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An innovative system for recovering exhaust gas is created to recycle the energy from industry cooling tower waste. Two Vertical Axis Wind Turbines (VAWTs) with enclosure are positioned at a specific position at the outlet of cooling tower to harness the wind energy for electricity generation. From structural dynamics aspect, adding two VAWTs or du...
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... exhaust air energy recovery system design comprises of two Vertical Axis Wind Turbines (VAWTs) or dualrotor with enclosure, which are installed on top of an exhaust outlet in cross wind orientation to harness the discharged wind energy [4]. A lab scale of this system has been built for various testing purposes as shown in Fig. 1. From the aspect of structural dynamics, adding two VAWTs with enclosure can contribute extra burden to the entire structure as additional mass is added on the cooling tower. This has changed the dynamic characteristics, namely natural frequencies, mode shapes and damping, of the cooling tower and may cause unexpected change in dynamic ...
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Citations
... The dynamic characteristics of the VAWT mounted and its enclosures was studied by Yap et al. (2014) where the researcher affirmed that any change of dynamic characteristics such as natural frequency, damping, and mode shape would result in potential damages of the VAWTs structure in addition to the long-term operation of VAWTs (without enclosure) that can be achieved with a vibration lower than 6 mm/s. In fact, when the diffuser integrates with the VAWTs, the vibration would increase to 26 U n i v e r s i t y o f M a l a y a mm/s. ...
Abstract
Over the past years, there are a considerable knowledge and continuous striving toward scavenging a sustainable power from piezoelectric harvesters, which convert the waste mechanical energy to useful electrical energy. Among the piezoelectric materials, non-ferroelectric materials are more cost-effective and ease to build using the wet chemical method. In this study, a novel non-ferroelectric was manufactured from 0.7PbZn0.3Ti0.7O3-0.3Na2TiO3 (PZnT-NT) through p-n junction construction. It was demonstrated that the increment of conductivity via adding the Na2TiO3 plays an essential role in increasing the permittivity of the non-ferroelectric harvester and hence improved the generated power density. The performance of the device was studied experimentally over a cantilever test rig; the vibrating cantilever (0.4 m/s2) was excited by a motor operated at 30 Hz. The generated power successfully illuminated a light emitting diode (LED). The PZnT-NT generator produced a volume power density of 0.106 ± 0.011 μW/mm3 and a surface power density of 10.6 ± 1.1 μW/cm2. The performance of the proposed device with a size of (20 × 15 × 1 mm3) was higher in terms of power output than that of the commercial piezoelectric PbZrTiO3 (PZT) (63.5 × 31.8 × 0.51 mm3), microfiber composite (MFC) (80 × 57 × 0.335 mm3) and piezoelectric bimorph device (70 × 50 × 0.7 mm3). Compared to other existing ferroelectric and non-ferroelectric generators, the proposed device demonstrated exceptional performance in harvesting the energy at low acceleration and in a low-frequency environment. Moreover, the performance of the proposed PZnT-NT as well as the commercial MFC and PZT bimorph was studied systematically over the Vertical Axis Wind Turbine (VAWT) beam, which was located above an exhaust air outlet of the cooling tower system. For successful implementation of the harvester on an operating VAWT beam, good harvester location which is rich in vibration energy must be known in a priori to avoid poor power generation at a bad location. Thus, an optimal location selection scheme using two non-destructive vibration techniques, i.e., the Experimental Modal Analysis (EMA) and Operating Deflection Shape (ODS) analysis techniques were adopted to measure the dynamic characteristics and visualise the operating vibration shape of the system. The results showed that the highest displacement was located at the free end (near the rotor part of the VAWT). Furthermore, higher vibration was observed in the horizontal movement compared to the vertical movement of the VAWT beam. As a result, the PZnT-NT generator produced the highest volume power density (i.e. 0.107 ± 0.008 μW/mm3) compared to the PZT (i.e. 0.036 ± 0.005 μW/mm3), MFC (i.e. 0.007 ± 0.001 μW/mm3) and PZT bimorphs (i.e.0.006 ± 0.001μW/mm3). The power density was improved by 66%, 93.8% and 94% using the proposed PZnT-NT over the PZT, MFC and the PZT bimorph respectively. Furthermore, PZnT-NT was the most cost-effective solution in term of the highest power generated per dollar, (μW/mm3 $) ×105 (i.e. 7066.7±733.3), compared to PZT (i.e. 22.1±1.4), MFC (i.e. 4.3 ± 0.4) and PZT bimorph (i.e. 35.0±5.0). This has verified the great potential of PZnT-NT materials in harvesting useful energy from the VAWT beam.
