Experiment Study And Engineering Model Of Condensation Of R410A In Micro-fin Tubes With Different Geometries

At present,China is faced with severe energy situation,striking environmental problems and urgent pressure to reduce carbon emissions.Energy conservation and environmental protection are the inevitable choices to implement total energy consumption control and national sustainable development.Micro-fin tubes have been widely used for its outstanding heat transfer performance,and R410A refrigerant is deemed to be the most suitable refrigerant to replace R22 because of its ODP 0,large cooling capacity and low cost.Based on the Experimental System of Flow and Heat Transfer in Horizontal Tube,condensation of R410A in seven kinds of micro-fin tubes has been carried out.According to the experimental results,the flow pattern and the influence of mass flow and tooth profile parameters are analyzed.Besides,the existing pressure drop and heat transfer correlations are evaluated and a novel heat transfer correlation is developed based on a large capacity database.The results show that increasing the tooth height,increasing the number of teeth and reducing the top angle of teeth are helpful to improve the condensation heat transfer coefficient.The phenomena of"falling instead of rising"and"first fast and then slow"of heat transfer coefficient on mass flow increase are related to flow pattern.A profile parameter Rx is introduced and there is a linear relationship between the condensation heat transfer coefficient and Rx~2 in a specified flow range.A novel model of condensation heat transfer coefficient is proposed,which not only has a good prediction ability for micro-fin tubes,but also is applicable for smooth tubes.The new model has better prediction ability under mass flow rate less than 600 kg/(m~2s)and root diameter is less than 10 mm.