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Wireless Data Acquisition System Development and Application on HVAC Equipment
Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 121 (2015) 2006 – 2013
9th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC) and the 3rd International Conference on Building Energy and Environment (COBEE)
Wireless Data Acquisition System Development and Application on HVAC Equipment Hao Yua,*, Jili Zhanga, Liang Zhaoa, Xiuming Lia a
Dalian University of Technology, Dalian, China
Abstract
An appropriate monitoring and control system of the HVAC system is necessary to reduce its energy consumption on the premise of ensure the users’ comfort. A suite of wireless data acquisition system for HVAC system have been developed in this paper to resolve the cabling difficulties existing in the installation process of the sensors distributed at the end of the HVAC system. The acquisition system utilized a low-power and high-performance stm32f103RBT6 microcontroller as the MCU and a wireless transceiver module nRF24L01 and an Ethernet transceiver module W5100 to transfer data. Then the data will be stored in the SQL database and can be observed online. The working process and the practical applications of the acquisition system have been introduced. Finally an acquisition experiment based on the water system of an actual air conditioning system is conducted and the result shows that the wireless data acquisition system works stably and can overcome the difficulties in cabling and signal attenuation. © Published by Elsevier Ltd. This © 2015 2015The TheAuthors. Authors. Published by Elsevier Ltd.is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ISHVACCOBEE 2015. of ISHVAC-COBEE 2015 Peer-review under responsibility of the organizing committee
Keywords: Wireless Data Acquisition System; HVAC Equipment; Embedded System
1. Introduction In recent years, a significant portion of total energy is consumed by buildings and there is no slowdown in sight [1]. About half of this energy comes from heating, ventilation, and air conditioning (HVAC) systems [2]. Therefore improving HVAC operating efficiency without compromising comfort or indoor air quality would have large energy and financial savings, at the same time leads to a significant reduction in CO2 emissions. HVAC operating efficiency improvement largely depends on the Monitoring and control system which sends * Corresponding author. Tel.: 13009416728; fax: 13009416728. E-mail address: [email protected]
1877-7058 © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ISHVAC-COBEE 2015
doi:10.1016/j.proeng.2015.09.199
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
2007
the appropriate operating commands to the HVAC system through analyzing its operational data.[3]The operational data of HVAC system is not only an important indicator to assess building energy consumption but also works as the feedback of the control system. Considering that the sensors of the HVAC system usually distribute dispersedly so the traditional data acquisition system encountered difficulties in cabling, maintenance and readjustment [4] and usually has a low efficiency and poor accuracy in data transmission [5]. Wireless Data Acquisition system developed in this paper is based on the Wireless Sensor Network and the embedded system technology. Wireless Sensor Network is an intelligent measurement and management Network which is constituted by a large number of tiny sensors distributed in the monitoring areas with the ability of sensing, computing and communicating [6]. The Wireless Data Acquisition system has the characters of easy installation and stable and efficiency data transmission, providing a good solution to the cabling problems exist in practical application and the signal attenuation in transmission process. 2. Description of the development process of the Wireless Data Acquisition system The system is divided into two parts, part one called slave device is used to collect real-time signal from the sensors distributed in the HVAC system and send it out. The other part called the master device is used to receive data sent from the slave devices and store it for the moment then upload the proceeded data to the host computer. The system is distributed into different collection area according to the actual circumstances around the HVAC system. Each collection area has one master device and a number of slave devices and the master device and slave devices are connected into a tree network.
Fig. 1. Architecture of Data Process and Transmission.
After the analog to digital conversion the slave devices send the digital data to the corresponding master device at a regular time through the wireless module. In different acquisition area each slave device is assigned a digital ID. When a new slave device join into the acquisition area the master device will assign the slave device a new ID and arrange a new piece of memory for it. Master device in different area are distinguished by IP address. During the acquisition process master device keeps receiving data sent from slave devices in each acquisition area and waiting
2008
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
for command from the host computer. Whenever receiving the data-transferring command from the host computer, master device packs the data in specific formation and transfer it to the host computer through the Ethernet module. The overall architecture of the system is shown in Fig.1. 2.1. Hardware Designation of the Wireless acquisition system As shown in Fig.2 the Master device consists of a MCU, a wireless module, user button, and an Ethernet module .the slave device consists of a MCU, acquisition circuit, wireless module, special power module. The master device and slave device utilize the same MCU and wireless module.
