WSN-based Data Acquisition And Analysis Of Train Air-conditioning System

Thermal comfort is an important indicator of the railway passenger design, due to the complexity of the structure passenger compartment, if not the air conditioning system for a reasonable organization, after the bus assembly is often not achieve the desired effect, the temperature field, velocity field is not rational, cause the local temperature is too high or too low, do not meet the body feel the heat of the body characteristics, fatigue and other passengers feel uncomfortable. Traditional air conditioning performance testing of train technology because of high inputs, energy consumption, application has been limited. Now, researchers and manufacturers of widely used numerical method of temperature field, the establishment of flow and heat transfer equations (including the continuity equation, momentum and energy equations), the discrete equations, re-use computational fluid dynamics (CFD) software on the passenger compartment temperature field simulation.This work is in accordance with the Changchun Railway Vehicles Co., Ltd. jointly developed the project "temperature measurement and analysis system" (contract number: 2009220101000482) are carried out. This paper presents a ZigBee-based data acquisition and analysis of passenger car air-conditioning system for studying the passenger compartment thermal comfort. The program achieved the detection of temperature field and thermal comfort evaluation, thermal comfort for the designers to improve the car provides the useful help.Train Air Data Acquisition and Analysis System for finishing on-site temperature, humidity, wind speed signal Real-time acquisition and analysis and processing. Data Acquisition system is flexible, that rapid adoption of data.Set the same time, can easily measure the signal points of the type and layout to cut and modify to suit Coupled with the air conditioning on the effect of vehicle research needs, and can achieve the necessary expansion and upgrade later. This Systems including wireless data acquisition subsystem, air conditioning and air-conditioning design software performance analysis database of three parts.As the system measurement points as well as scattered layout, signal types, and that the demand for quick installation and testing, to facilitate Disassembly. Overall technical program using wireless sensor network technology to build a wireless network based on local open Type of data acquisition system. Wireless data transmission requires measurement unit data will be measured by radio station Domain transfer to the host computer network and to ensure reliability of data transmission and real-time. Network protocol is not Line transmission of the core, used in network infrastructure and application levels to solve the problem of wireless data transfer. Because ZigBee has many advantages, so use this program IEEE802.15.4/ZigBee standard protocol Standard.Software interface can be set up location and types of measurement points, and can be read into the wireless network coordinator Measurement data; calculate the measured temperature and humidity inside the vehicles, wind channel of the pressure field, wind speed inside and empty Parameters such as carbon dioxide gas inside, according to the relevant standard of air-conditioning system performance, and form of newspaper Reported.ZigBee system software vendors of ZigBee in the MAC and PHY layer, which involves the cooperation with the sensor and network architecture and other issues. Protocol stack is divided into two kinds of paid and unpaid. This air-conditioned train ZigBee-based data acquisition and analysis system uses Jennic's solution. JN5139-Z01-M00's internal integrated ZigBee protocol, which is a protocol developed by Jennic. ZigBee is based on IEEE802.15.4, but only deal with low-level IEEE MAC layer and physical layer protocol, the ZigBee Alliance extends the IEEE, its network layer protocol and API were standardized. Complete ZigBee protocol stack from the top down by the application layer, application layer specifications, network layer, data link layer, MAC layer and physical layer. ZigBee networks can achieve the form of three network topologies: star, tree and mesh.ZigBee ZigBee protocol stack, application and turn on the processor and peripheral components operation, in order to achieve this goal, Jennic ZigBee protocol stack in the basis provided BOS. Application Framework Interface function is used to send data and processing equipment to solve the problem described, divided into two categories: AFDE API and AF AFME API. ZDP API is used and remote node ZigBee Device Objects link interface function. It consists mainly of three types of functions. Coordinator to the End Device to transfer data in two ways: direct transmission and indirect transmission.Taking into account the railway passenger cars, urban rail trains requirements of different models of measurement points may be different, and differences in the structural layout inside large air-conditioned train ZigBee-based data acquisition and analysis system uses the tree topology. When using a distributed address allocation strategy, the network layer to support tree routing algorithm using Cskip.The establishment of the data collection network is random, temporary, when the designers presented measurement program, you can create a tree network, the network building process consists of three parts: Coordinator networking, Router and End Device to join the network join the network. To compensate for the nonlinear temperature and humidity sensors to obtain accurate data, we use several formulas to amend the reading.Air Conditioning System part of the host computer data acquisition software workflow: Host PC, through the serial port configured to read out from the Coordinator of the measurement unit completed ID number, Coordinator tour constantly measuring unit to detect whether there is wrong, if wrong, then change measurement unit, measurement unit after saving changes ID number; if no error, Coordinator sent calibration, set cycle, operating parameters, circuit receive different data from the measurement unit, for data analysis and processing, and the data to file is stored in the database to prepare for future reference; same data also spread to common software interface, and numerical simulation software, complete with thermal comfort evaluation, to the designers provide design reference for the special effect to help improve the air conditioning.In order to measure the data of the designers have a better research value, we have introduced a numerical simulation of temperature field to be compared, judged. Passenger compartment temperature field simulation technology is mainly used numerical method of indoor temperature distribution. .Numerical method is based on its temperature field simulation for the completion of great significance. In this paper, the railway passenger compartment temperature field calculation model. Set the boundary conditions calculated.Passenger temperature field for the optimization of railway passenger car air-conditioning system design and thermal comfort evaluation is of great significance. To this end, we made a pre-set conditions, the simulation test results show that the data acquisition system running normally, to achieve the ZigBee networking and data transmission capabilities, accurate temperature and humidity measurements, the PC software free fault.The development direction of modern air conditioning technology is strongly based on the promotion of energy-saving technologies, focused on the research of the entire air conditioning system to improve the air conditioning comfort zone. Evaluation of a variety of thermal comfort index, PMV index which most scientific and practical value, and adopted international standards organizations;△ET-ADPI index for evaluation of thermal comfort is simple, the system uses the index.