14 Types of Heating Elements and Coils: Which Is Best for Your Application?

What is a heating coil?

A coil heater is an electrical heating element that consists of a resistive wire wound into a spiral or coil shape, typically enclosed in a protective sheath. The heating mechanism works on the principle of electrical resistance—when an electric current passes through the coil, the resistance of the wire generates heat, converting electrical energy into thermal energy. This heat is then transferred to the surrounding environment.

How Does a Coil Heater Work?

A coil heater uses the principle of electromagnetic induction to generate heat. When AC flows through the coil, it creates a varying magnetic field. This field induces eddy currents in the conductive workpiece. The heat is produced due to the resistance of the material to these currents, following the formula for power loss:

P=I²R

• $P$ is the power loss (heat generated) in watts (W),
• $I$ is the current induced in the workpiece in amperes (A),
• $R$ is the resistivity of the material in ohm-meters (Ω·m).

The Working Process of an Induction Heating Coil

Generation of Alternating Electromagnetic Field: When alternating current flows through the coil, it creates a dynamic electromagnetic field around the coil.

Induction of Eddy Currents: This electromagnetic field induces circulating currents (eddy currents) in the conductive workpiece placed within or near the coil.

Heat Generation：The induced eddy currents in the workpiece generate heat due to resistive losses (I²R), raising the temperature of the material.

Energy Transfer: The strength of the induced current in the workpiece is proportional to the strength of the electromagnetic field created by the coil. This energy transfer process is known as the transformer effect or eddy current effect, where the coil transfers energy to the workpiece without directly heating the coil itself.

In an induction heating system, coils are typically water-cooled copper conductors formed into various shapes, from simple helix or solenoid coils to more complex, precision-machined coils. The cooling system ensures that the coil remains at a safe operating temperature while efficiently transferring energy to the workpiece.

 

Types of Electric Coils

Residential Heating Coils, Industrial Heating Coils, and Commercial Heating Coils are designed for heating systems in homes, industries, and commercial establishments, respectively. The corresponding Residential Heating Elements, Industrial Heating Elements, and Commercial Heating Elements are the core components within these coils that generate heat. Here’s a concise list of the types of heating elements:

Residential Heating Elements

Steamer & Oven Heating Element: Used in home cooking appliances.

 

 

 

 

Refrigerator & Freezer Defrosting Heating Element: Used for defrosting in household refrigerators and freezers.

 

 

 

 

 

Washing & Drying Machine Tubular Heating Element: Used in home washing and drying machines.

 

 

 

 

 

Water Heater Heating Element: Commonly found in residential water heaters.

 

 

 

 

 

Towel Heating Element: Used in towel warmers for residential bathrooms.

Commercial Heating Elements

Commercial Boiler & Dryer Applied Heating Element: Used in commercial boilers and dryers.

 

 

 

 

 

 

PTFE Heating Element: Often used in commercial applications due to its high-temperature resistance and non-stick properties.

 

 

 

 

 

 

Cartridge Heating Element: Commonly used in various commercial heating applications.

 

 

 

 

 

 

Finned Heating Element: Used in commercial heating systems for better heat transfer.

 

 

 

 

 

Band Heater: Utilized in commercial equipment for heating cylindrical objects.

 

 

 

 

 

 

Immersion Heating Element: Used in commercial water heating applications.

Industrial Heating Elements

Casting Heating Element: Used in industrial casting processes.

 

 

 

 

 

Explosion-proof Heating Element: Designed for use in hazardous industrial environments.

 

 

 

 

Etched Foil Heating Element: Often used in industrial applications for precise heating.

Maintenance Tips for Heating elements

Proper maintenance is crucial for maximizing the lifespan and efficiency of heating coils. Here are some professional tips to ensure the coils perform optimally and avoid costly repairs:

1. Regular Cleaning

Ensure that heating coils are cleaned regularly to prevent buildup of dust, debris, or metal splashes. These contaminants can obstruct airflow and reduce heating efficiency, or even cause damage over time. Use a soft cloth or a non-abrasive brush to clean the surface of the coils to avoid any damage.

2. Routine Inspections

Conduct regular inspections of the heating coils to identify any signs of wear, damage, or degradation. Look for issues such as cracks, discoloration, or burnt areas that may indicate overheating or excessive wear. Timely detection of issues will help avoid more serious damage and costly replacements.

3. Temperature Monitoring

Closely monitor the operating temperature of the heating coils. Overheating can compromise the material of the coils, leading to shortened service life. Ensure that the coil is operating within the manufacturer’s recommended temperature range to prevent potential damage and to maintain efficient operation.

