Helium Helium Helium (from ) is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements. After hydrogen, helium is the second lightest and second most abundant element in the observable universe, being present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this figure in the Sun and in Jupiter. This
Nucleate boiling formula_6 is the Prandtl number of the liquid. The bubble Reynolds number, formula_7 is defined as, formula_8 Where formula_9 is the average mass velocity of the vapor leaving the surface and formula_10 is the liquid viscosity. Rohsenow has developed the first and most widely used correlation for nucleate boiling, <math>\frac{q}{A}= Nucleate boiling Nucleate boiling is a type of boiling that takes place when the surface temperature is hotter than the saturated fluid temperature by a certain amount but where the heat flux is below the critical heat flux. For water, as shown in the graph below, nucleate boiling occurs when