Search

In this study, a novel tilted axis hydrokinetic turbine system is presented and tested to generate electricity from surface water streams in off-grid locations. This system consists of a turbine, differential, reducer, and alternator, and resembles a Pelton turbine. It is used in shallow waters near river banks with the free flow velocity. This study reports significant hydrodynamic efficiencies with field tests consistent with theoretical estimates obtained at the design and fabrication stage, for different flow velocities (0.5–3 m/s in 0.5 m/s internal) and blade numbers (7, 9, and 11 blades) on the Namnam Stream in the Muğla province/Turkey. On the same turbine system, 7, 9, and 11 blades can be disassembled in the center of the turbine. In order to facilitate testing at different water flow velocities, the flow velocity is adjusted by excavation operations in the stream bed. The results of the study indicate that as the water speeds increase, the turbine power, speed, and efficiency of all blade turbines also increase. In terms of hydrokinetic energy potential, the water flow velocity and turbine speed are 2 m/s and 3 r/min, respectively. Because of parasitic drag and lift-induced drag, 7- and 11-blade turbines have higher mechanical losses, lower turbine efficiency, and increased cost due to weight. A 9-blade turbine is preferred for such a prototype due to torque, load power (800 W), and efficiency (15.9%) compared to the others. As a result, this study reports that such a prototype can be used in unpowered riverbanks or free surface currents. [ABSTRACT FROM AUTHOR]

Binary geothermal power plants (GPPs) are mostly encountered in geothermal fields with medium and low temperatures. The design and operation of dual binary GPPs can be difficult due to the geothermal fluid properties. This affects their performance and feasibility. Thermoeconomics are essential elements for the design and operation of the GPPs. In this study, advanced exergoeconomic analysis is applied to a true dual binary GPP (as a case study) to further evaluate it from performance and economic perspectives. In analysis, the specific exergy cost (SPECO) method is used. Then, some specific indicators are presented to evaluate the performance and economics of the GPP. Thus, technical and economic solutions have been developed in the design and operation stages through the analysis. The results of the study indicated that the total operating cost of 1218 USD/h could be reduced to 186 USD/h by improving the operating conditions. This corresponds to an 85% decrease. The cost per electricity generated, cost per geothermal energy input, and cost per CO2 emission of the GPP are determined as 0.049 USD/kWh, 5.3 USD/GJ, and 0.13 USD/kg, respectively. As a result, while the savings potential of the GPP is 15%, it can result in a 15% reduction in CO2 emission cost. [ABSTRACT FROM AUTHOR]

In this paper, the effect of various zinc oxide aluminate spinel (ZnOAl2O3) and titanium oxide (TiO2) nanoparticle concentrations on the thermal performance of the Diffusion Absorption Refrigeration (DAR) system is investigated. The main aim of the study is to increase the efficiency of DAR systems operating with low thermal performance. The first part of the study is experimentally tested on the system under the same ambient conditions in order to develop passive heat transfer using different nanofluids as working liquids, including ammonia/water solution containing different amounts (1 wt.% and 2 wt.%) of ZnOAl2O3 and TiO2 particles. In the next part of the study, the tested system is designed in MATLAB/Simulink toolbox environment to compare experimental and numerical results. The use of nanofluids can increase the surface area expansion and the heat capacity of the fluid, resulting in a significant positive increase in heat transfer. The results clarify that the use of nanofluid as working fluid in the DAR system helps quicker evaporation, which reduces operating time and increases heat transfer in the generator. Compared to a base DAR system, the nanofluid solution with a 2 wt.% ZnOAl2O3 nanoparticle concentration among other nanofluid and proportions causes a 57% increase in the coefficient of performance (COP) of DAR system. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigates the effect of using a latent heat storage unit (LHSU) equipped with fins and nanoparticles (NAPs) on the performance of a photovoltaic (PV) system. Various PV systems were assessed for their economic viability and environmental impact. Initially, three different PV systems were designed and analyzed: a conventional PV, a PV with a paraffin-containing LHSU, and a PV with LHSU integrating 3 fins and paraffin. Results from the first set of experiments indicated that the fin-integrated system delivered the best performance. In the second phase, the most effective system from the initial stage (PV with 3 fins-added LHSU) was compared to systems with 6 fins-integrated LHSU and LHSUs integrating 6 fins and iron (Fe) NAPs. The stage specifically examined the effects of doubling the number of fins and adding NAPs to the paraffin on performance. It was found that increasing the number of fins resulted in a levelized cost of electricity (LCOE) of 0.69 USD/kWh. The electrical (module) efficiency of the system incorporating 6 fins and NAPs improved by 15.51 % compared to the conventional system. Moreover, the surface temperature of the PV panel was reduced by 7.28–17.93 % using these modifications. Performance ratio values for the five different analyzed PV systems ranged between 0.597 and 0.689. From an environmental perspective, integrating aluminum into PV systems lead to a total environmental impact of 4.73 Pt/h and an environmental impact of electricity produced (EIE) of 0.90 mPts/kWh. However, introduction of NAPs significantly increased these values to 17.76 Pt/h and 3.09 mPts/kWh, respectively. This study highlights the potential of the proposed passive cooling technique for enhancing PV system efficiency while also pointing out the necessity for design improvements to optimize economic and environmental impacts. • Innovative use of fins and NAPs in LHSUs significantly improves PV system efficiency. • Increased fin count and NAP integration result in notable electrical efficiency gains. • Significant reduction in PV panel surface temperature achieved through design modifications. • Comprehensive environmental and economic impact assessment of PV cooling techniques. • Study strikes a balance between enhancing PV system performance and economic feasibility. [ABSTRACT FROM AUTHOR]