Introduction :
Discussed during our meetings related to Project A.S.H.E. is the unknown effectiveness of the proposed method of optimized cross-flow ventilation as compared to that of a purely exhaust based ventilation and that of a non-optimized cross flow that are used in similar products. The initial testing done will provide various pieces of temperature data at 4 points along the vehicle as well as the interior surface temperature of the dashboard, front seat, and back seat while making note of shading and differences in said temperature. This data will then be analyzed and conclusions drawn if any are apparent.
Test Setup :
As proposed in our project, a set of 4 centrifugal fans were mounted to an apparatus to be placed within the window of the vehicle. For this test, cardboard sheets were used with the outlet of the fans placed in the proper direction using additional cardboard and duct tape as necessary. The orientation of the fans for day 1 are shown below.
The orientation of the fans on the lower mount are done so that the intake on day two can be done easily by simply flipping the mount around. These mounts are then placed within the rear windows of a 2012 Kia Soul which is parked in the driveway. As the sun passes overhead throughout the day, the car is oriented roughly toward the South-East. The sun rises in roughly the same direction and has a heading that has it setting in roughly the South-West relative to North so as the day progresses, there is an imbalance in exposure to sunlight across the vehicle internally and externally but there are not obstructions such as walls or trees to provide shade. Only the car body and internal seats will cast shadows.
Within the Kia soul we place 4 internal sensors, one placed on the driver seat, one on the passenger seat, one on the back driver seat, and one on the back passenger seat. Then 4 external sensors are placed on the doors corresponding to these same sensors to read the external temperature of the vehicle. For surface temperatures within the car and the external portions of the car, an IR thermometer is used to gather data related to the Temperature of the Dashboard, Front Seat, and Back Seat and chassis at the sensor locations. The sensors are simply referred to as 1, 2, 3, and 4 denoting whether it is internal or external in our data gathering spreadsheet. The placement follows the chart shown below.
Figure 1 : Sensor Placement on Test Vehicle [1]
Power to the fans is provided via 2-Variable Power supplies connected to power via an extension cord that is routed beneath the ventilation mount. The fans used for this test were rated for 5V at 0.25A.
Day 1 : Exhaust Ventilation Only
Both fan and mounts were oriented such that all airflow would be out of the vehicle similar to existing products. Mounts placed at Sensors 2 and 4.
Initial temperature readings were taken at 11:00am with readings being taken every hour for 6 hours in order to see the change in temperature within and around the vehicle over time.
Day 2 : Cross-flow Ventilation
Fan mount near sensor 4 was shifted to point inward. Fan mount near sensor 2 was flipped to face outward. Crossflow is across backseat in a similar configuration to existing products. Initial temperature readings were taken at 11:00am with readings being taken every hour for 6 hours in order to see the change in temperature within and around the vehicle over time.
Day 3 : Optimized Cross-flow Ventilation
Fan mount near sensor 4 was moved to sensor three position and faced outward. Fan mount near sensor 2 was flipped to face inward. Crossflow is optimized, mount near sensor 2 corresponds to area of vehicle with lowest temperature over days 1 & 2, mount near sensor 3 corresponds to area of vehicle with highest temperature over days 1 & 2.
Initial temperature readings were taken at 11:00am with readings being taken every hour for 6 hours in order to see the change in temperature within and around the vehicle over time.
Results and Conclusions :
Results from the test are placed within an excel spreadsheet linked below
https://docs.google.com/spreadsheets/d/1mX9txdwakynS5VN1EHQMDHqK-oeoGAkVcDUNEGJCUQk/edit?usp=sharing
Summarizing the findings in the spreadsheet, there is a gradual increase in the temperature over the course of the day peaking between 1:00pm and 4:00pm. Any sensors exposed to direct sunlight have a much higher temperature than those not exposed to sunlight. External Sensors 1 and 2 were typically not exposed to direct sunlight due to the orientation of the car. External Sensors 3 and 4 were almost always in sunlight. Sunlight exposure corresponds almost directly with increased temperature whether internal or external.
The exhaust test acted as a baseline by which both crossflow methods would be compared against and was done so on a partly cloudy day.
Despite the exposure to sunlight being far greater on Day 2, the cross flow method managed to keep the average internal temperature at 116°F which is only 3 degrees higher than the previous day despite the average internal surface temperature being 11 degrees higher.
On Day 3, the test had to be called early due to potential rain. The day started cloudier than that of Days 1 and 2, but remained sunny throughout the majority of the test having an average internal and external surface temperatures that were only 2 to 3 degrees lower than that of Day 1. Although the cloud coverage could account for the difference, given that the peak temperatures of the various surfaces were higher faster, it stands to reason that the sun exposure for Day 1 is roughly comparable with that of Day 3 overall. The internal temperature difference between Day 1 and 2 is a notable 8 degrees.
Conclusions :
The exhaust method is only marginally effective. Pursuing this method would not be worth doing as there is not enough heat removed from the vehicle. Crossflow appears to be effective as the increase in sun exposure on Day 2 resulted in a nearly 11 degree increase in surface temperature, but only a 3 degree increase in the air temperature within the vehicle.
The Optimized Crossflow when compared to exhaust is much better at removing heat. The average internal temperature was degrees lower despite there only being a 2 degree difference in various surface temperatures. The tests for Crossflow vs Optimized Crossflow will need to be re-run under similar conditions.
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