Visual experimental study on residence time of particle in plate rotary heat exchanger

The plate rotary heat exchanger (PRHE) was developed as a new type of heat transfer equipment applied in coal moisture control (CMC) industrial process. Being an important factor during the producing process, the mean residence time (MRT) of particles inside PRHE was investigated. Visual experiments on MRT were carried out under identical filling degree (f = 10%), while the particle flow rate, rotating speed and inclination of PRHE were varied. A Perspex rotary drum was used with an inner diameter of 300 mm and a length of 1000 mm. Eight rectangular plates were designed as the “heating plates”. Two different types of particles were utilized as experimental materials. The results indicated that MRT decreased with the increments of particle flow rates, rotating speed and inclination of PRHE. Compared with particle flow rate, the variable of MRT was sensitive to the increasing of rotating speed and PRHE slope, especially when the rotating speed was low. And the distribution of MRT was similar ideally normal. Then, based on the experimental results two empirical correlations were regressed by least square method, both of the two correlations were valid under most of the conditions and the mean deviations in MRT prediction were 8.1% and 8.0% respectively.