Thermoelectricity Formula - Overview, Effect, Applications

Thermoelectricity formula is a fascinating branch of science that deals with the conversion of heat energy into electrical energy and vice versa through a phenomenon known as the "thermoelectric effect." This field has practical applications in various industries and technologies, including power generation, waste heat recovery, temperature sensing, and more.

What is Thermo Electricity?

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Heating Effect of Current

• Joule's Law: The amount of heat generated (Q) in a resistor is proportional to the square of the current (I) passing through it, the resistance (R) of the material, and the time (t) during which the current flows.

• Resistance and Heat Generation: Materials with higher resistance will generate more heat for a given current. This is why heating elements, such as those used in toasters, electric stoves, and water heaters, are made from materials with relatively high resistance.

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Application in Devices:

• Electric Heaters: Electric heaters use the heating effect to generate warmth. The electric current flows through a resistive element, which heats up and radiates thermal energy.
• Incandescent Light Bulbs: Incandescent light bulbs work by heating a filament to a high temperature through the heating effect. This high temperature causes the filament to emit visible light.
• Toasters and Electric Stoves: These appliances use heating elements to cook or heat food by converting electrical energy into heat energy.
• Hair Dryers: Hair dryers use the heating effect to warm the air blown onto the hair, helping to dry and style it.
• Soldering Irons: Soldering irons heat up to melt solder and join electronic components together.

Thermo Electric Effects

Seebeck Effect:

• This is the most fundamental thermoelectric effect discovered by Thomas Johann Seebeck in 1821. It occurs when a closed loop of two dissimilar conductors or semiconductors is subjected to a temperature difference. Electrons in the material move from the hotter region to the cooler region, creating a voltage difference (electric potential) between the two ends. This voltage can be measured and used to generate electric power.

• S is the Seebeck coefficient, which represents the voltage (electric potential) generated per unit temperature difference.
• V is the voltage difference (in volts) generated between the two ends of the materials or junctions.
• T is the temperature difference (in degrees Celsius or Kelvin) between the two ends of the materials or junctions.

• In the Peltier effect, if a current is passed through a junction of two different materials, a temperature difference is created at the junction. This phenomenon is reversible – applying a voltage across the junction can cause a temperature difference. The Peltier effect is commonly utilized in thermoelectric cooling and heating devices.

• 𝛱 is the Peltier coefficient (in volts per ampere or equivalent units).
• Q is the heat absorbed or released at the junction (in joules).
• I is the electric current flowing through the junction (in amperes).

• The Thomson effect refers to the development of a temperature gradient along a conductor or semiconductor when a current flows through it. It's related to the Seebeck effect and is often observed in materials with significant electrical conductivity.

The formula for the Thomson coefficient (μ) is given by:

• is the Thomson coefficient (in degrees Celsius per volt or equivalent units).
• ΔT is the temperature difference between two points along the conductor (in degrees Celsius).
• ΔV is the voltage difference between the same two points (in volts).

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Variation of Thermo-Emf with Temperature

Applications of Thermo Electricity

1. Power Generation: Thermoelectric generators (TEGs) are used to convert waste heat into electricity. They find applications in:
   1. Industrial processes: Capturing waste heat from manufacturing and power plants to improve energy efficiency.
   2. Automotive industry: Utilizing waste heat from engines and exhaust systems to enhance fuel efficiency.
   3. Aerospace: Generating power in space probes, satellites, and deep-space missions where traditional power sources may not be feasible.
2. Waste Heat Recovery: Thermoelectric materials are used to recover waste heat from various sources, reducing energy waste and improving overall efficiency in industrial processes and power generation.
3. Thermal Sensors: Thermoelectric materials are employed in temperature sensors and thermal imaging devices due to their ability to generate electrical signals in response to temperature changes. These sensors are widely used in industrial, medical, and research applications.
4. Wearable Energy Harvesting: Thermoelectric generators integrated into wearable devices can harness body heat to power small electronics, offering a sustainable energy source for wearables and remote sensors.
5. Energy-Efficient Electronics: Thermoelectric cooling modules are used to regulate temperatures in electronic devices and prevent overheating. They find applications in computer processors, LED lighting, and high-performance electronics.
6. Climate Control and HVAC: Thermoelectric devices can be used for localized cooling or heating in vehicles, buildings, and other enclosed spaces.
7. Medical Applications: Thermoelectric materials are used in medical devices for precise temperature control and regulation in applications such as laser surgery, tissue preservation, and diagnostics.
8. Powering Remote Sensors: Thermoelectric systems can provide power to remote sensors and monitoring devices in locations where traditional power sources are unavailable or impractical.
9. Portable and Remote Power Generation: Thermoelectric generators can serve as portable power sources for camping, hiking, and remote field operations, relying on heat sources like campfires or body heat.
10. Renewable Energy Integration: Thermoelectric devices can complement renewable energy sources by utilizing waste heat generated in solar panels or other renewable energy systems to improve overall energy efficiency.