1、412 ASHRAE TransactionsABSTRACT This is the fourth paper in a four-part series reporting on the test and evaluation of typical wall-mounted carbon-dioxide sensors used in building HVAC applications. Fifteen models of NDIR HVAC-grade wall-mounted CO2sensors were tested and evaluated to determine the
2、effect of ageing on the sensors performance. In all, 45 sensors were evaluated: three from each of the 15 models. Among the 15 models tested, eight models have a single-lamp, single-wavelength configuration, four models have a dual-lamp, single-wavelength configura-tion, and three models have a sing
3、le-lamp, dual-wavelength configuration. All single-lamp, single-wavelength sensors and one single-lamp, dual-wavelength sensor incorporate an “automatic baseline adjustment” algorithm in the sensors electronics package.Each sensor was tested under “as received” conditions, and then, over the course
4、of one year, performance tests were conducted at four-month intervals. All tests were conducted at 40% relative humidity, 73oF (22.8oC) temperature, 14.70 psia (101.35 kPa) pressure, and 1100 ppm CO2concentration. For each sensor, the readings from the four tests were compared in order to evaluate t
5、he effect of continuous operation on the sensors performance. The test results showed a wide variation in sensor performance among the various manufacturers. In one year, the maximum deviation in a sensors reading was observed to be 420 ppm (38%) while the minimum deviation in a sensors reading was
6、observed to be 0 ppm.INTRODUCTIONThis is part four of a four-part series of papers reporting on the test and evaluation of typical CO2sensors used in build-ing HVAC systems. In this study, fifteen models of NDIR (non-dispersive infrared) HVAC-grade CO2sensors were tested and evaluated to examine the
7、 affects of ageing on sensor performance. To compensate for sensor ageing, some sensors automatically reset the baseline value (normally 400 ppm) according to minimum CO2concentration observed over a time period. This technique relies on the fact that many build-ings experience unoccupied periods du
8、ring which CO2levels drop to outdoor levels. Other techniques used to compensate for the sensor ageing include dual-lamp, single-wavelength and single-lamp, dual-wavelength configurations. The work-ing principles, physical construction, advantages and disad-vantages of NDIR CO2sensors are well docum
9、ented in the literature (Raatschen (1990), Emmerich and Persily (2001), Schell and Int-House (2001), Fahlen et al. (1992).Among the 15 models tested, eight models have a single-lamp, single-wavelength configuration, four models have a dual-lamp, single-wavelength configuration, and three models have
10、 a single-lamp, dual-wavelength configuration. In all, 45 sensors (three from each model) were evaluated. The tests were designed to assess the performance of the sensors while they operated under typical building conditions for a one-year period.PREVIOUS STUDIESIn the past, limited studies have bee
11、n done to investigate the performance of HVAC-grade CO2sensors using a controlled environment. No published information is available that shows systematic study to quantify effect of ageing on NDIR CO2sensors.Fahlen et al. (1992) evaluated the performance of two CO2sensors, one photo-acoustic type a
12、nd one infrared spec-troscopy type, in lab tests and long-term field tests. The lab An Experimental Evaluation of HVAC-Grade Carbon Dioxide SensorsPart 4: Effects of Ageing on Sensor PerformanceSom S. Shrestha, PhD Gregory M. Maxwell, PhDMember ASHRAE Member ASHRAESom S. Shrestha is a R therefore, a
13、 deviation of 11 ppm corresponds to 1% change in the sensor reading. The accuracy of the CO2gas mixture in the test apparatus is 1% of the concentration which also corresponds to 11 ppm. Thus, within the uncertainty of the experimental apparatus, sensor with deviations of 1% or less can be considere
