Hello, this is Zac, Andy, Joe, Grant, and Michael and we are team 11, The Average Joes! The 5 of us are senior mechanical engineering students graduating in the Spring of 2015. The Average Joes decided to design a cooler that cools beverages faster than a regular cooler. With a portable, hand-operated design, the Crank-n-Chill cooler will make tailgating, going to the beach, or many other activities much simpler.
Throughout the semester, the Average Joes have made multiple changes to the design. The group originally planned to design a teaching aid for golfers, but decided to change projects mid-semester. While this put the group behind in some aspects of the projects, the switch to the Crank-n-Chill cooler re-energized the group. The fundamental theory behind the Crank-n-Chill Cooler is that spinning a beverage in ice water causes convection between the beverage and the surrounding ice water. This process enhances the heat transfer, and is more effective than simple conduction (allowing the beverage to sit in ice water with no motion. CAD drawings can be seen below.
Proof of Concept
For a majority of the semester, the Average Joes were in the design phase of the project. While this planning was necessary, the group was unsure of how functional the cooler would be. The proof of concept portion of the course allowed the Average Joes to test how well the device would cool beverages, and how long this process will take. For the proof of concept, the Average Joes decided to design a makeshift drill bit that would latch onto the top of a beverage. The beverage was then put in ice water and the drill was turned on, spinning the beverage. The beverages began at room temperature and were cranked for two minutes. The target was to chill the beverage to 36 degrees, but the best test only reached 39 degrees. This is the biggest challenge the group will face in the future. The drill attachment can be seen below.
The Crank-n-Chill Cooler uses forced convection to cool six beverages in approximately two minutes. The design is composed of primarily two parts, the cooler and the spinning apparatus. The cooler part of the design is made up of traditional cooler materials to ensure maximum temperature insulation. An igloo cooler was modified to work with the Crank-n-Chill Design. The initial design consisted of a circular cooler but was later replaced with a square cooler due to volume and space requirements. The spinning apparatus consists of a set of gears, bolts, washers, a spinning handle, and beverage holders. The gear set has a fixed gear ratio with 1 main gear, 72 teeth, and 6 outer gears with 24 teeth. The outer gears are held in place with 5/16 fasteners, 5/16 nuts, and 5/16 steel washers. These gears are able to rotate freely on the secured fasteners using two bearings per gear. The bearings are pressed into the gears on both sides, in similar fashion as a skateboard wheel. The main gear is held in place by a 3/8 fastener, steel washers, and a captive nut. There is a hexagon cutout on the main gear that the 3/8 head bolt fits into, allowing the bolt to transmit its rotation to the rotation of the gears. The handle has a cutout that matches the hexagonal shape of the captive nut. To operate the spinning apparatus the handle is placed on the captive nut and then spun, transmitting the rotation from the handle to the main gear. Lastly, the big gear will rotate which in turn rotates the smaller gears. Attached to the smaller gears are the beverage holders. Renderings and Pictures of the Crank-n-Chill cooler can be seen below.
For the gears on our cooler lid, we 3D printed from our Solidworks renderings. We bought washers, bolts and nuts from Lowes and used these to attach the gears to the cooler. Our crank consisted of a simple spinning handle which was welded to a socket. This socket then slipped onto the captive nut which was attached to the lid. The captive nut was attached by drilling a hole in the center of the lid and consequently tightening two bolts together to avoid slipping. Our beverage holders were made out of rubber hollow tubes which had a tightening metal belt around the upper portion. This allowed the cans to slip in easily while also holding them in place when our Crank-N-Chill is being operated.
DFX and Human Factors Considered
When designing the Crank-N-Chill many factors were taken into consideration. The goal of the design is to be able to be used anywhere and by most any age. In order to meet this criteria, the Crank-N-Chill had to be designed for portability, ease of use, and manufacturing and assembly.
Design for portability
In order to ensure easy transportation of the Crank-N-Chill, a cooler with wheels and an extendable handle was chosen to be the platform of the design. In addition to being equipped with wheels, the cooler was just big enough to accommodate the necessary gears and beverages with providing sufficient volume to hold enough water and ice for many cycles of drink cooling. This allowed for the cooler to take up as little room as possible for storing and transporting.
Design for manufacturing and assembly
With the exception of the gears and crank, all parts for assembly will be purchased off the shelf. All custom gears will be 3D printed in order to be modified for easy assembly with pre-manufactured parts. Additionally, 3D printing allows for quick and easy production of replacement parts and modifications. The crank is made with a 9/16 socket to attach to the hex coupling nut. The coupling nut was chosen so the gear can be turned by other means than the supplied crank such as a drill.
