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Hot Air Heating Calculation MethodCalculation Method to Determine the Hot Air Temperature for Selecting the Model
If hot air temperature heated with hot air heaters is T[ºC], air flow rate is F[L/min.], power consumed by air heater is P[w], T ≒ 50P/F [ºC] --- Formula to determine the hot air temperature P ≒ 0. 02FT [w] [ºC] --- Formula to determine required the power The simple formula given above is used. When the flow rate F has been selected, the heater power consumption P has to be set to obtain the target hot air temperature T. If P needs to be larger than the rated power of the available hot air heater, a different hot air heater model with a large output has to be selected. If the required power P is smaller than the rated power of the selected hot-air heater, it can be managed by lowering the supply voltage. The method of controlling the voltage will be described in a separate section. Thermal efficiency has to be considered when the air temperature is high and the flow rate is low. In models with metal cases, the thermal efficiency may decrease to ~60% and to about ~50% in glass tube exposed type. → Thermal efficiency The above hot air temperature T is actually the temperature rise value. That is, T = (T-out)- (T-in) Since T is a temperature rise value, usually T can be calculated as the hot air outlet temperature without any problems. (T-in) generally ranges from 32ºF (0ºC) to 86ºF (30ºC), T-out is generally as high as 1472ºF (800ºC), and the error will be negligible in most cases even if calculated assuming (T - in) is zero. However, when the hot air temperature is low or the air inlet temperature is high, the air inlet temperature (T-in) has to be taken into account. Capacity of hot air heater (air heater) - products are available in the range of 30 W ~ 70,000 W. Also, Fintech can manufacture any custom specifications provided such specifications are feasible. The service life of the air heater can vary significantly depending on the usage method, and assigning a specific value and offering warranty is not possible. Generally, the maximum temperature of the heating element in use state is measured with a non-contact thermometer such as a pyrometer, and the life of heating element is estimated from the graph using the measured temperature. This graph presents considerably fairly modest service life values for safety of the manufacturers. Actually, the service life is longer. Also, since the heating element temperature is approximately 572ºF (300ºC) higher than the hot air temperature, heating element temperature can also be estimated from the hot air temperature. This temperature difference varies depending on the flow rate and is a very rough estimation. From this, if hot air temperature is 1472ºF (800ºC), the life is approximately 1000 hours and if the hot air temperature is 1292ºF (700ºC) or less, the lifetime value approaches infinity and this indicates that service life need not be considered. However, this is a generalized statement and results will be significantly different depending on individual conditions. Service life is also significantly affected by the method of voltage control and by impurities (water, oil, metal powder) contained in air, shock, and vibration.
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