Study of NiO cathode modified by ZnO additive for MCFC

The preparation and subsequent oxidation of nickel cathodes modified by impregnation with zinc oxide (ZnO) were evaluated by surface and bulk analysis. The electrochemical behaviors of ZnO impregnated NiO cathodes was also evaluated in a molten 62 mol% Li₂CO₃ + 38 mol% K₂CO₃ eutectic at 650 °C by electrochemical impedance spectroscopy (EIS) as a function of ZnO content and immersion time. The ZnO impregnated nickel cathodes showed the similar porosity, pore size distribution and morphology to the reference nickel cathode. The stability tests of ZnO impregnated NiO cathodes showed that the ZnO additive could dramatically reduce the solubility of NiO in a eutectic carbonate mixture under the standard cathode gas condition. The impedance spectra for cathode materials show important variations during the 100 h of immersion. The incorporation of lithium in its structure and the low dissolution of nickel oxide and zinc oxide are responsible of these changes. After that, the structure reaches a stable state. The cathode material having 2 mol% of ZnO showed a very low dissolution and a good catalytic efficiency close to the NiO value. We thought that 2 mol% ZnO/NiO materials would be able to adapt as alternative cathode materials for MCFCs.     

A stabilized NiO cathode prepared by sol-impregnation of LiCoO2 precursors for molten carbonate fuel cells

Layers of LiCoO₂ were formed on the internal surface of a porous NiO cathode to reduce the rate of NiO dissolution into the molten carbonate. A sol-impregnation technique assisted by acrylic acid (AA) was used to deposit gel precursors of LiCoO₂ on the pore surface of the Ni plate. Thermal treatment of the gel-coated cathode above 400 °C produced LiCoO₂ layers on the porous cathode. A number of bench-scale single cells were fabricated with LiCoO₂-coated cathodes and the cell performance was examined at atmospheric pressure for 1000 h. With the increase in the LiCoO₂ content in the cathode, the initial cell voltage decreased, but the cell performance gradually improved during the cell test. It was found from symmetric cathode cell test that the cathode was initially flooded with electrolyte, but redistribution of the electrolyte took place during the test and cell performance became comparable to that of a conventional NiO cathode. The amount of Ni precipitated in the matrix during the cell operation for 1000 h was significantly reduced by the LiCoO₂ coating. For instance, coating 5 mol% of LiCoO₂ in the cathode led to a 56% reduction of Ni precipitation in the matrix. The results obtained in this study strongly suggest that LiCoO₂ layers formed on the internal surface of the porous NiO cathode effectively suppress the rate of NiO dissolution for 1000 h.     

In situ screen-printed BaZr0.1Ce0.7Y0.2O3−δ electrolyte-based protonic ceramic membrane fuel cells with layered SmBaCo2O5+x cathode

In order to develop a simple and cost-effective route to fabricate protonic ceramic membrane fuel cells (PCMFCs) with layered SmBaCo₂O_5+x (SBCO) cathode, a dense BaZr_0.1Ce_0.7Y_0.2O_3?δ (BZCY) electrolyte was fabricated on a porous anode by in situ screen printing. The porous NiO–BaZr_0.1Ce_0.7Y_0.2O_3?δ (NiO–BZCY) anode was directly prepared from metal oxide (NiO, BaCO₃, ZrO₂, CeO₂ and Y₂O₃) by a simple gel-casting process. An ink of metal oxide (BaCO₃, ZrO₂, CeO₂ and Y₂O₃) powders was then employed to deposit BaZr_0.1Ce_0.7Y_0.2O_3?δ (BZCY) thin layer by an in situ reaction-sintering screen printing process on NiO–BZCY anode. The bi-layer with 25 μm dense BZCY electrolyte was obtained by co-sintering at 1400 °C for 5 h. With layered SBCO cathode synthesized by gel-casting on the bi-layer, single cells were assembled and tested with H₂ as fuel and the static air as oxidant. A high open-circuit potential of 1.01 V, a maximum power density of 382 mW cm^?2, and a low polarization resistance of the electrodes of 0.15 Ω cm² was achieved at 700 °C.     

Natural convective heat transfer of heated packed beds

Natural convection heat transfer of heated packed bed was investigated. Experiments were performed for a single heated sphere buried in unheated packed beds varying its locations and for packed beds with all heated spheres varying the heights of packed beds from 0.02 m to 0.26 m. Mass transfer experiments using a copper electroplating system were performed based upon the analogy between heat and mass transfer. The diameter of sphere was 0.006 m, which corresponds to Ra_d of 1.8 × 10⁷. For the single heated sphere cases, the measured results agreed well with the existing natural convection heat transfer correlations for packed beds and even with those for a single sphere in an open channel. For all heated sphere cases, the average heat transfers decrease with increasing packed bed heights.     

