Experimental Study Of Forced Convection Condensation Heat Transfer Of Steam-Air Mixtures On Horizontal Three-Dimensional Externally Finned Tube

The technology of biomass pyrolysis liquefaction is a new way of utilizing biomass which is abundant in our country as the renewable energy. The bio-oil vapor come out from the pyrolysis equipment is a kind of mixed gas with complicated components, especially high content non-condensable gases with high temperature. How to condense the bio-fuel vapor rapidly becomes a key factor for the bio-oil productivity. Therefore the study of the mechanism of enhanced condensation heat transfer of steam in the presence of high content non-condensable gases is more important and urgent.The thesis just focus on the experimental study of forced convective condensation on horizontal three-dimensional externally finned tube for the steam-air mixtures with high content non-condensable gas. The experimental apparatus with double pipes heat exchanger was designed and set up for the condensation heat transfer. Then the experimental study on the forced convection condensation performance of steam-air mixture gas on a horizontal three-dimensional externally finned tube and a smooth tube were conducted within an experimental range of 0.60 to 0.75 in the mass fraction of non-condensable gas. The effects of the content of the non-condensable gas, heat transfer rate, mean vapor inlet velocity, the flow direction of vapor and cooling water and the superheat degree of the overheating vapor on the condensation heat transfer were analyzed. The correlation for the condensation heat transfer coefficients were carried out. Besides, based on the consideration of utilization of the biomass in the rural area of Chongqing, the chemical compositions analysis and proximate analysis are carried out experimentally for seven kinds of biomass from the rural area of Chongqing, corn stalk, corn cob, broomcorn stalk, rice straw, wheat straw, yellow Jue tree and bamboo. This can offer a good reference to the process of biomass pyrolysis. The following are the main outcomes of this study:1 By analyzing the chemical components of seven kinds of biomass from the rural area in Chongqing , it is obtained that the bamboo the and corn cob are the better biomass for biomass pyrolysis liquefaction;2 The forced convective condensation experimental results show that the heat transfer coefficient of the three-dimensional finned tube is 1.7-2.3 times larger than that of the smooth tube in the experimental range. The condensation heat transfer...