Next >

The Art of Measuring in the Thermal Sciences

A: Measuring in Thermal Systems: Reducing Errors and Error Analysis Measuring the Right Data—Verifying Experimental Boundary Conditions Introduction Thinking Ahead Case Studies Air Heat Exchanger—Thermal Fin Design/Optimization Expanding Gas Jet—Impingement Cooling on Pipe Walls Longitudinal Fin Cooling of Electronics Heated Pipe-in-Pipe Testing Multi-Pass Refrigerant Loop: Local Heat Transfer Coefficients Conclusions References Measurement Error or Data Trend? How to Conduct Meaningful Experiments Error Analysis in Experimental Investigations Error Analysis Uncertainty of Category A Uncertainty of Category B Error Propagation Design of Experiments for Validation of CFD Calculations References Uncertainty Analysis of Indirect Measurements in Thermal Science Introduction Importance of Uncertainty Analysis Direct and Indirect Measurements Objectives Measurement Uncertainty Sources and Types of Uncertainties Normal Distribution and Standard Deviation Dealing with Indirect Measurement Uncertainty Determination of Individual Variables Uncertainty Determination of a Multivariable Function Case Study Determination of Uncertainty of Direct Measurement Determination of Type A Uncertainty uA Determination of Type B Uncertainty uB Combined Standard Uncertainty uC Evaluation of Uncertainty of Indirect Measurements Remarks References Modern Error Analysis in Indirect Measurements in Thermal Science Introduction Model, Direct Measurements, and Definition of the Parameters That Are Looked For Statistical Characterization of Noise and Bias for a Parameter Estimation Problem Static Model and Estimation of the Parameters of a Probability Law Measurement of the Output of a Perfect Dynamical Model and Its Vector Form Model Bias Example of a Binormal Joint Distribution Properties of Random Vectors Example 1: Estimation of a Heat Transfer Coefficient in a One-State Experiment Least Squares and Estimation Residuals Least Square Sum and Residuals Linear Least Squares Nonlinear Least Squares Example 2: Estimation of a Heat Transfer Coefficient through Multiple-Steady State Measurements Conclusions References B: Convection Challenges and Energy Balances Wilson Plots and Measurement Accuracy Introduction Wilson Plot Method Estimation of HTC Standard Errors of the HTC Parameters Experimental Procedure and Limitations Modified Wilson Plot Methods Reynolds Exponent Limitation Variable Property Effects or Fin Resistance Limitations Constant Thermal Resistance Limitation Experimental Procedure and Limitations Weighted Fits General Wilson Plot Example Application Data HTC Calculation Wilson Plot Method Modified Wilson Plot Methods Weighted Wilson Plot Method General Wilson Plot Method Discussion References Test Sections for Heat Transfer and Pressure Drop Measurements: Construction, Calibration, and Validation Introduction Our Range and Experience Construction of Test Section Test Section Length and Layout Pressure Transducers Differential Pressure Transducers with Interchangeable Diaphragms Pressure Taps Thermocouples T-Type Thermocouples Thermocouple Preparation Copper Test Sections Stainless Steel Test Sections Tube-in-Tube Heat Exchangers Pt100 Probes Flow Meters Data Acquisition Heating Method Heating Wire In-Tube Heating Insulation Flow-Calming Section Mixing Section Calibration Pressure Transducers Pt100 Probes Thermocouples Drift and Recalibration Data Reduction Uncertainty Analysis Background Basic Procedure and Examples Linear Regression Analysis: PtlOO Probe Linear Regression Analysis: Pressure Transducer with a 2.2-kPa Diaphragm Uncertainty Analysis: Reynolds Number Uncertainty Analysis: Nusselt Number Uncertainty Analysis: Friction Factor Validation Unexplained Challenges Flow-Calming Section Contents Upstream Effects Caused by Exit Mixer Logging Frequency and Sampling Time Small Diameter Copper Test Section Electric Noise References Stability Evaluation, Measurements, and Presentations of Convective Heat Transfer Characteristics of Nanofluids Introduction Nanofluid Synthesis and Stability Evaluation Nanofluid Synthesis and Preparation Stability Evaluation of Nanofluids Thermophysical Properties of Nanofluids Thermal Conductivity Viscosity Specific Heat Convective Heat Transfer of Nanofluids—Experimental Studies Natural Convection and Channel Flows Measurements and Accuracy Data Reduction and Presentations Empirical Correlations Summary of Findings of Natural Convection in Cavities Convective Heat Transfer in Microchannels Conclusions and Remarks Acknowledgments References Determination of Energy Efficiency of Hot Water Boilers and Calculation of Measurement Uncertainties Introduction Procedure for Determining the Energy Efficiency of Hot Water Boiler Determination of the Nominal Heat Output Description of the Hot Water Boiler Testing Plant (Bypass Method)Calculation of the Nominal Heat Output Q̇out Calculation of Heat Input Q̇in Calculation of the Nominal Heat Input Q̇in When Oil Fuel or Solid Fuel Is Used Calculation of Heat Input Q̇in,r, When Gas Fuel Is Used Efficiency of Boiler at Full Nominal Load Efficiency Measurement with the Direct Method Efficiency Measurement with the Indirect Method of Thermal Losses Measurement Accuracies and Uncertainties Procedures for Calculation of the Uncertainty Efficiency in a Hot Water Boiler Evaluation Methods for Measuring Errors Definitions Uncertainty Calculation of Useful Heat Output Uncertainty Calculation of Heat Input Variability of Efficiency Measurement Parametric Analysis and Graphical Depiction of the Effect of the Measured Values of the Qin, Qout, and “n” Calculations General Conclusions from Parametric Analysis of the Absolute and Relative % Uncertainty of the Boiler Efficiency