Abstract Increasing energy consumption during summer periods is becoming an increasing problem worldwide, particularly in Iraq. Air-conditioning applications account for approximately half of the energy used in residential buildings. Thus, this study mainly aims to investigate the potential of using phase change material (PCM) numerically to reduce cooling energy consumption in residential buildings. Ansys Fluent software was used to study the heat transfer in the proposed geometrical model. Thermal performance, such as wall surface temperature, has been investigated. Different types of PCMs were examined to test their suitability for a selected weather data. Results show that the PCM with higher melting temperature was more efficient for locations with hot weather, such as the cities of Basra and Baghdad. The incorporation of PCM in the exterior layer of the external wall could reduce the peak interior wall surface temperature in summer and this will reduce the heat gain. As a result, the cooling energy consumption used to cool the building is reduced. The numerical results were validated with the experimental and numerical data available in the literature.
Publisher: The Authors. Published by Elsevier Ltd.
Abstract In this study, a concept of using phase change material (PCM) for improving cooling efficiency of an air-conditioner had been presented under Thai climate. Paraffin waxes melting point at around 20 °C was selected to evaluate the thermal performance by reducing the air temperature entering the evaporating coil. The model of PCM celluloid balls had been performed with the air-conditioner. Moreover, the mathematical model of the air-conditioner with the PCM storage was developed and verified with the testing results. From the study results, it could be seen that the simulated data agreed quite well with the experimental result at the discrepant around 2–4%. Finally, the model was used to analyze the economic result which was found that the electrical consumption of the modified air-conditioner could be decreased 3.09 kW h/d. The electrical power consumption of the modified unit was 36.27 kW h/d at the operating time 15 h/d compared with 39.36 kW h/d of the normal unit at the operating time 12 h/d. The saving cost of the PCM bed could be 9.10% or 170.03 USD and the payback period was 4.15 y.
The necessity to increase renewable energy consumption in the industrial, residential, and commercial use is crucial due to increasing use and decreasing reserve of fossil fuels. This paper is focused on the modelling and optimization of solar industrial process heating system using a flat plate collector and evacuated tube collector integrated into lead mining process for 7 different lead miner countries of the world: Australia, Canada, Indonesia, China, Peru, Russia, USA. Comparative analysis among seven miner countries is conducted by considering a few cases based on solar industrial process heating system design. The number of solar collectors installed is then optimized for three different designs of SHIP system in two different locations in Australia. To analyze the reduction potential of environmental burdens, life cycle assessment of lead mining process has been carried out based on the global average dataset. Environmental impact can be greatly reduced in global warming, human toxicity, and fossil fuel scarcity through the solar process heat integration. The evacuated-tube collector based solar process heating system with solar loop heat exchanger would have the highest efficiency and solar fraction over the other types of systems considered. Increasing the number of solar collector installation would result in higher solar fraction and capital cost.
Abstract Various drying techniques have been operated to determine the energy requirements for drying mint leaves. The investigates were approved with different air-drying temperature of 30, 40 and 50 °C at different air velocity of 1.0, 1.5 and 2.5 m/s in hot-air dryer. The infrared and hybrid dryers were performed at different infrared intensity 1000, 2000 and 4000 W/m2 with same conditions of air velocity and temperature of convection drying. Under hot air convection, the energy consumption reduced significantly by increasing the air temperature while increases with rise in velocity. While the energy consummation decreased by increasing the infrared intensity using hybrid and infrared dryer but rise air velocity increased the energy. The minimum SEC was verified 2.6 MJ/kg with air temperature of 50 °C and at intensity 4000 W/m2, while maximum SEC 19.7 MJ/kg was observed at 30 °C and 1000 W/m2 under air velocity 1 m/s. The lower SEC of 2.6 MJ/kg was noted applying the hybrid dryer, which was 92.1 and 49.4% lesser than infrared and hot-air dryers, respectively. The optimum condition was conducted to 1.0 m/s, 50 °C, and 4000 W/m2 under hybrid dryer for efficient drying of mint.
Abstract The development of wireless sensor technology has provided an alternative research direction for monitoring of the Internet of Things. However, the practical application of wireless sensor technology is currently constrained by power supply requirements and the rather laborious task of replacing or maintaining the sensor batteries. In this paper, a wireless node power supply system based on the temperature difference between the shallow soil-air was designed. The distinguishing features of this device include application of a gravity heat pipe, thermoelectric generators (TEGs), copper heat fins, and radiators to absorb, transfer and convert the thermal energy. The study measured the performance of the proposed device in an experimental outdoor platform, the results show that in the 8 h monitoring of a day, the temperature difference of thermoelectric device ranged from 12.96k to 24.69k, the peak voltage of the device was 722.13 mV and the peak power was 3.62 mW when the proposed device was at the optimal external load. Furthermore a power management system was designed to increase the output voltage and eventually store it in the supercapacitor. In conclusion, The system provides an effective mechanism for solving the energy supply problem of wireless sensor.
