Performance and thermal impact analysis of single cell solid oxide fuel cell by utilizing different fuels and its upgradation to stack level

A numerical model of a single planar and stack of solid oxide fuel cell (SOFC) is developed by coupling dynamics of electrochemical reacting flows, heat transfer, and thermal impacts (thermal strains and stresses) of solid electrolyte and porous electrodes for analysing the cell performance. The model is tested and the simulation results of hydrogen fuel SOFC performance are verified with the bench mark data of International Energy Agency (IEA) for co-flow case. Modelling results from test cases show that the coupling is necessary as the electrochemical and thermal properties of the cell strongly depends on temperature. The thermal strains and stresses generated in the cell are then predicted by implementing the temperature profile obtained from the decoupling (the thermal properties of materials are independent of temperature) and coupling simulations. The distributions of thermal strains and stresses, from which the locations with higher values are identified, provide data for optimizing design of SOFC. The thermal impacts of the cell are investigated by employing alternative fuels such as methane. The methane steam reforming (MSR) and water gas shift (WGS) reactions are strongly temperature dependents and play the key role on both the cell performance and thermal impacts. It has been found that temperature decreases along the main flow direction because of MSR reactions dominancy. The thermal strains and stresses generated in methane based SOFC are less than those by hydrogen fed SOFC if both operate to produce identical power. The parametric study is performed to investigate the effect of operating conditions such as inlet temperature, flow rates, flow configurations (co-flow and counter flow), geometrical parameters (porosity, change in cell thickness), and operating voltage on the cell performance and thermal impact. It has been identified that the inlet temperature has significant effect on the cell performance and thermal impact. The co-flow configuration offers better thermomechanical stability. The higher operating voltage results in lower thermal strain and stress generation. The methane fuel model is upgraded to the stack level and the performance of the 8 cells connected in parallel flow configuration has been investigated. The effect of Lanthanum Chromite interconnect between two cells on the cell performance has been analysed by investigations of the distributions of chemical species, reaction rates, temperature, and thermal strain and stress for each cell. It has been recognized that the difference in the performance of the bottom and top cells as compared to the cells in between them is high because of the presence of the interconnect. The temperature distribution along the stack height is non-uniform which leads to non-uniform thermal strain and stress generation. The non-uniform thermal strain and stress generation increases the possibilities of the cell failure which must be taken into account for cell design and operation monitoring

Applications of solar photovoltaics in powering cathodic protection systems: a review

Corrosion is a phenomenon that occurs on pipes, reinforced concrete structures, and storage tanks and causes a major impact on the facility structures and can have a major impact on a facility’s structural integrity. This can result in a serious failure in the system and lead to substantial economic losses. One of the solutions widely used to eliminate the corrosion effects is by applying cathodic protection, which depends on direct current as the supply potential. The technique of cathodic protection is used to control corrosion in the utilisation of reinforced concrete structures, pipelines, storage tanks, etc. A photovoltaic cathodic protection system is normally used as an energy source to supply the system. This research reviews the technique utilised for applying solar photovoltaics in powering systems of cathodic protection. Subsequently, it highlights the methods of cathodic protection systems, sacrificial anode cathodic protection and the impressed current cathodic protection. Finally, it is indicated that applying solar photovoltaics in powering cathodic protection systems has great efficacy in controlling the corrosion in the facility’s equipment in a smarter, controlled way. Furthermore, this study provides significant insight into the designing and operating the domain of solar photovoltaic systems that power cathode protection systems

ECONOMIC BENEFITS OF A GAS TURBINE COMPRESSOR WASHING AT DIFFERENT INTERVALS

Gas turbine compressor fouling is a major operational issue that affects engine performance. In desert oil and gas, field compressor fouling can be caused by pollution such as airborne ash, smog, hydrocarbons and dust. Accumulation of such pollution in the compressor annulus can lead to sticky fouling. This can ultimately result in the reduction of the compressor mass flow and pressure ratio. In order to maintain constant output power, it is then necessary to increase the turbine entry temperature (TET). The result of such an operational change will cause higher emission rates. In addition, it will decrease the creep life of engine hot components and overall engine thermal efficiency. The investigation of the effect of compressor on-line cleaning leads to the following findings: (i) Frequent cleaning maintains longer creep life of the high-pressure turbine. (ii) More financial benefits due to reduction on fuel flow. (iii) Less cost of cleaning materials per engine, cost of manpower and overheads. In summary from cost aspect with the best frequency of washing intervals (4 weekly), approximately $ 30,000 will be saved annually. On the other hand, in order to attain better engine performance, a weekly washing interval is necessary.&nbsp

Experimental and Performance Evaluation of the Soiling and Cooling Effect on the Solar Photovoltaic Modules

Solar photovoltaic (PV) system technology is a significant energy source that has no moving parts and can accomplish the desired work with less effort. The technology can help to alleviate the climate change phenomena and achieve sustainable development. One of the most important challenges to address before installing a solar PV system is dirt deposition, e.g., soil/sand/ash. The tiny debris particles accumulate on the top surface of the panel, which decreases the PV conversion efficiency and subsequently lowers the overall performance. This work aims to investigate the effect of soiling deposition (soil, sand, and ash) and surface temperature on the performance of PV modules. In this regard, the fabricated test rig was performed for experimental cleaning and cooling on the top of solar PV modules. Therefore, the module's performance in terms of the current produced, the voltage generated, and module efficiency is evaluated for different dust deposition volumes. The results indicate that the ash affects the PV performance badly, reducing 50 to 60 % of current production for only 50 mL volume, compared to sand and soil. Furthermore, the results also indicated that the efficiency of photovoltaic modules increases by 3-4% when water is used for cleaning and cooling purposes

