Simulation And Experimental Testing Of Regenerative Evaporative Cooling System

Evaporative cooling is a thermal process that utilizes the heat and mass exchange between water and air to cool the surrounding objects and air.Evaporative cooling system has the advantages of simple structure,low cost,energy saving and environmental protection.However,temperature drop of evaporation cooling is limited and highly dependent on the environment,so it is difficult to be used as the cooling system of buildings independently.Conventional evaporative cooling includes direct evaporative cooling and indirect evaporative cooling,in which the minimum temperature of the cooled air produced by direct evaporative cooling is not lower than the wet-bulb temperature.The wet-ball efficiency of conventional indirect evaporative cooling is usually below 80%.As conventional evaporative cooling technology is difficult to break through the limitation of wet-bulb temperature,a new evaporative cooling process,namely regenerative evaporative cooling,has been proposed recently.Regenerative evaporative cooling is a special indirect evaporative cooling system that introduces pre-cooled air into wet channels for heat and mass transfer so as to cool the surrounding air.Regenerative evaporative cooling's minimum temperature can drop to the vicinity of dew point temperature,and the wet-ball efficiency can exceed 100%.The excellent refrigeration efficiency of regenerative evaporative cooling has been widely concerned by scholars at home and abroad.In terms of theoretical models of regenerative evaporative cooling,researchers have put forward a variety of mathematical models which mainly based on eNTU methods to take into account factors such as transfer resistance in evaporative cooling,inconsistency of lewis number and curvature of saturated enthalpy curve.In terms of experimental research,the channel structure and working environment of regenerative evaporative cooling heat exchanger were studied.Previous research results show that researchers have done more work on the establishment and optimization of the theoretical model of regenerative evaporative cooling,and have done relatively little research on the application of regenerative evaporative cooling equipment.At the same time,the influence of longitudinal heat conduction and mass diffusion is seldom considered in theoretical research.In this paper,an optimized mathematical model of counter-flow regeneration evaporative cooling is established,considering the influence of longitudinal heat conduction and material diffusion in air flow,channel wall surface and water film.The model also combines the transient governing equation and the principle of heat and mass transfer.The simulation results show that the cooling efficiency of regenerative evaporative cooling is affected by the temperature of fresh air,the humidity of fresh air,the inlet air speed,the length of channel,the height of channel and the proportion of regenerative air.According to the simulation results,the vertical and horizontal laboratory equipment of regenerative evaporative are constructed and tested.The experimental results verify the accuracy of the mathematical model,and show that the water temperature in the non-circulation water supply system is one of the influencing factors of the cooling efficiency of regenerative evaporative cooling equipment.Based on theoretical and experimental analysis,the following conclusions can be drawn: when circulating water is used in the water supply system,fresh air temperature,fresh air humidity,inlet wind speed,channel length,channel height and proportion of working recycled air can all affect the cooling capacity and wet bulb efficiency of regenerative evaporative cooling,and channel width has no obvious influence on the cooling of the system.When the water supply system provides water with constant temperature,supply water temperature is also the influence factor of the refrigeration capacity and the refrigeration efficiency of the regenerative evaporative cooling system.