Construction of fuel reformer using proton conducting oxides electrolyte and hydrogen-permeable metal membrane cathode

We constructed a reformer of methane based on an electrochemical principle. This apparatus consists of the proton conducting ceramics electrolyte and the hydrogen-permeable metal membrane cathode. For methane reforming, a mixture of methane and oxygen gas is supplied to the porous Ag cathode. The hydrogen ions, which formed by the anode reaction: CH₄ + O₂ → CO₂ + 4H⁺ + 4e⁻, are transported through the proton conducting ceramics to the cathode. Then, the hydrogen is formed at the cathode by the reaction: 4H⁺ + 4e⁻ → 2H₂. The hydrogen, which permeates through the metal membrane cathode, is 100% purity.The hydrogen separation ability of the reformer was investigated at 400–650 °C by measuring the electric current through the proton conducting oxide electrolyte. Since the ionic transport number of the proton conducting oxide is nearly unity, the current through the electrolyte corresponds to the proton flux through the electrolyte.The current measurements showed that the extracted proton flux through the electrolyte increased with increasing the applied voltage as well as temperature as we expected. However, the current measurements under the low voltage revealed that the extracted current was lesser than the expected value from Ohm's law. The decrease of the current is possibly caused for the reduction of the effective voltage by the anode polarization. In order to separate the hydrogen with higher efficiency, the applied voltage must be as low as possible using the thinner electrolyte and the improved anode.     

100 t/a-Scale demonstration of direct dimethyl ether synthesis from corncob-derived syngas

Direct conversion of biomass-derived syngas (bio-syngas) to dimethyl ether (DME) at pilot-scale (100 t/a) was carried out via pyrolysis/gasification of corncob. The yield rate of raw bio-syngas was 40–45 Nm³/h with less than 20 mg/Nm³ of tar content when the feedrate of dried corncob was 45–50 kg/h. After absorption of O₂, S, Cl by a series of absorbers and partial removal of CO₂ by the pressure-swing adsorption (PSA) unit sequentially, the obtained bio-syngas (H₂/CO≈1) was directly synthesized to DME over Cu/Zn/Al/HZSM-5 catalyst in the fixed-bed tubular reactor. CO conversion and DME space-time yield (STY) were 67.7% and 281.2 kg/m_cat³/h respectively at 260 °C, 4.3 MPa and 3000 h^?1(GHSV, syngas hourly space velocity). Synthesis performance would be increased if the tail gas (H₂/CO > 2) was recycled to the reactor when GHSV was 650–3000 h^?1.     

Net carbon dioxide emissions from alternative firewood-production systems in Australia

The use of firewood for domestic heating has the potential to reduce fossil-fuel use and associated CO₂ emissions. The level of possible reductions depends upon the extent to which firewood off-sets the use of fossil fuels, the efficiency with which wood is burnt, and use of fossil fuels for collection and transport of firewood. Plantations grown for firewood also have a cost of emissions associated with their establishment. Applying the FullCAM model and additional calculations, these factors were examined for various management scenarios under three contrasting firewood production systems (native woodland, sustainably managed native forest, and newly established plantations) in low-medium rainfall (600–800 mm) regions of south-eastern Australia. Estimates of carbon dioxide emissions per unit of heat energy produced for all scenarios were lower than for non-renewable energy sources (which generally emit about 0.3–1.0 kg CO₂ kWh⁻¹). Amongst the scenarios, emissions were greatest when wood was periodically collected from dead wood in woodlands (0.11 kg CO₂ kWh⁻¹), and was much lower when obtained from harvest residues and dead wood in native forests (<0.03 kg CO₂ kWh⁻¹). When wood was obtained from plantations established on previously cleared agricultural land, use of firewood led to carbon sequestration equivalent to −0.06 kg CO₂ kWh⁻¹ for firewood obtained from a coppiced plantation, and −0.17 kg CO₂ kWh⁻¹ for firewood collected from thinnings, slash and other residue in a plantation grown for sawlog production. An uncertainty analysis, where inputs and assumptions were varied in relation to a plausible range of management practices, identified the most important influencing factors and an expected range in predicted net amount of CO₂ emitted per unit of heat energy produced from burning firewood.     

