The heat load of a heat exchanger can be derived from the following two formulas:

U = Q / (A x LMTD) Where Q is the heat duty, A is the heat transfer area of the exchanger and LMTD is tem- perature driving force.

Heating Guide Simply multiply the appropriate factor above by your home’s total heated square footage to arrive at your approximate required heating capacity. Then, to calculate the output on a given gas furnace, multiply it’s efficiency rating by it’s listed input rating to determine the actual Btu output of heat.

1. Heat load, Theta and LMTD calculation. Where: P = heat load (btu/h)
2. Heat transfer coefficient and design margin. The total overall heat transfer coefficient k is defined as:

Then you can calculate heat duty by the following equation.

1. For cooling or heating or for no phase change, heat duty is calculated by:- Q=m*Cp*∆T.
2. For condensation with subcooling, heat duty is calculated by :- Q= m*λ + (m*Cp*∆T)
3. For reboiler ,heat duty is calculated by:- Q=(m* λ)*1.05 (considering 5% heat loss)

The Heat duty can be defined as the amount of heat needed to transfer from a hot side to the cold side over a unit of time. The other can be used for latent heat transferred, this means that the fluid undergoes a phase change.

The reboiler heat duty is essentially a sum of the energy utilized for three main purposes: raising the temperature of CO2-loaded solution to the boiling point, breaking the chemical bonds between CO2 and absorp- tion solvent, and generating water vapor to establish an operating CO2 partial pressure needed for CO2 …

Heat duty of amine reboilers varies with the system design. The higher the reboiler duty, the higher the overhead condenser duty. This gives a higher reflux ratio and thus a smaller column with fewer trays. The lower the reboiler duty, the lower the reflux ratio will be and thus the tower must have more trays.

Applications: Boilers are generally used in industrial applications like power plants – where they heat water to make superheated steam (using a superheater of course) to run turbines or in steel plants. Whereas evaporators are used in industry as well as in house hold applications like inhalers, vaporisers, ACs, etc.

The Minimum Reflux Ratio (R min) is the lowest value of reflux at which separation can be achieved even with an infinite number of plates. It is possible to achieve a separation at any reflux ratio above the minimum reflux ratio. As the reflux ratio increases, the number of theoretical plates required decreases.

The location where the operating line touches or intersects the equilibrium curve is called the pinch point. The enriching operating line at minimum reflux is then defined. The minimum reflux Rm can be obtained from either the intercept of the slope of the enriching operating line.

Without reflux, your top/rectification section of your column is just a piece of pipe. What happens is that the LIQUID that is refluxed is rich in the desired top product. It is contacted with the VAPOUR that is rising, which contains some of (for binary distillation) both of the top and bottoms products.

When the reflux ratio is large and reflux is used to control the reflux-drum level, a frequently used scheme controls the reflux ratio by measuring the reflux flow rate and rationing the distillate flow rate to the reflux flow rate.

Generally boil-up is used to control the bottom composition, but it is possible to use it to control the reflux drum level. The easiest approach is to use the distillate stream to control the level leaving the reflux stream to control overhead composition.

Distillation is the process of separating components based on their different boiling points. Reflux is the return of process fluid after it has been cooled, condensed, heated or boiled.

In the separation of a mixture of volatile liquids by distillation, the more volatile component rises to the top of the distillation column for separation while the least volatile component is retained at the bottom of the column…. …

As the temperature and/or pressure (Q in the diagram) increases from condition 1 to condition 4, the relative volatility (α in the diagram) decreases to a value of 1, and separation of the components by distillation is no longer possible since at that point there is no difference in the vapor pressures of the binary …

In the table, boron is the least volatile and hydrogen the most volatile substance.