ENHANCEMENT IN OVERALL THERMAL EFFICIENCY OF A GAS TURBINE POWER PLANT USING COMBINED CYCLE SYSTEM

The gas turbines are one of the major resources of power generation in the world and its usage is increasing day by day. Although the gas turbines have several advantages over other systems (such as high power to weigh ratio, high rotational speed or fast activation capabilities) but they still waste the energy in the form of high temperature exhaust gases coming out of the gas turbine which pollute the atmosphere and affect the environment. A waste heat recovery system (WHRS) installed at Gas turbine exhaust helps not only to reduce the exhaust temperature of these gases emitting from the uptake into the atmosphere but also enables to produce useful steam for various processes. The air mass flow rate which enters the compressor has a direct relation with the performance of gas turbine power plant. The volumetric efficiency of the gas turbines decreases with rise in the temperature of the inlet air. The increase in temperature will reduce the density which results in the reduction of gas turbine efficiency. In the present work the steam produced from WHRS has been used in the vapor absorption system of refrigeration. The refrigeration system is utilized to cool the air at the entry of the gas turbine compressor power plant. It was observed in gas turbine power plant that there is a 10% increase in thermal efficiency

Design, simulation and performance analysis of photovoltaic solar water pumping system

The solar photovoltaic system is one of the technologies which is used to pump water in rural, isolated and desert areas where electric connection to the main grid is a problem. The study area is selected because of its higher natural resources of solar radiation over the year. Thus, that encourages us to adopt this study in order to understand the effects of various operating parameters on performance behaviour, which leads to enhancing the system design. This paper aims to assess the solar water pump system’s design and estimated performance in real environmental conditions. The PVsyst has been used to design and simulate a system which allows us to analyse the operating behaviour of a photovoltaic solar water pumping system. The solar PV pumping system design is considered; the photovoltaic module has characteristics and the pumping system characteristics. The photovoltaic array losses due to temperature were estimated about −14.3% and the soiling losses represented approximately −5%. The results showed that performance losses were significant variance in the months of the summer season from May to July. Therefore, their implication on the water flow rates significantly decreases throughout the months of the summer season from May to July, respectively

In-situ performance evaluation of photovoltaic solar water pumping system in the rural region

The Photovoltaic solar cells convert the radiant energy from the Sun directly to electricity. Solar photovoltaic systems can help to fulfil the entire energy demands in rural areas by harnessing all the opportunities and potentials. The water is an important element in the life of plants, animals and human being. In this paper, it has been studied that solar energy could be used for water pumping applications such as providing water to rural and remote areas. It is being practiced in south Libya. The data is being collected over two years by measuring the water flow on daily basis at pumping head of (35m). In addition, this presents an evaluation of PV system in water pumping and piping systems and estimation of pumping energy cost. The solar pumping systems depend on water flow rate, pumping head and solar irradiance. The system components contain inverter, pump and PV generator. Besides, the effects of the climate and operating conditions on the performance of PV pumping systems has been discussed

Modeling of thermal impacts in a single direct methane steam reforming solid oxide fuel cell

Solid oxide fuel cells (SOFCs) operate at high temperature which enables the direct methane steam reforming but results in high thermal impact. In this research, the developments of thermal strains and stresses (thermal impacts) of solid electrolyte and porous electrodes are investigated in a single direct methane steam reforming SOFC by numerical simulations. To understand thermal impact mechanisms, the heat sources and sinks due to a set of temperature dependent chemical and electrochemical reactions are modelled for predictions of temperature distributions in both the fluids and solid. It is identified from model simulations that the endothermic reactions of methane steam reforming, which are overall dominant, play the key role in improving the thermal loads to the solid electrolyte and porous electrodes. The temperature reductions are developed from a rate of -42.2 K/cm at the cell inlet to -1.98 K/cm at the centre of the cell under the operation temperature of 1173 K. This leads to a maximum thermal stress of 1867.6 MPa generated in solid electrolyte closing to the cell inlet and a 1770.2 MPa at the centre of the channel, associated with a rate of –19.48 MPa/cm at inlet and then the –3.28 MPa/cm at the centre, respectively. The maximum thermal strain ratios of anode to electrolyte and cathode to electrolyte are 1.30 and 1.10, however, the ratios of maximum thermal stress are 0.33 and 0.178, respectively. It is identified that high operation voltage results 3.1 percentage decrease in thermal stress when the cell operates from 0.4 V to 0.7 V. The further lower cell operation voltage results in fuel starvation

Coupling mechanism of kinetic and thermal impacts of Rayleigh surface acoustic waves on the microdroplet

An experimental study has been conducted to investigate the coupling mechanism between thermal and kinetic impacts of surface acoustic waves (SAW) using a water droplet (25 µl) on the zinc oxide (ZnO) thin-film piezoelectric substrate fabricated on an aluminium plate. The temperature is measured by an infrared (IR) thermal camera, and fluid streaming was detected by particles image velocimetry (PIV). The input power ranges from 0.096 W to 3.2 W resulting in a temperature rise and streaming velocity in the droplet up to 55 °C and 24.6 mm/s, respectively. It is found that the thermal impact is insignificant at lower input power (2.0 W. The study also found that heat inside the droplet is distributed via streaming from the heat source. The heat is distributed from the heat source where SAW power penetrates to the droplet. Another key finding of this investigation revealed that when the input power is>0.50 W, inverse heat transfer from the droplet to the substrate is observed due to the increase in fluid temperatures