NiO–YSZ cermets supported low temperature solid oxide fuel cells

Solid oxide fuel cells with thin electrolyte of two types, Sm_0.2Ce_0.8O_1.9 (SDC) (15 μm) single-layer and 8 mol% Yttria stabilized zirconia (YSZ) (5 μm) + SDC (15 μm) bi-layer on NiO–YSZ cermet substrates were fabricated by screen printing and co-firing. A Sm_0.5Sr_0.5CoO₃ cathode was printed, and in situ sintered during a cell performance test. The SDC single-layer electrolyte cell showed high electrochemical performance at low temperature, with a 1180 mW cm⁻² peak power density at 650 °C. The YSZ + SDC bi-layer electrolyte cell generated 340 mW cm⁻² peak power density at 650 °C, and showed good performance at 700–800 °C, with an open circuit voltage close to theoretical value. Many high Zr-content micro-islands were found on the SDC electrolyte surface prior to the cathode preparation. The influence of co-firing temperature and thin film preparation methods on the Zr-islands’ appearance was investigated.     

Condensation from superheated vapor flow of R744 and R410A at subcritical pressures in a horizontal smooth tube

This paper presents experimentally determined heat transfer coefficients for condensation from a superheated vapor of CO₂ and R410A. The superheated vapor was flowed through a smooth horizontal tube with 6.1 mm ID under almost uniform temperature cooling at reduced pressures from 0.55 to 0.95, heat fluxes from 3 to 20 kW m^?2, and superheats from 0 to 40 K. When the tube wall temperature reaches the saturation point, the measured results show that the heat transfer coefficient gradually starts deviating from the values predicted by a correlation valid for single-phase gas cooling. This point identifies the start of condensation from the superheated vapor. The condensation starts earlier at higher heat fluxes because the tube wall temperature reaches the saturation point earlier. The heat transfer coefficient reaches a value predicted by correlations for condensation at a thermodynamic vapor quality of 1. The measured heat transfer coefficient of CO₂ is roughly 20–70% higher than that of R410A at the same reduced pressures. This is mainly because the larger latent heat and liquid thermal conductivity of CO₂, compared to that of R410A, increase the heat transfer coefficient.     

Performance and efficiency of a DMFC using non-fluorinated composite membranes operating at low/medium temperatures

In order to increase the chemical/thermal stability of the sulfonated poly(ether ether ketone) (sPEEK) polymer for direct methanol fuel cell (DMFC) applications at medium temperatures (up to 130 °C), novel inorganic–organic composite membranes were prepared using sPEEK polymer as organic matrix (sulfonation degree, SD, of 42 and 68%) modified with zirconium phosphate (ZrPh) pretreated with n-propylamine and polybenzimidazole (PBI). The final compositions obtained were: 10.0 wt.% ZrPh and 5.6 wt.% PBI; 20.0 wt.% ZrPh and 11.2 wt.% PBI. These composite membranes were tested in DMFC at several temperatures by evaluating the current–voltage polarization curve, open circuit voltage (OCV) and constant voltage current (CV, 35 mV). The fuel cell ohmic resistance (null phase angle impedance, NPAI) and CO₂ concentration in the cathode outlet were also measured. A method is also proposed to evaluate the fuel cell Faraday and global efficiency considering the CH₃OH, CO₂, H₂O, O₂ and N₂ permeation through the proton exchange membrane (PEM) and parasitic oxidation of the crossover methanol in the cathode. In order to improve the analysis of the composite membrane properties, selected characterization results presented in [V.S. Silva, B. Ruffmann, S. Vetter, A. Mendes, L.M. Madeira, S.P. Nunes, Catal. Today, in press] were also used in the present study. The unmodified sPEEK membrane with SD = 42% (S42) was used as the reference material. In the present study, the composite membrane prepared with sPEEK SD = 68% and inorganic composition of 20.0 wt.% ZrPh and 11.2 wt.% PBI proved to have a good relationship between proton conductivity, aqueous methanol swelling and permeability. DMFC tests results for this membrane showed similar current density output and higher open circuit voltage compared to that of sPEEK with SD = 42%, but with much lower CO₂ concentration in the cathode outlet (thus higher global efficiency) and higher thermal/chemical stability. This membrane was also tested at 130 °C with pure oxygen (cathode inlet) and achieved a maximum power density of 50.1 mW cm⁻² at 250 mA cm⁻².     

