P13421: Ice Pile Air Conditioning

Build, Test, Document

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System Build

Picture of complete system (Click to Enlarge):

Utilizing 80/20 as a frame for construction, components were installed with 80/20 T-nuts. All pluming was done with standard 1" Schedule 40 PVC. "Shark-bite" connectors were used to connect PVC to the 1" copper pipes of the radiator. All PVC pipes were glued using standard PVC primer and adhesive to prevent leaks.

Box was constructed from 18 gauge 1018 cold rolled steel sheets. 3 sheets were bent and welded and a plexi-glass window was sealed in place using silicon seal. A screen protecting the components from debris found in the ice was tack welded in place.

Removable insulation was attached to the outside of the tank.

Thermocouples were constructed and installed on the unit. Small holes were drilled into the PVC before and after the radiator. The thermocouples were siliconed into place to prevent leaks. An additional thermocouple was placed in the output airflow as a backup measurement for the COP.

Issues During the Build

Leaks were found in the plumbing but a simple overall tightening of joints resolved this issue.

Testing Plan and Technique

Part I: Determination of Spray Pattern

Since the constructed system was very similar to a standard air conditioner, the most interesting part of the unit was the way the ice melted and if it would affect the average COP of the system. Three individual spray patterns were brainstormed and tested.

Pattern 1: Standard single overhead input

Time Series of Ice Melt: (click on picture to view animation of 4 minute increments)

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Pattern 2: Cross pattern input

Time Series of Ice Melt: (click on picture to view animation of 4 minute increments)

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Pattern 3: Single down pipe input

Time Series of Ice Melt: (click on picture to view animation of 4 minute increments)

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After a test of each pattern, the standard single input was eliminated purely by data. The other two spray patterns were equally better, and a vote was conducted based on best melting and circulation patterns.

After reviewing the photos and observations, the down pipe was chosen as the best input. This input demonstrated excellent circulation as well as simplicity in implementation.

Part II: Optimization of Water:Ice Ratio

After selection of the spray pattern, a series of tests were completed to determine the optimal combination of water and ice. Ice volume was held at a constant volume of 30 L while water was varied. A technique of bisection was used to narrow down the intervals of water volume to an optimal value of 12.5 L.

Summary of Testing Results

Optimal Ice-Water Ratio

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Average COP Results

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For more detail, refer to the links below:

Final Presentation

Technical Paper

Final Poster

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