Experimental and parametric studies of a louvered fin and flat tube compact heat exchanger using computational fluid dynamics

AbstractThe present study aimed to perform the parametric analysis on thermo-hydraulic performance of a compact heat exchanger using computational fluid dynamics (CFD). The analysis has been carried out at different frontal air velocities by varying the geometrical parameters such as fin pitch, transverse tube pitch, longitudinal tube pitch, louver pitch and louver angle. The air side performance of the heat exchanger has been evaluated by calculating Colburn factor (j) and Fanning friction factor (f). The comparison of CFD results with the experimental data exhibited a good agreement and the influence of various geometrical parameters for the selected range of values on the pressure drop, heat transfer coefficient and goodness factor was analyzed. The results obtained from the analysis will be very useful to optimize the louvered fin and flat tube compact heat exchanger for better thermo-hydraulic performance analysis without the need of time consuming and expensive experimentation

Effect of parabolic solar energy collectors for water distillation

This research article briefly summarizes the augmentation of condensate output using concentrators. This study compares a single-slope solar still, a compound conical concentrator (CCC) solar still, and a compound parabolic concentrator–tubular solar still (CPC–TSS). The effect of miniaturization of the absorber (increase in the concentration factor) and some modifications in the solar still assembly show a remarkable increase in output. The measured daily yield rate per square meter of absorber area of the single slope solar still, CCC solar still, and CPC–TSS is 2,100, 18,000, and 6,100 ml, respectively. It was found that the CCC solar still provides the maximum yield

Substrate finishing and niobium content effects on the high temperature corrosion resistance in steam atmosphere of CrN/NbN superlattice coatings deposited by PVD-HIPIMS

The main objective of this work was to evaluate the oxidation resistance of three PVD-HIPIMS CrN/NbN coatings, studying the effect of the surface finishing of the substrate and the role of niobium content into the coating composition. CrN/NbN nano-multilayered films on P92 steel were tested at 650°C in pure steam atmosphere. The mass gain was measured at fixed intervals to study their oxidation kinetics. The morphology and thickness of nanoscales were measured by transmission electron microscopy (TEM). Characterization of coatings before and after the thermal treatment was performed by scanning electron microscopy-energy with facilities of dispersive X-ray spectroscopy (SEM–EDX) and X-ray diffraction (XRD). All coatings improved the oxidation resistance of the substrate material, but the best behaviour was exhibited by the CrN/NbN with the high niobium (Nb) content and deposited on the substrate with the finest surface finishing

FTIR and FT-Raman spectroscopic studies of fired clay artifacts recently excavated in Tamilnadu, India

501-508The spectroscopic techniques represent one of the most powerful tools to investigate the structure of all the materials and chemical composition of the cultural objects like potteries, tiles and ceramics. The spectroscopic techniques that have been used in the present study are FTIR absorption and Raman scattering spectroscopy. The potteries maintain aesthetic characteristics so that this type of artifacts can be considered very specific trace of every civilization. Therefore, it is of great importance to acquire knowledge about the chemical composition and the manufacturing techniques of an artifact. From the behaviour of the absorption bands and their corresponding Raman shifts in specific regions and their intensity showing the presence of minerals, traces of elements in the clay, the knowledge of the artisans and the conditions of the temperature control to make qualitatively good materials of archaeological artifacts. The temperature of firing and the vitrification stage are also being established in the case of potteries from the recent excavations at Maligaimedu, Thiruverkadu and Palur in Tamilnadu, India

Solar cookers with and without thermal storage--A review

The continuous increase in the level of green house gas emissions and the increase in fuel prices are the main driving forces behind efforts to more effectively utilize various sources of renewable energy. In many parts of the world, direct solar radiation is considered to be one of the most prospective sources of energy. Among the different energy end uses, energy for cooking is one of the basic and dominant end uses in developing countries. Energy requirement for cooking accounts for 36% of total primary energy consumption in India. Hence, there is a critical need for the development of alternative, appropriate, affordable mode of cooking for use in developing countries. However, the large scale utilization of this form of energy is possible only if the effective technology for its storage can be developed with acceptable capital and running costs. Thermal energy storage is essential whenever there is a mismatch between the supply and consumption of energy. Latent heat storage in a phase change material is very attractive because of its high storage density with small temperature swing. The choice of PCM plays an important role in addition to heat transfer mechanism in the PCM. In this present work a review has been made to study all the research and development work carried out in the field of solar cooker in particular the storage type solar cookers. A novel concept of PCM-based storage type solar cooker is also presented which is under experimental investigation.Solar cooker Thermal energy storage Phase change material Box type cooker Concentrating type cooker Indirect cooker

Environmental emissions and efficiency of a direct injection diesel engine fueled with various fatty acid methyl esters

Environmental emissions and efficiency of a direct injection diesel engine fueled with fatty acid methyl esters (FAMEs) have been experimentally investigated and compared with petro-diesel. Rubber seed oil methyl ester, cotton seed oil methyl ester, neem oil methyl ester, and mahua oil methyl ester were used as fuels. The brake specific fuel consumption, brake thermal efficiency, and exhaust gas temperature, nitrogen oxides, carbon monoxide, hydrocarbons, and smoke emissions were investigated. Mahua oil methyl ester exhibits higher brake thermal efficiency compared to other FAMEs. The NOx was found to be higher, while CO, HC, and smoke emissions of rubber seed oil methyl ester were lower than the other fuels at all loads