Unit 1 Basic Concepts

9 lecture hours

• Overview of applications of heat transfer in different fields of engineering
• modes of heat transfer- conduction
• convection and radiation
• heat transfer with and without change of phase
• Conduction: Mechanism of heat conduction
• Fourier’s law, thermal conductivity of solids
• liquids and gases
• effect of temperature on thermal conductivity
• General heat conduction equation in Cartesian coordinates
• Boundary conditions
• Formulation of heat transfer problems without generation of heat
• Conduction through systems of constant thermal conductivity :- conduction through plane
• cylindrical and spherical wall
• combined boundary condition systems (conduction-convection systems)
• conduction through composite slab
• cylindrical and spherical shells
• Electrical analogy to heat flow
• Critical and Optimum thickness of Insulation
• Unsteady State heat Conduction: Analysis of transient heat flow with negligible internal resistance-lumped capacity analysis
• concept of Biot Modulus and Fourier number

Unit 2 Convection

• thermal and velocity boundary layers
• boundary layer thickness
• relationship between hydrodynamic and thermal boundary 9 30 layer thickness for flow over flat plates
• the convective heat transfer coefficient
• reference temperatures
• thermal boundary layers for the cases of flow over a flat plate and flow through pipe
• dimensionless numbers in heat transfer and their significance
• Forced Convection: General methods for estimation of convection heat transfer coefficient
• Correlation equations for heat transfer in laminar and turbulent flow for external and internal flows for constant heat flux and wall temperature conditions- flow in a circular tube Analogy between momentum and heat transfer: Development of Reynold’s and Prandtl analogy
• Overview of Colburn and Von-Karman analogies (No derivation required)
• Comparison of different analogy expressions
• Natural Convection: Dimensional analysis
• natural convection from vertical and horizontal surfaces under laminar and turbulent conditions for plates
• physical significance of Grashoff and Rayleigh numbers
• Heat transfer by radiation: Introduction- theories of radiation
• electromagnetic spectrum
• thermal radiation
• spectral emissive power
• surface emission- total emissive power
• Radiative properties
• reflectivity and transmissitivity
• Concept of black and grey body
• radiation intensity
• Laws of black body radiation
• non-black surfaces- Grey
• white and real surface
• Lambert’s cosine law, radiation between black surfaces and gray surfaces

Unit 3 Heat Exchangers

9 lecture hours

• Classification of heat exchangers: Classification according to transfer processes
• number of passes
• surface compactness
• construction features
• flow arrangements
• heat transfer mechanisms
• Shell and tube heat exchanger
• concept of overall heat transfer coefficient
• correction factor for LMTD
• Sizing and rating problem using LMTD method in parallel flow
• counter flow exchanger
• cross flow and multi-pass heat exchangers
• Temperature – distance plots for different flow arrangements in single and multi-pass heat exchangers
• Determination of area
• number of tubes required for a given duty in different configurations using LMTD method of analysis
• Concept of Effectiveness- NTU method
• definition of effectiveness
• effectiveness NTU relations for single pass exchangers in counter-flow and parallel flow configurations
• Double pipe heat exchangers: - construction
• various steps for the design of double pipe heat exchangers
• Plate and spiral heat exchangers

Unit 4 Boiling and Condensation

9 lecture hours

• Pool boiling - Boiling curve
• hysteresis in the boiling curve
• mechanism of nucleate boiling
• Forced convection boiling - Brief over view of internal forced convection boiling
• Condensation: Physical mechanisms
• types of condensation
• factors affecting condensation
• Evaporation: Principle of Evaporation
• types of evaporators- their construction and operation
• Natural circulation evaporators
• short tube vertical or calendria type evaporators
• basket type vertical evaporators
• long tube vertical evaporators
• forced circulation evaporators
• falling film evaporators
• climbing or rising film evaporators
• agitated thin film evaporators
• the plate evaporator
• Single effect and multiple effect evaporators
• Performance of evaporators
• capacity and economy of evaporators
• Overall heat transfer coefficient
• effect of liquid head and boiling point elevation
• Material and energy balances for single effect evaporator and the calculations on single effect evaporator
• Multiple effect evaporators
• Energy Balance