Chemical Engineering
M. Zamani; R. Shafaghat; B. Alizadeh Kharkeshi
Abstract
Due to the necessity of utilizing renewable energies, the Archimedes screw turbine can be used as a power generation converter for the use of hydropower energy from river flows. A laboratory-scale model of this turbine with a scale of 1:6 has been designed and constructed. In the experimental tests, ...
Read More
Due to the necessity of utilizing renewable energies, the Archimedes screw turbine can be used as a power generation converter for the use of hydropower energy from river flows. A laboratory-scale model of this turbine with a scale of 1:6 has been designed and constructed. In the experimental tests, the performance characteristics of the turbine were investigated based on variations in the flow rate and electrical resistance. The optimal flow rate for the turbine was determined with the aim of achieving maximum efficiency. The performance characteistics of the turbine at this flow rate were evaluated using empirical equations derived from the experimental tests for various parameters. These equations indicated higher values for these parameters at this flow rate. Furthermore, for the scaling of the Archimedes screw turbine, dimensionless numbers such as Froude number and flow rates ratio were introduced. The experimental results were extrapolated to the prototype scale at the optimal flow rate of 2.6 (lit/s), where the maximum turbine efficiency occurs. The results showed that the use of Froude scaling led to approximately 25% higher values for the performance characteristics of the turbine compared to scaling based on flow rates ratio.
Chemical Engineering
A. Graeeli; M. Rahimi-Esbo; V. Kord Firouzjaee; M. Sedighi; M. Rezaee Firouzjaee
Abstract
Considering the escalating significance of hydrogen production as a high-energy-density fuel, coupled with the challenges associated with its transportation and storage, the necessity to generate hydrogen at the point of consumption has become more pronounced than ever before. Thus, this research endeavors ...
Read More
Considering the escalating significance of hydrogen production as a high-energy-density fuel, coupled with the challenges associated with its transportation and storage, the necessity to generate hydrogen at the point of consumption has become more pronounced than ever before. Thus, this research endeavors to comprehensively investigate various hydrogen production processes and elucidate the merits and drawbacks of each technique. Additionally, the catalysts employed in these processes were examined, ultimately leading to the selection of methanol steam reforming using a Cu/ZnO/Al2O3 catalyst within a fixed bed reactor for hydrogen production. Subsequently, the process underwent initial simulation utilizing Aspen Plus software, enabling a close-to-reality assessment of the simulation's challenges. Following the validation of the simulation results, a comparative analysis was conducted between a reactor operating at a specified temperature (T=220℃) and a co-current reactor. Each reactor possessed distinct advantages and disadvantages. Through this comparison, it was observed that, in order to achieve the same conversion, the length of the co-current reactor could be reduced by 5.7 cm compared to the specified temperature reactor. Consequently, the construction cost was reduced; however, this modification resulted in an increased production of carbon monoxide, necessitating further investigation.
Chemical Engineering
M. Mahmoudi; I. Mirzaee; M. Khalilian
Abstract
The exploitation of nanofluids is the most noteworthy way to make better the rate of heat transfer in solar collectors. Moreover, recently utilizing thermoelectric generators are widely studied to direct the conversion of heat into electricity. The objective of the present study is to deal with a novel ...
Read More
The exploitation of nanofluids is the most noteworthy way to make better the rate of heat transfer in solar collectors. Moreover, recently utilizing thermoelectric generators are widely studied to direct the conversion of heat into electricity. The objective of the present study is to deal with a novel multigeneration system that includes a nanofluid-based parabolic trough collector integrated with a quadruple effect absorption refrigeration cycle (cooling), a thermoelectric generator (power), a PEM electrolyzer (hydrogen), vapor generator and domestic water heater. A parametric study is accomplished to consider the effect of significant parameters such as the volume concentration of nanoparticles, solar radiation, absorption system’s generator load, strong solution concentration, and TEG’s figure of merit on the overall system performance, hydrogen production rate, cooling load, COP and useful energy obtained by the collector. It is observed that the power generated by the system is 18.78 kW and the collector energy and exergy efficiency are 82.21% and 80.48%, respectively. Furthermore, the results showed that the highest exergy destruction rate occurs in the solar system at the rate of 4461 kW. The energy and exergy COPs of the absorption chiller are discovered to be 1.527 and 0.936, respectively. By increasing the concentration of nanoparticles and the amount of solar radiation, the amount of collector useful energy increases while the hydrogen production rate and the generated power in the TEG decreased. The cooling capacity and COPs of the absorption system increased with an increase in VHTG load and decreased with an increase in concentration of the strong solution.
