A thermoelectric cooler, also known as a Peltier device or thermoelectric module, is a solid-state heat pump that utilizes the Peltier effect to transfer heat from one side of the device to the other. It can work as both a cooler and a heater depending on the direction of the electrical current passing through it.
The Peltier effect is a phenomenon observed in certain materials known as thermoelectric materials. These materials are typically semiconductors with special properties that allow them to conduct electricity and heat simultaneously. When an electrical current flows through these materials, it causes the movement of charge carriers (electrons and holes), which in turn leads to heat transfer.
The working principle of a thermoelectric cooler can be understood through the following steps:
Thermoelectric materials: The Peltier device is made up of two different types of thermoelectric materials, usually n-type and p-type semiconductors. These materials are selected for their specific properties that enable the Peltier effect.
Electric current application: When a direct current (DC) electrical voltage is applied to the thermoelectric cooler, the current flows through the two semiconductor materials.
Electron movement: In the n-type material, electrons carry negative charge and move from the cold side to the hot side of the device. In the p-type material, holes (absence of electrons) carry positive charge and move from the hot side to the cold side.
Heat absorption and release: As the electrons move from the cold side to the hot side, they absorb thermal energy from the cold side, cooling it down. Simultaneously, on the hot side, holes moving from the hot side to the cold side release thermal energy, heating it up.
Heat transfer: The heat absorbed on the cold side and the heat released on the hot side contribute to the cooling effect. The heat is essentially pumped from one side to the other, creating a temperature differential across the device.
Thermoelectric cooling effect: The cumulative effect of these electron movements and heat transfers results in cooling on one side of the device and heating on the other side. The cooling side can achieve temperatures lower than the ambient temperature, making it useful for various cooling applications.
It's important to note that thermoelectric coolers are not as efficient as conventional refrigeration methods, such as compressor-based systems. They are most effective for small-scale applications and situations where compactness and solid-state operation are essential. They find use in electronic devices, portable refrigeration, thermal management of electronics, and niche cooling applications.