Coolpac: Cooling Device for Firefighters

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Sylvia Melton
6 years ago
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1 Coolpac: Cooling Device for Firefighters Alternative Designs Team 2: BME: Jaspreet Mankoo, Kerri Blanc ME: Nedim Begovac, Sean Meehan Sponsor: Createc Consulting LLC Sponsor Advisor: Hans Almqvist, , 1

2 Alternative Design I For this modification of the CoolPac cooling sleeve, the design team wanted to implement a true sleeve-like feel and fit from a mechanical perspective. The design schematic is shown in figure 1 and although it is very unrefined in its preliminary model, still highlights the key aspects of what differentiates it from the current prototype. Specifically the nylon/mesh base material of the sleeve will make it more compressive overall and will provide a more snug fit for the user. This material will be similar to the compressive sleeves worn by athletes, such as that shown in figure 2, in that it will be lightweight and won t need an additional fastening mechanism to secure it to the forearm. Ideally using a moisture wicking dri-fit material would be optimal for this design because it would help carry moisture to the surface so it can dry, keeping moisture from collecting near the user s skin. Also, moisture-wicking material doesn't absorb moisture itself, so it dries quickly. Therefore the user, in this case a firefighter, would feel drier and more comfortable when performing active work in the field. Yet at the same time dri-fit material is not an absolute necessity for this design because the phase change material (PCM) will be the primary source of cooling through heat transfer. With respect to the PCM implementation within the sleeve, the compression design would create maximum contact between the PCM packs and the skin. Consequently greater surface area contact between the PCM and the forearm skin should maximize heat transfer via the increased blood flow to the extremities during heat stress settings. From figure 1, one can see that the design team chose to employ PCM units which are approximately 11x1. The team believes that these slender and longer units will better conform to the forearm in comparison to the current 3x4 PCM units used in the current prototype and prevent slipping of the CoolPac sleeve as a whole. To the implement this design, the team will first scale the CoolPac sleeve for the length of an average male and/or female forearm length. The model in figure 1 has a length of 11.8 inches, which is close to the average male forearm length of 11.5 inches. Even though the material will be elastic and should be able to compensate for varying forearm widths, similar research will we done to ensure that the elastic material will be comfortable for arm widths above and below the average. The sleeve will be created by taking pre-existing athletic sleeves on the market and cutting them to the desired size. An extra layer of to be determined fabric will be attached to the inside layer of the sleeve to create pockets in which the PCM units will be 2

3 housed. The team will attempt to make these pockets re-sealable so that different PCM units can be replaced if need be. Figure 1 displays a CAD image of the design for the CoolPac cooling sleeve design proposed above. This design meets all the specification set forth in the project proposal and the technical specifications. Figure 1. Parallel PCM CoolPac Design Figure 2. Athletic Compression Sleeve 3

4 Alternative Design II As stated in the first alternative design concept sheet the goal set out by our team is to implement a new sleeve design which will be drastically improved in both comfort and durability. Such as the previous schematic for the first alteration, this current one also somewhat crude and does not depict the perfect picture; but it does point out the key design features and benefits. The material holding together the sleeve is a spandex/nylon mesh, and is implemented such to provide a firm and snug hold on the wearers forearm. Ideally both re-designs have incorporated the same material as their base material thus allowing a greater focus on the phase change material (PCM) optimization as well as alignment. Similar to the previous design one of the key points when altering the PCM Alignment is to focus on how much surface area is being occupied by the PCM. By covering more surface area we are able to increase the effectiveness at which the PCM cools the forearm. The current prototype had 3x4 blocks of PCM aligned around the sleeve, and the first re-design had slimmer rectangular blocks of about 1x11 oriented around the sleeve. For this design the curvature aspect of the human forearm was taken into greater consideration. With that in mind the second re-design entails semi-circular/elliptical patterns oriented around the sleeve such that when pressed against the forearm, via the spandex/nylon material, it will conform more efficiently than that of its flatter rectangular predecessors. Currently there are many steps that need to be taking to finalize these re-designs such as measuring the full scope of dimensions of the CoolPac prototype as well as designing custom containers for the PCM such that it may be implemented within our improved/re-designed prototype. Figure 3 displays the Solidworks drawing for the second re-design of the CoolPac prototype. 4

5 Figure 3. Concentric Circles PCM CoolPac Design Alternative Design III The idea behind this design of the CoolPac cooling sleeve is to combine a true sleeve-like feel, similar to the first design, with a redesign of the phase change material (PCM) positioning for better comfort and skin contact. The team has agreed that long, slender PCM pads that run axially along the arm will perform better due to maximal contact with the skin in order to absorb more heat overall. However, when tightened down to fit the wearer, these perfectly straight PCM pads will cause a slight tapered gap to occur on the upper portion of the sleeve due to the way the arm muscles expand the cross-sectional area of the forearm overall. This design will include a drawstring-style tightening mechanism on both the entrance and exit of the sleeve. The wearer will be able to slide on the sleeve, which will be large enough to fit loosely on (ideally) any person. Upon pulling the drawstrings tightly and securing them, the sleeve will conform to fit the wearer, and the PCM pads will tighten to fit together along the curved upper area of each piece. This will allow for a greater overall area of the forearm to be covered with PCM material and thus absorb more endemic heat generated by the wearer. 5