Chemical Engineering
M. Moory Shirbani; M. Shishehsaz
Abstract
This paper introduces a novel harvester to store the electrical power, which comes from the power of external applied electrical voltage. In the last decade, most of the energy harvesters have been designed and analyzed in the form of cantilever beams. In the present article, the harvesters are analyzed ...
Read More
This paper introduces a novel harvester to store the electrical power, which comes from the power of external applied electrical voltage. In the last decade, most of the energy harvesters have been designed and analyzed in the form of cantilever beams. In the present article, the harvesters are analyzed as a cantilever beam with the Euler-Bernoulli beam assumptions. The beam of energy harvester consists of an active Magneto-electro-elastic (MEE) layer attached to the piezoelectric layer. Assuming that the connection of these layers is perfect, the uni-morph configuration is investigated. The magneto-electro-elastic governing coupled equations of the MEE energy harvester are derived for a harmonic external applied electrical voltage in the transversal direction based on Euler-Bernoulli theory, Gaussian law, and Faraday law. These equations are solved analytically to find out the amount of harvested power and voltage. The obtained results state that by adjusting the electromechanical parameters, up to 66% of the input power and 27% of the applied voltage can be harvested. Choosing the right geometric parameters can increase the harvested power and voltages connected to the electrodes and external coil by 120.31%, 49.05% and 60.98%, respectively. Finally, the results prove the usefulness and efficiency of the dual-usage (actuator-harvester) of the new energy harvester.
Chemical Engineering
A. Kamani; I. Mirzaee; N. Pourmahmoud
Abstract
In this study, first-law, second-law, and exergo-economic investigations are accomplished to recover the waste heat of a two-shaft turbofan engine applying a supercritical carbon dioxide Brayton cycle. The efficacy of different operating parameters including the inlet temperature of the turbine, the ...
Read More
In this study, first-law, second-law, and exergo-economic investigations are accomplished to recover the waste heat of a two-shaft turbofan engine applying a supercritical carbon dioxide Brayton cycle. The efficacy of different operating parameters including the inlet temperature of the turbine, the pressure ratio of the compressor, and Mach number on the performance of the proposed system in terms of energy and exergy performance, exergy destruction rate, and annual levelized cost of investment have been examined. The results indicate that the energy performance of the cycle is specified as 42.94%, the second-law performance of the cycle is calculated as 85.88% and the whole power generation amount of the system is achieved to be 9806 kW. Also, the results display that among the various components of the proposed system, the maximum amount of exergy destruction occurred in the low-pressure compressor, the fan, and the mixer. It is found that by increasing the inlet temperature of the high-pressure turbine, the first-law efficiency and the second-law efficiency of the proposed cycle decrease while the total cost rate and exergy destruction rate increase. Moreover, it is inferred that the thermodynamic efficiency of the system rises when the pressure ratio of the compressor and Mach number increase. The outcomes also demonstrate that concerning the capital costs and exergy destruction costs of components, the highest amount is obtained for high-pressure turbine and recuperator, which are 326.3 $/h and 358.4 $/h, respectively.
Chemical Engineering
Z. Aouissi; F. Chabane; M. S. Teguia; N. Belghar; N. Moummi; A. Brima
Abstract
This numerical and experimental work aims to improve the heat transfer inside a solar thermal collector. By incorporating rectangular baffles in the middle of the distributed air passing channel at different angles of inclination (ß= 90°, ß= 180°, ß= 180° and ß= 90°). ...
Read More
This numerical and experimental work aims to improve the heat transfer inside a solar thermal collector. By incorporating rectangular baffles in the middle of the distributed air passing channel at different angles of inclination (ß= 90°, ß= 180°, ß= 180° and ß= 90°). That is called the model H. These experiments were carried out in the Biskra region of Algeria in good natural conditions with an average solar radiation approximately constant I= 869 W/m2 varying from 11:30 to 14:00. After the completion of the experimental investigation, a computational fluid dynamics (CFD) model was created that matches this experimental model with the same experimental boundary conditions. In the numerical study, ANSYS Fluent 18.1 was used to conduct simulations and compare the results of the thermal and hydraulic performance of the collector. It was concluded that the effectiveness of the CFD model, meaning that the theoretical and numerical data were very close to each other for all mass flow rates. As the mass flow increased the heat transfer process increased, while the absorber plate temperature inside the collector for experimental and numerical studies decreased. Addition of baffles increased heat transfer, due to the creation of turbulent flow that leads to crack the dead thermal layers near the absorber plate, which leads to an increase in heat transfer from the absorber plate to the air.
