Oasys will cool hikers, campers, and all out door enthusiasts.
The goal of Oasys is to deliver chilled drinking water to outdoor enthusiasts who are active in a warm environment. Oasys will provide the chilled water for a prolonged period of time in order to account for longer duration activities that the user is taking part in. The chilled water will be delivered through a system similar to that of existing hydration packs with the addition of an electronically controlled cooling system that is easily applied to any hydration unit. The cooling system consists of Peltier coolers powered by a battery with substantial capacity for prolonged use. The capacity of the battery is determined by the activities performed by the average user. In order to cool the Peltier , Oasys incorporates a fan-cooled heat sink to reject waste heat at a high rate and allow for optimal cooling of the heat sink. The adaptability of the Oasys unit to any existing hydration pack will be achieved through a thermal wrap that is easily applied. Oasys as a final product is affordable, functional, and adaptable.
Proof of Concept
The proof of concept for the preliminary Oasys system consisted of simplified thermal testing. The product requirements indicate that the system needs to reach a cool temperature around 17 degrees Celsius or 62.5 degrees Fahrenheit. In order to confirm the concept and continue with further testing, the results needed to indicate that the temperature would be possible to reach. The testing apparatus consisted of a data acquisition system, a LABview program, a signal conditioner, a thermocouple, a quart freezer bag full of water, and the current design concept. The current design concept is composed of two high performance Peltier coolers, a heat sink, a 12v custom battery pack, and an axial fan all performing above our expectations. Expectations needed to be exceeded in order to prove the concept effectively and allo
w for reduction in certain areas of the design to improve size and energy efficiency. The testing procedure consisted of taking temperature data of the water over time as the Peltier coolers performed at their specified efficiency. Although the indicated temperature was never reached due to time constraints, results indicated that the water could be cooled down to the required temperature based on the constant and unvarying slope of the temperature data with respect to time. The data revealed that the Peltier coolers were able to cool the water at a rate of one degree Celsius every 3.5 minutes. Although this rate is not very fast, the performance of the coolers can be improved upon. Another test that will be conducted is to analyze the stabilization of the temperature of the water in a very hot environment. The test will ensure that the coolers will be able to extract any heat from the bag that is added to it by the hot environment simulating the product’s use in warmer climates. The test will need to include a control that will consist of a bag of water without insulation nor any cooling devise alongside an insulated and temperature controlled bag. The test in the heated environment will prove that the coolers can extract heat at the same rate that the environment adds heat to the bag.
The heart of Oasys’ device is the thermoelectric Peltier Cooler. This little plate has material inside that pumps heat from one side to the other whenever a voltage is applied to it. While the science behind the Peltier Cooler is pretty involved, the end result is a hot side and a cold side of the cooling module. By placing the cold side in contact with the water reservoir, heat can be removed, lowering the temperature of the water. Next the heat moves to the hot side of the Peltier Module, where it touches a heat sink. The heat sink has an array of fins that increase the surface area of the sink, and finally, the fans bring in air at ambient temperature, which is cooler than the fins, and the heat is removed.
The concept is a one-size-fits-all design that adds a thermoelectric cooler to an insulating pouch. The pouch will enclose a water reservoir inside the backpack and maintain a constant temperature of 16-20oC. A rectangular cut will be made in the pouch in order to conduct heat more effectively to the water from the cold side of the thermoelectric.Waste heat produced by the thermoelectric will be ducted out of the backpack and away from the consumer using a heat-sink and fan. Rechargeable light weight lithium ion batteries will power the electronics, and both the batteries and electronics will be waterproofed using Flex Seal®. Waterproofing will ensure that the cooling system will continue to work without interruption while keeping the customer safe. All of the components, including the batteries and pouch, will fit in the base of the backpack insuring that the weight is equally distributed throughout the system and does not hinder the movement of the user. To decrease the amount of heat that is transferred to the reservoir from the surrounding atmosphere, the reservoir and the cooling apparatus will be insulated with Neoprene. The entire Oasys system will be controlled with a temperature controller and a thermistor. The addition of a controller to the Oasys system will eliminate the amount of input by the user and allow the temperature to remain constant.
