Research On The Effect Of EHD Condensation Heat Transfer Enhancement In The Model Of Low Temperature Waste Heat Power Generation

EHD (Electrohydrodynamics) heat transfer enhancement refers to the active heat transfer enhancement technique that an electric field is exerted on a dielectric fluid medium to increase the heat transfer coefficient and heat transfer efficiency greatly by coupling up the flow field and temperature field. Aimed at overcoming the bottleneck problems about low temperature difference and poor heat transfer capability of heat exchangers existed in low temperature waste heat power generation, the experiments and mechanism of EHD condensation heat transfer enhancement were researched in this thesis.Based on sufficient investigation of related fields at domestic and abroad, aimed at the characteristics of low temperature waste heat power generation, the thermodynamic system model on the base of Rankine-cycle, which mainly consisted of evaporator, EHD condenser and steam turbine-generator group with R11 as working fluid was designed and constructed, and the experiments on EHD condensation heat transfer enhancement and power generation were conducted. The experimental results indicated that the condensation heat transfer coefficient increased with the applied voltage when the high-voltage electric field was exerted on the fluid in condenser under the condition of the same heat transfer surface area and flow rate of working fluid. And the increase of the condensation heat transfer coefficient became to be larger when corona discharge happened. The electric field lines coordinate method was employed to simulate the distributions of electric field, potential, charge density and Coulomb force exerted on the fluid in the wire-plane electrode system numerically. The analysis of computing results indicated that the electric field with corona discharge could cause turbulence in gas fluid and result in heat transfer enhancement. Finally the theoretical discussion on EHD condensation heat transfer enhancement and the analysis of experimental results were made from the electric force exerted on fluids. It was concluded that the EHD technique could enhance condensation heat transfer obviously. What researched in this thesis is a practical application of EHD condensation heat transfer enhancement in low temperature waste heat power generation, it offers an experimental foundation to the practical application of this technique, and is valuable to extend the theoretical investigation of EHD condensation heat transfer enhancement.