Abstract: Changing the previous research technique relying mainly on experiment,we attempt to analyze and calculate quantificationally the evaporation rate from the perspective of phenomenological theory. The basic formula of evaporation rate is deduced under the condition of no wind,and the result has shown that the main influence factor are temperature and humidity; the humidity and evaporation rate are in a certain linear relationship with certain temperature. Comparing with Dalton evaporation model,the physical meaning of the Dalton model parameters is obtained. In the case of nonlinear area,the wind speed model is generalized,the concrete expression of evaporation phenomenological coefficient is calculated under the condition of no wind. The nonlinear model coincides with the experimental results preferably. It also shows certain rationality after comparing the wind speed model with the experimental data.

Key words: phenomenological equation, evaporation rate, chemical potential, wind speed, humidity