Refrigeration System | Section 7 |
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DISCHARGE LINE TEMPERATURE ANALYSIS General
Knowing if the discharge line temperature is increasing, decreasing or remaining constant can be an important diagnostic tool. Maximum compressor discharge line temperature on a normally operating ice machine steadily increases throughout the freeze cycle. Comparing the temperatures over several cycles will result in a consistent maximum discharge line temperature.
Ambient air temperatures affect the maximum discharge line temperature.
Higher ambient air temperatures at the condenser and/ or higher inlet water temperature = higher discharge line temperatures at the compressor.
Lower ambient air temperatures at the condenser and/or lower supply water temperature= lower discharge line temperatures at the compressor.
Regardless of ambient and water temperatures, the freeze cycle discharge line temperature will be higher than 160°F (71.1°C) on a normally operating ice machine.
Procedure
Connect a temperature probe on the compressor discharge line
Observe the discharge line temperature for the last three minutes of the freeze cycle and record the maximum discharge line temperature.
Discharge Line Temperature Above 160°F (71.1°C) At End Of Freeze Cycle:
Ice machines that are operating normally will have consistent maximum discharge line temperatures above 160°F (71.1°C).
Discharge Line Temperature Below 160°F (71.1°C) At End Of Freeze Cycle
Ice machines that have a flooding expansion valve will have a maximum discharge line temperature that decreases each cycle.
Verify the expansion valve sensing bulb is 100% insulated and sealed airtight. Condenser air contacting an incorrectly insulated sensing bulb will cause overfeeding of the expansion valve.
Verify the expansion valve sensing bulb is positioned and secured correctly.
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