A Smart Jacket with Portable Thermoelectric Cooling System

This paper introduces a cutting-edge, self-contained cooling jacket design and its practical implementation. The jacket utilizes Peltier modules and a water circulation system to efficiently transfer heat, completely eliminating the need for traditional compressors or refrigerants. The key components of this innovative system include aluminum blocks housing Peltier modules, dual-loop water coolant systems, a compact suction fan, a radiator, two submersible pumps, and a rechargeable Lipo battery. The cooling process involves water circulating through the aluminum blocks to effectively dissipate heat generated by the Peltier modules. The heated water then traverses a path through plastic pipes, the radiator, and a holding tank, and ultimately returns to the aluminum blocks, while the cold water travels from the tank to the aluminum blocks via copper tubing. This ingenious configuration delivers remarkable cooling performance without relying on conventional cooling components. Extensive laboratory testing of the system confirmed its capability to achieve cooling temperatures up to 10°C below the ambient temperature. These results signify the promising potential of the cooling jacket across various applications, especially those requiring a portable and self-contained cooling solution. Such applications include critical scenarios like military and first responder operations, demanding industrial and construction settings, and scenarios involving individuals with medical conditions exacerbated by heat. The innovative cooling jacket offers a highly efficient and versatile solution for a wide range of practical needs.


Introduction
The use of cooling jackets has become commonplace in hot environments to regulate body temperature and improve physical and mental performance.While many existing cooling jackets use complex systems such as condensers and cylinders, our project has a simpler design using a Peltier.Combined with a water circulation system and copper coil.Our jackets can be easily controlled with an Android application, ensuring user-friendly operation and maintenance.Designed specifically for military applications, this cooling jacket addresses the challenges soldiers often face in harsh conditions characterized by hot and dry climates.These conditions often lead to dehydration and illness.By preventing body temperature from reaching dangerous levels, our cooling jackets keep soldiers cool and focused on their mission.Best of all, our jackets are easy to repair, making them even more suitable for military use.Additionally, people working in hot environments, such as miners and athletes, may also get benefits.We further propose that the same technical principles could be extended to the development of cooling helmets for soldiers, potentially saving lives, especially in extreme heat.Harnessing the efficiency and adaptability of cooling jackets presents an opportunity to extend their impact to provide critical cooling solutions to other areas.Most existing wearable systems provide only single-functionality, either heating or cooling.However, several alternative systems have been developed that can be compared to the proposed solution.Some of the recent research on Cooling Heat Exchanging machines are: (i)The Protective Jacket for workers in cold climates [1], for instance, features built-in sensors that provide real-time temperature information, helping workers to adapt to extreme cold weather without disruption.(ii)A jacket with built-in air conditioning [2] utilizes two fans to regulate temperature by circulating cool air around the wearer but is limited in extreme winter due to a balloon effect [3]. (iii)The Flex Warm Jacket [4] is equipped with temperature sensors and can be controlled via an iOS or Android app.(iv)The Water Flow Body Temperature Controlling Jacket [5] eliminates moisture from the body and the jacket's outer surface guards against temperature variations.(v) The Temperature Programmable Suit [6] uses water circulation to control internal temperature.(vi) The Solar-Powered Thermal Jackets [7] harness solar energy to provide better protection for people working in unfavorable weather conditions.(vii) A heating and cooling suit (battery powered) [8] incorporates TECs (Thermo Electric Coolers) and other devices to enable temperature control.(viii) Adaptable jackets based on climate [9] use the Peltier effect to control internal temperature.(ix) The Cooling Vest [10] provides a cooling effect for the body in high temperatures.(x) The Milwaukee Heated Jacket [11] uses adjustable heat technology to allow the user to vary the temperature level.(xi) The Solar and Thermal Energy Obtained with a Wearable Jacket [12] receives energy from photovoltaic cells and TEGs (Thermo Electric Generators) to heat the body in outdoor environments.So, after analyzing the current situations and research, we decided to make an easy portable simple controlled Cooling Jacket for field uses.The main Objectives of this research are: (i) The purpose of this research project was to develop a cooling jacket suitable for use by individuals working in scorching environments, including military personnel and civilians.(ii) Another main purpose of the study was to determine the effectiveness of air cooling and heat sink efficiency in metal-to-air heat convection while investigating how heat transfer changes with different numbers and areas of fins.(iii) Another goal was to reduce the noise generated by the system.

