Pool boiling heat transfer to CuO-H2O nanofluid on finned surfaces
TL;DR: In this paper, the potential effect of the surface shape and geometrical specification of rectangular parallel fins developed on the surface on the heat transfer coefficient, bubble formation, and fouling of the nanoparticles was analyzed.
About: This article is published in International Journal of Heat and Mass Transfer.The article was published on 2020-08-01. It has received 103 citations till now. The article focuses on the topics: Boiling & Thermal resistance.
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TL;DR: In this article , a multi-way twisted tape (MWTT) was applied to enhance the thermal treatment of Linear Fresnel Reflector (LFR) unit, and the operating fluid is Al 2 O 3 -water and temperature dependent formulas were employed.
189 citations
TL;DR: In this article, a diesel engine is operated in RCCI mode with gaseous fuels viz. CNG as a primary fuel and a blend of diesel and Karanja biodiesel (BD20) as pilot fuel.
Abstract: Heterogeneous combustion in a diesel engine is noisier, uncontrolled and more polluting. This can be achieved with a strategic approach of a reactivity-controlled compression ignition (RCCI) mode engine that operates with low and high reactive fuel combinations. In the present work, a diesel engine is operated in RCCI mode with gaseous fuels viz. CNG as a primary fuel and a blend of diesel and Karanja biodiesel (BD20) as pilot fuel. This research aims to determine the operating limits of CNG fuel for less noisy combustion and clean exhaust. Further, relative air-fuel ratio (λ), cycle to cycle variations, combustion noise and emissions were studied for full load operation. The CRDI engine is optimized for diesel operation with a split injection strategy. The knock limits for CNG as the primary fuel are obtained. The combustion noise increases at a higher energy share by CNG. Also, higher values of HC and CO emissions are observed. This may be due to higher energy share values, flame speed and octane number of CNG fuel. Further, NOx emissions and smoke are decreased. The CNG induction of 10 ms with 90% ES can be noted as a knock limit for 3.5 kW power. The highest BTHE of 24.2% and least BSFC 0.3 kg/kWhr reported by 60%ES of LRF is better than diesel and KBD20 fuel. An optimum 60% energy share of CNG is observed for clean combustion and emissions strategy using the RCCI mode of a modified diesel engine.
84 citations
TL;DR: In this article, the effects of melting phenomena and nonlinear thermal radiation in cross nanofluid bioconvection flow with motile microorganisms with a convective boundary over a cylinder were investigated.
66 citations
TL;DR: In this paper, the freezing process inside an annulus zone was reported numerically in three time stages and the average values of significant parameters were extracted as function of time, where the domain is filled with paraffin and nanoparticles were added.
Abstract: Freezing process inside an annulus zone was reported numerically in this article. The domain is filled with paraffin (Tm=82 °C) and for improving thermal features, nanoparticles were added. Fins with various sizes and positions were applied and two levels for fraction of nanomaterial were utilized. Exergy drop is main outputs of current research and contours in three time stages were reported. Unsteady phenomena were reported with considering structure grid. Average values of significant parameters were extracted as function of time. Non-zero values of velocity show the impact of buoyancy force. For verification, experimental outputs of published paper have been utilized. Exergy drop (Xd) declines with rise of time because of reduction of temperature. The value of Xd decrease about 91.14% when time increases from 1 to 15 min for case 8. The geatest case win lowest needed time is case with thinner fins over the outer wall and it needs 17.86 min to reach complete solidification. Inclusion of alumina in to paraffin makes freezing time to decrease about 11.7%. Changing the position of fins from inner to outer causes the freezing rate to increase about 14.45%.
64 citations
TL;DR: In this paper, a combination of hybrid nanoparticles (MoS2 - Fe3O4) and novel fin configuration in triplex-tube storage was used for phase change material (PCM) solidification.
Abstract: Latent thermal energy storage dependent on Phase Change Materials (PCMs) proposes a possible answer for modifying the availability of alternating energy from renewable sources such as wind and solar. They can possibly store large amounts of energy in moderately tiny dimensions as well as through almost isothermal procedures. Notwithstanding, low thermal conductivity values is a significant disadvantage of the present PCMs which critically restrict their energy storage usage. Likewise, this unacceptably decreases the solidification/melting rates, hence causing the system response time to be excessively lengthy. The present examination accomplished a better PCM solidification rate with a combination of hybrid nanoparticle (MoS2 - Fe3O4) and novel fin configuration in triplex-tube storage. A computational model that considers the natural conduction was represented and validated against previous experimental data. The influences of applying various nanoparticle volume fractions, radiation parameter, and shape factor on the assessment of the liquid-solid interfaces, phase change rate, and solidification process time over the whole solidification procedure was calculated and reported. The outputs demonstrate that PCM solidification is becoming better by utilizing the aforementioned methods. The obtained results disclose that the radiation parameter has a significant impact on the phase change rate, which shows a 74.58% contribution to the full solidification process time (FST). Additionally, the optimum parameters have designed to optimize the full solidification process time in the triplex-tube latent heat energy storage system (LHESS) system by using the Taguchi and Response Surface Methodology (RSM) methods. As a novelty, an accurate correlation for FST is developed with sensibly great precision.
62 citations
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01 Jan 1951
1,114 citations
Book•
27 Jul 2009
TL;DR: This work focuses on using the Taylor Series Method for Uncertainty Propagation in Experiments and Validation to assess the importance of uncertainty in the design and execution of experiments and applications.
