HT 1

1.Shell and Tube heat exchanger

1.Tube side heat transfer coefficient

2.Ligament efficiency

When a shell or drum is drilled for tubes in a line parallel to the axis of the shell or drum, the efficiency of ligament between tube holes shall be given as ligament efficiency.

3.Number of baffles

Number of baffles (NB) on the shell side of a heat exchanger

4.Shell side cross flow area
The cross-flow area of shell side in a shell and tube heat exchanger

5.The effectiveness of a heat exchanger
h and c denote hot and cold fluid respectively; 1 and 2 denote inlet and outlet fluid respectively

6.Hydraulic diameter
Hydraulic diameter for square pitch shell and tube heat exchanger

Hydraulic diameter for triangular pitch shell and tube heat exchanger

2.Nusselt number
Nusselt number is defined as

Nusselt number is used in heat transfer, mainly in forced convection

1.Fluid flowing in a pipe

For fluid flowing in a pipe, Nusselt number is defined as

2.Laminar flow over r flat plate

Nusselt number (local and average) for heat transfer due to laminar flow over flat plate is given by

3.Conduction and convection across the wall

A nusselt number for heat transfer across a wall of length L involving conduction and convection

4.Natural convection
The nusselt number in case of natural convection is a function of grass off the number and Prandtl number


3.Biot number

Biot number is defined as

Biot number gives a simple index of the ratio of the heat transfer
resistances inside of and at the surface of a body. Bi = 0 means that temperature within the solid is uniform small compared to the resistance to heat transfer from a rod surface to the

4.Unsteady state heat transfer model

1.Lump parameter model

Lump parameter model for unsteady state heat conduction / Transient heat conditions

2. Time is taken for the temperature to reach Tf
To calculate time taken for the temperature to reach Tf

3.Semi-infinite slab
For transient heat conduction equation for a semi-infinite slab, the heat flux is inversely proportional to square root of time

4.Transient 3-D heat conduction
Transient 3-D heat conduction equation

5.Heat transfer coefficient
1. Steam condensing on a vertical plate

2.Cylindrical tube
Overall heat transfer coefficient based on an outer diameter of cylindrical tube

6.Resistance to heat transfer
Resistance to heat transfer is given as

For heat transfer across a series of slabs, heat transfer equation
correlating total resistance is

Consider two composite slabs joined parallel to each other such that one end of both the slabs is at temperature T1 and other ends of the slabs are at temperature T2. Let R1 and R2 be the individual resistance to heat transfer offered by slab 1 and 2 respectively. The total resistance (R) to heat transfer when both the slabs are joined in parallel

7.Critical radius of insulation

8.Wein’s displacement law

At any given temperature, the maximum monochromatic radiating power is attained at a definite wavelength, denoted by λmax. Wein’s displacement law states that λmax is inversely proportional to the absolute temperature T

9.Film-wise condensation
Reynolds number for filmwise condensation on a vertical plate

10.Forced Convection

1.Dittus-Boelter equation

It is used for turbulent flow inside tube, i.e. 10,000 < Re < 120,000, fluid property to be evaluated at bulk temperature.

2.Sieder-Tate equation
It is used when highly viscous oil is used