Presentation on theme: "Ta-Te Lin, Yi-Chung Chang"— Presentation transcript:
1MODELING AND ANALYSES OF EVAPORATIVE COOLING EFFICIENCY FOR MIST-FOG SYSTEMS Ta-Te Lin, Yi-Chung ChangDepartment of Agricultural Machinery Engineering,National Taiwan University,Taipei, Taiwan, R.O.C.
2INTRODUCTIONMODEL DEVELOPMENTSIMULATION AND ANALYSESCONCLUSIONS
3INTRODUCTION EVAPORATIVE COOLING AND ITS APPLICATIONS FACTORS AFFECTING EVAPORATIVE COOLINGOBJECTIVES
6OBJECTIVESTo develop a theoretical model for the calculation of evaporative cooling efficiency base on mass transfer and particle dynamic theories.To validate the model with existing laboratory data.To analyze the influences of selected parameters, such as temperature and relative humidity, on the evaporative cooling efficiency of mist-fog systems.
7MODEL DEVELOPMENT MASS TRANSFER OF DROPLETS PARTICLE DYNAMICS CALCULATION OF PSYCHROMETRIC PARAMETERS
8MASS TRANSFER OF DROPLETS The Basic Mass Transfer Equation:The Goering Model:
9MASS TRANSFER OF DROPLETS DiffusivityPressure DifferencePartial Pressure of AirPressure Difference
10PARTICLE DYNAMICSParticle Motion:Drag Force Calculation:
11PARTICLE DYNAMICS Effect of Wind Direction and Droplet Moving Angle: Effect of Spray Nozzle Gauge Pressure:
34CONCLUSIONSA theoretical model to predict evaporative cooling efficiency for mist-fog systems was established based on mass transfer theory and particle dynamics.The model was validated with experimental data from existing literature and the predicted evaporation efficiency agreed well with the measured values.The effects of temperature, relative humidity and the size of spray droplet on the cooling efficiency of mist-fog systems were analyzed with the developed model. Useful information can be generated with model simulations as an aid in designing effective mist-fog systems.