Oasys was designed from the beginning with fabrication in mind. Many of our parts are straight from the manufacturer. While the prototype’s case was 3D printed, future production runs of the system will be injection molded to the same specification as the 3D printed case. The Peltier Modules, fans, and heat sink were used in their shipped condition. First, the heat sink is inserted into the main housing, where thermal tape and Peltier coolers are attached. Next, the fan mounts and fan cages are glued to the fans, and then glued to the main housing to make a wind tunnel around the heat sink. Simultaneously, the fabrication for the insulating liner begins with cutting and sewing. All electrical components were soldered onto the bread board to decrease the amount of damage possible to the electrical component. The breadboard also simplifies the overall design and decreased the size of the circuit. The battery case snaps around the outside of the other case. The main housing and the entire water pouch will be set into the insulation shape pouch, and the Oasys system will be ready.
There were two test completed to evaluate the performance of the prototype. The first test was a control test, where the temperature of the water, with the prototype off, was measured at three different ambient air temperatures. The second test was the same as the control, but with the prototype turned on. The last test was a longevity test, measuring the run time of the system in an outdoor environment. Each test had 1.5 liters water in the water reservoir.
The Oasys Hydration Pack prototype met the main objectives that the team set for it. In a test environment with an ambient air temperature of 90ºF the cooling system cooled a liter of water at a rate of 1.1ºF/min, and hit the optimum water temperature in approximately six minutes. Insulation also proved to be way more effective at maintaining the water at a cool temperature than expected. The water temperature increased at a very slow rate of 2.5ºF every 90 minutes with a half inch of neoprene wrapped around the bladder.The batteries are capable of running the entire cooling system nonstop for four hours, which is already close to the five hour goal. This means that if the system was turned off after the controller ramped down the system at 16ºC, and turned back on after three hours it would keep the water in the 16-20ºC range and greatly extend the systems use off a single charge to well over the five hour objective. The entire prototype weighs 8.3 lbs, which is under the ten pound objective we set. The team was unable to meet the waterproof and impact resistant objectives due to time restrictions.
The pack excels at the main objectives outlined by the team. It is lightweight, cools the water to the optimal range, and can be ran for a long periods of time to meet the varying needs of outdoor enthusiasts. It could be improved by making the system waterproof by sealing all of the electrical components. The components could also be surrounded by damping material and arranged so that they would survive a fall from nine to ten feet and still work. If the team had more time and resources, waterproofing and making the pack impact resistant would be the main focus. Team Oasys was able to create a pack that achieved the majority of their objectives in the time frame given with the resources allocated to them. The pack is the first of its kind and could use some improvement, but it is definitely possible to create a portable hydration pack using peltier coolers in order to keep water at the optimal drinking temperature. In the future battery technology will improve; peltier coolers will become more efficient; creative designs could be implemented to a create a simpler, and more effective portable cooling hydration pack.
MEET THE TEAM
|Doug Stadler||Oasys’ team leader, Doug Stadler is a senior in mechanical engineering at the University of Nevada, Reno.|
|Chris Haas||Chris Haas is a senior pursuing his degree in mechanical engineering. He has been a member of the University of Nevada Cheer Team for the past four years. In his spare time he enjoys kite boarding, and snowboarding along side with designing and building prototype boards for use in the sport.|
|Tyler Creek||Tyler Creek is a senior in Mechanical Engineering. When he is not studying he is outside either dirt biking, snowboarding or playing paintball. His past work experiences include working on gold mine sites for Newmont.|
|Kyle Church||Kyle Church is a senior pursuing a bachelor’s of science in Mechanical Engineering and a minor is Business Administration. He is Currently Working as an intern at PCC Structurals in Carson City.|
|Jamie Dotras||Jamie Dotras is a senior in mechanical engineering and is the Secretary for the American Society of Mechanical Engineers.|