Study on a wire-type Joule Thomson microcooler with a concentric heat exchanger

This study examines the performance of a wire-type Joule Thomson microcooler utilizing a flexible concentric counterflow heat exchanger. Three gases: C₂H₄, CO₂ and N₂ were used separately for trials conducted at inlet pressures ranging from 0.5 MPa to 5 MPa with C₂H₄ having the best performance. During unloaded tests at an inlet pressure of 2.0 MPa, C₂H₄ obtained a minimum temperature of 225 K while CO₂ obtained a minimum temperature of 232 K. Using CO₂ the microcooler was able to maintain a temperature of 273 K at 100 mW heat input and 2 MPa inlet pressure. An inlet pressure of 3 MPa allowed a 550 mW heat input at 273 K. Theoretical performance calculations were conducted and compared to experimental results revealing considerable reduction of microcooler performance due to the presence of heat in-leak. Results have displayed that the JT coefficient of the coolant gas is a more dominant factor than heat transfer properties in determining the performance of the coolant. Due to the microscale of the device, relevant scaling effects were evaluated, particularly entrance effects, surface roughness and axial conduction.     

A study of Ni + 8YSZ/8YSZ/La0.6Sr0.4CoO3−δ ITSOFC fabricated by atmospheric plasma spraying

An intermediate temperature solid oxide fuel cell (ITSOFC) based on 8YSZ electrolyte, La_0.6Sr_0.4CoO_3−δ (LSCo) cathode, and Ni − 8YSZ anode coatings were consecutively deposited onto a porous Ni-plate substrate by atmospheric plasma spraying (APS). The spray parameters including current, argon and hydrogen flow rate, and powder feed rate were investigated by an orthogonal experiment to fabricate a thin gas-tight 8YSZ electrolyte coating (80 μm). By proper selection of the spray parameters to decrease the particles velocity and temperature, the sprayed NiO + 8YSZ coating after reducing with hydrogen shows a good electrocatalytic activity for H₂ oxidation. With the same treatment, 100–170 μm dimensions LSCo particle could keep phase structure after spraying. And the deposited LSCo cathode shows a good cathode performance and chemical compatibility with 8YSZ electrolyte after operating at 800 °C for 50 h. Output power density of the sprayed cell achieved 410 mW cm⁻² at 850 °C and 260 mW cm⁻² at 800 °C. Electrochemical characterization indicated that IR drop of 8YSZ electrolyte, cathodic polarization, and the contact resistance at LSCo/8YSZ interface were the main factors restricting the cell performance. The results suggested that the use of APS cell allowed the reduction of the operating temperature of the SOFC to below 850 °C with lower production costs.     

Comparative studies of nickel oxide films on different substrates for electrochemical supercapacitors

Thin nickel oxide (NiO) films were obtained by post-heating of the corresponding precursor films of nickel hydroxide (Ni(OH)₂) cathodically deposited onto different substrates, i.e., nickel foils, and graphite at 25 °C from a bath containing 1.5 mol L⁻¹ Ni(NO₃)₂ and 0.1 mol L⁻¹ NaNO₃ in a solvent of 50% (v/v) ethanol. The surface morphology of the obtained films was observed by scanning electron microscope (SEM). Electrochemical characterization was performed using cyclic voltammetrty (CV), chronopotentiometry (CP) and electrochemical impedance analysis (EIS). When heated at 300 °C for 2 h in air, the specific capacitance of the prepared NiO films on nickel foils and graphite, with a deposition charge of 250 mC cm⁻², were 135, 195 F g⁻¹, respectively. When the deposition charge is less than 280 mC cm⁻², the capacitance of both appears to keep the linear relationship with the deposition charge. The specific capacitance, cyclic stability of the NiO/graphite hybrid electrodes in 1 mol L⁻¹ KOH solution were superior to those on nickel foils mainly due to the favorable adhesion, the good interface behavior between graphite and the NiO films, and the extra pseudo-capacitance of the heated graphite substrates.     

