It is found that the effectiveness of parallelflow heat exchanger could be larger than the counterflow heat exchanger under some conditions when there is a heat sink (source) on the stream .

• 对带有热汇(源)的逆顺流换热器,在一定的条件下,顺流换热器的效能可大于逆流换热器的效能,其原因就是此时顺流换热器的温差场要比逆流换热器均匀。