Recycle loops

This unit has been designed to explain the principle of recirculation and to carry out mass and energy balances in steady-state or unsteady-state conditions. This is the typical application of an industrial heating system where the temperature of a product can be increased or reduced by the recirculation of part of the product through a heat exchanger.
This equipment consists of a pipe crossed by tap water and connected with a proper drain; this pipe is equipped with a recirculation circuit including a pump and an electric heating element. This heating resistor can be switched off and on to provoke step changes and to study the system response. Temperature is measured at the inlet and outlet of the pipe and across the recirculation circuit. Flow rate is measured in the same positions.