Experimental investigation of convective heat transfer of hydrocarbon fuels at supercritical pressures within rotating centrifugal channel

Abstract

An experimental investigation concerning the convective heat transfer of n-decane maintained at supercritical operating pressures and flowing through a 2-mm-diameter and 200-mm-long pipe under conditions of varying rotational speeds, mass flow rates, inlet temperatures, and heat flux has been reported. The wall temperature was measured at four positions around the pipe periphery at five selected cross-sections along the pipe length. Maximum convective heat transfer was observed along the trailing edge of the centrifugal section while its corresponding minimum was observed along the leading edge. Heat transfers along the two sides of the channel were observed to be nearly identical. The average sectional convective heat-transfer coefficient demonstrated an increase with increase in rotational speed, and its value corresponding to 1500 rpm was observed to lie within the range of approximately 2–2.5 times its corresponding value under static conditions. The strong effect of the buoyancy force caused by the centrifugal force and flow deceleration due to pressure drop tended to limit the deterioration of local heat transfer. This study proposes an expression for a dimensionless criterion concerning the buoyancy force generated under rotating conditions along with a new local Nusselt number correlation apropos the heat transfer of n-decane flowing through a rotating centrifugal section under supercritical operating pressures.