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- 저자 : Jayadeep, U.B. (검색결과 2 건)
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Kaiprath Jayadeep,V. V. Kishor Kumar 대한설비공학회 2023 International Journal of Air-Conditioning and Refr Vol.31 No.1
The average global temperature has increased by approximately 0.7 °C since the last century. If the current trend continues, the temperature may further increase by 1.4 – 4.5 °C until 2100. It is estimated that air-conditioning and refrigeration systems contribute about 15% of world electrical energy demand. The rapid depletion of non-renewable resources such as fossil fuels and the associated emissions lead to the development of alternative solutions which employ renewable energy resources for refrigeration. The conventional vapour compression (VC) and vapour absorption (or adsorption) (VA) refrigeration systems usually rely on fossil fuels for their operation which ultimately leads to large amount of CO 2 emissions. Thermoelectric (TE) refrigeration systems working on the principle of Peltier effect are an alternative for the conventional systems. The thermoelectric refrigerators will not produce any noise and vibration due to the absence of any moving parts. They are refrigerant-free as electrons act as heat carriers. The greatest advantage of a TE system is that it can directly be powered by solar photovoltaic (PVs) since they give a DC output. The main drawback of thermoelectric refrigeration system is their low coefficient of performance (COP). The COP of a thermoelectric cooler (TEC) operating with a temperature difference of 20 °C is about 0.5. The improvement of heat transfer at the hot side of the cooler is a key aspect for a better COP. A good thermoelectric material should possess high Seebeck coefficient, low-thermal conductivity, and high electrical conductivity. Since these three are interrelated, these parameters must be optimized. It is important to reduce the electric contact and thermal resistances and get an optimized configuration of thermoelectric cooler. The recent developments in material science has enabled the usage of better thermoelectric materials with a positive Thomson coefficient to produce a better cooling performance. The total efficiency of a TEC powered by solar cell is the product of PV system efficiency and the COP of the cooler. Therefore, the enhancement of PV system efficiency and the selection of materials with better thermoelectric performance are important in the design of solar-powered thermoelectric cooler. The performance of solar cell-powered TEC depends on solar insolation which varies with weather, climate, and geographic location. Due to the variation in insolation and unavailability of solar power in the night, a battery must be used to store the energy. This paper presents a comprehensive review about the thermoelectric coolers and the dependance of performance of TECs on various operating and design parameters. The results reported for the performance improvement of solar PV-powered thermoelectric coolers were critically analysed.
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Mesoscopic numerical analysis of reinforced concrete beams using a modified micro truss model
Nagarajan, Praveen,Jayadeep, U.B.,Madhavan Pillai, T.M. Techno-Press 2010 Interaction and multiscale mechanics Vol.3 No.1
Concrete is a heterogeneous material consisting of coarse aggregate, mortar matrix and interfacial zones at the meso level. Though studies have been done to interpret the fracture process in concrete using meso level models, not much work has been done for simulating the macroscopic behaviour of reinforced concrete structures using the meso level models. This paper presents a procedure for the mesoscopic analysis of reinforced concrete beams using a modified micro truss model. The micro truss model is derived based on the framework method and uses the lattice meshes for representing the coarse aggregate (CA), mortar matrix, interfacial zones and reinforcement bars. A simple procedure for generating a random aggregate structure is developed using the constitutive model at meso level. The study reveals the potential of the mesoscopic numerical simulation using a modified micro truss model to predict the nonlinear response of reinforced concrete structures. The modified micro truss model correctly predicts the load-deflection behaviour, crack pattern and ultimate load of reinforced concrete beams failing under different failure modes.
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