Chemical Engineering
S. Talesh Amiri; R. Shafaghat; O. Jahanian; G. Sadripour
Abstract
For decreasing the fuel consumption of internal combustion engines, and also reducing the emissions, investigation of the effective parameters on power, emissions, and the combustion phasing is important. In this study, the influence of adding water to a Reactivity Controlled Compression Ignition (RCCI) ...
Read More
For decreasing the fuel consumption of internal combustion engines, and also reducing the emissions, investigation of the effective parameters on power, emissions, and the combustion phasing is important. In this study, the influence of adding water to a Reactivity Controlled Compression Ignition (RCCI) engine has been numerically investigated. For this purpose, water with different mass fractions was added to the air-fuel mixture. In order to simulate the engine, AVL Fire software was used. The results show that substituting a portion of gasoline fuel with water, up to 10% mass fraction, raises the combustion chamber pressure. In this condition, the production of hydroxyl free radicals, as one of the characteristics for the start of combustion, occurs earlier. Furthermore, Indicated Mean Effective Pressure (IMEP) remains unchanged. By further increasing the water mass the production of hydroxyl radical decreases, and the high-temperature heat release is delayed; also comparing to when water was not added, average temperature of the combustion chamber reduces, while the amount of CO production does not change. Increasing the number of water moles increases the maximum in-cylinder pressures so that compared to pure gasoline mode, by replacing 20% of gasoline mass with water, the indicated mean effective pressure approximately stays the same.
Chemical Engineering
A. Mohammadi
Abstract
Semiclathrate hydrate formers such as tetra-n-butylammonium bromide (TBAB), chloride (TBAC) and fluoride (TBAF) are promising compounds that mild the thermodynamic conditions of gas hydrates, considerably. The Clausius-Clapeyron equation is employed in this manuscript to calculate the dissociation enthalpies ...
Read More
Semiclathrate hydrate formers such as tetra-n-butylammonium bromide (TBAB), chloride (TBAC) and fluoride (TBAF) are promising compounds that mild the thermodynamic conditions of gas hydrates, considerably. The Clausius-Clapeyron equation is employed in this manuscript to calculate the dissociation enthalpies of methane/carbon dioxide/nitrogen + TBAF semiclathrate hydrates. A 460 cm3 stirred batch reactor was used to measure the phase equilibria of gas + TBAF semiclathrate hydrates at various concentrations of tetra-n-butylammonium fluoride. The dissociation P-T data were obtained using an isochoric pressure-search method in the temperature range of 275.15 to 304.7 K and the pressure range of 0.53 to 10.24 MPa at 0.0 - 0.4482 mass fraction of TBAF. Investigating the obtained dissociation data showed that the addition of TBAF to the solution increases the amount of dissociation enthalpy of semiclathrate hydrates per mole of the hydrated gas. Increasing the mass fraction of tetra-n-butylammonium fluoride, showed a straight relation with the amount of dissociation enthalpy per mole of hydrated gas.
Chemical Engineering
M. Benali
Abstract
This paper presents the experimental investigation of biogas production from cow dung as an alternative for fossil fuels for energy consumption. This was carried out using an 18 Liters capacity plastic keg prototype biogas plant, constructed to investigate the anaerobic digestion for generation of biogas. ...
Read More
This paper presents the experimental investigation of biogas production from cow dung as an alternative for fossil fuels for energy consumption. This was carried out using an 18 Liters capacity plastic keg prototype biogas plant, constructed to investigate the anaerobic digestion for generation of biogas. Batch experiment was operated and daily gas yield from the plant was monitored for duration of 30 days. The digester was charged with these wastes in the ratio of 1:1, of waste to water, respectively. The mesophilic temperature ranges attained within the testing period were 20 – 35 °C. The Biogas production from cow dung fluctuates from the first day to the thirtieth day between 0 and 340 ml. The pH of cow dung gradually reduced due to acid former and methanogenes within the 30 days retention period.
