Units of power vs thermal energy in refrigeration:

• Power is the time rate of energy consumption ($1\text{ W} = 1\text{ J/s}$). The electrical/mechanical power input consumed by refrigeration compressor drives is measured in kilowatts ($\text{kW}$). Specific power consumption is expressed as $\text{kW/TR}$.
• Kilocalorie ($\text{kcal}$) is a metric unit of thermal heat energy, not power.
• Kilojoule ($\text{kJ}$) is an SI unit of energy/work.
• British thermal unit ($\text{Btu}$) is an imperial unit of thermal energy.

Design features of hermetically sealed refrigeration compressors:

• In a hermetic compressor, the motor and compressor are mounted on a common shaft and completely enclosed within a welded, gas-tight steel casing without external shaft seals, effectively eliminating the primary source of refrigerant leakage to the atmosphere.
• Lubrication is self-contained and simple (splash or forced internal oiling).
• Hermetic compressors are quieter due to internal spring suspension and acoustic muffling within the welded shell.
• The electric motor is internal, not external.

Refrigerant metering and liquid level controllers:

• Condensers liquefy compressed discharge vapor.
• Capillary tubes provide fixed frictional pressure drop without modulating to liquid level variations.
• float valve (specifically a low-pressure float valve in flooded evaporators) responds directly to liquid refrigerant level inside the surge drum/evaporator shell, opening to admit makeup liquid when the level drops and closing when the target flooded level is satisfied.
• Filters remove particulate debris.