Volume-19-Issue 1 (2022)
Assessment of ultrasound assisted coalescence of water-in-crude oil emulsion: Influence of piezoelectric transducer material under batch and continuous conditions
IJTEE, Volume-19, Issue 1 (2022) , PP 47 - 54
Published: 26 Oct 2022
by Idowu Adeyemi, Mahmoud Meribout, Lyes Khezzar, Nabil Kharoua, Khalid AlHammadi from Department of Mechanical Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates, Department of Electrical Engineering and Computer Science, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates, and Department of Mechanical Engineering, Ecole Nationale Polytechnique de Constantine, Constantine, Algeria
Abstract: In this work, the potentiality of lead free ultrasound (US) materials towards crude oil emulsion demulsification was assessed. The assessment is crucial because of the detrimental environmental and health impacts of lead zirconate titanate, which is widely used for US coalescence presently. The production or utilization of lead zirconate titanate (PZT) results in the release of vaporized hazardous lead oxide (PbO) at elevated temperature or dissolution of poisonous lead into aqueous medium. Hence, the analysis of the effect of different piezoelectric material type (PZT, polyvinylidene fluoride (PVDF) and lithium niobate (LiNbO3)) on domain acoustic pressure distribution and the subsequent coalescence of binary droplets under batch conditions was conducted. The lead-free piezoelectric materials (PVDF and LiNbO3) were assessed with the PZT in order to determine their viability for droplet coalescence. The piezoelectric materials were subjected to mechanical oscillation under resonance in order to allow for optimum performance. Moreover, the US coalescence was examined under continuous flow conditions to determine coalescence behavior and performance during online emulsion treatment. The eigen-frequency analysis provided the resonance frequencies of 19.61, 26.04 and 57.80 kHz for PVDF, PZT and Lithium niobate, respectively. Moreover, the acoustic pressure in the emulsion domain varied in magnitude and distribution. The order of the coalescence time for the binary droplets followed the order PZT<PVDF<LiNbO3. Furthermore, increasing the flow velocities resulted in slight reduction in the coalescence time and energy consumed for the different piezoelectric materials evaluated. read more... read less...
Keywords: Piezoelectric transducer, Ultrasound, Coalescence, Demulsification, Lead free, Crude Oil Emulsion
Thermoacoustic Refrigeration: Short Review
IJTEE, Volume-19, Issue 1 (2022) , PP 29 - 45
Published: 26 Oct 2022
by Omar Ahmed Al-Mufti and Isam Janajreh from Department of Mechanical Engineering, Khalifa University of Science and Technology, Abu Dhabi, UAE
Abstract: Thermoacoustic is the science that studies the conversion of the heat into acoustical sound and vice versa. The conversion of heat to acoustic power is done through Thermoacoustic engine (TAE). This generated acoustic power can be converted to another and useful form such as mechanical or electrical energy. On the other hand, Thermoacoustic refrigerator (TAR) or heat pump is a device that uses acoustic sound to pump heat from a lower temperature reservoir. The most distinct feature of thermoacoustic systems is that they do not have moving parts, which makes them reliable. Thermoacoustic engine can recycle any source of waste heat and use sustainable heat like concentrated solar. Also, in contrast to conventional refrigeration methods, thermoacoustic refrigerator spares the usage of environmentally harmful gases that is daunting the centralized cooling industry. There is no doubt the thermoacoustic technology has been considered in various applications with some unspoken advancement. In this manuscript we intend to review the fundamentals of thermoacoustics and highlight their recent developments. Additionally, analytical simulation of thermoacoustic refrigerator will be discussed and validated against experimental published work. The goal is to reveal the effect of different parameters on the performance in an attempt to establish design guidelines for an improved technology metrics. The future prospects of thermoacoustic refrigeration are also presented at the end of this study. read more... read less...
Keywords: Thermoacoustic engine; Thermoacoustic refrigerator; Thermal and viscous penetration depth; Standing and traveling wave
Thermal Investigation of Nanofluids in Heat Exchanger Tubes using Two-Phase Approach
IJTEE, Volume-19, Issue 1 (2022) , PP 23 - 28
Published: 19 Sep 2022
by M Mubashir Farid, Samia Sadaf, M Shahid Farooq, Ussama Ali from Department of Mechanical Engineering, University of Engineering and Technology Lahore, Pakistan
Abstract: This paper investigates the effect of nanofluids in a flat-tube heat exchanger on the heat transfer under the influence of constant heat flux using computational fluid dynamics (CFD) analysis. Two nanofluids: Titanium Oxide (TiO2)/water and Aluminum Oxide (Al2O3)/water were used with nanoparticles of diameter 10 nm. A two-phase approach with a mixture model is adopted in the CFD analysis. The heat transfer coefficient was evaluated at Reynolds number of 1750 utilizing various volume concentrations of nanoparticles (1%, 3%, 5%, and 7%). It was observed that an increase in the concentration of the nanoparticles resulted in an increase in the value of heat transfer coefficient. The results observed at 7% volume concentration, using two-phase approach, showed 5% and 8% enhancement in the heat transfer coefficient for TiO2/water and Al2O3/water, respectively, when compared with the results of single-phase technique. read more... read less...
