Thermoelectric Coolers (TEC) Construction Guide for Temperature Control System
01 Application Scenarios and Advantages of Thermoelectric Coolers (TEC)
Thermoelectric coolers (TEC, thermoelectric cooling plates) are based on the Peltier effect: when current passes through the junction of two semiconductors (N/P types), one end absorbs heat (cooling), and the other end releases heat (heating).
Core characteristics:
- No mechanical components, zero noise, and long service life;
- Small thermal inertia, reaching the maximum temperature difference within 1 minute of power-on;
- Cold-heat switching only requires changing the current direction, with a maximum temperature difference between the cold and hot surfaces generally ranging from 65 to 75°C;
- Relatively low efficiency (requires high-efficiency heat dissipation), with cooling capacity depending on the current and heat dissipation capacity; under ideal heat dissipation conditions, the maximum cooling capacity is 60-70% of the input power;
- Cold-heat switching: Correctly switch the current direction, but note that instantaneous reverse voltage can damage the TEC, requiring circuit protection.
02 Core Components for System Construction
1、Thermoelectric Cooler (TEC)
Select appropriate models based on the required cooling/heating power and temperature difference (common sizes include 40x40mm, 50x50mm, etc.). Pay attention to the rated voltage, current, maximum temperature difference, and maximum cooling power, and it is recommended to leave a 20-30% margin.
Note: Generally, the side with text is the cold surface (heat absorption), and the side without text is the hot surface (heat release). However, the cold and hot surfaces need to be confirmed through short-term power-on testing, as manufacturer markings may vary. Reverse installation will cause system failure. Meanwhile, avoid overvoltage, high current, or instantaneous reverse voltage to prevent service life reduction.
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2、Hot-End Heat Dissipation System
The efficiency of the TEC largely depends on the quality of heat dissipation on the hot surface[1].
- Heat sink: TEC efficiency is highly dependent on hot-end heat dissipation, and poor heat dissipation is the most common cause of system failure (accounting for over 70% of failure cases). Use aluminum or copper heat sinks, and the size should match the TEC power (heat dissipation capacity > hot-surface power, i.e., input electrical power + cold-end heat absorption).
- Fan: Forced air cooling is a cost-effective choice. Select a fan with high air volume and appropriate static pressure, and install it tightly on the heat sink to ensure smooth airflow.
- Thermal conductive silicone grease: Apply high-quality thermal conductive silicone grease between the TEC hot surface and the heat sink base to reduce contact thermal resistance.
- Water cooling head + water pump + water tank/heat dissipation row: If air cooling cannot meet the heat dissipation requirements (e.g., high-power TEC or pursuit of silence), water cooling is a more efficient option.
3、Temperature Sensor
It is recommended to use NTC (negative temperature coefficient thermistor) or platinum resistance (PT1000/PT100), with an accuracy of ±0.1°C to support high-precision temperature control. Layout specification: The sensor should be closely attached to the temperature control surface, and the thermal conductive adhesive should be fixed to ensure good thermal contact. Avoid direct exposure of the cold end or interference from heat sources to prevent measurement deviations (for example, in a closed space, place the sensor in a well-ventilated area rather than in direct contact with the cold surface).[2]
4、Temperature Controller
- Function: Reads the signal from the temperature sensor, compares it with the user-set target temperature, and determines PID parameters based on the comparison result.
- Types: Dedicated temperature control modules or microcontroller development boards.
- Dedicated modules: Such as the SenseFuture temperature controller (supporting PID self-tuning, with temperature control stability of ±0.01°C).
5、Power Supply
- Power supply selection: The voltage should match the TEC rated value (commonly 12-24V), and the current output should have a 20-30% margin over the rated current. Use a DC power supply with low ripple and high stability (ripple <5%). Poor-quality power supplies can easily lead to reduced efficiency or TEC damage. Instantaneous reverse voltage must be avoided to prevent component failure.
