Biological Process Engineering An Analogical Approach to Fluid Flow, Heat Transfer, and Mass Transfer Applied to Biological Systems

Transcription

1 Biological Process Engineering An Analogical Approach to Fluid Flow, Heat Transfer, and Mass Transfer Applied to Biological Systems Arthur T. Johnson, PhD, PE Biological Resources Engineering Department University of Maryland College Park, MD

2 This book is dedicated to all the little children in my life who made me smile even on the grayest of days.

3 Table of Contents Page Foreword... xii 1 SYSTEMS CONCEPTS FOR TRANSPORT PROCESSES INTRODUCTION EFFORT VARIABLES FLOW VARIABLES RELATIONSHIPS BETWEEN FLOW AND EFFORT VARIABLES Power Resistance Capacity Inertia Nonlinearities Biological Variation SOURCES COMBINATION OF ELEMENTS Sources Resistances Capacity Inertia Combinations Involving Time Alternative Representations BALANCES Chemical Balances Force Balances Law of Laplace General Flow Balances Mass and Materials Balance Field Equation Solutions of the General Field Equation Other Coordinate Systems One Dimensional Flow with Distributed Constant ù& Source One Dimensional Flow with Central ù& Source One Dimensional Unsteady State Solution i

4 Energy Balance Differences Between Effort and Flow Balances Kirchhoff's Laws Visualizing Boundary Conditions SYSTEM APPLICATIONS Flow Through Porous Media Conduction Heat Transfer Binary Diffusion Mass Transfer Conduction of Electricity Other Transport Systems SYSTEMS APPROACH Problems References FLUID FLOW SYSTEMS INTRODUCTION CONSERVATION OF MASS Continuity Equation Elemental Form of Continuity Equation CONSERVATION OF ENERGY Potential Energy Kinetic Energy Modified Bernoulli Equation Energy Allocation Within the Fluid General Form of Energy Balance Equation MOMENTUM BALANCE Viscosity Momentum Balance in a Circular Pipe Flow Velocity Profile General Form for Momentum Balance Navier-Stokes Equations Drag Coefficient and Settling Velocity ii

5 2.5 FRICTION LOSSES IN PIPES Pipe Losses Minor Losses Loss Coefficients Entrance Length Pipe Discharge Fluid System Impedance Compliance Inertance Resistance Time Relationships NonIsothermal Flow Elastic Tubes Pulsating Flow Steady Flow Bifurcations Compressible Flow Sonic Velocity Pressure Drop and Maximum Flow Rate Viscosity and Density Dependence Compression Heating Fluid Flow in Plants Deposition of Suspended Particles NON-NEWTONIAN FLUID FLOW Rheological Properties Pipe Flow Velocity Profiles Kinetic Energy Friction Losses OPEN CHANNEL FLOW DESIGN PROCEDURE FOR PUMP SPECIFICATION Problems Design Problems References iii

6 3 HEAT TRANSFER SYSTEMS INTRODUCTION CONDUCTION Thermal Conductivity Thermal Conductance Clothing Fur and Feathers Multidimensional Conduction Unsteady State Conduction CONVECTION Convection Coefficients Dimensionless Numbers Forced Convection Equations Natural Convection Equations Mixed Convection Cylinders Spheres Fruits Inaccuracies Convection with Viscous Dissipation Boiling and Condensation Convection Thermal Resistance Theoretical Relationships Among Parameters RADIATION Black Body Radiation Shape Factors Spectral Distribution Real Surfaces Radiation Exchange Among Gray Bodies One Body Completely Enclosed in Another Radiation Through Absorbing Gases Radiation Coefficient Solar Flux iv

7 3.5 HEAT GENERATION Diffuse Heat Production Temperature Dependence Biological Heat Production Microbial Systems Human and Animal Heat Production Basal Metabolic Rate Food Ingestion Muscular Activity Living Plants Stored Fruits and Vegetables Ecological Scale Non-Biological Heat Production Microwaves and Other Electromagnetically- Induced Heat Conduction with Heat Generation Constant Rate of Heat Production Temperature Dependent Heat Production HEAT STORAGE Specific Heats Flow Systems Convection Determination Heat Storage in Biological Systems Thermal Capacity MIXED MODE HEAT TRANSFER Heat Exchangers Heat Exchanger Types Change of State Parallel Flow Counter Flow Cross Flow Heat Transferred All Inlet and Outlet Temperatures Known v

8 All Inlet and Outlet Temperatures Not Known Fouling Factors Heat Exchanger Specification Transient Heat Transfer Dimensionless Numbers Heisler Charts Chart Use Composite Shapes Interior Fluid Sterilization of Food and Medical Devices Extended Surfaces CHANGE OF PHASE Change of State Freezing Freezing Point Depression Chilling Freezing Time Evaporation Sublimation Heat of Solution Phase Changes HEAT SYSTEM DESIGN Problems Design Problems References MASS TRANSFER INTRODUCTION MASS BALANCE vi

9 4.3 MOLECULAR DIFFUSION Fick's Laws Mass Diffusivity Gas Diffusivities Liquid Diffusivities Solid Diffusivities Porous Solids Knudsen Diffusion Food and Biological Materials Diffusion Through Membranes and Films Nonporous Membranes Partition Coefficient Diffusion Permeability Porous Membranes Ultrafiltration Membranes Osmotic Pressure Reverse Osmosis Mass Transfer Ionic Equilibria Skin Permeability Drug Delivery Diffusion Resistance CONVECTION Analogies with Heat Transfer Packed Beds MASS GENERATION Enzymatic Reactions Enzyme-Substrate Kinetics Immunoassays Biosensors Plant Root Nutrient Uptake vii

10 4.5.3 Bacterial Growth Rate MASS STORAGE Mass Storage in Solution Mass Capacitance MIXED-MODE MASS TRANSFER Extended Surfaces Simultaneous Diffusion and Convection Dispersion Static Dispersion Dispersion in Flowing Fluid Taylor Dispersion Turbulent Dispersion in Pipes Atmospheric Dispersion Odor Dispersion Within Soil Dispersion Impedances Unsteady-State Mass Transfer Mass Exchangers SIMULTANEOUS HEAT AND MASS TRANSFER Psychrometrics Ideal Atmosphere Saturated Water Vapor Pressure Measurements of the Amount of Water in the Air Temperature Measures Enthalpy Psychrometric Charts Sensible Heating or Cooling Adiabatic Saturation Mixing Dehumidification Ventilation Drying Moisture Content Equilibrium Moisture Content viii

11 Drying Rate Constant Rate Drying Sweating Falling Rate Drying Thick Layer Drying Thin Layer Drying Shrinkage DESIGN OF MASS TRANSFER SYSTEMS Problems Design Problems References LIFE SYSTEMS References ix