Fig. 2. Hardware designation of master and slave devices.
In this system STM32F103RBT6 works as the MCU, which contains a Cortex-M3 core, 128K FLASH and 16K SRAM for data storage and application. With 72MHZ maximum operating frequency, STM32F103RBT6 also contains many kinds of peripheral interface resources, including multiple 12-bit A / D converter, CAN bus interface, SPI communication interface and multiple serial ports [7]. NRF24L01 is used as the Wireless communication module because of its characteristics as follows: With 2.4GHz opening global ISM band, high transmission power, low voltage, high transfer rate, nRF24L01 supports up to six channels of data reception and hardware CRC error detection are built in the module. [8] Master device communicates with the host computer through the W5100 Ethernet module. W5100 chip integrates a stable TCP / IP protocol stack, an Ethernet media transport layer (MAC) and a physical layer (PHY) inside itself. The internal hardware in the form of TCP / IP protocol stack of w5100 supports such as TCP, UDP, IPv4, ARP, IGMP and all these agreements have been utilized in many areas after years of testing. [9] Users do not need to care much about the control of Ethernet communication protocol layer and W5100 has a simple programming interface supporting both parallel and SPI serial mode and the interface can be easily connected to the microcontroller. Hardware connection of the nRF24L01 and W5100 are shown in Fig. 3. 2.2. Software Designation of the Wireless acquisition system In the acquisition process master device waiting for wireless interrupt and network interrupt. In the wireless interrupt response function master device process the data received from slave devices. In network interrupt response function master device analyze the interrupt status and complete corresponding task. The working process of master device is shown in Fig. 4. Slave device stays in a loop in which it first keeps in waiting state until sampling time has come then it begins data acquisition and sending process. The working process of slave device is shown in Fig. 5.
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
Fig. 3. Hardware circuit of the W5100 and nRF24L01.
Fig. 4. Flow chart of the master device.
2009
2010
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
An corresponding acquisition software has also been developed on the host computer to communicate with all the master device in UDP and aggregate data to the native database. After the UDP communication has been built up, the software build up two independent thread (sending thread and receiving thread) to work synchronously in the acquisition process. The work flow chart is shown in Fig. 6.
Fig. 5. Flow chart of the slave device.
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
2011
Fig. 6. Software workflow of host computer.
3. Results and discussion Fig.7 shows an experiment of the wireless data Acquisition system based on the water system of an air conditioning system. There is one temperature sensor installed at the export of each FCU and one pressure sensor installed between the export and import of each FCU. One pressure sensor and one temperature sensor are installed at the export and import of the evaporator. The evaporator and the FCU are distributed in three separated rooms. Despite the presence of high power electrical equipment in the laboratory which has strong electromagnetic interference to the acquisition system, the system works stably without data loss in a relatively close range (20 meters or less). But when the distance between master and slave devices increases or there are more obstacles existed between master and slave devices much more serious data loss will occur.
2012
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
Fig. 7. The experiment of the wireless data Acquisition system.
4. Conclusions Wireless Data Acquisition System is feasible to replace traditional acquisition system under most conditions because of the facts such as that compared to fast time-varying systems HVAC systems has much lower amount of data and real-time requirement and that the sensors of the HVAC systems are usually distributed in relatively open space. Wireless communication quality has much depends on the distance and the number of obstacles between the devices. Within 20 meters or less the influence of the distance on communication quality is not obvious but when the distance between master and slave devices increases up to 30 meters or more the communication quality will sharply decline.