Abstract: Preface. 1 Experimentation, Errors, and Uncertainty. 1-1 Experimentation. 1-2 Experimental Approach. 1-3 Basic Concepts and Definitions. 1-4 Experimental Results Determined from Multiple Measured Variables. 1-5 Guides and Standards. 1-6 A Note on Nomenclature. References. Problems. 2 Errors and Uncertainties in a Measured Variable. 2-1 Statistical Distributions. 2-2 Gaussian Distribution. 2-3 Samples from Gaussian Parent Population. 2-4 Statistical Rejection of Outliers from a Sample. 2-5 Uncertainty of a Measured Variable. 2-6 Summary. References. Problems. 3 Uncertainty in a Result Determined from Multiple Variables. 3-1 Taylor Series Method for Propagation of Uncertainties. 3-2 Monte Carlo Method for Propagation of Uncertainties. References. Problems. 4 General Uncertainty Analysis: Planning an Experiment and Application in Validation. 4-1 Overview: Using Uncertainty Propagation in Experiments and Validation. 4-2 General Uncertainty Analysis Using the Taylor Series Method. 4-3 Application to Experiment Planning (TSM). 4-4 Using TSM Uncertainty Analysis in Planning an Experiment. 4-5 Example: Analysis of Proposed Particulate Measuring System. 4-6 Example: Analysis of Proposed Heat Transfer Experiment. 4-7 Examples of Presentation of Results from Actual Applications. 4-8 Application in Validation: Estimating Uncertainty in Simulation Result Due to Uncertainties in Inputs. References. Problems. 5 Detailed Uncertainty Analysis: Designing, Debugging, and Executing an Experiment. 5-1 Using Detailed Uncertainty Analysis. 5-2 Detailed Uncertainty Analysis: Overview of Complete Methodology. 5-3 Determining Random Uncertainty of Experimental Result. 5-4 Determining Systematic Uncertainty of Experimental Result. 5-5 Comprehensive Example: Sample-to-Sample Experiment. 5-6 Comprehensive Example: Debugging and Qualification of a Timewise Experiment. 5-7 Some Additional Considerations in Experiment Execution. References. Problems. 6 Validation Of Simulations. 6-1 Introduction to Validation Methodology. 6-2 Errors and Uncertainties. 6-3 Validation Nomenclature. 6-4 Validation Approach. 6-5 Code and Solution Verification. 6-6 Estimation of Validation Uncertainty u val . 6-7 Interpretation of Validation Results Using E and u val . 6-8 Some Practical Points. References. 7 Data Analysis, Regression, and Reporting of Results. 7-1 Overview of Regression Analysis and Its Uncertainty. 7-2 Least-Squares Estimation. 7-3 Classical Linear Regression Uncertainty: Random Uncertainty. 7-4 Comprehensive Approach to Linear Regression Uncertainty. 7-5 Reporting Regression Uncertainties. 7-6 Regressions in Which X and Y Are Functional Relations. 7-7 Examples of Determining Regressions and Their Uncertainties. 7-8 Multiple Linear Regression. References. Problems. Appendix A Useful Statistics. Appendix B Taylor Series Method (TSM) for Uncertainty Propagation. B-1 Derivation of Uncertainty Propagation Equation. B-2 Comparison with Previous Approaches. B-3 Additional Assumptions for Engineering Applications. References. Appendix C Comparison of Models for Calculation of Uncertainty. C-1 Monte Carlo Simulations. C-2 Simulation Results. References. Appendix D Shortest Coverage Interval for Monte Carlo Method. Reference. Appendix E Asymmetric Systematic Uncertainties. E-1 Procedure for Asymmetric Systematic Uncertainties Using TSM Propagation. E-2 Procedure for Asymmetric Systematic Uncertainties Using MCM Propagation. E-3 Example: Biases in a Gas Temperature Measurement System. References. Appendix F Dynamic Response of Instrument Systems. F-1 General Instrument Response. F-2 Response of Zero-Order Instruments. F-3 Response of First-Order Instruments. F-4 Response of Second-Order Instruments. F-5 Summary. References. Index.
1,110 citations
TL;DR: In this article, the authors present a critical review of heat transfer applications of nanofluids, including radiators, circular tube heat exchangers, plate heat exchanger, shell and tube heat exchange, and heat sinks.
Abstract: This paper presents a critical review of heat transfer applications of nanofluids. The effects of nanoparticle concentration, size, shape, and nanofluid flow rate on Nusselt number, heat transfer coefficient, thermal conductivity, thermal resistance, friction factor and pressure drop from numerous studies reported recently are presented. Effects of various geometric parameters on heat transfer enhancement of system using nanofluids have also been reviewed. Heat transfer devices covered in this paper include radiators, circular tube heat exchangers, plate heat exchangers, shell and tube heat exchangers and heat sinks. Various correlations used for experimental validation or developed in reviewed studies are also compiled, compared and analyzed. The pros and cons associated to the applications of nanofluids in heat transfer devices are presented in details to determine the future direction of research in this arena.
388 citations
TL;DR: In this paper, a comprehensive review of published articles addressing passive enhancement of pool boiling using surface modification techniques is provided, including macroscale, microscale, and nanoscale surfaces, as well as multiscale (hybrid-scale), and hybrid-wettability techniques.
343 citations
TL;DR: In this paper, water-based nanofluids have been used to enhance the heat transfer performance of a car radiator by adding ZnO nanoparticles to base fluid in different volumetric concentrations (0.01, 0.08), 0.2% and 0.3%).
226 citations