Study Of UV-LED Photocatalytic Reactor Design And Operating Characteristics

With the rapid development of the printing and dyeing industry,printing and dyeing wastewater has caused severe damage to the water environment.Non-homogeneous photocatalytic technology is an effective treatment method for printing and dyeing wastewater,and the key to its application is an energy-saving and efficient photocatalytic reaction system.High-power LED as UV light can achieve energy saving of light source,but its luminous characteristics depend on whether the LED can effectively dissipate heat.Therefore,the effective heat dissipation of LED has become the leading technical bottleneck restricting large-scale application.Combining the needs of the pollution industry and the advantages and disadvantages of LED themselves,designing a system that can meet the effective heat dissipation of LED beads while achieving efficient removal efficiency of printing and dyeing wastewater is the focus of this paper.To this end,this paper proposes to combine photocatalytic water treatment with high-power LED cooling,using wastewater cooling high-power LED,while completing the removal of pollutants.This enables designing and optimizing a highly efficient coupled UV-LED/TiO₂ photocatalytic reactor and provides data support for subsequent engineering utilization.The main research findings of this paper are:（1）The optimal arrangement of LEDs was first investigated using simulation combined with experiments.For single-layer structures,the uniform arrangement of UV-LED arrays has higher irradiation uniformity and average irradiance.For a two-layer structure,a plum-shaped arrangement is the best choice.Considering the symmetry of the structure,the top/bottom lattice arrangement（3 beads）and the rectangular arrangement（4 beads）of the middle layer are the best choices for the three-layer structure.Based on this,the heat transfer and photocatalytic efficiency of the above-structure reactors were compared.The experimental results of heat transfer characteristics show that the double/triple layer structure is suitable for heat dissipation,which showed that the UV-LED junction temperature of double and triple-layer structures was lower than that of single-layer structures（44℃vs 53℃）.The efficiency of three photocatalytic reactor structures for AR 26 wastewater degradation was ranked as follows:double-layer structure>single-layer structure>triple-layer structure.Considering both heat transfer characteristics and photocatalytic efficiency,the double-layer structure reactor combines good lamp bead heat dissipation and excellent dye degradation.（2）The effect of effluent cooling on LED was obtained by comparing it with no cooling conditions.The effluent cooling system can reduce the LED junction temperature and thermal resistance（41.2%and 59.3%）.Thus,on the one hand,the effluent degradation efficiency can be improved（1.68 times）.On the other hand,the LED luminous stability can be effectively improved（only 15%luminous decay after 85 days of the aging experiment）.Based on this,the condition factors affecting the reaction were analyzed by single-factor analysis.The results show that the p H=2,the 80 ml/min flow rate,and the TiO₂ concentration of 0.75 g/L could ensure the best photocatalytic reaction efficiency under 20℃and 45 ml/L of AR 26.Finally,a comparison was made with the conventional ring-gap photocatalytic reactor.The degradation efficiency and apparent quantum yield of the coupled reactor for AR 26 is 2.1 times and 1.5times higher than the conventional photocatalytic reactor,respectively.The unit power consumption of the coupled reactor is only 193.90 k W·h,which is 18%of that of the conventional photocatalytic reactor.The unit power consumption and parasitic energy consumption of the coupled reactor are only 18%and 21.4%of those of the conventional photocatalytic reactor,proving that the coupled system has great advantages in terms of both efficiency and energy saving.In this paper,the above two parts were used to design and demonstrate the use of wastewater coupled with UV-LED lamps.It can be used in the field of wastewater treatment,which can not only achieve high-efficiency photocatalytic efficiency but also maximize the energy-saving requirement.