Influence of packed honeycomb ceramic on heat extraction rate of packed bed embedded heat exchanger and heat transfer modes in heat transfer process

Under the condition that the transient oxidation heat extraction process of coal mine ventilation air methane (VAM) is equivalent to a series of steady state process, the steady state heat extraction experiment platform is built. The influence of the honeycomb ceramic packed in heat extraction zone and its two-side space on heat extraction rate and heat transfer modes is investigated. The experimental results show that the honeycomb ceramic packed in heat extraction zone two-side space can always strengthen heat extract ion of heat exchanger by increasing gas physical flow velocity in bed and radiation heat exchanging area and disturbing heat exchanger leeward side flow field. The contradictory dual characteristic of the influence of the honeycomb ceramic packed in heat extraction zone on heat exchanger heat extraction rate determines that the honeycomb ceramic has no great influence on heat extraction rate and doesn't always strengthen heat exchanger heat extraction. Contribution of heat transfer modes on packed bed embedded heat exchanger heat extraction is investigated using the method of coating heat exchanger outer surface silver; the experimental result shows that 55% contribution of packed bed embedded heat exchanger heat extraction rate is from radiation when gas mass flow rate is 0.15 kg·s^− 1·m^− 2 and its temperature is 1113 k; with the gas temperature being increased further, radiation will become the main way of packed bed embedded heat exchanger heat extraction.     

Electrochemical behavior of polyamides with cyclic disulfide structure and their application to positive active material for lithium secondary battery

Polyamides (DTA-I, DTA-II, and DTA-III) containing cyclic disulfide structure were prepared by condensation between 1,2-dithiane-3,6-dicarboxylic acid (DTA) and alkyl diamine, NH₂–(CH₂)_n–NH₂ (DTA-I; n=4, DTA-II; n=6, DTA-III; n=8) and their application to positive active material for lithium secondary batteries was investigated. Cyclic voltammetry (CV) measurements under slow sweep rate (0.5 mV s⁻¹) with a carbon paste electrode containing the polyamide (DTA-I, DTA-II, or DTA-III) were performed. The results indicated that the polyamides were electroactive in the organic electrolyte solution (propylene carbonate (PC)-1,2-dimethoxyethane (DME), 1:1 by volume containing lithium salt, such as LiClO₄). The responses based on the redox of the disulfide bonds in the polyamide were observed.Test cells, Li/PC-DME (1:1. by volume) with 1 mol dm⁻³ LiClO₄/the polyamide cathode, were constructed and their performance was tested under constant current charge/discharge condition. The average capacity of the test cells with the DTA-III cathode was 64.3 Ah kg⁻¹ of cathode (135 Wh kg⁻¹ of cathode, capacity (Ah kg⁻¹) of the cathode×average cell voltage (2.10 V)). Performance of the cell with linear polyamide containing disulfide bond (–CO–(CH₂)₂–S–S–(CH₂)₂–CONH–(CH₂)₈–NH–, GTA-III) was also investigated and the average capacity was 56.8 Ah kg⁻¹ of cathode (100 Wh kg⁻¹ of cathode, capacity (Ah kg⁻¹) of the cathode×average cell voltage (1.76 V)). Cycle efficiency of the test cell with the DTA-III cathode was higher than that with the GTA-III cathode.     

Hydrogen storage in an activated carbon bed: Effect of energy release on storage capacity of the tank

Thermal effects during dynamic charging of a two-liter, adsorbent, packed bed, hydrogen storage tank were studied through numerical modeling. For packed-bed materials having adsorption capacities smaller than 2 wt%, the conversion to heat of the mechanical work required to feed the tank produces more than 60% of the temperature increase that occurs during the charging process. However, for materials having adsorption capacities greater than 3 wt%, 60% of the heating is due to the adsorption process. The temperature increase for a material that would fulfill the DOE recommendation of 6 wt% storage capacity is 130 K. This reduces the storage capacity by 20% relative to what would be obtained from an isothermal charging process. Simulations showed that the limitation in the storage capacity can be reduced to less than 10%, if a packed bed having an effective conductivity of a few W m^?1 K^?1 can be used.     

Carbon dioxide fixation by microalgae cultivated in open bioreactors

The biofixation of carbon dioxide (CO₂) by microalgae has been proven to be an efficient and economical method, mainly due to the photosynthetic ability of these microorganisms to use this gas as a source of nutrients for their development. The aim of this work was to study the growth of Spirulina LEB18 and Chlorella kessleri microalgae, exposed to controlled and non-controlled conditions, with the injection of different concentrations of CO₂. The cultures was carried out in 6 L open raceway ponds, under controlled conditions at 30 °C and 39 μE m^?2 s^?1 and under non-controlled conditions, protected by a tunnel of transparent film. The experiments were subjected to CO₂ injections at concentrations of 0.038, 6, 12 and 18% (v/v). The highest concentration of biomass (4.95 g L^?1) and maximum daily fixation (0.21 g g^?1 d^?1) were obtained for Spirulina LEB18 in culture that was prepared in non-controlled conditions with an injection of 6% (v/v) of CO₂. C. kessleri had maximum (p < 0.0008) specific growth rate (0.84 d^?1) when grown with 18% (v/v) of CO₂ in non-controlled conditions of cultivation.     