- Wiring specifications: Use power cables larger than the maximum output current of the load
03 Construction Steps
1、Clarify Requirements and Selection
- Step 1: Select an appropriate temperature sensor based on the temperature control range;
- Step 2: Select heating and cooling components (such as TEC), and test in your system to ensure their power meets the temperature control range requirements;
- Step 3: Select a temperature controller that covers the voltage and current range of the heating and cooling components based on their voltage and current;
- Step 4: Select a power supply whose voltage and current cover those of the heating and cooling components, with a certain margin;
- Step 5:Build the system according to the temperature controller instructions.
2、Assemble the System
（1）Heat dissipation system installation:
- Plan 1: Air cooling: Evenly apply a thin layer of thermal conductive silicone grease on the TEC hot surface, closely attach it to the heat sink base, and fix it firmly with clamps or screws (note uniform force to avoid cracking the ceramic plate). Install the fan on the heat sink to ensure the correct air direction.
- Plan 2: Water cooling: If using water cooling, install the water cooling head on the hot surface, connect the pipes, water pump, water tank/heat dissipation row, and perform a tightness test (prevent water leakage).
（2）Install the TEC and cold end:
Evenly apply a thin layer of thermal conductive silicone grease on the TEC cold surface. Closely attach the cold surface to the surface needing cooling (such as a cold-conducting aluminum plate or equipment housing), and fix it with uniform pressure. If cooling a space, ensure the cold end (cold-conducting plate) is inside the space and isolated from the "external" environment where the hot end (heat sink) is located using thermal insulation materials.
（3）Install the temperature sensor:
Firmly install the sensor at the position requiring precise temperature measurement (such as the cold-conducting plate surface or inside the space). Ensure good thermal contact, which can be enhanced by adding thermal conductive silicone grease, and fix it with thermal conductive adhesive if necessary. Secure the sensor cables, and avoid interference in position selection[3].
3、Testing and Debugging
（1）Initial power-on: Do not connect the TEC first! Check whether the controller and sensor work normally. Ensure all wiring is correct, especially the power polarity!
（2）Direction test: Power on briefly (<10 seconds) with limited output voltage and power to confirm that the cold surface cools and the hot surface heats; otherwise, check the polarity or installation. Poor heat dissipation is indicated by a hot hot surface and no change in the cold surface.
（3）Temperature control test:
- Set the target temperature, start cooling, and observe the cooling speed and stability.
- When using PID control: Adjust parameters (P, I, D) to reduce overshoot and fluctuations (e.g., target accuracy ±0.01°C).
- Use a serial plotting tool to record the temperature curve and optimize the response.
- Add overcooling protection: Set a minimum temperature limit (e.g., 5°C) in the software to prevent condensation or equipment damage.
04 Important Notes and Common Issues
（1）Hot-end heat dissipation: Poor heat dissipation is the main cause of 80% of failure cases. Use a large heat sink or a powerful fan/water cooling system. When the hot surface temperature exceeds 80°C, the COP will significantly decrease.
（2） Efficiency issue: The COP of thermoelectric cooling is typically 0.3-0.5, much lower than compression refrigeration (COP >3). It is suitable for small-power (<200W) and small-space applications, with relatively high power consumption.
（3）Current and wire diameter: Use thick wires for high-current circuits, and ensure reliable welding or crimping at connections to avoid voltage drop >5%.
（4）Power supply power: Insufficient power will cause voltage drop (e.g., 12V drops to 9V), reducing cooling efficiency by more than 50%; it is recommended that the power supply power is 1.3 times the TEC rated power.
（5）Overcooling protection: Set a minimum temperature limit (e.g., 5°C) in the software and control the ambient humidity <80% to prevent condensation.
05 Summary
The key to building a TEC-based temperature control system lies in selecting appropriate components (especially TEC power, heat dissipation capacity, and power supply power), ensuring efficient hot-surface heat dissipation, correct connection and driving, precise temperature measurement, implementing effective control algorithms (preferably PID), and performing thermal insulation and anti-condensation measures.
06 References