Papers by Keyword: Thermal

Abstract: In recent years, complex district heating systems will become the main style in most of big cities of china. How to simulate the hydraulic and thermal operation becomes more and more import. In this paper, the simulation mathematical model and method on the hydraulic and thermal operation for complex district heating system is proposed. By using the optimal of economical operation efficiency of the heating networks as the objective function and thermal balance as boundary conditions, the mathematical model is established. Meanwhile, the simulation software of hydraulic and thermal operation for complex district heating system has been developed. Functions of software involve information compilation, hydraulic calculation analysis, source thermal operation calculation, etc.

Abstract: For excessive wet masonry rehabilitation, except for other methods, the method of air cavities is used. These can be wall or floor cavities. The wall cavities may be situated either on the internal or the external side of the wall. From the height point of view, internal side cavities can be located under the floor or above the floor level. This contribution only deals with the cavities above the floor level. In the projection practice, the air cavities usually are designed only empirically. But it is necessary to carry out their thermal technical evaluation for their correct capacity. The matter of the evaluation is the topic of the following contribution.

Abstract: Borazine-silicon-containing arylacetylene (PBZSA) resin was a novel organic inorganic hybrid polymer and prepared through condensation reaction among B,B’,B’’-trichloroborazine, dichlorosilane and arylacetylene Grignard reagent. The chemical structure of PBZSA resin was characterized by FT-IR and ¹H NMR. The thermal stability and dielectric properties of cured PBZSA were investigated by TGA and broadband dielectric spectrometer. The results indicated that cured PBZSA showed high thermal stability with char yield up to 87.1% at 1000°C and at decompose temperature (T_d5) 580°C, and low dielectric constant (2.8-2.9) and dielectric loss (<0.005).

Abstract: Thermoplastic starch/poly (butylene succinate),an entirely biodegradable polymer blend was prepared using a two-step extrusion process. The mechanical properties and thermal behavior of TPS/PBS blends were investigated. The results demonstrated that the strength and elongation at break of TPS/PBS blends were greatly improved with the addition of rPBS in PBS blends due to its contribution in the improvement of interfacial compatibilizing and miscibility.

Abstract: The performances of PP/MMT nanocomposite (70μm thick films), in terms of thermal and rheological properties were investigated. A twin-screw extruder was used to compound PP, MMT, compatibilizer, and extruded nanocomposite films were collected for test. All results were compared and the influence of MMT contents on the final properties were observed and reported. The thermal properties of PP had improved by increasing MMT content from 0-3 phr. However at 4 phr thermal stability of the nanocomposite had slightly dropped. In terms of rhelogical properties, the addition of MMT to the PP blend increased the complex viscosity of the nanocomposites, particularly at low frequency regions.

Abstract: The chitosan filled thermoplastic elastomer (TPE) composites with different filler loading was prepared by melt mixing at 180 °C. The effect of 3-aminopropyltriethoxysilane (3-APE) as coupling agent on the rheological and thermal properties of composites were investigated. The melt flow indexer was used to characterize the melt flow index (MFI) of TPE/Chitosan composites at temperature of 180 to 210 °C. It was found that addition of chitosan into composites had reduced the MFI values. Besides that, the MFI values of composites were found to increase linearly with temperature. The treated composites demonstrated lower MFI values, indicated that better interfacial bonding was established between chitosan and TPE and the flowability of the composite melts was hindered. The TGA results reported that the treated composites had better thermal stability and lower total weight loss as compared to untreated composites at similar filler loading.

Abstract: The article deals with various optional combinations of upper and lower basins in pumped-storage power plants (PSPP) which determine ice conditions that may appear on water surfaces, headwater discharge basins and slopes basins. There are also examples of calculation methods of ice regimes that are given in this article.

Abstract: Exhaust passage is a significant part of the gasoline engine, its structure will affects the gas flow characteristics of the engine directly [1]. So, research and analysis of the exhaust tract is essential. In this paper, a detailed analysis of the flow field under cold state and hot state was made. For a start, the method of laser scanning and UG software were used to reverse modeling engine exhaust port and get the three-dimensional model. The next, the unstructured grid with local mesh refinement scheme was used to mesh this three-dimensional model with ICEM. After this, numerical simulations of the exhaust passage with five different valve lifts were carried out under thermal and cold conditions. Finally, comparing the velocity field and pressure field of the exhaust passage under cold state and thermal state, it can be find that the flow field under hot and cold state have similar characteristics. The results of this paper can provide a theoretical basis for following researches of the engine exhaust port.

Abstract: A thermo-mechanical finite element model was developed by using FEA commercial software, in order to estimate thermal stress levels in a refractory lined steelmaking ladle shell during its first preheating stage. The model considers two refractory linings: an inner working lining and a permanent one besides the external ladle shell. In this way, stresses on both refractory lining and metallic shell due to restricted lining thermal expansion were simulated. Stress-strain curves of refractory lining materials at different temperatures were obtained through lab tests and then used for model optimization. Additionally, creep behavior in the steel shell under different tensile stresses and temperatures was also estimated taking into account previously obtained results from laboratory tests. In plant strain and temperature measurements were done by instrumenting the lower part of the ladle sidewall shell with high temperature strain gauges and thermocouples. Predicted stress evolution showed good agreement with results obtained from in plant measurements.

Abstract: Influences of arc-shaped baffles turbulators (ASB) on thermal behaviors in a solar air heater channel are studied. In the experiment, the ASB with three pitch ratios (P/e) are placed on the absorber plate (bottom channel wall in this case) to generate stronger turbulence intensity in the channel. The distributions of temperature and local Nusselt number contours in the absorber plate fitted with ASB are observed with thermochromic liquid crystal (TLC) sheet. The results reveal that the heat transfer increases with the decrease in P/e due to longitudinal vortex flow effect. The heat transfer from employing the ASB at P/e = 4.0, 6.0 and 8.0 is higher than the smooth channel around 116%, 120% and 127%, respectively. This indicates that the ASB pitch spacing is optimal at 8 times baffle height in the present work.