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
... insulation , radiation shields , and calibration techniques . Key words : Conduction error ; radiation error ; resistance thermometer ; temperature measurement ; thermistor ; thermocouple . * Present address : 4534-47th St. , N.W. ...
... insulation , radiation shields , and calibration techniques . Key words : Conduction error ; radiation error ; resistance thermometer ; temperature measurement ; thermistor ; thermocouple . * Present address : 4534-47th St. , N.W. ...
Page 2
... insulated , round metal duct with an air - mixing device near the in- let . Air was drawn through the duct at ... insulate the plastic tube carrying the leads through the duct wall and which was useful in determining if there were any ...
... insulated , round metal duct with an air - mixing device near the in- let . Air was drawn through the duct at ... insulate the plastic tube carrying the leads through the duct wall and which was useful in determining if there were any ...
Page 3
... insulated in vinyl plastic sheathing , were fixed rigidly through the center of thin - walled methyl metha- crylate tubing bent at a right angle ( fig . 1 ) . Holes about 0.1 in diameter were placed in the tubing to allow the flow of ...
... insulated in vinyl plastic sheathing , were fixed rigidly through the center of thin - walled methyl metha- crylate tubing bent at a right angle ( fig . 1 ) . Holes about 0.1 in diameter were placed in the tubing to allow the flow of ...
Page 4
... INSULATION THERMOCOUPLE ARRAY NO.1- NO . 2 NO . 3 UNHEATED SECTION THE VERTICAL DIMENSION IS EXAGGERATED FOR THE PURPOSE OF CLARITY . DETAILS OF THE PROBE ARE NOT SHOWN . + PROBE 2- -MEASURING SECTION- 2 ' TO BLOWER AND EXHAUST a ...
... INSULATION THERMOCOUPLE ARRAY NO.1- NO . 2 NO . 3 UNHEATED SECTION THE VERTICAL DIMENSION IS EXAGGERATED FOR THE PURPOSE OF CLARITY . DETAILS OF THE PROBE ARE NOT SHOWN . + PROBE 2- -MEASURING SECTION- 2 ' TO BLOWER AND EXHAUST a ...
Page 6
... insulated cover was over the flask during calibration . FIGURE 7. Calibration chamber for calibrating the therm ... insulating the sensors electrically . When determining the magnitudes of the small errors in each reference sensor by the ...
... insulated cover was over the flask during calibration . FIGURE 7. Calibration chamber for calibrating the therm ... insulating the sensors electrically . When determining the magnitudes of the small errors in each reference sensor by the ...
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
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