Radiation Errors in Air Ducts Under Nonisothermal Conditions Using Thermocouples, Thermistors, and a Resistance ThermometerU.S. National Bureau of Standards, 1969 - 12 pages Studies were made to determine the radiation error in temperature measurements made with thermocouples, thermistors, and a resistance thermometer in moving air at velocities ranging from 300 to 1300 fpm when the temperature of the duct wall surrounding the air stream was from 0 to 50 deg F higher than that of the air in the center of the duct. To eliminate all but the variable under study, conduction errors were minimized to a point where they were almost nonexistent by using Chromel P-constantan thermocouple wire and by employing other techniques. Radiation effects were studied when the probe housing the three types of temperature sensors was unshielded and again when it was shielded. Under the test conditions that prevail in the testing of air conditioners and heat pumps in laboratories, it should be possible to reduce the error in temperature measurement of the moving air to about 0.2 deg F by a suitable combination of air mixers, duct insulation, radiation shields, and calibration techniques. (Author). |
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Page 1
... observed temperature . In a previous paper by Davis , Faison , and Achenbach [ 1 ] showing the results of the study of the errors of thermocouples , thermistors , and mercury - in - glass thermometers used in moving air , and where the ...
... observed temperature . In a previous paper by Davis , Faison , and Achenbach [ 1 ] showing the results of the study of the errors of thermocouples , thermistors , and mercury - in - glass thermometers used in moving air , and where the ...
Page 4
... observe the degree of temperature uniformity throughout a test , constant monitoring of air mix- ing took place using three arrays of 17 butt- welded Chromel P - constantan thermocouples in cross sectional areas in the duct . The butt ...
... observe the degree of temperature uniformity throughout a test , constant monitoring of air mix- ing took place using three arrays of 17 butt- welded Chromel P - constantan thermocouples in cross sectional areas in the duct . The butt ...
Page 5
... observed readings of the resistance thermometer in the probe were compared in still air with ob- served readings of another resistance ther- mometer calibrated by the NBS Thermometry 5 laboratory . At the four temperatures within the ...
... observed readings of the resistance thermometer in the probe were compared in still air with ob- served readings of another resistance ther- mometer calibrated by the NBS Thermometry 5 laboratory . At the four temperatures within the ...
Page 6
... observed readings of the two thermometers . The thermocouples , thermistors , and the large reference sensor were calibrated four times within a year , and the small reference sensor twice , one year apart . These sensors were ...
... observed readings of the two thermometers . The thermocouples , thermistors , and the large reference sensor were calibrated four times within a year , and the small reference sensor twice , one year apart . These sensors were ...
Page 8
... OBSERVED READINGS OF SENSORS. ERROR , deg F RADIATION 40 .30 SMALL REFERENCE SENSOR .20 9 F 35 300 FPM .25 15 500 FPM .10 1.03 LARGE REFERENCE SENSOR .10 300 FPM 500 FPM .08 .06 L04 1 30 40 50 60 70 10 sensors . Tests were performed at ...
... OBSERVED READINGS OF SENSORS. ERROR , deg F RADIATION 40 .30 SMALL REFERENCE SENSOR .20 9 F 35 300 FPM .25 15 500 FPM .10 1.03 LARGE REFERENCE SENSOR .10 300 FPM 500 FPM .08 .06 L04 1 30 40 50 60 70 10 sensors . Tests were performed at ...
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15 cents 50 deg F access door Achenbach air mixing air velocity aspirated assembly automatic data processing Building Science Series Bureau of Standards calibration Cement and Concrete Chromel P-constantan thermocouple Concrete Properties Conditions Using Thermocouples curves deg F 28 determined Dewar flask diameter DIFFERENCE IN TEMPERATURE duct wall error in temperature experimental Faison FPM UNSHIELDED heat pumps heated section ice bath immediately upstream inlet air inner shield Institute for Applied instrument room insulated Interrelations Between Cement junction box large reference sensor mercury-in-glass thermometers minimizing conduction errors moving air National Bureau Nonisothermal Conditions OBSERVED READINGS platinum resistance thermometer Portland Cement radiation error radiation shields Reinhold Publ SENSORS dag F set of shields shielded probe shielded sensors shown in figure small reference sensor techniques temperature difference temperature measurement temperature sensors test conditions test duct test probe thermal conductivity thermistors thermo thermocouple wire types of sensors U.S. Government Printing velocity of 300
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