4. Electrical Check

Inspect the electrical connections and wiring of the heating elements to ensure they are secure and functioning properly. Loose or frayed wires can cause inconsistent heating or even pose a fire hazard. Regularly check for any signs of electrical wear, and replace any damaged

• Regular Cleaning: Periodically clean heating elements to prevent the buildup of dust, dirt, or scale that can hinder performance.
• Check Connectors and Cables: Ensure that the connectors and cables connecting the heater element to the power source are in good condition. Replace damaged or swollen cables.
• Verify Voltage: Make sure the electrical voltage supplied is in line with the heater element’s specifications. Incorrect voltage can damage the element.
• Inspect Insulation: Check that the insulation of the heater element is not damaged. Damaged insulation can lead to electrical leakage or even fires. Replace damaged elements promptly.
• Check the Thermocouple (If Applicable): If your heater element is equipped with a thermocouple, verify that it functions properly. Thermocouples are crucial components for temperature control.
• Temperature Monitoring: If possible, use a thermometer or temperature sensor to regularly monitor the temperature of the element. This can help you detect issues early.
• Seeking Professional Help.

 

If troubleshooting does not resolve the issue, consult the manufacturer’  guidelines or a qualified technician to help identify and address the problem. Professional maintenance services can diagnose issues more accurately and ensure that the heating coils are repaired or replaced according to industry standards.

How to Choose the Right Size and Power for Heating elements?

Selecting the correct size and power for heating elements is critical for achieving optimal performance and energy efficiency. Whether you are heating a specific room, space, or industrial equipment, the right heating element configuration can significantly impact both heating efficiency and energy consumption. Elekheat electric heater experts can provide you with a detailed guide to size and power selection.

1.Thermal Conduction Efficiency of Heating Elements

The thermal conduction efficiency of heating elements is a core indicator of their energy conversion effect. It is influenced by the thermal conductivity of the material, the shape of the heating element, and the temperature of the working environment, among other factors. The thermal conduction formula is as follows:

Q=k⋅A⋅(T1−T2)dQ=dk⋅A⋅(T1​−T2​)​

• $Q$ is the heat transfer rate (unit: W);
• $k$ is the thermal conductivity of the material (unit: W/m·K);
• A is the cross-sectional area of the heating element (unit: m²);
• T1 and T2 are the temperatures at the two ends of the heating element (unit: K);
• d is the length or thickness of the heating element (unit: m).

By optimizing the thermal conductivity of materials and increasing the contact area of heating elements, the heating effect can be significantly improved. In addition, appropriate material selection (such as copper, aluminum, or alloys) can ensure that heating elements maintain high thermal stability in high-temperature environments.

2.Heating Power Density and System Efficiency

Heating power density refers to the heating power that can be provided per unit volume or unit surface area. The calculation formula is:

P=QVP=VQ​

• P is the power density (unit: W/m³ or W/m²);
• Q is the heat transfer rate (unit: W);
• V is the volume or surface area of the heating element (unit: m³ or m²).

Increasing heating power density not only improves the system’s response speed but also achieves higher heating efficiency within a limited space. When selecting heating elements, by calculating power density and combining it with the needs of the application scenario, the size and output power of the heating elements can be matched to avoid overdesign or underdesign.

3.Thermal Stability of Heating Elements

Thermal stability refers to the ability of heating elements to maintain their thermal performance without significant changes during long-term use. Thermal cycling tests on heating elements can help determine their thermal stability. The standard formula for thermal cycling tests is:

ΔT=ΔQC⋅mΔT=C⋅mΔQ​

• ΔT is the temperature change (unit: K);
• ΔQ is the heat absorbed or released by the heating element (unit: J);
• C is the specific heat capacity of the material (unit: J/kg·K);
• m is the mass of the heating element (unit: kg).

The thermal stability of heating elements determines their durability in high-temperature environments. By improving the material’s resistance to thermal fatigue and optimizing structural design, the service life of heating elements can be extended, and their stability under high-load operation can be ensured.

4.Strategies for Optimization in Real-World Applications

In real-world scenarios, the strategic selection of heating elements, such as spiral heating coils, can significantly enhance the thermal efficiency of a system. For instance, employing multiple coil heaters helps to distribute heat evenly, preventing localized overheating that can result from concentrated heat. Moreover, by utilizing intelligent control systems to monitor the temperature fluctuations of heating elements in real time, the heating power can be dynamically adjusted to match the load, achieving both energy conservation and improved efficiency.

In industrial drying processes, for example, increasing the surface area of heating elements and refining the heating technique could potentially boost overall heating efficiency by 10-15%.

5.Future Directions

As technology advances and the need for energy conservation grows, the design of heating element is evolving. Future designs of heating element are expected to integrate intelligent control technologies to achieve more accurate temperature management and optimize energy efficiency. When selecting heating element, it is crucial to consider not only thermal conductivity and power density but also their long-term stability and endurance to ensure consistent and efficient system operation across various conditions.

The future promises more efficient and eco-friendly heating solutions for a range of sectors, including industry, commerce, and residential use, as breakthroughs in heating coil technology continue to emerge.