Final Design Schematics

Final Design Electronic Mounting/Layout

How It Works

The final design is a wearable cooling garment, available in the form of a vest or shirt, engineered to remain flexible and comfortable during movement. Unlike conventional cooling garments that rely on ice packs or other bulky methods, this innovative design integrates flexible thermoelectric cooling (TEC) devices and compact, flexible heatsinks, each measuring approximately 4 cm × 4 cm × 4 cm. The TEC units function as miniature refrigerators by drawing heat away from the body and transferring it to the heatsinks, which then dissipate the heat into the surrounding environment.

To enhance cooling efficiency, a silicone tube is routed across the back of the garment in a horizontal, serpentine pattern. As the wearer’s body warms, the circulating water within the tubing is heated, and the heated water is pumped back to the TEC assembly using a micro pump, where it is cooled and recirculated. This closed-loop system ensures continuous thermal regulation.

The system includes a battery-powered control unit, allowing users to adjust the temperature of the circulating water to their preference. All components are designed to be lightweight, with the entire setup weighing under 2 kg, and compact enough to be comfortably worn throughout the day. For ease of maintenance and hygiene, the electronic and mechanical components are removable, allowing the garment itself to be machine-washable. Additionally, components requiring airflow, such as the heatsinks, are designed to be attachable via clips, making it easy to position them in a pocket or an external area with adequate ventilation.

The Cooling Garment has numerous electrical components that require power from the singular rechargeable battery. Each component requires optional an optimal current and voltage input for increased system performance. Based on these requirements, the electrical schematic in was constructed to outline the final wiring connections of the garment. The wiring diagram takes into account components that require different voltages lower than the 12V battery. To provide the components with the proper voltage requirements, DC to DC converters were used. The TECs were arranged in a parallel-series configuration to optimize their performance, and reduce the load on the power supply. This design also increases circuit short circuit protections, allowing for the remaining TECs to continue to operate, even if another device looses power. To ensure the TECs are correctly andd accurately powered, a DC-DC voltage converter was installed. These converters were verified to support high current and voltage input and output values, per the specifications of the devices. Additionally, the parallel and series layout ensures the current draw from the battery is reduced, decreasing strains on the battery and protecting it from overcurrent and thermal runaway. 

 For increased protection for users, a high current fuse will be placed between the converter and the TEC parallel-series connection. His will ensure the battery is not quickly depleted, leading to an increase in cell damage and fire risks. To protect the controllers, a smaller fuse will be inserted to ensure overcurrent does not occur.

Performance Results

Initial testing consisted of isolated components, such as the TECs with various heat sink configurations and an externally mounted fan. In isolated testing, custom 3D printed heatsinks allowed the TECs to achieve a cold side temperature as low as 11.5°C at 1.5A of current input, delivering a total cooling power of 25.2W across four units. At a higher input of 1.75A, the system reached 14.3°C and a cooling power of 27.58W, limited by the heatsink’s ability to dissipate heat. However, with improved airflow, the TEC could reach temperatures below 10.5°C, increasing cooling capacity to a theoretical maximum of 35.07 W.

For maximum performance, alternate heatsinks made of aluminum increased TEC temperature capability to just 6.1°C at 2A of current input, pushing the system to 39.36 W of cooling power. However, they come at the cost of added weight and rigidity. The lightweight 3D-printed heatsinks remain optimal for wearable comfort, offering strong performance while keeping the system flexible and below the 2kg net weight restriction.

The tubing arrangement on the user's body is optimized for a total pressure drop of 12.7 kPa, which is low enough to be ineffective against the system's performance. The water pump and silicone tubing material also allow for 2.881 W of cooling per foot of material, appropriately transferring the desired amount of heat away from the user's body.

Ultimately, in the final design, testing showed that all four TEC cooling units in the system performed consistently with each other across multiple trials, having cold side temperatures between 19°C to 14.2°C. An average cold side temperature of 14.9°C at the highest cooling setting of 100% power resulted in a net cooling capacity of 27.58 W.  The system also maintained an internal water temperature around 19.5°C, despite exposure to a 40°C heating pad on a mannequin wearing the cooling garment. While not fully accurate to demonstrate the effective operation of this cooling garment in a 40°C external environment, this test was still a preliminary method of determining the garment’s performance when facing an external heat source as a form of resistance to cooling efforts made by the cooling garment. Various battery configurations also showed that while a lightweight battery configuration could reduce the total weight of the garment to 1.6 kg, it only offered around 53 minutes of runtime. A heavier battery configuration would raise the net weight to 2.2 kg, but could achieve up to an estimated 4 hours of runtime. The weight and battery requirements of the project could not be fully balanced, with the system only meeting one at the cost of the other, indicating that further testing should be conducted to optimize the system in order to meet both requirements simultaneously.

The majority of the desired functional requirements of the cooling garment were met with the final design. While some experimental measurements fell short quantitatively, the garment was fully able to achieve flexibility, comfort, and modularity. Qualitative features of the garment were effectively delivered in the final product, with certain performance benchmarks only needing slightly more tests and further optimization to improve the system overall.