different catalyst materials, i.e. Pt-Pd, Raney-Ni and Ni-porphyrin complex, are tested in an anode half-cell configuration with one neutral-state (battery water) and with two near-neutral-state aqueous electrolytes, i.e. modified Krebs-Ringer (K-R) and phosphate, both buffered to a pH value of 7.4. Pt-Pd catalyst in the aqueous K-R electrolyte maintains the negative voltage of the anode half cell with higher current densities that the nickel catalysts do. To estimate the operation of the direct-mode glucose fuel cell, the K-R electrolyte from the anode half-cell tests is tested also in the cathode half-cell with combined catalyst of cobalt porphyrin complex and of spinel. The open circuit voltages and polarisation curves are measured. Also, preliminary results and oxidation degrees of glucose in the tests are shown. Based on our half cell measurements, there are high development demands for the electro-catalysts, which could work efficiently in the near-neutral-state electrolytes.
Notes: Pls note! There remained many harmfull writing errors in the published paper.
Abstract: This study deals with the R&D regarding the direct glucose fuel cell with a capacity of increasing the power density with glucose as a fuel. The direct-mode fuel cell in which the fuel and the alkaline electrolyte are mixed with each other is tested at room temperature. The direct-mode fuel cell is exposed to an externally generated electromagnetic field with 4 GHz sine signals between electrodes to cause both the splitting of the fuel molecule and the electrochemical oxidation. As a result from the use of the higher frequency signals, a maximum current density of 15 mAcm-2 has been achieved with the total voltage of 0.5 V.
Abstract: This paper is a study about a direct mode fuel cell with a near-neutral-state and alkaline electrolytes. The aim of study was to develop a fuel cell, which operates directly by mixing the fuel with the electrolyte. This arrangement helps to avoid inserting membranes and additional bacterial cultures in fuel cell. The target is also to create a fuel cell with a capacity of few mWcm-2 with the starch as a fuel. Also, glucose and sorbitol have been tested as fuel for the fuel cell.
Abstract: Organic emissions during the thermal drying process are strongly dependent on the drying temperature. In the traditional single stage drying system, the inlet temperature of the drying air has to be relatively high in order to keep the airflow for drying small. In the multistage drying system, the drying airflow is heated up again after the first drying stage with higher moisture content, and then again after the second, and subsequent drying stages. In this method, the drying temperatures are limited in all stages to acceptable low levels, and only the moisture content of the drying air is increasing from one stage to another. As a result the multistage drying system has a lower drying temperature. We have studied the dependence of the organic emissions on the drying temperature, and present the results from drying units operating at temperatures of 100-200°C and below 100°C. The results are compared to previous measurements found in the literature. The estimates for the emissions at higher drying temperatures are derived from the literature values.
Abstract: In biofuel drying in industrial power plants, a new multistage drying system (MSDS) can now be applied before combustion. By reducing the drying air mass flow, MSDS makes it possible to use a proportion of the combustion air in drying, and to lead that moist drying air into the combustion stages of the power plant boiler. MSDS increases the power-to-heat ratio and capacity of the power plant compared to power plants without drying systems. Previous increases came from biofuel homogenization and increased energy efficiency. Biofuel homogenization also reduces unburned organic emissions as a result of more complete combustion.
Abstract: The drying of moist biofuels such as wood-based biomasses should be as effluent-free and as energy-efficient as possible in order to ensure the safe and economical operation of industrial CHP plants. This work presents a multistage drying system (MSDS), which provides significant benefits in comparison with earlier conventional single dryer systems. This new application is installed most promisingly in integrated pulp and paper mills. The MSDS, which simultaneously uses secondary process energy, as well as backpressure and extraction steam as the drying energy, enables a smaller volume flow of drying air than single dryer systems. Depending on the structure of the system, up to 100 % of the exhaust drying air can be utilized as combustion air. The use of MSDSs enables an increase in CHP plant boiler capacity, which in turn boosts the production of power and heat in combined heat and power (CHP) plants. Additionally, the improvement in CHP can be achieved with reduced organic emissions from moist biomass drying. Also, the amount of unburned organic compounds and of CO in flue gases from combustion is reduced as a result of the improved quality of the biofuels. When compared to direct steam drying, the MSDS also better minimizes, or even eliminates, the formation of organically loaded condensates in the drying operation.
