基于压降模型的多联机配管长度评估方法及试验验证

Evaluation of the length of refrigerant pipeline for multi-Unit air conditioners based on pressure drop model and validation

多联机的配管长度决定了制冷剂输配、回油方案,掌握多联机配管长度识别的精确算法,可以针对性改进制冷剂输配、回油,使得系统更加节能。提出了一种基于阻力模型的多联机配管长度识别方法,包括利用基于等熵效率的压缩机广义热平衡法迭代计算系统制冷剂的循环量;建立基于内机开机台数的阻力加权系数的联机主支管和末端支管压降模型,以精确的评估不同负荷率下的主管和支管压降;建立以末端支管长度和阻力为引导的包含不确定度的多联机配管长度模型,客观评估预测的联机管长度。试验验证表明所述方法,对于短配管(L为15m),通过模型计算得到的长度均值16 m,各工况下计算误差不超过10%;对于长配管(L为150m),通过模型计算得到的长度均值141 m,各工况下计算误差不超过20%。该算法可以克服直接采用压降难以识别配管长度的难题。

The length of refrigerant pipeline of the multi-unit air conditioners determines the refrigerant transmission and oil return scheme.Accurately identifying the pipe length of the multi-unit air conditioners can improve the refrigerant transmission and oil return,consequently making the system more energy saving.A method for identifying the length of refrigerant pipeline based on refrigerant pressure drop model is proposed.In this method,a generalized heat balance method for compressor based on isentropic efficiency is established to iteratively calculate the mass flow rate of refrigerant;a pressure drop model of the main and end branches is established based on the drag weighting coefficient of the number of indoor unit to accurately evaluate the pressure drop of the main and branch pipes under different load rates;a refrigerant pipe length model with uncertainty guided by the length and resistance of the end branch pipe is proposed to evaluate the length of the refrigerant pipeline.The experimental validation shows that for the pipe length calculated by the method described in this paper,for the short pipe(L=15 m),the average length calculation error under each working condition is less than 10%;for the long pipe(L=150 m),the average length calculated by the model is 141 m,and the calculation error under each working condition is less than 20%.The proposed model can effectively overcome the difficulty to distinguish pipe length by simple pressure drop under part load conditions.