Abstract:

In order to reveal the influence of structural parameters on distribution of ultraviolet radiation in the ultraviolet LED nutrient solution sterilization （UV-NSS） module and optimize key structural parameters， the engineering software Tracepro was used to model and ray-trace the UV-NSS module. The inner diameter of tube， the thickness of tube wall， the tube-lamp distance and the bidirectional reflectance distribution function （BRDF） of the inner surface of light bar were the parameter factors， the effective UV radiation ratio （EURR） and the irradiance dispersion （ID） were the response. The results showed that when the UV-NSS module model had the tube inner diameter of 28 mm， the tube wall thickness of 2 mm， the tube-lamp distance of 4 mm， and the BRDF of 0， its EURR was 12.14%， ID was 0.320 6， and the difference between the simulated value and the measured value of ultraviolet irradiance was only 3.68%， which meaned that the model could accurately show the irradiance distribution in the module. Based on the model， the central composite bounded design was carried out， and the response surface method was used to analyze the quadratic regression equations of EURR and ID. Their determination coefficients were 0.962 0 and 0.967 8， respectively， which meaned the fitting was significant （P<0.05）. With the goal of maximizing EURR and minimizing ID， the optimal combination of parameter factors was determined with response surface method under the consideration of actual situation： the inner diameter of tube was 50 mm， the thickness of tube wall was 3 mm， the tube-lamp distance was 0.6 mm， BRDF was 0.55. After being substituted into model， its EURR and ID were 32.11% and 0.317 8， which increased and decreased by 164.50% and 0.87% compared with before optimization， respectively. Using these parameters to manufacture the UV-NSS module， the difference between the measured value and the simulated value of the ultraviolet irradiance was only 1.73%.

Key words: UV sterilization, Tracepro, model, central composite inscribed design, parameter optimization

摘要：

为了研究营养液紫外LED杀菌（ultraviolet LED nutrient solution sterilization， UV-NSS）模组内紫外辐照分布并优化其关键结构参数，采用Tracepro光学仿真软件对UV-NSS模组进行建模和光线追迹，并以模组管道内径、管壁厚度、管灯距离及灯条内表面双向反射分布函数（bidirectional reflectance distribution function， BRDF）为参数因子，以有效紫外辐照比例（effective UV radiation ratio， EURR）和辐照离散度（irradiance dispersion， ID）为响应值进行响应面法参数优化。结果表明，当UV-NSS模组管道内径28 mm、管壁厚度2 mm、管灯距离4 mm、BRDF为0时，其模型EURR为12.14%，ID为0.320 6，模型中心位置紫外辐照度模拟值与实测值仅相差3.68%，可准确反映模组内辐照分布情况。基于上述模型开展中心复合有界设计，以响应面法拟合EURR和ID的二次回归方程，其决定系数分别为0.962 0和0.967 8，拟合显著（P<0.05）。以EURR最大化、ID最小化为目标，结合响应面法与实际情况确定参数因子的最优组合为管道内径50 mm、管壁厚度3 mm、管灯距离0.6 mm、BRDF为0.55。代入模型后EURR为32.11%，较优化前提升了164.50%；ID为0.317 8，较优化前降低了0.87%。采用该参数制造UV-NSS模组，其紫外辐照度实测值与模拟值仅相差1.73%。

关键词: 紫外杀菌, Tracepro, 模型, 中心复合有界设计, 参数优化