This paper presents the results of a study on the pressure drop and the film boiling heat transfer for a two-phase flow of hydrogen in a horizontal tube.
Experiments were made on two types of tube; two pieces of vacuum insulated straight tubes of 4m long, inside diameters of which are 18.4 and 23.9mm, respectively; Anuninsulated tube of 8m long with 90 degree bends at two locations, inside diameter of which is 12.3mm.
Experimental conditions were as follows; Flow rate (l/min.); 5 to 50 Vapor quality; 0.01 to 0.90 Pressure (bar); 1.4 to 5.8 Conclusions obtained from the experiments are summarized below.
1) The frictional pressure drop of two-phase flow of hydrogen for a straight tube is well related to a modified Lockhart-Martinelli (L-M) curve, that is, L-M pressure ratio parameter, φl multiplied by 0.8, for both adiabatic and diabatic conditions. More than 90% of data fell within the scatter band of ±20% from the modified L-M curve.
The pressure drop for a bend was also correlated by using parameters analogically introduced from L-M parameters for a straight tube.
2) As for the heat transfer by forced-convection film boiling, the following relationship was established based on the method proposed by Ellerbrock.
(Nuf/Nufm)⋅Bo-0.4=9.46Xtt-0.131
More than 90% of data obtained were in agreement with the the expression shown above with no more than ±20% error.
In this study, it was known that the heat transfer for two-phase flow of nitrogen as well as hydrogen follow Ellerbrock's theory.
