Heat and mass transfer characteristics of a new combined absorber-evaporator exchanger operating near the triple point of water

Abstract

The present experimental study investigates the controlling mechanism involved in a new combined vertical film-type absorber-evaporator exchanger operating near the condition of the triple point of water. This peculiar exchanger plays the most important role in the VFVPE process that can be utilized in many industrial applications, water pollution prevention, desalination, and purification of chemicals, for example. The method of analogy of the heat and mass transfer near the film surface is used to calculate the interfacial concentration and temperature, and thus determining the heat and mass transfer coefficients. It is shown that the working temperature level has the negligible effect on the characteristics of the mass transfer. The mass transfer coefficients are higher than those obtained in the case of isothermal absorption due to the convective effect arisen from vapor absorption in the falling solution film. The water flow rate in the evaporator side has a minor effect on the performance of this combined exchanger. The overall mean heat transfer coefficient remains nearly constant in the lower range of the solution flow rate of the absorber; however, it would increase with increasing solution flow rate in the higher range. The correlating equations for both the heat and mass transfer coefficients are suggested.