Heating Capacity of a Furnace

The temperature achievable in a <...furnace...> is that where the heat coming out equals the heat going in. Radiation, convection and conduction are simply the mechanisms by which heat transfer takes place.

All other things being equal the materials of construction of the heating elements will have little-to-no influence on the final temperature achieved. The performance of the equipment is more readily influenced by shapes and configurations than other things.

There is more to be gained by improving insulation than changing the materials that constitute the heating elements; if it's not leaking out so much, then less needs to be put in to maintain temperature and the quicker it will respond to changes in demand.

The heating elements should be chosen for particular application and environment...

Shape should be optimized...

https://www.keithcompany.com/documents/Silicon_Carbide_Heating_Element_Operating_Data.pdf

https://www.kanthal.com/en/products/material-datasheets/strip/kanthal-apm/

The temperature of the heating element is determined by its radiative efficiency (its efficacy). At steady-state conditions, the energy input is transferred into the oven, just by elements that have either higher or lower surface (black body) temperatures determined by their radiative efficacy. In an oven, the interior temperature will be the controlled by the input electrical energy, not the element type.

This will be true with a closed (batch process) oven or with an open-ended (continuous process) oven. The objects are exposed to the same amount of radiative energy, regardless of element type (although the surface temperatures of the elements may be different).

The only slight difference in energy use may be due to the mass of the elements themselves, with the SiC rods requiring a slightly longer heating time before they come to equilibrium. The power required for the furnace will be the same, regardless of the element used.

--JMM

The frequency of the radiation can affect the coupling efficiency to the object being heated. This concept is used in paper drying, where the IR radiation is tuned to the web, water and filler material present on the web.

The amount of heat transferred from the element to the ambient surroundings is dependent on the distribution of the heat and the temperature differential.

The insulation and the thermal conductivity of the containing vessel,or oven, is also an important factor.

I would consider the expected life of the elements to be a major concern,with the silicon rods probably being the most durable,having the highest operating range of the two choices you specified.

What does the furnace manufacturer recommend?

Manufacturers are usually on the cutting edge of the technology due to competition.

What are you heating?

Materials to be heated are metal and ceramic parts for heat treatment.

I would choose the silicon rods for durability.

No difference in power consumption.

There are no inductive or capacitive losses in heater elements,so 1watt in =1 watt out.

The coupling of the heat to the object of interest will depend on relative placement of the object to the heater element source and the insulation of the environment.

The best way to improve efficiency is to reduce the duty cycle ( on-off time) of the element by reducing heat loss.

Do this by using an infrared scanner to detect weak spots in the insulation and add insulation where needed.

A single candle can heat a stadium if it is insulated perfectly and given enough time.