An Experimental Study Of The Heat Transfer Performance And Heat Transfer Enhancement For Heat Exchangers In Tobacco Flue-curing Industry

With the improvement of national economy, the tobacco industry has rapidly developed and it now plays an important part in the economy. Tobacco flue-curing is a necessary process in the industry. Its energy consumption is large. The study of the heat transfer performance of the heat exchanger tube used in tobacco flue-curing industry is very important. In this thesis, the heat transfer performance of the tubes typically used in the tobacco flue-curing industry is studied experimentally. The determination of thermal conductivity of tube material and heat transfer coefficient of different tubes can be used to evaluate their heat transfer performance. Based on this information and the practical-principle, the appropriate technology of heat transfer enhancement is applied. Then the evaluation method of heat transfer enhancement is adopted. The study also points out what should be done in the future.In the paper, the conductivity of two typical heat exchanger tube materials is measured. The process of heat transfer under different conditions is studied on the self-established experimental facility to measure the conductivity of the heat exchanger materials, the convection heat transfer coefficient inside the tube and outside the tube and then determine the overall heat transfer coefficient. The results from the experiments indicate: the conductivity of the materials adopted by the heat transfer tube is low; the heat transfer performance is bad; the heat transfer performance of the heat exchanger is determined by the conductivity of heat exchanger's material and the convection heat transfer coefficient inside the tube and outside of the tube; good heat exchanger structure is also important to the heat transfer performance.At the end of this paper, based on the experiments some methods of heat transfer enhancement are proposed, such as reducing the diameter of tube of the heat exchanger, using materials of higher thermal conductivity and installing fins on the tube. Those methods can be used in practice.