American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED

The present research work investigates the effect of CuO nanoparticles on the nucleate boiling heat transfer characteristics of Isobutane (R600a) refrigerant. All the pool boiling experiments are carried with both pure and nano-refrigerants of 0.01, 0.025, 0.05 and 0.1 percentage by volume. The heat flux is varied from 2 kW.m-2 to 20 kW.m-2 at a regular interval of 2 kW.m-2. The heat transfer coefficient values for the pool boiling condition of R600a refrigerant are calculated experimentally, which are less deviating from the established theoretical correlations. The added CuO nanoparticles significantly influenced the nucleate boiling heat transfer coefficient of R600a refrigerant at higher heat flux values. The experiment results reveal that the thermophoretic mobility of nanoparticles play a major role in nanofluids heat transport. In the present work, CuO nanoparticles addition in R600a is optimized and is justified based on gravity and agglomeration effect.

Nucleate pool boiling heat transfer characteristics of R600a with CuO nanoparticles

In order to improve the overall performance of diesel particulate filter (DPF) in the soot capture process, a multi-objective optimization model is developed based on the objective functions of maximum pressure drop and initial filtration efficiency. Firstly, the sensitivity analysis of the structural parameters of DPF are performed. Then the response surface model based on Box-Behnken is constructed, and diagnostic analysis and analysis of variance (ANOVA) are carried out for each response. Finally, the non-dominated sorting genetic algorithm-II (NSGA-II) is used to obtain the Pareto optimal solution. The research results show that the sensitivity of filter diameter to maximum pressure drop and initial filtration efficiency is higher than other parameters. The multi-objective optimization results are verified by GT-SUITE software, and the maximum relative errors of maximum pressure drop and initial filtration efficiency between the simulation and optimization results are 1.41% and 3.28%, respectively. Compared with the original performance, the initial filtration efficiency of DPF is improved by 16.42%. The optimized DPF pressure drop decreased by 15% and 36.33% at the beginning and end of the filtration period, respectively. 

Sensitivity analysis of diesel particulate filters to geometric parameters during soot loading and its multi-objective optimization

The thermal management and reduction of energy consumption in cooling systems have become major trends with the continued growth of high heat dissipation data centers and the challenging energy situation. However, the existing studies have been limited to studying the influences of individual factors on energy saving and thermal management and have not been systematically summarized. Thus, this paper reviews the key factors in achieving thermal management and reducing energy consumption in each cooling system, the corresponding research, and optimization methods. To achieve these goals, in this paper, literature surveys on data center cooling systems are investigated. For data center air cooling, thermal management is mainly related to the uniform distribution of hot and cold air. Adjusting the porosity of perforated tiles can reduce energy consumption. For liquid cooling and free cooling systems, climate conditions, cooling system structural design, coolant type, and flow rate are key factors in achieving thermal management and reducing energy consumption. This paper provides the power usage effectiveness (PUE) values of the cooling systems in some cases. A summary of the key factors can provide directions for research on thermal management and energy reduction, and a summary of previous research can provide a basis for future optimization.

/pdf/thermal-management-and-energy-consumption-in-air-liquid-and-2btbv7xz.pdf

Thermal Management and Energy Consumption in Air, Liquid, and Free Cooling Systems for Data Centers: A Review

In this study, the thermal analysis of an aluminum piston coated with MgOZrO2
 to create a thermal barrier with the COMSOL multiphysics program and the
 changes in exhaust gas temperature, fuel consumption, and engine torque
 values obtained as a result of engine test experiments were examined. For
 this purpose, the MgOZrO2 coated and uncoated piston engine was started with
 biodiesel and 5% water + 15% ethanol doped biodiesel fuel at engine speeds
 of 1000 rpm, 1500 rpm, 2000 rpm, and 2500 rpm. In the thermal analysis
 results obtained in the COMSOL, it was found that the temperature values
 increased in the upper regions of the coated pistons. Likewise, in engine
 experiments, increased exhaust gas temperature and engine torque showed a
 tendency to decrease fuel consumption values. It has been observed that the
 data obtained in the analysis in the COMSOL program are in parallel with the
 results of the engine experiments.

/pdf/analysis-of-thermal-barrier-coated-pistons-in-the-comsol-and-2q94mii3.pdf

Analysis of thermal barrier coated pistons in the COMSOL and the effects of their use with water + ethanol doped biodiesel

Improvement in production line efficiency of hemming unit using line balancing techniques

Thermal barrier coatings for internal combustion engines: A review

Numerical simulation of the single-phase immersion cooling process using a dielectric fluid in a data server

https://iopscience.iop.org/article/10.1088/1755-1315/573/1/012003/pdf

Investigations on biogas fuelled Homogeneous Charged Compression Ignition engine with Di ethyl ether -Biodiesel-Butanol blend as Pilot fuel

Analysis of major heat transfer mechanisms in nanofluids specifically, thermophoresis and diffusiophoresis under pool boiling condition is attempted in this paper. Basic approach of the study tries to correlate thermophoresis in nanofluids to the behavior of rigid particles in gases. Ultimate objective of the study is to elucidate the thermophoresis/diffusiophoresis mechanism in nanofluids using thermophoretic velocity and viscosity of nanofluids. Thermophoretic velocity of water-alumina nanofluid analyzed in this study is assumed to be inversely proportional to fluid viscosity. Experiments and Computational Fluid Dynamics (CFD) tool are used for analyzing the effects of thermophoresis and diffusiophoresis on the heat transfer enhancement process. The numerical model considered for the study is a (2-D) rectangular container with the dimensions of the experimental set-up and a stainless steel heater inside it. Energy equation constituent of ANSYS Fluent is solved using a pressure based implicit solver and appropriate boundary conditions to obtain the temperature distribution pattern of the model. SIMPLE is used as the pressure correction method with Gauss-Siedel iterative method. Numerical simulation results for temperature distribution are validated using experimental readings. Thermophoretic velocity outputs derived from numerical simulation show significant movement of nanoparticles very close to realistic values. However, numerical results of viscosity, specific heat and diffusion coefficient of nanofluids were found to deviate from the results of the experiments. The dependency effect of these parameters needs further attention.

N. Gobinath

Papers

Improvement in production line efficiency of hemming unit using line balancing techniques

Thermal barrier coatings for internal combustion engines: A review

Numerical simulation of the single-phase immersion cooling process using a dielectric fluid in a data server

Investigations on biogas fuelled Homogeneous Charged Compression Ignition engine with Di ethyl ether -Biodiesel-Butanol blend as Pilot fuel

Numerical Modeling of Thermophoresis and Diffusiophoresis in Water-Alumina Nano Fluids