Hot Air Temperature Distribution
Heat distribution in the glass tube of the air heater The heat distribution in the glass tube of the air heater is not constant. The figure below shows the measurement of heat distribution in the quartz glass tube of the air heater (15AH type) with internal diameter ∅12.5 mm. When actually measured, there is a considerable difference compared to the set temperature 1022ºF (550ºC) of the built-in temperature sensor. Even with a little difference in the position of the sensor, approximately ±10% appears as an error immediately.
Therefore there is no point in being concerned about the set temperature of the air heaters. The advantage of adjusting the temperature, the temperature will stabilize as it is but do not worry much about the absolute value of the temperature.
When using many air heaters, the actual temperature varies even if the set temperature is the same.
The cause for this temperature distribution is because the glass tube wall cools the hot air near the glass wall, and the temperature of the hot air reduces. The temperature rapidly declines as the distance from the heating element (toward the lower end) increases. Also, the heating element of the air heater will move to some extent and there is also a variation in the production of the heating element itself. Such issues cannot be avoided to a certain extent.