Figure above shows a fluid flowing through a pipe and exchanges heat with another fluid through an
annulus surrounding the pipe. In a parallel-flow heat exchanger fluids flow in the same direction. If the
specific heat capacity of fluids are constant, it can be shown that:
where, dQ/dt= Rate of heat transfer between two fluids U= Overall heat transfer coefficient A= Area of the tube T= Logarithmic mean temperature difference defined by:
T= Logarithmic mean temperature difference defined by: 