Proposed Systems
• The first approach was air-to-air cooling.Air was used as the conductor of heat on both the cooling and heating sides.At first, we thought about Baffle's path of circulating the air through the entire cold surface, but the problem arises that there are so many bends in the way.For the friction loss of fluid, the duct fan couldn't send all the air to the end of the zigzag path.Rather an unusual backflow occurs at the inlet for this reason.This can be solved by giving filets to the 90-degree bends but still, we were not confident enough that this would even work or not, the probability was in favor of failure.So, wasting no more time we immediately migrated to another plan.• The second plan was to eliminate the baffles and make a straight path for the airflow and also place the Peltier close to each other, reducing the overall area and increasing the cooling density.Secondly, the same machine was made but on a smaller scale and with increased cooling density.The problem this time was the air couldn't efficiently take the cold from the surface, maybe because the total surface area of the cold side or the number of fins on the heatsink wasn't enough or the convection coefficient of air is very low compared to other fluids.We focused on a hassle-free way to do the job by using air which would be a great choice if it worked as air is everywhere in the environment so the users need not worry about the fluid or any leaks or refilling the fluid etc. • Final Successful Design: After extensive efforts, our air-cooled cooling jacket project was unable to achieve our desired cooling performance.Therefore, we pursued a water-cooling Peltier radiator system as our final approach.Water is a superior coolant to air, and we found that air and fins alone could not provide us with the desired results.We therefore implemented a water and radiator system with aluminum blocks.The final proposed system is a battery-powered cooling system that provides a cooling effect as per the user's requirement.Water is used as both the hot side and the cold side coolant in our design.Moreover, A mini water radiator is used to dissipate the heat of hot water.Here Aluminum blocks are used to extract the heat and cooling effect from the Peltiers by circulating water through its internal passage.Then the water from the hot side is circulated through the radiator then the reservoir and finally the Aluminum block using plastic pipes.A submersible pump (12v) is placed inside the reservoir to force the hot side water to flow through the entire system.Another small submersible pump (6v) is also used in the cold side reservoir to pressurize the water to flow through the Aluminum block, to the copper pipes.

Materials & Method
Major elements that were used & and their function in the final system are mentioned below serially.
• 5000 mAh Lipo Battery: Power supplier.It supplies electricity to our whole system of cooling jackets.We needed big sizes of more than 5000, but the budget made us stick to 5000.The cooling jacket system works by using a Peltier thermoelectric cooler (TEC) to create a temperature difference between the two sides of the jacket.The hot side of the TEC is attached to an aluminum block that is in contact with the user's body.The cold side of the TEC is attached to a copper coil exposed to the environment.When direct current is applied to the TEC, one side of the TEC becomes hot and the other side becomes cold.This is due to the Peltier effect, which is the phenomenon in which heat is transferred from one side of a semiconductor material to the other when an electric current passes through it.The heat generated by TEC is transferred to the aluminum block, which in turn transfers heat to the user's body.This helps refresh the user and improve comfort.The copper coil dissipates heat generated by TEC into the environment.This is done by convection and radiation.The copper coil is also cooled by the liquid flowing through it.The system's two pumps circulate fluid through the aluminum block and copper coils.This improves heat transfer and keeps the system running efficiently.A vessel containing a liquid is used for heat transfer.This also helps keep the liquid fresh.

Results and Discussion
This research paper holds three of our experimented approaches on cooling jackets and the last approach was the most successful one.The Water Cooling Radiator system successfully decreased the temperature below down to 10 deg from the environment temperature, as water is a better coolant than air.
While making this project, we faced some issues.But with time we have overcome these issues.
• Over Heating of Peltiers: We solved this problem by implementing a water cooling System with 4 Aluminum Blocks & Radiator.• Water Leakage: We sealed all the boundaries many times with Hot Glue Guns and super Glue.• Overheating of Wires: Peltiers Draw huge currents from the batteries and the thin wires can't take that much load, so we moved to Super Heavy Wires.• Peltiers need high voltage and current, 1 battery can't distribute that load and runs off the power so quickly, so we connected 2 batteries.
The final design experimental results are listed below with tables and graphs.We calculated the Temperature by DHT11 (temperature and humidity Sensor).Table 4 shows the results.The graph also depicts that the cold water temperature drops substantially at the beginning and reaches a steady state at around 9.5 degrees Celsius after almost 50 seconds.Whereas the Copper pipe temperature lags in terms of cooling and reaches a minimum steady state temperature at only around 20 degrees Celsius which is only 45.78% of the source that is the cold water.This disparity means either the cooling effect transmission was not perfect and it was gaining heat before reaching the copper coils, or the copper coil was taking too much heat from the environment and failed to reach the minimum possible temperature.The former was not the case since we used plastic tubes for cold water transmission and insulating material for the reservoir.The cooling jacket is very efficient at removing heat from the user which is clear from the rapid initial drop in temperature.

