A thermocouple junction of spherical form is to be used to measure the temperature of the gas stream. The junction is at 20 degree Celsius and is placed in a gas stream which is at 200 degree Celsius. Make calculations for junction diameter needed for the thermocouple to have thermal time constant of one second. Assume the thermos-physical properties as given belowk = 20 W/ m Kh = 350 W/m2 Kc = 0.4 k J/kg Kp = 8000 kg/m3

A thermocouple junction of spherical form is to be used to measure th

1.	A thermocouple junction of spherical form is to be used to measure the temperature of the gas stream. The junction is at 20 degree Celsius and is placed in a gas stream which is at 200 degree Celsius. Make calculations for junction diameter needed for the thermocouple to have thermal time constant of one second. Assume the thermos-physical properties as given belowk = 20 W/ m Kh = 350 W/m2 Kc = 0.4 k J/kg Kp = 8000 kg/m3
A.	0.556 mm
B.	0.656 mm
C.	0.756 mm
D.	0.856 mm
Answer» C. 0.756 mm

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A thermocouple junction of spherical form is to be used to measure the temperature of the gas stream. The junction is at 20 degree Celsius and is placed in a gas stream which is at 200 degree Celsius. Make calculations for junction diameter needed for the thermocouple to have thermal time constant of one second. Assume the thermos-physical properties as given belowk = 20 W/ m Kh = 350 W/m2 Kc = 0.4 k J/kg Kp = 8000 kg/m3
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