The selection basis for tubular electric heaters can refer to standards such as JB/T 2379 "Metal Tubular Heating Elements". Design and selection personnel usually need to clarify three parameters: rated voltage, rated power, and the specific heat capacity and flow rate of the heating medium at the working temperature. If the medium is thermal oil, attention should also be paid to its allowable film temperature and flow velocity.
Excessively high power density will cause the surface temperature of the heating element to exceed the allowable range of the medium, leading to coking or cracking. For thermal oil, it is recommended to control the surface load at 1.5–2.5 W/cm²; for water, it can be appropriately increased to 3–5 W/cm². During calculation, first derive the required total power from the medium flow rate, temperature rise, and specific heat capacity, then back-calculate the power density based on the effective heat exchange area of the heater, ensuring a margin of 10%–15%.
The FGR-25 type adopts a straight single-end outlet structure, with the wiring cavity isolated from the heating section, making it suitable for space-constrained heating tanks or pipelines. During installation, it is necessary to ensure that the heating section is fully immersed in the medium to avoid dry burning. If the medium liquid level may fluctuate, it is recommended to configure low-level interlock protection to cut off the heating power supply when the liquid level falls below a safe value, thereby extending the service life of the heating element.
Compared with steam heat exchange, tubular electric heaters do not require boilers and piping, making them suitable for medium- and small-power, distributed heating points, with fast startup and direct temperature control. For scenarios requiring uniform medium temperature, multiple heaters can be arranged in a staggered manner and combined with a circulation pump to make the medium temperature uniform and meet process requirements.
