A variable velocity airflow within the small diameter circular duct is provided by an integral centrifugal fan and allows the effects on convective heat transfer from the cylinder to be investigated.

The surface temperature of a duct mounted, matt black cylinder may be varied over a wide range; thereby allowing the increasing effects of radiant heat transfer to be investigated as the temperature is increased.

An integral thermocouple on the surface of the electrically heated cylinder allows surface temperature to be measured at all operating conditions. The heater power supply and temperature sensors connect to the Heat transfer service unit while velocity is recorded on auxiliary instrumentation supplied as part of the demonstration unit. This combined with a duct-mounted thermocouple, heater input power measurement and in duct air velocity measurement allows all of the relevant parameters to be recorded.