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
2013
Acknowledgements This research was supported by the Key Projects in the National Science & Technology Program in the Twelfth Five-year Plan Period of China (Grant No. 2011BAJ03B12-3, 2013BAJ10B02-03)ˈthe Fundamental Research Funds for the Central Universities of China (DUT14ZD210). And the Fundamental Research Funds for the Central Universities of China (DUT14ZD210)ˈNational Natural Science Foundation of China (Grant No. 51378005) and the Fundamental Research Funds for the Central Universities of China (DUT12RC(3)25) References [1]A. Leavey, Y. Fu, M. Sha, A. Kutta, Air quality metrics and wireless technology to maximize the energy efficiency of HVAC in a working auditorium, Build. Environ. 85(2015) 287-297. [2]J. Brooks, S. Kumar, S. Goyal, Energy-efficient control of under- actuated HVAC zones in commercial buildings, Journal of Energy and Building, 93(2015) 160-168. [3] S. Bengea, A. Kelman, F. Borrelli, R. Taylor, S. Narayanan, Model predictive control for mid-size commercial building HVAC: implementation results and energy savings, in: 2nd International Conference on Building Energ. Environ. 2012. [4] Y. Xie, J.L. Liu, C.W. Li, Application of Wireless Sensor Networks in the Intelligent Buildings, Journal of Building Electricity,12(26) (2013) 25-28. [5]J. song, Measurement and Control System Based on Wireless Sensor Network for Granary, Physics Procedia. 24(2012) 566-571. [6] R.X. Jiang, K.Y. Lin, J.H. Wu, Study & Design on Monitoring and Controlling System for Greenhouse Group Based on Zigbee, Journal of Shanghai Jiaotong University, 26(2008) 440-444. [7]L. Zhao, J.L. Zhang, R.B. Liang, Development of an energy monitoring system for Large public buildings, Journal of Energy and Building, 66(2013) 41-48. [8]Nordic Semiconductor ASA, NRF24L01 product specification, 2006. [9]L. Zhao, Design and implementation of general gateway for internet of building energy, Journal of Dalian University of Technology, 54(1) (2014) 85-90 (in Chinese). [10]H. Gao, J.X. Su, Design of the temperature signal wireless receiver and display system on polishing interface in chemical mechanical polishing, Journal of Procedia Engineering, 24(2011) 417-421.
ScienceDirect Procedia Engineering 121 (2015) 2006 – 2013
9th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC) and the 3rd International Conference on Building Energy and Environment (COBEE)
Wireless Data Acquisition System Development and Application on HVAC Equipment Hao Yua,*, Jili Zhanga, Liang Zhaoa, Xiuming Lia a
Dalian University of Technology, Dalian, China
Abstract
An appropriate monitoring and control system of the HVAC system is necessary to reduce its energy consumption on the premise of ensure the users’ comfort. A suite of wireless data acquisition system for HVAC system have been developed in this paper to resolve the cabling difficulties existing in the installation process of the sensors distributed at the end of the HVAC system. The acquisition system utilized a low-power and high-performance stm32f103RBT6 microcontroller as the MCU and a wireless transceiver module nRF24L01 and an Ethernet transceiver module W5100 to transfer data. Then the data will be stored in the SQL database and can be observed online. The working process and the practical applications of the acquisition system have been introduced. Finally an acquisition experiment based on the water system of an actual air conditioning system is conducted and the result shows that the wireless data acquisition system works stably and can overcome the difficulties in cabling and signal attenuation. © Published by Elsevier Ltd. This © 2015 2015The TheAuthors. Authors. Published by Elsevier Ltd.is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ISHVACCOBEE 2015. of ISHVAC-COBEE 2015 Peer-review under responsibility of the organizing committee
Keywords: Wireless Data Acquisition System; HVAC Equipment; Embedded System
1. Introduction In recent years, a significant portion of total energy is consumed by buildings and there is no slowdown in sight [1]. About half of this energy comes from heating, ventilation, and air conditioning (HVAC) systems [2]. Therefore improving HVAC operating efficiency without compromising comfort or indoor air quality would have large energy and financial savings, at the same time leads to a significant reduction in CO2 emissions. HVAC operating efficiency improvement largely depends on the Monitoring and control system which sends * Corresponding author. Tel.: 13009416728; fax: 13009416728. E-mail address: [email protected]
1877-7058 © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ISHVAC-COBEE 2015
doi:10.1016/j.proeng.2015.09.199
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
2007
