Research On Optimization Method Of Reliability Index For Air-source Heat-pump Water Heater

Air-source heat-pump water heater, as a new generation of water heater, its reliability and price become the focuses of consumer requirements. The fault modes are analyzed and the reliability allocation model is established for the air-source heat-pump water heater in the paper. The optimal scheme of the reliability allocation is obtained through the genetic algorithm. The main contents of this paper are as follows.1. Analyze the reliability design of the air-source heat-pump water heater. The structure, working principle and characteristics of the air-source heat-pump water heater are introduced in detail. Using the fault mode efforts and criticality analysis (FMECA), the paper establishes the fault mode efforts analysis (FMEA) table of the air-source heat-pump water heater.And then, the fault tree model of the air-source heat-pump water heater is established by using the fault tree analysis (FTA). Finally, with the help of the minimum cut set of the fault tree, the key components of the air-source heat-pump water heater are found. The qualitative and quantitative reliability requirements, which are based on the market demand and technical conditions of the air-source heat-pump water heater, are put forward.2. Establish the reliability allocation model of the air-source heat-pump water heater. The reliability mathematical models are established and the reliability allocation model is built on the basis of the introduction of the function relations between reliability and cost for the air-source heat-pump water heater. The reliability allocation problem is transformed into the problem of nonlinear mathematical programming and the optimal solution of the nonlinear mathematical programming problem is the best reliability allocation scheme for the air-source heat-pump water heater.3. Solve the reliability allocation mathematical model of the air-source heat-pump water heater. The characteristics of reliability allocation mathematical model are analyzed and then solved by using the real-coded genetic algorithm.4. Develop the reliability allocation prototype system of the air-source heat-pump heater water. Based on the above theoretical study, the demands and functions of the reliability allocation system are analyzed. The prototype system is developed on the MATLAB platform. The main functions of the system are demonstrated by an example.The reference information is provided for product reliability design by the FMEA table and the fault tree which have been established in the paper. A practical method that solves the contradiction between the reliability and the cost,is provided by the reliability allocation model that has been constructed in the paper. With the help of the developed system, the reliability allocation model is conveniently applied.