Publications, from the last 60 years, on the evaporation coefficient o
f water have been collated and the experimental methods, results and c
onclusions from these investigations are discussed. Reported values of
evaporation coefficient of water range from 0.1 to 1 and despite many
attempts to explain this large variation the evaporation coefficient
is sill a subject of dispute. Three explanations which have often been
used to account for low evaporation coefficients are. molecular struc
ture, molecular collision in the vapour phase and heat transfer limita
tions in the liquid phase. Following an extensive discussion, it is co
ncluded that molecular collision and heat transfer limitations can hav
e a considerable influence on experimental evaporation rates and thus
apparent evaporation coefficients. However, it now seems unlikely that
molecular structure has a major effect on this coefficient. We conclu
de From this investigation that for pure water evaporating into a spac
e containing only water vapour, the true evaporation coefficient is un
ity under all conditions of pressure and temperature. (C) 1997 Elsevie
r Science Ltd.