Tube outlet temperature, tube wall thermal conductivity,
and tube wall thickness were considered as parameters
influencing on gas flow temperature profiles. Fig. 6 shows
gas flow temperature profiles within the tube with various
tube outlet temperatures for gas flow rate of 100 standard
ml min1. As can be seen, gas flow temperature profiles
were affected by tube wall longitudinal heat
conduction at the last 10 cm of tube for all tube outlet temperatures.
In other words, at constant gas flow rate and
constant wall thermal conductivity, the main cooling effect