the appropriate operating commands to the HVAC system through analyzing its operational data.[3]The operational data of HVAC system is not only an important indicator to assess building energy consumption but also works as the feedback of the control system. Considering that the sensors of the HVAC system usually distribute dispersedly so the traditional data acquisition system encountered difficulties in cabling, maintenance and readjustment [4] and usually has a low efficiency and poor accuracy in data transmission [5]. Wireless Data Acquisition system developed in this paper is based on the Wireless Sensor Network and the embedded system technology. Wireless Sensor Network is an intelligent measurement and management Network which is constituted by a large number of tiny sensors distributed in the monitoring areas with the ability of sensing, computing and communicating [6]. The Wireless Data Acquisition system has the characters of easy installation and stable and efficiency data transmission, providing a good solution to the cabling problems exist in practical application and the signal attenuation in transmission process. 2. Description of the development process of the Wireless Data Acquisition system The system is divided into two parts, part one called slave device is used to collect real-time signal from the sensors distributed in the HVAC system and send it out. The other part called the master device is used to receive data sent from the slave devices and store it for the moment then upload the proceeded data to the host computer. The system is distributed into different collection area according to the actual circumstances around the HVAC system. Each collection area has one master device and a number of slave devices and the master device and slave devices are connected into a tree network.
Fig. 1. Architecture of Data Process and Transmission.
After the analog to digital conversion the slave devices send the digital data to the corresponding master device at a regular time through the wireless module. In different acquisition area each slave device is assigned a digital ID. When a new slave device join into the acquisition area the master device will assign the slave device a new ID and arrange a new piece of memory for it. Master device in different area are distinguished by IP address. During the acquisition process master device keeps receiving data sent from slave devices in each acquisition area and waiting
2008
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
for command from the host computer. Whenever receiving the data-transferring command from the host computer, master device packs the data in specific formation and transfer it to the host computer through the Ethernet module. The overall architecture of the system is shown in Fig.1. 2.1. Hardware Designation of the Wireless acquisition system As shown in Fig.2 the Master device consists of a MCU, a wireless module, user button, and an Ethernet module .the slave device consists of a MCU, acquisition circuit, wireless module, special power module. The master device and slave device utilize the same MCU and wireless module.
Fig. 2. Hardware designation of master and slave devices.
In this system STM32F103RBT6 works as the MCU, which contains a Cortex-M3 core, 128K FLASH and 16K SRAM for data storage and application. With 72MHZ maximum operating frequency, STM32F103RBT6 also contains many kinds of peripheral interface resources, including multiple 12-bit A / D converter, CAN bus interface, SPI communication interface and multiple serial ports [7]. NRF24L01 is used as the Wireless communication module because of its characteristics as follows: With 2.4GHz opening global ISM band, high transmission power, low voltage, high transfer rate, nRF24L01 supports up to six channels of data reception and hardware CRC error detection are built in the module. [8] Master device communicates with the host computer through the W5100 Ethernet module. W5100 chip integrates a stable TCP / IP protocol stack, an Ethernet media transport layer (MAC) and a physical layer (PHY) inside itself. The internal hardware in the form of TCP / IP protocol stack of w5100 supports such as TCP, UDP, IPv4, ARP, IGMP and all these agreements have been utilized in many areas after years of testing. [9] Users do not need to care much about the control of Ethernet communication protocol layer and W5100 has a simple programming interface supporting both parallel and SPI serial mode and the interface can be easily connected to the microcontroller. Hardware connection of the nRF24L01 and W5100 are shown in Fig. 3. 2.2. Software Designation of the Wireless acquisition system In the acquisition process master device waiting for wireless interrupt and network interrupt. In the wireless interrupt response function master device process the data received from slave devices. In network interrupt response function master device analyze the interrupt status and complete corresponding task. The working process of master device is shown in Fig. 4. Slave device stays in a loop in which it first keeps in waiting state until sampling time has come then it begins data acquisition and sending process. The working process of slave device is shown in Fig. 5.
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
Fig. 3. Hardware circuit of the W5100 and nRF24L01.
