Santosh K. Sahu

Thermal Performance of Automobile Radiator Using Carbon Nanotube-Water Nanofluid—Experimental Study

In the present study, the convective heat transfer enhancement of carbon nanotube (CNT)-water nanofluid has been studied experimentally inside an automobile radiator. Heat removal rate of the coolant flowing through the automobile radiators is of great importance for the optimization of fuel consumption. In this study, four different concentrations of nanofluids in the range of 0.15–1 vol. % were prepared with the addition of CNT nanoparticles into water. The CNT nanocoolants are synthesized by functionalization (FCNT) and surface treatment (SCNT) method. The effects of various parameters, namely synthesis method, variation in pH values and nanoparticle concentration on the Nusselt number are examined through the experimental investigation. Results demonstrate that both nanocoolants exhibit enormous change Nusselt number compared with water. The results of functionalized CNT nanocoolant with 5.5 pH exhibits better performance compared to the nanocoolant with pH value of 6.5 and 9. The surface treated CNT nanocoolant exhibits the deterioration in heat transfer performance. In addition, Nusselt number found to increase with the increase in the nanoparticle concentration and nanofluid velocity.

Thermal Performance of Nanofluid Charged Heat Pipe With Phase Change Material for Electronics Cooling

The paper reports the thermal performance of a nanofluid (MCNT/water) charged heatpipe with phase change material (PCM) as energy storage material (ESM) for electroniccooling. The adiabatic section of heat pipe is covered by the PCM stored in a containermade of acrylic material. Here, paraffin is used as PCM. PCM can absorb and releasethermal energy depending upon the fluctuations in the heating load. Tests are conductedto obtain the temperature distributions in PCM during charge/discharge processes. Pres-ent study utilizes two different ESM (water and paraffin), different fan speeds and heatingpowers in the PCM cooling module. The cooling module with heat pipe and paraffin asESM found to save higher fan power consumption compared to the cooling module thatutilities only a heat pipe. [DOI: 10.1115/1.4028994]Keywords: heat pipe, nanofluid, phase change material, electronics cooling

Rewetting Analysis of Hot Vertical Surfaces With Precursory Cooling by the Heat Balance Integral Method

The effect of precursory cooling on conduction-controlled rewetting of both slab and solid cylinder is analyzed by the heat balance integral method. A constant heat transfer coefficient is assumed in the wet region behind the wet front, while an exponentially decaying heat flux is assumed in the dry region ahead of the wet front. The physical problem is characterized by two dimensionless constants describing the extent of precursory cooling and three dimensionless numbers, namely, Peclet number, Biot number, and the nondimensional temperature. Results of the present solution are found to be in good agreement with other analytical solutions obtained through the Weiner-Hopf technique and the separation of variables as well as with the published experimental data for different coolants over a varied range of coolant flow rate. It is seen that precursory cooling increases the rewetting velocity particularly at higher flow rates. If it is neglected, the model grossly underpredicts the quench velocities.

An Experimental Study on the Rewetting of a Hot Vertical Surface by Circular Water Jet Impingement

The present experimental study analyzes the rewetting behavior of a hot vertical stainless-steel foil by a circular impinging liquid jet. The transient temperature of the hot foil, recorded by an infrared camera, is used to evaluate the rewetting velocity and heat flux distribution. The rewetting velocity varies within 2.0–20.0 cm/sec. Maximum surface heat flux is highest at the stagnation point and reduces in the downstream direction. A correlation for the rewetting velocity is developed that predicts 85% of test data within an error band of ± 30%. Present results agree well with the available theoretical models and test data.

Comparative Study on Heat Transfer Enhancement of Low Volume Concentration of Al2o3–Water and Carbon Nano-Tube–Water Nano-Fluids in Transition Regime Using Helical Screw Tape Inserts

This study reports the comparison of heat transfer and friction factor characteristics of helical screw inserts in Al2O3–water and carbon nano-tube–water nano-fluids through a straight pipe in transition regime with constant heat flux boundary condition. Experiments were carried out by using 0.15% volume concentration of Al2O3–water and carbon nano-tube–water nano-fluid with helical tape inserts of twist ratio, TR = 1.5, 2.5, and 3. The thermal performance of helical screw tape inserts with the carbon nano-tube–water nano-fluid is found -to be higher when compared to the Al2O3–water nano-fluid. In addition, the maximum enhancement in heat transfer was obtained for the carbon nano-tube–water nano-fluid with helical tape inserts of twist ratio 1.5. The increase in pressure drop of the Al2O3–water nano-fluid with helical screw tape inserts is found to be higher compared to the carbon nano-tube–water nano-fluid helical screw tape inserts at lower value of twist ratio.

