Direct measurement of the latent heat of evaporation by flowmetric method

This paper describes an original and very simple device dedicated to measure the latent heat of evaporation of various liquids at ambient temperature. This apparatus is composed of two very thin heat flow sensors glued to a heat sink. One of these sensors is covered with oiled textile, and the other one with an identical dry textile intended to receive the liquid to be characterized. This differential system allows compensating the disturbances due to environment. A thermodynamic model is established to determine the heat flow induced by evaporation. By integrating this flow, one calculates the quantity of latent heat absorbed by evaporation. Numerous experiments with different liquids such as alcohol, acetone, water, and trichloroethylene have been carried out. The results are compared with theoretical values, and the maximum error is less than 6%.