The design optimization of water basins for the refrigeration of intermittent high-power heat sources, by mean of CFD simulations, is presented. A case study of an experimental facility is considered, that foreseen two large water basins as thermal storage, with volume of 315 m3 and 500 m3 respectively, and an installed nominal cooling power around 25 MW for the cooling of an intermittent load, with peak power of around 65 MW. A strong horizontal stratification has been looked after in the preliminary design, which include a labyrinth of walls and weirs, and water inlet/outlet plugs positioned at the opposite side of the basins. The intensity and the role of this stratification have been explored using a CFD software, simulating both winter and summer sceneries. Some variants to the original design have been studied, in order to optimize the stratification of water temperatures. It is shown that a large water storage with an optimal design could help very much in reducing cooling power demand in case of intermittent thermal load. Keywords: Large water storage, Thermal stratification, CFD
Abstract In this study, photovoltaic module temperature has been predicted according to outlet air temperature and solar radiation. For this investigation, photovoltaic module temperatures have been determined in the experimental system for 10, 20, 30, and 40 °C ambient air temperature and different solar radiations. This experimental study was made in open air and solar radiation was measured and then this measured data was used for the training of ANN. Photovoltaic module temperatures have been predicted according to solar radiation and outside air temperature for the Aegean region in Turkey. Electrical efficiency and power was also calculated depending on the predicted module temperature. Kutahya, Usak and Afyon are the most suitable cities in terms of electrical efficiency and power product in the Aegean region in Turkey.
Abstract This paper presents the results of an evaluation of two solar-assisted refrigeration systems in protecting permafrost foundations in railway and roadway engineering. A technical comparison was conducted between two types of traditional permafrost cooling measures and refrigeration systems: vapor compression and heat-driven adsorption. The investigated refrigeration systems have better real-time performance and effectiveness than traditional passive heat regulation measures. Moreover, the permafrost regions in China have good potential for solar energy, addressing the issue of decentralized power supply for refrigeration. Two special permafrost cooling systems were designed, manufactured, and tested; the solar photovoltaic vapor compression refrigeration system (SPV-VCRS) and the solar photothermal adsorption refrigeration system (SPT-ARS). The SPV-VCRS prototype exhibits greater potential for permafrost protection, with a consecutive average temperature of −23.55 °C and a coefficient of performance (COP) of 0.41 in the warm season. The SPT-ARS prototype is characterized by an intermittent refrigeration temperature of −1.83 °C and a significantly lower COP of 0.054 per day. Based on the results, suggestions have been given for the selection of solar refrigeration systems for application in the protection of the permafrost under embankments.
Abstract This study investigates an alternative fuel methodology for diesel engines that focus on the influence of ethanol as an additive agent in biodiesel blends derived from the industrial liquid waste of palm oil and sunflower oil residues. Specifically, the study addresses relevant aspects of the combustion performance and emissions characteristics in a single-cylinder diesel engine. For the experimental development, four different fuels were tested: commercial diesel, a blend of biodiesel formed from the residual material of palm oil and sunflower oil (PB3SB2), two blends with an addition of 2%, and 4% ethanol in the biodiesel produced (PB3SB2E2 and PB3SB2E4). The engine operated under nine different operation modes following international testing methodologies. Results indicated that incorporating ethanol in the PB3SB2 biodiesel blend improves thermal efficiency by 0.8%. Increasing the ethanol mixing ratio to 4% provides a further efficiency improvement of up to 1.2%. The emissions analysis showed that the addition of ethanol below 4% in the biodiesel blend facilitates the minimization of pollutant levels of CO, CO2, NOx, HC, and smoke opacity compared to the biodiesel formed by the two residual oils (PB3SB2). Overall, ethanol incorporation reduced emissions levels between 7.5 and 13.87% compared to PB3SB2. In conclusion, integrating biodiesel and ethanol as additive agent emerges as a promising alternative to promote a reliable and sustainable operation in diesel engines.
Heat recovery is the reutilization of lavished thermal energy. This paper proposes a hybrid heat recovery system that utilizes exhaust gases of a generator to heat water and produce electricity using thermoelectric generators. The system is composed of a concentric tank with a copper tube passing through it. At the inner surface of the tube, a layer of TEGs is located. The main purpose of the paper is to study the effect of changing the load of the generator on the water temperature and power generated. Knowing that 100 TEGs are utilized, results show that 47 °C hot water and 141 W are produced when load is 10 kW. It increases to 97 °C hot water and 1412 W when the generator load is 38 kW (14.12 W per TEG). Keywords: Heat recovery, Thermoelectric generators, Cogeneration, Domestic hot water, Generators, Exhaust gases
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