Wetted wall column - Coursework Example

According to Mass balance (also known as material balance), and assuming that there no accumulation of materials in the system, or there is no loss associated with process under which the materials entering the system are undergoing, the mass of materials entering the system is equal to the mass of materials (components) leaving the system (Atkins 1997). See the diagram below. If accumulation occurs in the system, the mass of materials entering the system is equal to the mass of materials leaving the system plus the mass of materials that have accumulated in the system.

This can be as shown in the equation below, One of the ways in which mass balance can be studied theoretically is through wetted column. A wetted column experiment consists of a vertical tube in which a gas is flowing either co-current or counter current to a liquid (the liquid has to be volatile in nature) (Sinnott 2007). The interface area between the liquid column (thin film) and the gas can be measured and is usually constant (Dainitiyh 1996). In the wetted column the volatile liquid is usually flowing down the surface of the wetted tube in a very thin film (Kim 2007).

From the rate at which the volatile liquid change to gaseous state (evaporation), the coefficient of the mass transfer of the gas phase can be calculated. The rate of mass transfer in wetted column (also rate of evaporation) normally depends on the conditions that prevail in the area (interface) between the gas stream and the thin liquid column (film). In the wetted column, the gas flow is either laminar or turbulent, that is, the flow of the gas is either smooth or associated with ripples at the interface.

The mass balance of the materials (in this case water vapour) that are transferred from the film of the liquid to the air along the column (assuming that the transfer has taken place throughout the length of the tube (column)) is