Experimental Investigation of Heat Transfer Augmentation in Automobile Radiator With CNT/Water Nanofluid

The trend toward higher engine power leads to larger radiators in automobile sector and increased frontal areas, resulting increased fuel consumption. Heat transfer of coolant flow through the automobile radiators is of great importance for the optimization of fuel consumption. Compaq cooling system can be manufactured by introducing nanocoolant with in automobile radiator. In this paper, heat transfer of CNT based nanocoolant has experimentally compared to that of pure water in an automobile radiator. Four different concentrations of nanofluids in the range of 0.15–1 vol. % have been prepared by the addition of CNT nanoparticles into the water. The test liquid flows through the radiator consisted of vertical tubes with rectangle cross section and air makes a cross flow inside the tube bank with constant speed. The CNT nanocoolants are synthesized by functionalization CNT (FCNT) and surface treatment (SCNT) method. The effects of type of nanofluid, variation in pH and nanoparticle concentration on the Nusselt number are deeply investigated. Results demonstrate that both nanocoolant show enormous change Nusselt number in comparison with water. The results of functionalized CNT nanocoolant with 5.5 pH show better performance than 6.8 and 9 pH nanocoolant. The surface treated CNT nanocoolant show results deterioration in heat transfer performance. Furthermore, increasing the nanoparticle concentration and nanofluid velocity enhances the Nusselt number.© 2013 ASME

Model of heat conduction in hybrid nanofluid

A theoretical study model has been proposed for predicting the thermal conductivity of hybrid nanofluid. Present model takes an important step towards understanding the heat conduction in hybrid nanofluids. Effect of surface area and size of nanoparticles is considered. The model predictions are in good agreement with experimental data over a wide range of particle sizes, volume fractions and their thermal conductivity of individual nanoparticles of hybrid nanofluid.

Performance of Carbon Nanotubes–Water Nanofluid Charged Wickless Heat Pipe Flat Plate Solar Collectors Having Different Filling Ratio

An experimental study was carried out to investigate the thermal performance of solar heat pipe collector at outdoor test condition. The thermal performance of wickless heat pipe solar collector was investigated by using CNT–water nanofluid. Carbon nanotubes (CNT) nanoparticles with diameter 10–12 nm and 0.1–10 μm length were used in the present experimental investigation. The effects of various filling ratio (F.R.) (50%, 60%, and 70%) and coolant flow rate on thermal performance were discussed in this study.

A Study of K-Means and C-Means Clustering Algorithms for Intrusion Detection Product Development

The increase in Internet and Internet based application, the business premises have now spread throughout the world. Due to the extreme competitions among the business, one tries to demolish other. Hence, secure product design techniques should be adopted. To protect the applications from intruder, intrusion detection system becomes utmost requirement for every organization. In intrusion detection models enormous quantity of training data is required. As a result, sophisticated algorithms and high computational resources are required. In Intrusion Detection System, to separate normal activities from abnormal activities clustering algorithms are used. To select an efficient clustering algorithm is a challenging task. In this paper, a comparison has been made between K-Means and C-Means clustering on intrusion datasets. The simulation contains all proximity measures of K-Means and C-Means clustering techniques. The accuracy of these clustering algorithms is compared using the confusion matrix. The result shows that K-Means provides better clustering accuracy in comparison with C-Means. Therefore, to design intelligent intrusion detection product K-Means is a better option.

Supply chain performance appraisement, benchmarking and decision-making: empirical study using grey theory and grey-MOORA

Present work aims to develop efficient decision-support systems to facilitate supply chain performance appraisement, benchmarking and related decision-making. Supply chain performance extent depends on multiple criteria/attributes. Most of the criterions/attributes being intangible in nature; supply chain performance appraisement relies on the judgement (evaluation) of the decision-makers. Moreover, quantitative appraisement of supply chain performance appears very difficult due to involvement of ill-defined (vague) performance measures as well as metrics. In order to overcome this, the study explores theory of grey numbers in order to tackle incomplete and inconsistent subjective judgement of the decision-makers. Firstly, a grey-based decision support system has been postulated to evaluate a unique performance index of a supply chain; to identify ill-performing areas and to benchmark performance of candidate enterprises possessing similar supply chain architecture. Finally, grey-MOORA approach has been inculcated to provide a strong mathematic base of the said performance appraisement platform. Empirical data have been analysed and results obtained thereof, have been reported to exhibit application potential of the decision-support systems in appropriate situation.