Energy efficiency enhancement of natural rubber smoking process by flow improvement using a CFD technique

A non-uniform flow and large temperature variation in a natural rubber smoking-room cause an inefficient use of energy. Flow uniformity and temperature variation can be improved by using a computational fluid dynamics (CFD) simulation. The effects of the size, position and number of gas supply ducts and ventilating lids which were at the inlets and the outlets of the smoking-room were investigated. The optimal rubber smoking-room of size 2.6 m x 6.2 m x 3.6 m contains 154 50 mm-diameter hot gas supply ducts, and four 0.25 x 0.25 m and four 0.25 x 0.20 m ventilating lids. The velocity distribution of this model in the rubber-hanging area was rather uniform. The average monitoring temperature of 54 positions was 62.1 °C. This model could reduce the temperature variation by a factor of three from the original room model, i.e., from 15 to 5.5 °C. In a further study, the heat input of an appropriate room model was finely adjusted to obtain a suitable temperature (60 °C) for the smoking process. It was found that an appropriate heat supply at this temperature is 11 kW. At this rate, the temperature variation is 5.3 °C. This improved model should help the rubber smoking cooperatives to achieve at least a 31.25% saving in energy.