Thermal Energy-Pressure Wave Conversion Of Liquid R134a And Its Effect On Heat Transfer

In recent years,the research team found that under certain thermodynamic conditions.The heat absorbed by the liquid working medium will be converted into pressure wave.This phenomenon is called the hot-pressure conversion effect.The“enhanced heat transfer technology based on the hot-pressure conversion effect”is proposed.The heat-pressure conversion effect essentially utilizes the coupling of internal energy and mechanical work of the working medium to achieve high-intensity heat transfer.However,the mechanism of the heat-pressure conversion effect has not been fully revealed.It is impossible to achieve a quantitative description of the hot-press transition effect.Based on the experimental data,this paper analyzes the influencing factors of the hot pressing process and calculates the theoretical conversion efficiency.A new heat transfer conversion effect heat transfer model is proposed.The process of mechanical energy conversion between internal energy and pressure wave is deduced theoretically.The influence and law of heat transfer effect on heat transfer enhancement were analyzed by numerical simulation.Accurate fitting calculation is needed,because the existing literature has no relevant thermal property parameters of R134a working fluid in the range of temperature 293K³13K and pressure 1.1MPa¹.5MPa.Firstly,The fitting equation between density and temperature of liquid R134a is obtained.Pressure is obtained by the structure addition method and the Chueh-Prausnitz compressed liquid equation.Then the fitting equation of the isothermal compression coefficient and the constant expansion coefficient is obtained.Then the fitting of the specific heat capacity is obtained by the equation of enthalpy equation.In this way,lay the foundation for subsequent theoretical derivation.In the compressed fluid R134a,the change of fluid density leads to the change of fluid pressure which produces pressure wave.By expanding the energy term Taylor series,it is concluded that the energy is carried.The unit volume fluid pressure wave is related to the propagation velocity of the pressure wave in the fluid.The pressure wave amplitude.According to the wave number equation,the sound velocity of the homogeneous phase flow is the smallest when the gas content is about 51%.According to the cycle equation and the state equation,the pressure wave amplitude is the largest when the liquid filling rate approaches 100%.According to the experimental data theory,the maximum energy efficiency of heat conversion into pressure wave in the experiment was calculated to be 2.43%.Thus,it can’t be verified that the heat-pressure conversion effect can generate sufficient pressure wave to transmit the internal energy of the working medium.Thereby it can be predicted that the pressure wave acts to enhance heat transfer in the hot-pressure effect.In this paper,the theoretical model of pressure wave enhanced heat transfer is proposed.The initial working mass unit is in the compressed state under the action of pressure wave,radiates heat to the surrounding.The phase of the pressure wave changes after half a cycle,and the working medium unit is in the expanded state.It absorbs heat around.The heat release cycle is performed in this manner.According to the newly established theoretical model,it is calculated that the mechanical heat transfer of the unit heat transfer amount needs to consume up to 0.52%of the pressure wave in each cycle.It is verified that the hot pressure conversion effect process can generate sufficient pressure wave to enhance the heat transfer effect.The actual heat transfer phenomenon is explained reasonably.In this paper,a one-dimensional closed model is established and a pulsed heat source is applied to the left boundary.The effect of hot-pressure conversion effects on heat transfer under different conditions are simulated.The kinetic energy,internal energy variation,compression work and proportion of the working fluid are calculated.The heat transfer coefficient of the working fluid R134a under the hot-pressure conversion effect is converted.The heat transfer characteristics of the heat transfer phenomena of different length models are similar.The higher the heating power is,the compression power ratio is higher.The compression power of pressure wave increases the heat transfer ratio.The longer the heating time is,the amplitude attenuation coefficient is greater.In the heat exchange process,the heat transfer coefficient is about 50,000W·m^-2·K^-1.The higher the hot-pressure conversion efficiency is,the heat transfer coefficient is larger.