Conclusions
The challenge in the initial air-to-air heat transfer approach stemmed from the limited surface area, which impeded effective heat exchange with the module for cooling or heating.This presented a tradeoff between cooling density and surface area.As cooling density increased, surface area decreased, thereby constraining the air's heat exchange capacity.Conversely, increased surface area led to reduced cooling density due to their inverse relationship.Attempts to rectify this with baffles resulted in excessive air flow restriction and air backflow, rendering the solution ineffective due to bent air ducts obstructing airflow.The subsequent adoption of water-to-water heat transfer, leveraging water's superior thermal conductivity, yielded successful outcomes.A strategic approach involved varying the heat transfer coefficients on the cold and hot sides in a 2:1 ratio.This adjustment led to a heat dissipation rate twice that of the cooling rate, resolving issues related to inadequate heat dissipation and limited Peltier cooling effectiveness.Through iterative experimentation, a water-cooled heat exchanger was developed for attachment to the shroud.Additionally, a 3D-printed ducted fan was integrated into the shroud to facilitate airflow.Cold copper tubes, driven by forced convection, contributed to effective cooling.The final product, a specialized jacket, achieves the desired cooling temperature and now offers remote control via a self-programmed mobile app.Users can set their preferred internal body temperature, with an Arduino controller regulating the Peltier device to attain the target temperature.Experimental results at a room temperature of 31.2°Cshowed that the Peltier cooler achieved a cold-water tank temperature of 5.5°C and a copper tube temperature of 21.5°C within one minute, but it required 4-5 minutes to reach 10°C.It is noteworthy that while Peltier devices have the potential to cool to -60 degrees Celsius, practical limitations related to batteries and the need for high voltage or current rendered them impractical for this project.Future research should focus on uncertainty analysis and potential enhancements for the system.1305 (2024) 012007 IOP Publishing doi:10.1088/1757-899X/1305/1/0120079 6.Uncertainty Analysis:

Heat Transfer Efficiency:
Uncertainty Statement: The efficiency of the heat transfer process in the cooling jacket, particularly in the Peltier cooler, needs to be assessed.Variability in heat transfer coefficients and thermal conductivities of materials could introduce uncertainty.Suggested Analysis: Conduct sensitivity analysis to determine how changes in heat transfer coefficients and material properties affect the cooling or heating performance of the system.Perform experiments with different materials or working conditions to quantify this uncertainty.

Temperature Control and Uniformity:
Uncertainty Statement: Achieving precise temperature control and uniform cooling throughout the body is crucial for user comfort.The accuracy and uniformity of temperature control are potential sources of uncertainty.Suggested Analysis: Perform experiments to evaluate the temperature control accuracy and uniformity at various points within the jacket.Analyze how deviations from the desired temperature settings impact user comfort and quantify this uncertainty.

Peltier Cooler Limitations:
Uncertainty Statement: The limitations of Peltier coolers, including overheating, power consumption, and the time required to achieve desired temperatures, pose challenges.Understanding the extent of these limitations is essential.Suggested Analysis: Investigate the effects of different environmental conditions (ambient temperature, humidity) on Peltier cooler performance.Quantify the uncertainty associated with power consumption and time required to reach specific temperature targets.

Battery and Weight Constraints:
Uncertainty Statement: The practicality of the cooling jacket is affected by the limitations of batteries and the weight of the system.The extent to which these factors constrain the device's usability is uncertain.Suggested Analysis: Analyze the relationship between battery capacity, weight like carrying the machine inside the backpack, and the cooling jacket's operational time.Assess the impact of different battery types and their uncertainty on device portability and usage.

Peltier Durability:
Uncertainty Statement: The long-term durability of Peltier coolers used in the cooling jacket is a potential concern.The uncertainty surrounding the lifetime of Peltiers should be addressed.Suggested Analysis: Conduct accelerated aging tests on Peltier coolers to estimate their lifespan under different usage conditions.Evaluate the impact of Peltier wear and tear on the cooling jacket's overall performance.

User Experience and Marketability:
Uncertainty Statement: Assessing the user experience and marketability of the cooling jacket involves subjective factors.It is uncertain how user preferences and demands may impact the device's success in the market.