Keywords: Flat tube, Heat transfer coefficient, Two-phase approach, Nanofluids
Parametric Sensitivity of Water Collection on Desiccant Coated Heat Exchanger
IJTEE, Volume-19, Issue 1 (2022) , PP 15 - 22
Published: 19 Sep 2022
by Muna AlQaydi, Md Islam, Isam Janajreh from Khalifa University of Science and Technology, Abu Dhabi, UAE
Abstract: Atmospheric water harvesting (AWH) is used to address the current scarcity of fresh water. Sorption-based AWH technology using desiccant coated heat exchanger (DCHE) could enable a good water supply in arid regions since sorbents can grab moisture from arid environment and then release water once it is thermally generated. Recent developments focus on novel adsorbents with high sorption capacity at low humidity and low regeneration temperature. However, a thermodynamic analysis on overall system to predict the best operating parameters and how it affects system efficiency has not been studied. In this study, we investigated the energy and heat transfer properties of desiccant-coated heat exchanger. A one-dimensional mathematical model is developed to predict the performance of a DCHE system which uses super-porous hydrogel (SPH) made of N-isopropylacrylamide (NIPAM) as a desiccant material. The effects of inlet temperature, inlet humidity ratio, air mass flow rate, and cold side temperature brought by using thermo-electric cooling (TEC) on the amount of water collected, COP, and second law efficiency of the system were analyzed. The results suggest that the rate of water production and COP of the system increased as the temperature and humidity of the air increased. It emerged that increasing airflow increases water intake and COP due to the improved heat transfer through the system. However, rising cold side temperature of TEC decreases water production rate and COP while it improves second law efficiency because of reduced heat transfer and entropy generation. The obtained results show that water harvesting using the proposed system with thermoelectric cooling device and solar energy is feasible. read more... read less...
Keywords: Cooling Load, Air-Conditioning, Desiccant coated heat exchanger, Atmospheric water collection
Numerical Simulation of Laminar Flow Over a Transversely Oscillating Circular Cylinder
IJTEE, Volume-19, Issue 1 (2022) , PP 07 - 13
Published: 19 Sep 2022
by Ussama Ali, Ayoola Brimmo, Md Islam, Isam Janajreh from Department of Mechanical Engineering, Khalifa University of Science and Technology, Abu Dhabi, UAE and Department of Mechanical Engineering, University of Engineering and Technology, Lahore, 54890, Pakistan
Abstract: Two-dimensional low Reynolds number flow (Re = 100) over a transversely oscillating circular cylinder placed in a uniform stream is numerically investigated in this work using the commercial software Ansys/Fluent. The forced transverse oscillations of the cylinder are carried out to mimic the specific cases of flow-induced vibrations. The frequency ratio is varied between 0 – 2, where 0 corresponds to stationary cylinder. The layering technique of dynamic mesh is employed to incorporate the cylinder motion. The unsteady flow simulations are performed to solve for URANS. The parameters studied are the coefficients of lift and drag, vortex shedding frequency, and the vortex shedding patterns. The results reveal that the cylinder oscillation induces modulation in the lift and drag coefficients in terms of their frequency and amplitude. The lock-in occurs at frequency ratio of 1 where the frequency of cylinder oscillation matches with the natural vortex shedding frequency of the cylinder. Maximum average drag coefficient is observed at the lock-in condition however the lift coefficient is found to increase with the frequency ratio. The 2S vortex shedding pattern is observed in the vorticity contours for all the cases studied. read more... read less...
Keywords: Forced transverse oscillations, Unsteady flow, Lift and drag coefficients, Vortex shedding pattern
Effect of Building Orientation on The Cooling Load: The UAE Case Study
IJTEE, Volume-19, Issue 1 (2022) , PP 01 - 05
Published: 19 Sep 2022
by Ahmad Hasan, Md Islam, Isam Janajreh from Khalifa University of Science and Technology, Abu Dhabi, UAE
Abstract: UAE’s climate is considered one of the hottest and humid regions in the world, making air conditioning systems essential in each house nearly all year long. Air-conditioning systems consume most of the buildings’ electricity and that comes at a hefty energy cost. Therefore, any serious improvements in this technology in reducing the needed cooling load will lead to economical gain. Different parameters affect the cooling load of a building including the type of air conditioning system (centralized or decentralized units), the outdoor temperature and humidity, and the orientation of the building. Proper building orientation in Malaysia lead to 7.9% cooling load saving. The aim of this work is to study the effect of building orientation located in UAE on the cooling load. A single room is considered as the baseline building and TRNSYS software is used to calculate its cooling load when oriented to north, west, north–west, and south. The ASHRAE Standard 55 is adopted where the zone temperature ranges between 20°C – 25°C, and the relative humidity between and 40 – 60%. The study concludes that when the room is oriented to north–west the cooling load was at the minimum of 2627 Ton-hr. Whereas the maximum cooling load occurs when the room was oriented to west at 3161 Ton-hr. This led to nearly 17% cooling load saving. Therefore, it is recommended to orient buildings facing the north–west direction in the UAE. read more... read less...
Keywords: Cooling Load, Building Orientation, Air-Conditioning