Advanced Materials Research Vols. 622-623

Abstract: Heat generated in machining is significant to study, as number of technical and economic problems has root into it. The high temperatures on cutting tool needs better understanding of contact processes at tool-chip ,tool-workpiece interfaces. The contact length at tool-chip interface is significant to study as it governs the heat moving to the tool as well as many tribological conditions like stresses, tool wear. Understanding of Tool-workpiece interface is significant as it affects the heat moving to workpiece, tool, chip as well as tool flank wear and major machined surface characteristics. Non-sliding type tool wear mechanisms which are highly sensitive to temperature changes are important to study. The latest trends of using High Speed Machining, Dry and Near Dry Machining, Finish hard turning results in more heat generation demanding significant understanding of effect of heat generated and temperatures.

Abstract: Tetrahedral amorphous diamond-like carbon films were deposited on magnetic recording head by Filtered Cathodic Arc and subsequently thermally heated to various conditions. Raman spectroscopy was then performed to understand film structure; and mechanical property in terms of wear resistance was investigated by nanoindenter. The Raman spectra revealed that G position, FWHM of G peak and Id/Ig changed as a function of heating temperature and time which also agree well with wear depth measured.

Abstract: The formulation of a brake pad requires the optimization of multiple performance criteria. To achieve a stable and adequate friction (µ), the brake pad materials should have low fade and higher recovery characteristics coupled with less wear and noise. Among the properties mentioned, resistance to fade is very difficult to achieve. The type and amount of resin in the friction material is very critical for structural integrity of the composites. The binder should not deteriorate under any diverse conditions. The thermal stability of friction materials and its capacity to bind its ingredients collectively under diverse conditions depend upon the quality and proportion of resin. The current work evaluates the fade and recovery behaviour of developed friction composites from two different resins which are traditional straight phenolic resin and the alkyl benzene modified phenolic resin. Two brake pads with these different resins were fabricated as per Industrial Standard. TGA is carried between 150 – 400⁰ C as this zone of temperature is very critical which accounts for the weight loss (Thermal degradation). Friction and wear studies were carried out on a friction coefficient test rig as per SAE J661a standard. The results showed that the fade and wear of the friction materials were closely related to the thermal decomposition of the binder resin and durability of the contact plateaus, which were produced by the compaction of wear debris around hard ingredients on the rubbing surface. It was clearly observed that the friction materials with modified resin showed significant reduction in fade %. Friction materials made with higher thermal stability showed resistance to fade. However wear didn’t show much noticeable changes.

Abstract: This paper reports results of an experimental and theoretical study of the air flow in a vertical stack driven by thermal buoyancy and induced by surrounding wind. Tubular stacks with water jacket were constructed for experiments. To investigate the effect of the buoyancy force on the air flow, hot water was circulated through the stack jacket each experimental case with a different temperature. The effect due to the surrounding wind was studied using a wind tunnel to produce wind at different velocities. In this study, a simple model was developed to characterize the air flow caused by the effects. From the experimental validation, it was found that the model can predict well the volumetric rate of the air flow in the stack.

Abstract: This paper presents an experimental study of radiant cooling for building air-conditioning in a tropical climate. To prevent condensation of moisture on the cooling panel, the temperature of chilled water supplied to the panel was limited to 25°C. This led to the limitations of heat extraction capacity at the panel and its application to only space with low thermal load and low metabolic rate activity of people in the space. A simple calculation of radiative and convective heat exchange between the interior room surfaces and the room air was applied to determine the rate of heat extraction by the panels. The calculation results can match well with the measurement results. Using a comfort index of predicted mean vote (PMV), the results from experiments show that thermal comfort could be achieved with the application of radiant cooling.

Abstract: This paper presents an experimental and simulation study on application of a rotating desiccant dehumidification system under a tropical climate. The system was used to dehumidify the ventilation air before supplying to a space where a radiant cooling system was installed to provide thermal comfort. In the study, a computer program of the desiccant system was coded and used to evaluate the system performances. The experimental results show good agreement with the results from coded program. Using the program, the simulation results demonstrate that the desiccant system can reduce and handle the load of the ventilation air. The results also show that in order to remove the whole latent load, the minimum regeneration temperature is 80°C.

Abstract: The objective of this research were to evaulate equilibrium moisture contents (EMC) of black pepper using the gravimetric-static method and to study the drying kinetics of pepper using 1-stage hot air (HA) drying, 1-stage infrared (IR) drying, 2-stages drying with microwave (MW) and IR and 2-stages drying with MW and HA including to the specific energy consumption determination. For the first objective, the five saturated salt solutions were used for providing equlibrate state between pepper and surrounding at temperature ranging of 40-65°C correlated to relative humidity ranging of 10-90%. The results showed that EMC value decreased with increasing temperature at constant relative humidity. To evaluate the EMC value, the experimental data was simulated by four conventional EMC models and the criteria of the best fiiting models were determined by the determination of coefficient (R2) and the root mean square error (RMSE) value. The results showed that the calculated value using the Modified Oswin model was the most suitable for describing the relationship among equilibrium moisture content, relative humidity and temperature. To study effect of drying condition on drying kinetics, the initial moisture content and final moisture content after drying of papper sample was in ranges of 300-400% dry-basis and 12-16% dry-basis, respectively. The experimetal data were simulsted using empirical drying models and the results showed that the drying temperature relatively affected to drying rate of pepper while the evolution of moisture transfer was in the drying falling ratefor all drying strategies. The 1-stage IR drying and 2-stages drying with MW and IR provided low specific energy consumption (SEC) (0.11-0.15 MJ/kg of water evaporated) compared to the other drying strategies (0.87-1.52 MJ/kg of water evaporated). Moreover, the SEC of pepper drying decreased with increasing of drying temperature.

Abstract: From the viewpoints of energy and environmental problems, an effective energy utilization system for thermal energy management using chemical heat pump container (CHPC) is proposed. In this system, waste heat etc. is stored as chemical energy in CHPC. The stored heat is transported with almost no heat loss by CHPC transportation using truck, train, ship etc. At heat supply area, the stored heat is upgraded to higher temperature heat for heating/drying or lower temperature heat for cooling/refrigerating/dehumidifying without adding extra energy by the chemical heat pump function. In this study, the simulation on local recycling energy system using CHPC for heating/drying and cooling/dehumidifying was performed. The heat storing/releasing characteristics, the energy efficiencies and the CO2 emissions were shown. As a result, the system using CHPC was found to be much more effective than domestic boiler system and even more effective than similar transportation systems using latent heat storage container etc. Especially, the system using CHPC can supply hot-heat and cold-heat effectively without adding extra energy at heat supply area.

Abstract: The shape of the house significantly affects its energy intensity. For general design has not yet been established proven theoretical basis for assessing changes in heat loss, depending on the shape of the object and the object size normal family home. The proposed series of standard to function with which to compare the specific cases of precise calculations, but the standard pre-defined with a reasonable probability region closer to what the reality will move.

Abstract: The thermal barrier coatings have many potential applications in the protection of gas turbine engine components, essentially the turbine blades.In this study micro analysis was carried out on Yitria Stabilized Zirconia(YSZ) coated turbine blades and the results are compared with the uncoated blades.We have used the atmosphere plasma sprayed thermal barrier coating with a thickness of 0.25mm to withstand the high temperature of about 2000 C.We observed that by increasing the thermal coating thickness of about 0.25mm cause to increase 50% of the surface temperature of the turbine blade,which in turn increased the aero engine thrust.