Three-dimensional measurement of gas dissolution process in gas–liquid microchannel flow

The three-dimensional CO₂ dissolution process through a gas–liquid interface in microfluidic devices was investigated experimentally, for the precise control of CO₂ dissolution. The gas dissolution was evaluated by using confocal micron-resolution particle image velocimetry (micro-PIV) combined with laser induced fluorescence (LIF), which has the ability to measure the velocity and dissolved CO₂ concentration distribution in a liquid flow field. The measurement system is based on the confocal microscope, which has excellent depth resolution and enables visualization of the three-dimensional distributions of velocity and dissolved CO₂ concentration by rendering two-dimensional data. The device is comprised of a polydimethylsiloxane chip, whose microchannels were fabricated by using a cryogenic micromachining system. The width and depth of the liquid flow channel are larger than those of the gas flow channel. This is due to the need for decreasing the width of the gas–liquid interface and increasing the hydraulic diameter of the liquid channel, whose conditions generate a static gas–liquid interface. The experiments were performed for three different liquid flow conditions corresponding to Reynolds numbers of 1.0 × 10^?2, 1.2 × 10^?2 and 1.7 × 10^?2, and the gas flow rate was set to be constant at 150 μL/min. The LIF measurements indicate that an increase in the Reynolds number yields a decrease in dissolved gas in the spanwise directions. Furthermore, molar fluxes by convection and diffusion were evaluated from the experimental data. The molar fluxes in the streamwise direction were at least 20 times as large as those in the spanwise and depthwise directions. This reveals that an increase in momentum transport in the spanwise and depthwise directions is an important factor for enhancing mass transfer in the gas–liquid microchannel flow.     

Optimisation of processing and microstructural parameters of LSM cathodes to improve the electrochemical performance of anode-supported SOFCs

To improve the electrochemical performance of LSM-based anode-supported single cells, a systematic approach was taken for optimising processing and materials parameters. Four parameters were investigated in more detail: (1) the LSM/YSZ mass ratio of the cathode functional layer, (2) the grain size of LSM powder for the cathode current collector layer, (3) the thickness of the cathode functional layer and the cathode current collector layer, and (4) the influence of calcination of YSZ powder used for the cathode functional layer.Results from electrochemical measurements performed between 700 and 900 °C with H₂ (3 vol.% H₂O) as fuel gas and air as the oxidant showed that the performance was the highest using an LSM/YSZ mass ratio of 50/50. A further increase of the electrochemical performance was obtained by increasing the grain size of the outer cathode current collector layer: the highest performance was achieved with non-ground LSM powder. In addition, it was found that the thickness of the cathode functional layer and cathode current collector layer also affects the electrochemical performance, whereas no obvious detrimental effects occurred with the different qualities of YSZ powder for the cathode functional layer. The highest performance, i.e. 1.50 ± 0.05 A cm⁻² at 800 °C and 700 mV, was obtained with a cathode functional layer, characterised by an LSM/YSZ mass ratio of 50/50, a d₉₀ of the LSM powder of 1.0 μm, non-calcined YSZ powder, and a thickness of about 30 μm, and a cathode current collector layer, characterised by d₉₀ of the LSM powder of 26.0 μm (non-ground), and a thickness of 50–60 μm. Also interesting to note is that the use of non-ground LSM for the cathode current collector layer and non-calcined YSZ powder for the cathode functional layer obviously simplifies the production route of this type of fuel cell.     

Effect of residual gas on the dynamics of water adsorption under isobaric stages of adsorption heat pumps: Mathematical modelling

A mathematical model of the coupled heat and mass transfer in an adsorbent layer was developed to study the effect of a non-adsorbable gas (air, hydrogen) on kinetics of water adsorption on loose grains of the composite adsorbent SWS-1L (silica modified by calcium chloride). The adsorbent monolayer was placed on the surface of an isothermal metal plate at T = 60 °C and equilibrated with the mixture of water vapor at constant P = 10.3 mbar in the presence of the non-adsorbable gas at a variable partial pressure P_A = 0.06–14.3 mbar. After that the metal plate is subjected to a temperature drop down to 35 °C that initiates water adsorption. It is shown that the adsorption of water causes effective gas sweeping to the surface where it was accumulated as a gas-rich layer. This results in dramatic slowing down of the adsorption and heat transfer processes.