Papers by Keyword: Thermal

Abstract: Heat removal from nuclear reactor core has been one of the major Engineering considerations in the construction of nuclear power plant. At the center of this consideration is the nuclear fuel pellet whose burning efficiency determines the rate of heat transfer to the coolant. This research, focuses on the study of temperature distribution of solid fuel, temperature distribution of annular fuel with external cooling and the temperature distribution of annular fuel with internal and external cooling. We analyzed the different distribution and made a conclusion on the possibility of improving temperature management of Nuclear fuel rod, by designing fuel pellets based on this geometrical and thermal Analysis. To date, a lot of studies has been done on the thermal and geometrical properties of Nuclear fuel pellet, it is observed that annular fuel pellet with simulteneous internal and external cooling can achieve better temperature distribution which leads to high linear heat generation rate, thus generating more power in the design [1]. It has also been observed that annular fuel pellets has low fission gas release [10]. In large LOCA, the peak cladding temperature of annular fuel is about 600 which is significantly less than that of solid fuel (920 ), this is due to the fact that annular fuel cladding has lower initial temperature and the thinner annular fuel can be cooled more efficiently than the solid fuel. One of drawbacks of annular fuel technology is “the fuel gap conductance assymmetry” which is caused by outward thermal expansion, it has a potential effect on the MDNBR (Minimum Departure from Nucleate Boiling Ratio), which is the minimum ratio of the critical to actual heat flux found in the core [10]. In this model, we used the ceramic fuel pellet of UO₂ as our case study. All the parameters in this model are assumed parameters of UO₂. The Heat Transfer tool (ANSYS APDL) was used to validate the Analytical Model of this research.

Abstract: The paper considers the application of wear resistant coatings by methods of gas thermal and flame spraying. It demonstrates the relationship between adhesion strength of the sprayed coating and surface roughness after abrasive jet machining using piston rings with steel-molybdenum coating as an example. The authors consider the results of studies aimed defining the relationship between surface roughness and of jet-abrasive machining conditions: the distance between the nozzle exit and the workpiece, the number of passages, the operating air pressure and frequency of the shot swapping.

Abstract: Effects of irradiated rPP compatibilizer, on the mechanical and thermal properties of recycled polypropylene/microcrystalline cellulose composites (rPP/MCC), are investigated. rPP is irradiated with an electron beam at dosages ranging from 10, 20, 30 to 50kGy. A matrix, containing of unirradiated and irradiated rPP (50:50 by ratio), is then added to 5, 20 and 40wt% MCC fibres. The composites are prepared using a twin screw extruder, followed by injection moulding. The properties are then characterized using tensile and thermal degradation tests. The improvement of Young’s modulus by up to about 45% suggests a compatibilising effect of the irradiated rPP. Fracture surface observations reveal an adhesion between rPP matrix and MCC fibres. However, the thermal stability deteriorated with the addition of MCC and irradiated rPP.

Abstract: 8 mol% of Yttrium oxide doped Zirconia (8YSZ) is one of the most explored compositions which give high ionic conductivities and good power output at 1000 °C. Generally, dopant was added to improve the sinterability of 8YSZ ceramics. In this present study, granulated 8YSZ powders with multimodal size was mixed with ZnO (0,1,2,3 wt%) using mortar and pestle. The mixed powder was compacted and sintered at 1550°C for 2 hours. 2 distinct endothermic peaks were observed in DTA plot of all samples. However, samples contain high amount of ZnO had a broader endothermic peak which resulted from the melting of ZnO. Rietveld refinement results indicate that the tetragonal phase appeared as the dominant phase for all doped and undoped samples, while cubic and monoclinic phase as the secondary phase. The monoclinic phase decreased as the amount of ZnO increased.

Abstract: The world’s energy requirement has been dominated by petroleum oil resources for years in many applications, especially in the area of electricity generation and utilization. Mineral oil application in power system equipment can be potentially hazardous to the environment, especially when there are incidents of transformer explosion, which caused spillages of oil to the soils or water streams and thereby pollute the surrounding environments. This paper is aimed at finding a substitute for the use of mineral oil as transformer oil. Experiments on breakdown voltages, flash points, pour points, viscosities, densities and insulation resistances on conventional mineral oil and some selected vegetable oils were conducted, analyzed and compared to the internationally accepted standards, ASTM (America Standard Test of Material). Rubber seed oil, Palm oil, Mellon oil, Ground oil and Palm kernel oil were found to have good electrical, chemical and thermal properties which the transformer oil has.