Design for ease of use
The Crank-N-Chill is designed to be cranked with minimal effort allowing for less fatigue when spinning for long durations of time as well as for use by all ages. In order to meet this specification all gears must be able to rotate with minimal friction. Each small gear is designed to house two bearings, one on each side to allow for as close to frictionless spin as possible.
|Test #||1 Minute||2 Minutes|
|1||45º F||39⁰ F|
|2||50⁰ F||42⁰ F|
|3||44⁰ F||41⁰ F|
|Average||46⁰ F||41⁰ F|
Table 2: Testing Results
After completing the PoC testing, a better understanding of the physical heat transfer and beverage cooling time were obtained. It was noted that spinning the beverage indeed did cool the liquid down at a much faster rate than simply placing a beverage in ice water. However, after our target time of 2 minutes had passed, the liquid had not quite met the desired final temperature specified in the project. This impacted the design of the project by finding alternative ways to increase the rate of heat transfer from the beverage to the ice bath. It was determined that max RPM’s must be achieved by designing the highest gear ratio possible while also fitting the dimensions of the Crank-N-Chill cooler. Lastly, as seen in the calculations in the engineering analysis, increasing the temperature difference between the initial temperature of the beverage and the temperature of the ice bath will in turn increase our heat transfer rate. This will be achieved by using a rock salt, ice and water solution to be used as our cold fluid in the Crank-N-Chill cooler.
Laboratory Tests Plans and Results:
The proof of concept showed that the time taken to cool a room temperature beverage was considerably faster by spinning the can in ice water than it was by simply being placed in a cooler of ice water. Testing of the final prototype needed to be conducted in order to test the durability, reliability and functionality of the cooler design. To begin the experiment, the Crank-N-Chill cooler was filled halfway with ice and the remainder with water. An electric thermometer was used to test the temperature of the warm beverage as well as the ice water. After the ice water had reached roughly 32 degrees F, one of the room temperature beverages was placed into the beverage sleeve, the lid was closed and the crank was spun for two minutes. After two minutes, the beverage was removed and the temperature was taken. This test was performed by 6 different individuals in order to see if there was any fluctuation in final temperature with different individuals.
In addition to the temperature testing, the mechanical elements of the cooler were inspected for any kind of wear, cracks or deformations. After the first round of testing it was found that the main gear would often times slip around the rod if there was not a consistent rotational speed held throughout the two minutes. This issue was solved by redesigning the gear so that the hex head bolt would fit pressed into the gear as opposed to being pinched down with a washer and nut. After the final gear designs were printed and assembled, the same test procedure was done. All of the mechanical elements held up as expected with no cracking, wearing or deformations. The results of the initial and final temperatures of the beverages after the second six tests are shown in the figures below.
Figure 16: Temperature vs. Time graph
The results of this test showed that the final temperature reached an average of 42.2 degrees F. This compared very closely with our initial PoC testing of 41 degrees F.
Figure 17: Crank-n-Chill vs. Conventional coolers
The final test was to compare the final temperatures of the beverages from the Crank-N-Chill to the final temperatures of the beverages placed in a cooler. Before every test cycle was performed, a single beverage can was placed in a cooler for the two minute duration of the test. After the two minutes had passed the beverage was removed and its temperature was recorded. The final values of both the Crank-N-Chill and the cooler were averaged and are shown on the figure above
The results of the final prototype testing revealed that our target goal of 40 degrees is obtainable. In addition to quickly cooling the beverage from room temperature, further testing concluded that the Crank-N-Chill cooler reduced the temperature of the beverage by roughly 10 more degrees over a two minute time span than the conventional cooler. Outlined below are the design specifications, tests performed and their results.
|Able to crank for two minutes without overtiring||Different ages and gender||The younger population was unable to crank the cooler consistently for two minutes. However, it was found that the final temperatures from the slower cranking did not deviate much from the average.|
|Cool beverage to 40⁰F in two minutes||Multiple two minute cycles in ice water solution||The average final temperature was found to be 42.2 degrees F. Though slightly higher than the design specification it is within a reachable margin.|
|Structural components with low stress||Visual inspection after 20 cycles||
After three test cycles it was found that the main gear was slipping around the rod. New gear designs were fabricated and the issue was solved. No other signs of failure were detected.
Team 11 Average Joe’s Inc. would like to thank:
University of Nevada, Reno senior capstone class for providing the funding for our project
Daniel Wetta, Rachel Green, and Dr. Geiger for their help and support
Triton Manzo for mentoring us throughout our project
Tri-Dimensions 3D Printing for printing out our gears
Meet the Team!
Andy is a senior mechanical engineering student. He is expected to graduate in Spring 2015. His experiences include working in the HVAC industry as well as working for a SMT compnay that builds circuit boards as well as small mechanical builds. His experience in the electronics and circuit board industry will aid in the developing of the electrical aspect of the project.Zac WalshZac is a senior mechanical engineering student. He plans on graduating in the spring of 2015. He is not currently in an internship, but works on campus at the Joe Crowley Student Union as a supervisor. This experience gives Zac strong multi-tasking and problem solving skills.Granville ChapmanGrant is a senior studying Mechanical Engineering at UNR. He currently works as an intern at Hamilton Robotics. He was Born in the Bay Area and moved up to Reno to complete his engineering degree. His hobbies include wakeboarding, snowboarding, dirt biking, building motorcycles, and working on cars.Joe BetancourtJoe is a senior at UNR and is working towards his B.S in mechanical engineering with a minor in statistics. He is driven by the challenge that UNR has to offer in its Engineering program. Joe is looking to further his knowledge in the aeronautical aspect of engineering, and is expecting to graduate in the fall of 2015.Michael MoriartyMichael Moriarty is a senior mechanical engineering student. He is exspected to graduate in Spring 2015. His experiences include working as an intern in the HVAC industry for the past two years in the Bay Area. His experiences in the design and manufacturing processes in the HVAC industry will be helpful in the development and design of the project.