What action would lead to an increase in system efficiency?

Choosing to reduce the specific volume at the compressor inlet is indeed a sound action that leads to an increase in system efficiency. When the specific volume is reduced, it indicates that the refrigerant is denser, allowing the compressor to draw in more mass flow of refrigerant. This is particularly important because a higher mass flow can enhance the heat transfer capabilities of the system, improving the overall cooling performance.

In compressor systems, efficiency is critical as it determines how effectively the system operates to transfer heat. A denser refrigerant at the inlet allows the compressor to perform work more effectively, which can lead to lower energy consumption for the same cooling output.

In contrast, increasing the compressor inlet temperature would generally result in lower efficiency due to increased energy input into the system without a corresponding increase in cooling effect. Increasing refrigerant charge can lead to an overcharged system, which may cause issues like increased pressure and decreased efficiency. Lastly, elevating the ambient temperature may increase the workload on the system, further decreasing efficiency as it must work harder to maintain the desired temperature. Therefore, reducing the specific volume at the compressor inlet stands out as the most effective means to enhance the efficiency of the system.