Development Of Large Capacity VRF And Study Of The Influence Of Pipe Length On Performance

Multi – connected air-condition(heat pump)unit is a single vapor compression refrigeration cycle system which can connect several different or similar forms and capacities of a direct evaporative indoor units,it can provide air handled directly to one or several areas.Its English abbreviation is VRF,because its characteristics of variable refrigeration flow.VRF originated in Japan and developed in China.With the development of the national economy,the VRF business is developing rapidly in China and rapidly expanding abroad.VRF was introduced to China about in 1996.Its sales was about 10 billion yuan in 2006 and about 32.6 billion yuan in 2016.Its share in the central air conditioning market is about 28.6 percent in 2006 and about 45.9 percent in 2016.Business development and technical features of VRF are inseparable.First of all,from the product structure,compared with the traditional air-condition system of air and water,VRF is direct expand evaporation system of refrigerant,and having not secondary refrigerant that make it has faster response speed;Compared with the traditional air and water systems,the outdoor and indoor units of VRF system are connected by copper pipes,which save the installation space and cost due to the smaller diameter of pipe than air or water pipe.Secondly,from the perspective of control technology,due to control technology such as DC speed regulation,the system reaction speed is fast and comfortable,and the indoor temperature fluctuation is small after the start-up operation.Also,from the engineering installation,the installation is simple and the maintenance is easy because of the modular design and no secondary refrigerant.Because of the many types of indoors and free combination,VRF is harmony with interior decoration of house or building.The rapid development of VRF has attracted more and more attention.In this paper,there are design and test of refrigeration system based on a small volume,large capacity and full frequency new product leading the market.And the processes have certain guiding significance for the product development of VRF.Meanwhile,in this paper,there are the pressure drop model of the pipeline,the analysis of the pressure drop characteristic and the optimization path of the pipeline,And the processes have certain reference significance for the VRF engineering application.In the introduction,the characteristics and development of VRF are summarized according to related literatures and lead to the research of this topic.This topic is based on new product development and its contents are showed below.First,the new product development process and project development background are introduced.Secondly,the thermodynamic calculation of the refrigeration system is analyzed,including the calculation of the thermal process of the compressor,condenser and evaporator,and the components are designed and selected according to the calculation results.The process could be the heoretical reference for the design of VRF refrigeration system.Then the machine performance test is arranged and executed,including the introduction of test equipment and method,test tool accuracy test,the machine performance test,and the analysis of test data.The process could be the reference for the test of VRF.Finally,the influence of the length of the suction pipe on the refrigerating capacity of evaporator is analyzed,including the experience summarization,the analysis of the pressure drop theory model and the theoretical reference for the practical application of the project.