Applied Mechanics and Materials Vols. 813-814

Abstract: The temperature inside the vehicle cabin will be higher than the outside environment temperature in parked conditions due to radiative effects. This increased temperature is not uniformly spread within the driver cabin due to absorption capacities of the various materials used for construction and the angle of incidence of the incoming radiation. The objective of the work is to predict the accumulation of heat inside the cabin numerically and find hotspots throughout the cabin. The path of the sun in different seasons and timings on a particular location was calculated and is implemented for the angle of incidence of radiation on the cabin. The investigation provides the variations of temperature, transmitted solar radiation and amount of absorption by various components that are subjected to assessment. Thus the major contributing factor for the abrupt increase in temperature was found.

Abstract: Results from numerical investigation of laminar natural convection inside a differentially heated square enclosure with a thin baffle attached to the cold wall are reported. The effect of the baffles on the flow and temperature fields were analyzed for baffle lengths equal to 20, 35 and 50 percent of the width of the enclosure, attached at three locations for Ra = 10⁴, 10⁵, 10⁶ and Pr = 0.707. The presence of a baffle on the cold right wall affects the strength of the clockwise rotating primary vortex. Reduced flow and heat transfer are observed. Longer the baffle more pronounced the effect on the flow field. Secondary convection cells are seen between the baffle and the bottom wall for certain cases. Reduction in average Nusselt Number is observed on the cold wall with the baffle than the hot wall.

Abstract: This paper presents the numerical studies of an irregular surface – a circular dimpled surface with different patterns of dimple arrangement (i.e., inline and staggered) and to identify the one that gives maximum heat transfer rate under laminar flow conditions. The comparative studies are made with a flat plate. The studies are carried out with inlet velocities 1 m/s and 49 m/s at laminar flow regimes. The investigations revealed that heat transfer rate increases as the air flow velocity increases and it decreases as the air flow velocity is decreased. Also, air flow contact with heated plate plays a vital role in heat transfer rate. Based on the study, it is concluded that the heat transfer rate depends on the surface area, air flow velocity and the air flow contact with the heated plate. At air velocities 1 m/s and 49 m/s, the heat transfer rate is highest for the circular dimple with staggered pattern under the laminar flow conditions.

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: In present study, transient state one-dimensional heat conduction is analyzed using polynomial approximation method. In comparison with the classical lumped model, an improved lumped model have been employed as the classical lumped model is applicable for biot number of less than 0.1 and it cannot be used for high temperature gradient. An improved lumped model has been employed for sphere to calculate average temperature as a function of time for higher and lower values of biot number. The study shows that the lumped model provides better accuracy as compared to finite difference model.

Abstract: Energy conservation is a major topic of concern since our energy sources are exhausting exponentially. This paper focuses on waste heat recovery using which scrap preheating is done in metal castings using sand molds. During solidification of molten metal, most of the heat is lost to the sand. The proposal is to prepare the sand mould with aluminium shots surrounding the mold cavity. These shots absorb some of the heat from the solidifying metal in the mold cavity. The heated shots are separated from the mold and they are allowed to transfer their heat energy to the metal scrap by conduction. The experiments indicate that at least 6.4% of heat recovery is achievable. This will be instrumental in reducing the enormous amount of energy spent to melt the metal considering the fact that casting is the most widely used manufacturing process globally.

Abstract: The microchannel cooling technique appears to be a viable solution to high heat rejection requirements of today’s high-power electronic devices. The thermal design of the small electronics cooling devices is a key issue that needs to be optimized in order to keep the system temperatures at certain levels. Thus the need of microchannel became vital. This present work investigates the experimental work conducted in a coated rectangular microchannel heat sink of hydraulic diameter of 0.763 mm for a heat input of 250 to 1020 Watt with water to study the heat transfer characteristics with two types of header arrangement such as rectangular header and trapezoidal header. The header plays a significant role in distributing the water in to the channels. The uniform distribution of water leads to uniform heat transfer in microchannels. From the experimental results carried with two types of header arrangements, it was found that coated rectangular microchannel with trapezoidal header gives better heat transfer characteristics for the range of heat inputs.

Abstract: This review gives an idea of thermal conductivity and its dependent on several factor.

Abstract: Contemporary product design and development efforts of various engineering organizations have experienced the emergence of Additive Manufacturing (AM) or 3D printing technology as a competent fabrication option for converting digital data into physical parts without using part-specific tools or fixtures. This paper presents the results of coupled field structural thermal analysis carried out on an innovative variant of AM technology called selective inhibition sintering wherein near net shape parts are fabricated through sintering of thin layers of powdered material while inhibiting the boundaries. Thermal gradients that are inherent to the process cause significant residual stresses affecting the part stability. Hence this study evaluates the effect of layer thickness and heater spot size on temperature gradient, displacement and thermal stress of two different polymers is assessed by numerical analysis. Results of the current study are relevant to enhancing the quality of sintered polymer parts with reference to dimensional fidelity and stability.