Incorporating under-cooling (sub-cooling) into a refrigeration cycle leads to_________________?
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Answer: A. increases COP
Explanation
Sub-cooling the liquid refrigerant increases the net refrigeration effect without increasing the compression work, thereby increasing the COP. By lowering the liquid enthalpy entering the expansion valve, each kilogram of refrigerant absorbs more heat in the evaporator. Because compressor power input remains unchanged, the resulting higher cooling capacity directly improves system efficiency. Coefficient of performance measures refrigeration efficiency as the ratio of cooling effect to electrical work input. Thermodynamic cycle optimization seeks methods to maximize enthalpy gains across the evaporator coil. Sub-cooling shifts the liquid line state to the left on pressure-enthalpy charts, expanding the refrigeration cycle envelope.
Energy-conscious facility managers install efficient liquid-suction heat exchangers to maximize sub-cooling benefits. Improving COP reduces facility operational costs and lowers carbon emissions associated with electricity generation. Modern commercial refrigeration units incorporate advanced sub-cooling coils to meet strict energy efficiency standards. Decreasing COP contradicts basic thermodynamic principles since sub-cooling consistently improves cycle efficiency. Stating that COP remains unaltered ignores the measurable increase in net refrigeration effect per unit mass. Sub-cooling results in completely predictable thermodynamic improvements rather than random or erratic performance.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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