While flowing a kerosene-type gas turbine fuel through a direct-resistance heated tube, a condition was found which resulted in a tube wall temperature profile with two peaks near the tube entrance. The downstream peak gradually diminished as deposits formed inside the tube and only one peak remained after seven hours. On the basis of existing analytical studies and experimental data pertaining to heat transfer in the entrance region of tubes, it was concluded that the temperature profile can be divided into five regions: development of the thermal boundary layer, appearance of secondary flows, fully developed thermal boundary layer, transition to turbulent flow and turbulent flow. Deposits increased the tube roughness and reduced the length required for laminar-turbulent transition.