14、d as stable with no affect of ageing.From Table 1, sensor model S5 is expected to have a devi-ation less than 40 ppm over 15 years and sensor model S7 is expected to have a deviation of 75 ppm per year at 1200 ppm. Upon examination of the performance of these sensors as shown in Table 2, at the end
15、of one year, these sensors were within the specified limits.Dual-Lamp, Single-Wavelength Sensors: The test results for sensor models S9 through S12 are shown graphi-cally in Figure 10 and are presented numerically in Table 3. From Table 1, sensor models S10 and S12 are expected to have a deviation o
16、f 20 ppm per year. When compared to the results in Table 3, these sensor models closely follow the specified deviation. Sensor model S9 shows the largest deviations for all three sensors of this model.Single-Lamp, Dual-Wavelength Sensors: The test results for sensor models S13 through S15 are shown
17、graphi-cally in Figure 11 and are presented numerically in Table 4. From Table 1, sensor models S13 and S15 have deviation less Figure 1 Test chamber.Figure 2 Lab station.2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Trans
18、actions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.416 ASHRAE Transactionsthan 100 ppm in 5 years ( 5.0% FS / 5 years). When compared to the values i
19、n Table 4, except for the “A” sensor of model S13, these sensors are within the specified deviation.Sensor model S14 uses an “automatic baseline adjust-ment” algorithm. There is not specified value for the deviation of this sensor (refer to Table 1); however, the deviations for this sensor model pre
20、sented in Table 4 are consistent with the other sensors that employ an “automatic baseline adjustment” scheme.CONCLUSIONThe result from the tests conducted under accurate and repeatable condition showed a wide variation in ageing effect among CO2sensor models. Some sensor models showed nomi-nal agei
21、ng effect of less than 30 ppm deviation, whereas all three sensors of one model that use dual-lamp, single-wavelength configuration showed significant ageing effect, up to -376 ppm deviation, in one year at 1100 ppm CO2concentration.Sensor manufacturers use one of three configurations (single-lamp,
22、single-wavelength, dual-lamp, single-wave-length, or single-lamp, dual-wavelength) to compensate for the ageing effects of operational and environmental condi-tions. However there is no clear indication to conclude that any one configuration is better than the rest, at least for one year of operatio
23、n.ACKNOWLEDGMENTThis work is performed for National Building Controls Information Program (NBCIP), which is sponsored by the Iowa Energy Center, NSTAR Electric & Gas Corporation and the California Energy Commission.REFERENCES Emmerich, S.J., and A.K. Persily. 2001. State-of-the-art review of CO2dema
24、nd controlled ventilation technology and application, Report NISTIR 6729, National Institute of Science and Technology (NIST), USA.Fahlen, P., H. Andersson, and S. Ruud. 1992. Demand Con-trolled Ventilating Systems - Sensor Tests. Swedish National Testing and Research Institute, Boras, Sweden, SP Re
25、port 1992:13.House, J. 2006. Personal communication.Figure 3 CO2concentration in the laboratory.Figure 4 Temperature and pressure in the laboratory.2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116
26、, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.2010 ASHRAE 417Figure 5 Power-up and conditioning of single-lamp, single-wavelength sensors.2010, American Society of Hea
27、ting, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permissio
28、n.418 ASHRAE TransactionsFisk, W.J., D. Faulkner, and D.P. Sullivan. 2006. Accuracy of CO2sensors in commercial buildings: a pilot study. LBNL-61962, Lawrence Berkeley National Laboratory, Berkeley, CA.Pandey, S.K., K. Kim, and S. Lee. 2007. Use of a dynamic enclosure approach to test the accuracy o
29、f the NDIR sensor: evaluation based on the CO2equilibration pat-tern. Molecular Diversity Preservation International, Matthaeusstrasse, Switzerland, ISSN: 1424-8220.Raatschen, W., ed. 1990. Demand Controlled Ventilating System. State of the Art Review. Stockholm, Sweden: Swedish Council for Building
