US Patent 7954544 Heat transfer unit for high reynolds number flow

In one aspect, a heat transfer unit is provided for increasing the temperature of process fluids, such as gas-phase fluids, having a Reynolds Number (RE) of at least about 275,000 with a low overall pressure drop and without exceeding the wall temperature limits of the material used to construct the heater. The heater generally includes a heater conduit having the gas-phase fluid flowing therethrough and a heat source, such as a radiant heat source, providing an inconsistent or variable heat flux along a length of the heater conduit where the heat source has a peak heat flux greater than an average heat flux.