First Experiment:

The first experiment (Expr #1) aims to:

1- Compressor operation test with nitrogen gas instead of R-134a,

2- Make sure that the Kelvinator refrigerator is running correctly

3- Ensure that the expansion valve is compatible with the design.

Therefore, the three heat exchangers (HX-N2/N2, HX-N2/O2 main, and HX-N2/O2 2nd) will be excluded from this experiment.

In this experiment, the oxygen will not be liquefied, but only the components will be tested and designed to ensure the proper functioning of the refrigeration cycle.

The first experiment consists of a simple cycle consisting of a compressor (LR25B Laboratory) with a condenser, cooling through a Kelvinator refrigerator, and an expansion valve (taken from an LR25B Laboratory refrigerator).

The components that must be provided to carry out this experiment:

• Filling the design with nitrogen gas, immediately before the pump.
• Covering the design with thermal insulation material to maintain the temperature of the refrigeration cycle,
• The presence of a thermometer (below -100˚C (173 K)) to measure the cooling outlet (an inlet of the expansion valve) and the outlet of the expansion valve,
• Also, a weather thermometer (from -10˚C to 20˚C (263 K to 293 K)) to measure the temperature of the compressor inlet.

For the safety of the compressor:

- In the first hour of operation, a 5-minute break must be taken for the compressor every 15 minutes of operation, in order to avoid an explosion of the compressor or one of the designed cables.

- Also, the compressor must not run for more than two hours in a row.

- Also, cold nitrogen gas must be entered into the compressor to reduce the speed of nitrogen flow, in addition to its role in cooling the compressor.

During this experiment (Expr. #1), the amount of nitrogen gas filled in the cycle, the time of the experiment, the temperature reached by the refrigeration cycle, and the pressure during operation will be calculated.

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