6 While capitalizing on some of the pitfalls of other designs, this version of the CoolPac cooling sleeve is not without its faults. The team has predicted that this design may be difficult or costly to implement due to the oddly shaped PCM pads. Ensuring that each one is exactly the same size and shape would be difficult to do given the precise nature of the curve. Also, it may be difficult to make sure this design will function properly for any wearer, since people certainly have a wide variety of arm sizes. That being said, the latter is an issue common to any design and the team has been doing its best to design around these difficulties. Figure 3 displays the Solidworks drawing of the aforementioned concept. Figure 4. Wavy PCM CoolPac Design 6

7 Alternative Design - Experimental Setup I Although the validation testing requirements for the CoolPac cooling sleeve given by the client are very clear, there are multiple approaches that can be taken in order to meet these goals. Essentially the main requirements are to obtain physiological data, specifically heart rate and body temperature, from users wearing the cooling sleeve under applied heat stress settings. For this experimental setup the design team will acquire a bicycle ergometer in order to provide a controlled means to increase the core body temperature of the human subjects. The cycle ergometer, such as the model shown in figure 5, is vital because it serves as a consistent way to measure the 300 W of work necessary and induce heat stress on each subject repeatedly. In comparison, an experimental setup involving running or performing other physical tasks in a designed manner might produce variation based on how that person performs the task. Each subject will wear a full body suit in order simulate the restrictive properties and effects of the personal protective equipment firefighters wear in the field, specifically the lack of sweat evaporation. Also a temperature controlled testing room will be used to carry out testing at room or elevated temperatures. Regarding instrumentation setup each subject will have sensor(s) for heart rate as well as temperature whose data will be fed to the Biopac software for analysis. Standard Biopac leads will be used to connect the sensors to the hardware. Heart rate and body temperature measurements will be taken before and after each cycle of physical activity. Each subject will wear a pair of cooling sleeves (1 per forearm) during the testing cycle. In order to differentiate the cooling effect of the CoolPac, some subjects will be selected as controls and will not be given cooling sleeves and will still carry out the same work load. Ultimately, comparing the physiologically data and trends for subjects who have the CoolPac versus those who do not will help determines the product s effectiveness. The following is a sample preliminary procedure that will serve as the basis for experimental testing: 1.) Testing summary is presented to the subject along with safety procedures 2.) Subjects sign consent form 3.) Individual data including gender, age, weight, height, are recorded for future analysis 7

4.) Non-control subjects put on the CoolPac sleeve 5.) Sensors are placed on all subjects and are connected to the biopac hardware. 6.) All subjects wear full body suit. 7.

8 4.) Non-control subjects put on the CoolPac sleeve 5.) Sensors are placed on all subjects and are connected to the biopac hardware. 6.) All subjects wear full body suit. 7.) Bicycle ergometer and Biopac software are initialized 8.) Initial heart rate and body temperate measurements are taken 9.) Each subject performs approximately 20 minutes of exercise on the bicycle 10.) Heart rate and body temperate measurements are taken 11.) Each subject receives 10 minutes of rest which is involves sitting in a chair with the suit still on 12.) Another 20 minutes of exercise performed 13.) Final heart rate and body temperate measurements are taken 14.) Data is saved and the test subjects are relieved of all equipment and gear Figure 5. Bicycle Ergometer 8

Alternative Design - Experimental Setup II In the field, firefighters are required to wear numerous protective garments which weigh down their bodies.

As the heavy lifting leads to perspiration, firefighters become susceptible to heat stress.

9 Alternative Design - Experimental Setup II In the field, firefighters are required to wear numerous protective garments which weigh down their bodies. Amongst many physically strenuous activities they must perform, firefighters are forced to do a lot of heavy lifting whether it is their tools, falling debris, or people. As the heavy lifting leads to perspiration, firefighters become susceptible to heat stress. In this setup, to simulate the stress put on the body due to heavy lifting under simultaneous movement, the test subject is situated on an ergometer treadmill while holding a five pound hand weight in each hand: Figure 6. Experimental Setup #2 Summarized Procedure 1. Measure initial vital signs and core body temperature 2. Put on the Coolpac Sleeve device and the body suit 3. Perform reps with hand weights while walking on treadmill at 100 watts for 20 minutes. 4. Rest for 10 minutes 5. Perform reps with hand weights while walking on treadmill at 100 watts for another 20 minutes 6. Stop test and measure final vital signs and core body temperature 9

10 References Brecon No-Wrap Sleeves. Digital image. Medico Sports Medicine. Web. 14 Oct < Free Weights. Digital image. Modern Guide to Men's Health. Web. 15 Oct < Lifespan Treadmill. Digital image. HealthStyles Exercise Equipment. Web. 15 Oct < Monark 839E Ergometer Upright Bike. Digital image. Exercise Bike Superstore Web. 14 Oct < 10

Body Bar FLEX. Exercises for the Core and Abdominals. by Gordon L. Brown, Jr. for Body Bar, Inc.

Body Bar FLEX. Exercises for the Core and Abdominals. by Gordon L. Brown, Jr. for Body Bar, Inc. Body Bar FLEX Exercises for the Core and Abdominals by Gordon L. Brown, Jr. for Body Bar, Inc. 1 Exercises for the Core and Abdominals This presentation features stretching and strengthening exercises