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). |
From inside the book
Results 1-5 of 6
Page 1
... indicated that radiation error would be negligible at this velocity . Under the test conditions that prevail in the ... indicate the literature references on page 12 . 2. Description of Apparatus 1 Contents Page.
... indicated that radiation error would be negligible at this velocity . Under the test conditions that prevail in the ... indicate the literature references on page 12 . 2. Description of Apparatus 1 Contents Page.
Page 2
... indicating the temperature of moving air in ducts under conditions where the temperature of the duct wall may be ... indicate application techniques that would minimize conduction errors . In the previous studies , thermocouples ...
... indicating the temperature of moving air in ducts under conditions where the temperature of the duct wall may be ... indicate application techniques that would minimize conduction errors . In the previous studies , thermocouples ...
Page 6
... indicated at the bottom of the curves for each reference sensor by a horizontal line across the figures at a distance about 0.04 deg F above the zero error line at the 0 ° F point . For both reference sensors , the indicated ...
... indicated at the bottom of the curves for each reference sensor by a horizontal line across the figures at a distance about 0.04 deg F above the zero error line at the 0 ° F point . For both reference sensors , the indicated ...
Page 8
... indicating instruments for the thermocouples , the thermis- tors , or the resistance thermometer . The same tech- nique was used for the reference sensors . In each case there was no indication of temperature change . All air velocity ...
... indicating instruments for the thermocouples , the thermis- tors , or the resistance thermometer . The same tech- nique was used for the reference sensors . In each case there was no indication of temperature change . All air velocity ...
Page 9
... ) , respec- tively . When the sensors were shielded , at both 300 and 500 fpm and under the same test conditions , the error was less than 0.2 deg F ( 0.1 K ) . The indicated radiation error was greater for the thermistors than Results -
... ) , respec- tively . When the sensors were shielded , at both 300 and 500 fpm and under the same test conditions , the error was less than 0.2 deg F ( 0.1 K ) . The indicated radiation error was greater for the thermistors than Results -
Common terms and phrases
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
Popular passages
Page 2 - States as a signatory to the General Conference on Weights and Measures, which gave official status to the metric SI system of units in 1960...