30、 Research, Stockholm, Sweden, D9:1990.Schell, M., and D. Int-Hout. 2001. Demand control ventila-tion using CO2. ASHRAE Journal Vol. 43, No. 2: 18-24.Shrestha, S.S., and G.M. Maxwell. 2009. An experimental evaluation of HVAC-grade carbon-dioxide sensors: part 1, test and evaluation procedure. ASHRAE
31、Transactions115(2).Shrestha, S.S., and G.M. Maxwell. An experimental evalua-tion of HVAC-grade carbon-dioxide sensors: part 2, per-formance test results. ASHRAE Transactions 116(1). DISCUSSIONKevin Carpenter, Associate Member ASHRAE, CLEAResults Consulting, Inc., El Paso, TX: Can you make a recommen
32、dation as to what to look for when selecting CO2sensors?Som Shrestha: The effectiveness of CO2-based demand controlled ventilation (DCV) relies upon the performance of CO2sensors. The study showed that, in some cases, signifi-cant variations in sensor performance exist between sensors of the same mo
33、del, while in other cases, all sensors of the same model showed almost identical behavior. Consistency in performance among the same sensor model is important.Accuracy, humidity sensitivity, and long-term stability are important parameters when selecting CO2sensors. All sensors that use NDIR technol
34、ogy are sensitive to pressure and temperature variation unless the sensor reading is adjusted for the variations. However, for the range of temperature and pres-sure variation in an air-conditioned space, the effect of temper-ature variation is insignificant compared to the effect of pressure variat
35、ion. Nonlinearity, repeatability, and hysteresis do not seem to be an issue. Part 2 and Part 3 of this paper describe those issues and research findings. Figure 6 Power-up and conditioning of dual-lamp, single-wavelength sensors.2010, American Society of Heating, Refrigerating and Air-Conditioning E
36、ngineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.2010 ASHRAE 419Figure 7 Power-up and con
37、ditioning of single-lamp, dual-wavelength sensors.2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either
38、 print or digital form is not permitted without ASHRAEs prior written permission.420 ASHRAE TransactionsFigure 8 Lab station apparatus CO2concentration during exercise period.Figure 9 Deviation from the reading from the first test for single-lamp, single-wavelength sensors.2010, American Society of
39、Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permis
40、sion.2010 ASHRAE 421Table 2. Ageing Test Result of Single-Lamp, Single-Wavelength SensorsSensor Model SensorDeviation from Reading at First Test, ppmSecond Test Third Test Fourth TestS1A 83 17 11B 77 17 3C 53 22 20S2A 45 26 0B 65 4 6C 25 42 33S3A 15 39 33B 25 38 40C 2 78 53S4A 63 141 53B 13 72 46C 1
41、0 74 25S5A 19 45 19B 25 50 40C 17 49 38S6A 60 44 52B 76 30 12C 49 38 17S7A 14 47 65B 52 113 55C 44 47 34S8A 101 18 33B 92 4 11C 52 24 192010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116, Part 2). F
42、or personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.422 ASHRAE TransactionsTable 3. Ageing Test Result of Dual-Lamp, Single-Wavelength SensorsSensor Model SensorDeviation from Reading a
43、t First Test, ppmSecond Test Third Test Fourth TestS9A 226 420 376B 181 274 256C 155 221 152S10A 63 28 56B 24 30 61C 15 0 28S11A 34 32 2B 34 37 36C 186 0 66S12A 42 8 26B 13 21 3C 15 13 34Figure 10 Deviation from the reading from the first test for dual-lamp, single-wavelength sensors.2010, American
44、Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior wri
45、tten permission.2010 ASHRAE 423Table 4. Ageing Test Result of Single-Lamp, Dual-Wavelength SensorsSensor Model SensorDeviation from Reading at First Test, ppmSecond Test Third Test Fourth TestS13A 49 125 142B 36 8 9C 9 32 18S14A 150 90 35B 48 15 31C 10 64 45S15A 4 30 24B 11 25 27C 15 16 10Figure 11
46、Deviation from the reading from the first test for single-lamp, dual-wavelength sensors.2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.