Abstract: In this study, a typical kitchen having a standard dimension of 213cm × 243cm × 305cm was modeled with single open door exit. Steady state simulations were performed using three dimensional commercial CFD solver with appropriate boundary conditions. Two heat sources were used for modelling the kitchen that resembles the double burner gas stoves of urban residential kitchen in developing countries. In the earlier works, for the same model the predictions validated at an optimum grid resolution and the results have been presented for thermal comfort, carbon dioxide gas emission under natural, forced and no ventilation cases. The effect of kitchen hood system on the thermal comfort and emission has also been analyzed. In this present work, three different positions of the kitchen hood suction have been studied for the effect on thermal distribution and emission rate. The investigated positions of the kitchen hood are the Front, Top and Bottom with respect to the gas stove. It was observed that both front and bottom hood extraction method significantly reduces the emissions to well below the safe limit. They also can maintain thermal comfort quite well inside the kitchen space.

Abstract: Proliferation in the use of digital data in manufacturing led to a new industrial revolution by virtue of which user groups and researchers from multiple industrial enterprises have introduced Rapid Prototyping (RP) into their product development processes. This paper presents a coupled field thermos-structural analysis of new RP process namely, Selective Inhibition Sintering Process (SISP) for the evaluation on the effect of temperature in various polymer materials. The present study provides information of the requirement of heat source to achieve effective sintering phenomenon. The structured Finite Element (FE) model with a dimension of 30 X 30 X 1.5 mm is considered for the analysis where in different heat quantity is applied in an iterative manner to examine the sintering temperature. Based on the simulation results, for each polymer, required amount of heat to observe sintering characteristics is evaluated. The effect of applied heat on the examination of structural aspects of polymer materials including thermal stress, distortion and displacement is carried out. The simulation results affirms that the polymer materials are within in the safe structural and thermal limit and the selection of low cost heat source will be useful for the development of cost-effective SISP system.

Abstract: The present scenario of energy conservation has witnessed many innovative and eco-friendly techniques and one such area where there is a necessity to conserve energy is foundries. Foundries also pollute the atmosphere with greenhouse gases contributing to 296143037.6 metric tons annually. The proposed technique in this paper aims at reducing the energy utilized in melting the scrap material at foundries by solar thermal energy. In the methodology proposed, solar energy is concentrated onto the scrap placed on a receiving platform using a parabolic trough and heats it up so that the heated scrap takes lesser energy to melt. The experiments resulted in preheating temperature of 100 °C when placed on a receiving platform and 110°C when copper shots are used to conduct heat from receiver to the scrap. This translates to energy conservation of 6%. This eco-friendly technique when adopted can result in substantial savings in consumption and environmental protection.

Abstract: An Investigation on thermal conductivity of woven fabrics is reported. Thermal conductivity knitted fabrics to be found to be lower that of woven fabrics. Finishes also had an effect on Thermal conductivity.

Abstract: Application of nanoparticles provides an effective way of improving heat transfer characteristics of fluids. Particles less than 100 nm in diameter exhibit different properties from those of conventional solids. Compared with micron-sized particles, nanophase powders have much larger relative surface areas and a great potential for heat transfer enhancement. Some researchers tried to suspend nanoparticles into fluids to form high effective heat transfer fluids. Some preliminary experimental results showed that increase in thermal conductivity of approximately 60% can be obtained for some nanofluids consisting of water and 5 vol% CuO nanoparticles. So, the thermal conductivity of nanofluid was found to be strongly dependent on the nanoparticle volume fraction. So far it has been an unsolved problem to develop a sophisticated theory to predict thermal conductivity of nanofluids, although there are some semi empirical correlations to calculate the apparent conductivity of two-phase mixture. In this article, several correlations for predicting the nanofluid thermal conductivity will be compared and results will be discussed for three water based nanofluids.