Conflict of interest: Nothing to declare
We hereby declare that we have no conflicts of interest related to the research and development of the cooling jacket described in this thesis paper.This project was conducted with the primary objective of advancing scientific knowledge and technological innovation in the field of personal climate control.
We have not received any financial or non-financial benefits from any external organizations, or companies, that could potentially influence the research process or the results presented in this thesis.Additionally, we have not engaged in any collaborations or partnerships that could create a conflict of interest in the presentation or interpretation of the findings.Our commitment is solely to the pursuit of academic excellence and the dissemination of knowledge to benefit the scientific community and society at large.We have conducted this research with integrity and transparency, adhering to ethical principles and professional standards throughout the project.We affirm that this Conflict-of-Interest statement accurately reflects our involvement in the research and development of the cooling jacket presented in this thesis paper.For making a comparison with the other research we are giving some similar research references: In a thesis-presenting a climatecontrolled jacket based on the Peltier effect, offering adjustable temperature control to protect users from extreme weather conditions.It enhances comfort, practicality, and mobility, particularly for mountain climbers.[22] However, in our research, we experimented with both air and water fluid and calculated heat transfer coefficients and temperature decrement with analysis and graphical changes.In another research, the cooling jacket was made especially for manufactory works.This study investigated the impact of a personal cooling vest on enhancing the thermal comfort of individuals working in warm and hot indoor environments.The research involved experiments conducted at temperatures of 27°C, 29°C, and 31°C, with twenty participants (10 males and 10 females) engaging in three different activities.The study compared two scenarios: one with participants wearing the cooling vest (CV) and the other without the vest (NCV).[23] But in our case, the jacket is given flexibility.This jacket can be used for multiple purposes as it allows users to sense and control the temperature by very simple means.The temperature can be varied by a wide range by controlling the Peltier effect with the help of an Android phone and associated apps.So, The Authors have no Conflict of Interest.

Figure 3 :Figure 4 :
Figure 3: Hot & Cold section Reservoir (left one is Hot side, right one is Cold side) • O-LED Display & TEMPERATURE SENSORS LM-35: Sensors sense the coldness & and hotness of the blocks and show us the temperature at the Display.• We used 2 O-LED displays & sensors.[13]• ARDUINO UNO: Arduino calculates the required Temperature to cool the body and passes this signal to Peltier.It operates a motor driver, pumps, Bluetooth Module, and relay modules.[14]• MINI ALUMINUM BLOCK: The Aluminum block is a device that has an internal spiral path where water flows and exchanges its heat with the surrounding surface.So, it is a heat exchanger without any fins or fans.• WATER TANKS: We used 2 water reservoirs, one is hot and the other is cold, Hot water tank is connected to the radiator and Hot side Aluminum Blocks, and the cold tank is connected to the cold side Aluminum Blocks and Copper Pipe.• PELTIER: We used 8 Peltier.Peltiers are placed in between the Aluminum Blocks.Peltier cools the water in the water tank.Thermoelectric coolers operate according to the Peltier effect.The effect creates a temperature difference by transferring heat between two electrical junctions.[15][16]

Figure 6 :
Figure 6: Operational Diagram of the system

Figure 7 : 8 Figure 8 :
Figure 7: Graph 1 shows the Hot Tank Temperature vs.Time The line graph illustrates the change in temperature of the hot side water over 1 minute.The graph shows that the hot side temperature rises rapidly in the beginning, then eventually reaches a maximum steady state temperature at around 35.5 degrees Celsius.

Table 1 :
shows the Heat transfer coefficients of our 1st Experimental Trials (Baffle design)

Table 3 :
shows the Heat transfer coefficients of our final Experimental Trials (water-radiator system) Type of ConvectionConvective Heat Transfer Coefficient hW/ (m2 ⋅ K) (c) Liquids (forced) 9045

Table 4 :
Hot side water temperature increase and temperature decrease in the cold side reservoir and copper pipe in 1 minute 6.7.Suggested Analysis: So, have to conduct surveys or user trials to collect data on user preferences and satisfaction.Analyzed market trends and competitor products to assess the level of uncertainty in successfully bringing the cooling jacket to market.Incorporating these uncertainty analyses can help provide a comprehensive understanding of the challenges and potential improvements for the cooling jacket system.It can also guide future research and development efforts in addressing these uncertainties for a more successful and reliable product.This sort of research would have been impossible without sufficient technical help from the MIST (Military Institute of Science and Technology).We thank Group Captain A.K.M Zahidur Rahman Sir for advising and supervising us till the end.We express our deepest appreciation to Brig.General Humayun Sir, Assistant Professor Sayem Sir, and Professor RGM Hasan Sir for their support & and technical help.