... Multiple air flow channels are formed between the exhaust outlet and the VAWTs by guide valves, which direct the exhaust wind in the most efficient direction on the turbine blade [56][57][58][59][60][61]. Nonetheless, a hybrid, non-destructive assessment approach is proposed to investigate the dynamic behaviour and reliability of this new design, which examines the possible causes of high vibration and corrects the vibration issue [62]. ...
... The cooling tower's dynamic characteristics have changed because of this. To investigate the complex behaviour and reliability of this new design, a hybrid non-destructive evaluation approach is proposed Yap et al., [62]. The overall vibration of the cooling tower increased from 3mm/s to 26mm/s after the VAWTs with enclosure were mounted, according to this process. ...
... In this simulation, two mesh types were created which define the VAWT blade rotation as "airfoil" and the "diffuser" as representing the diffuser plate and the air flow inlet. Following investigation, the Computer-Aided Design (CAD) software and Finite Element Analysis (FEA) were the computational tools utilized for validation with experimental analysis by Yap et al., [62]. Next, comprehensive study of CFD parameters, including mesh resolution, turbulence model and transient time step values, is then presented in the study by Tabatabaeikia et al., [54], the simulation results are compared to the experimental results to ensure that they are accurate. ...
Presently the worldwide lockdown from Covid-19 give a huge effect on different sectors across the board, notably on energy consumption. Lockdowns have fuelled the intensification of low-carbon resources in terms of electricity production, yet a drastic upswing in electricity use in residential districts during the pandemic. By exploring economic renewable energy resources, the world is trying to overcome the crisis and one of them is wind energy, where this sustainable energy system is highly demanded, thus reducing global CO2 emissions. Researchers have carried out several findings on wind energy obtained from wind turbines at various potential locations, but most of it used natural sources as a wind stream. Therefore, a revolutionary concept on extracting clean energy from manufactured wind resources with wind turbine system for power generation is introduced in recent studies. The main goal of this review paper is to emphasize the performances of power generation through Exhaust Air Energy Recovery Wind Turbine. The potentiality of wind extractions is reviewed to achieve the clear overview of this new progressive ideas and the important configurations is accentuated. Most findings indicated that this energy recovery device converts wasted energy to a more profitable form by converting it to electricity, resulting in a rapid return on investment. Moreover, the enclosing the output area of wind turbines for recovering energy enhances overall efficiency.
... In order to reduce power block, size of upstream rotor was considered small as compared to downstream rotor. Yap et al. [13] discussed the electricity generation due to dual rotor wind turbine located near the exhausting gases in a plant and its effects on the performance of cooling tower. Habash et al. [14] investigated a dual rotor scaled down turbine structure and conclude that a dual rotor turbine may produce up to 60% more power than a single rotor turbine. ...
Power production of a wind turbine is dependent upon its rotor size and at present wind turbines with large rotor diameter (>175 m) are available in the market. However major problems associated with such large size conventional turbines are their cost & noise pollution. Due to these reason researchers have diverted their attention towards lower sized equivalent multi-rotor wind turbines. These turbines are found to be cheaper and good performers. Keeping it in view, in this paper an effort has been made to compare the energy yield and economics of two types of wind turbines i.e. single rotor & multi rotor wind turbine. Power, energy and cost models as proposed are used to determine the annual energy yield and economics of multi-rotor turbines. Simulation results as presented in this paper justify the suitability of multi-rotor wind turbine in place of single rotor configuration. Such turbines deliver more energy yield with low installation cost in contrast to single rotor turbines.