References Psychrometric Performance Testing for HVAC&R Components and Equipment Introduction Psychrometric Conditioning Airflow Distribution Common Practices and Limitations Experimental Evaluation of Airflow Application of CFD and Effects onto Equipment Tests Psychrometric Measurements Air Sampling Temperature Sensors Thermocouples (TCs)Resistance Temperature Devices Temperature Grids and Air Mixers Recommendation for Selecting Temperature Sensors Psychrometers Relative Humidity Sensors Dew-Point Meters Other Recommendations Airflow Measurements Code Tester/Nozzle Box Anemometers Pitot Tubes Leakage Testing Controls of Psychrometric Testing Facilities Steady-State Operation Safety Mechanisms References C: Heat Flux Measurements, Optical Techniques, and Infrared Thermography Surface Temperature Measurement on Complex Topology by Infrared Thermography Introduction Basic Theoretical Considerations Camera Types and Practical Application Camera Types Practical Application Window Materials Camera Calibration Linearization NUC: Non-Uniformity Correction Single-Point NUC Two-Point NUC High Dynamic Range (HDR)Position Estimation Focus Stacking Temperature Calibration The Semiempirical Calibration Function The Improved Calibration Technique Adapting the Calibration to Local Effects Surface Curvature Non-Constant Offset Radiation Measurement Uncertainty Conclusion References Optical Measurements for Phase Change Heat Transfer Introduction Infrared Thermography Optical Techniques (Visible Light)Fluorescence-Based Temperature Mapping Temperature-Sensitive Paints Phosphor Thermography Pool and Flow Boiling Measurements Using Temperature-Sensitive Paints TSP Formulation and Characterization TSP Characterization Temperature and Pressure Dependence Aging of TSPs Pool Boiling Test Apparatus and Demonstration Test Section Construction Data Reduction Pool Boiling Measurements Flow Boiling Test Apparatus and Demonstration Test Section Construction Data Reduction Flow Boiling Measurements Pool Boiling Measurements Using Fluorescence Microscopy Conclusions References Practical Heat Flux Measurement Introduction Heat Flux Sensing Basic Fundamentals of Temperature and Heat Flux Measurement One-Dimensional Planar Sensors Insert Heat Flux Gages Calibration Thermal Measurement Details (Errors to Avoid)Example Uses Summary Heated Meter Bar Techniques: What You Should Know and Why Introduction and Principle Characterizing Heat Transfer Properties The Heated Meter Bar Techniques Assessing Uncertainty in the HMBT Calculating Uncertainty Using the HMBT Monte Carlo Simulation of Uncertainties An Example: High-Precision Thermal Interface Material Testing An Example: High-Heat-Flux Forced Convective Boiling Summary Inverse Problems in Heat Conduction: Accurate Sensor System Calibration Introduction Mathematical Model One-Dimensional, Semi-Infinite Heat Conduction Problem Heat Conduction System System Identification Inverse Heat Conduction Problem Solution Using NISI Sensor System Calibration Application Further Applications Summary Acknowledgments References D: Measuring in Two-Phase Flow Challenges and Advances in Measuring Temperatures at Liquid–Solid Interfaces Introduction Intrusive Techniques: Thermistors and Thermocouples Overview and State-of-the-Art Solutions Local Measurement of Surface Temperature with High Temporal Resolution Eroding-Type Fast Response Thermocouples Thin-Film Thermocouple Heat Flux Exchanged in Liquid–Solid Interfaces Transient Heat Transfer Assuming a Semi-Infinite Solid Transient Heat Transfer in a Finite Slab with an Imposed Heat Flux Semi-Intrusive and Non-Intrusive Techniques Overview Infrared (IR) Thermography with High Temporal and Spatial Resolutions Working Principles and Influencing Parameters Calibration and Data Reduction Procedures Surface Temperature and Heat Flux Measurements at Liquid–Solid Interfaces Final Remarks and Future Prospects Acknowledgments References Measuring Heat Transfer Coefficient during Condensation Inside Channels Introduction Approach Based on Wilson Plot Method Modified Wilson Plot Method Evaluation of the Experimental Uncertainty Direct Wall Temperature Measurement Approach Local Measurement Determination of the Local Heat Transfer Coefficient and Vapor Quality Evaluation of the Experimental Uncertainty The Weighted Least Squares (WLS) Method Results from the Uncertainty Analysis Conclusions References Optical Measurement Techniques for Liquid–Vapor Phase Change Heat Transfer Introduction High-Speed Videography for the Analysis of Boiling Good Practices, Experimental Biases, and Artifacts Recent Progresses in the Understanding of Bubble Dynamics Owing to High-Speed Videography High-Speed Videography: A Major Contribution to the Analysis of Flow Boiling Liquid–Vapor Interface Characterization Using Confocal Microscopy Introduction Functional Principle Experimental Implementation of the Optical Method and Examples Wall Temperature Measurement of a Transparent Tube during Flow Boiling Using IR Camera Functional Principle of Measurement with IR Camera Experimental Configuration and Data Acquisition Post-Processing Analysis Determination of the Wall Emissivity by Means of a Calibration Procedure Conclusion References Selected Problems of Experimental Investigations during Refrigerants Condensation in Minichannels Introduction Some Research Problems of Compact Minicondensers The Mechanism of Refrigeration Condensation in Minichannels and Basic Research Problems Methodology of Experimental Investigations of Refrigerants Condensation in Minichannels Experimental Investigations of Thermal and Flow Characteristics of Condensation Investigations of Two-Phase Flow Structures during Refrigerants Condensation in Minichannels Summary References

Next >