Final answer:
Capacity control on centrifugal liquid chillers is managed using inlet guide vanes, VFDs, and variable geometry diffusers to adjust refrigerant flow and match cooling load demands, ensuring efficient operation.
Step-by-step explanation:
Capacity control in centrifugal liquid chillers is typically achieved through various methods including inlet guide vanes, variable frequency drives (VFDs), and variable geometry diffusers. These technologies regulate the flow of refrigerant and adapt to the cooling load requirements, leading to energy efficiency and system reliability. Inlet guide vanes adjust the angle of the refrigerant flow entering the impeller, which can vary the chiller capacity. Variable frequency drives control the speed of the compressor motor, directly affecting refrigerant flow rates and capacity. Lastly, variable geometry diffusers can adjust the area through which the refrigerant is discharged from the impeller, which also affects the chiller capacity.
As an example, incorporating capacity control can greatly enhance the efficiency of a chiller system. If we consider a system based on a capacity of 200 L, taking in cold water at 5°C and heating it to 55°C, the energy required would be substantial. Proper capacity control mechanisms ensure that the system operates efficiently by adjusting to the actual cooling demand rather than running at full capacity at all times.