Fig. 4. Flow chart of the master device.
2009
2010
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
An corresponding acquisition software has also been developed on the host computer to communicate with all the master device in UDP and aggregate data to the native database. After the UDP communication has been built up, the software build up two independent thread (sending thread and receiving thread) to work synchronously in the acquisition process. The work flow chart is shown in Fig. 6.
Fig. 5. Flow chart of the slave device.
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
2011
Fig. 6. Software workflow of host computer.
3. Results and discussion Fig.7 shows an experiment of the wireless data Acquisition system based on the water system of an air conditioning system. There is one temperature sensor installed at the export of each FCU and one pressure sensor installed between the export and import of each FCU. One pressure sensor and one temperature sensor are installed at the export and import of the evaporator. The evaporator and the FCU are distributed in three separated rooms. Despite the presence of high power electrical equipment in the laboratory which has strong electromagnetic interference to the acquisition system, the system works stably without data loss in a relatively close range (20 meters or less). But when the distance between master and slave devices increases or there are more obstacles existed between master and slave devices much more serious data loss will occur.
2012
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
Fig. 7. The experiment of the wireless data Acquisition system.
4. Conclusions Wireless Data Acquisition System is feasible to replace traditional acquisition system under most conditions because of the facts such as that compared to fast time-varying systems HVAC systems has much lower amount of data and real-time requirement and that the sensors of the HVAC systems are usually distributed in relatively open space. Wireless communication quality has much depends on the distance and the number of obstacles between the devices. Within 20 meters or less the influence of the distance on communication quality is not obvious but when the distance between master and slave devices increases up to 30 meters or more the communication quality will sharply decline.
Hao Yu et al. / Procedia Engineering 121 (2015) 2006 – 2013
2013
Acknowledgements This research was supported by the Key Projects in the National Science & Technology Program in the Twelfth Five-year Plan Period of China (Grant No. 2011BAJ03B12-3, 2013BAJ10B02-03)ˈthe Fundamental Research Funds for the Central Universities of China (DUT14ZD210). And the Fundamental Research Funds for the Central Universities of China (DUT14ZD210)ˈNational Natural Science Foundation of China (Grant No. 51378005) and the Fundamental Research Funds for the Central Universities of China (DUT12RC(3)25) References [1]A. Leavey, Y. Fu, M. Sha, A. Kutta, Air quality metrics and wireless technology to maximize the energy efficiency of HVAC in a working auditorium, Build. Environ. 85(2015) 287-297. [2]J. Brooks, S. Kumar, S. Goyal, Energy-efficient control of under- actuated HVAC zones in commercial buildings, Journal of Energy and Building, 93(2015) 160-168. [3] S. Bengea, A. Kelman, F. Borrelli, R. Taylor, S. Narayanan, Model predictive control for mid-size commercial building HVAC: implementation results and energy savings, in: 2nd International Conference on Building Energ. Environ. 2012. [4] Y. Xie, J.L. Liu, C.W. Li, Application of Wireless Sensor Networks in the Intelligent Buildings, Journal of Building Electricity,12(26) (2013) 25-28. [5]J. song, Measurement and Control System Based on Wireless Sensor Network for Granary, Physics Procedia. 24(2012) 566-571. [6] R.X. Jiang, K.Y. Lin, J.H. Wu, Study & Design on Monitoring and Controlling System for Greenhouse Group Based on Zigbee, Journal of Shanghai Jiaotong University, 26(2008) 440-444. [7]L. Zhao, J.L. Zhang, R.B. Liang, Development of an energy monitoring system for Large public buildings, Journal of Energy and Building, 66(2013) 41-48. [8]Nordic Semiconductor ASA, NRF24L01 product specification, 2006. [9]L. Zhao, Design and implementation of general gateway for internet of building energy, Journal of Dalian University of Technology, 54(1) (2014) 85-90 (in Chinese). [10]H. Gao, J.X. Su, Design of the temperature signal wireless receiver and display system on polishing interface in chemical mechanical polishing, Journal of Procedia Engineering, 24(2011) 417-421.