Question 2Refrigeration/AC - 1st Asst/Chief70% to pass
The fluid used as a source of actuating power against the underside of the unloader power element piston of the refrigeration compressor capacity control mechanism illustrated is obtained from where? Illustration GS-RA-13
AI Explanation
The correct answer is B) discharge of the compressor lube oil pump.
The fluid used as a source of actuating power against the underside of the unloader power element piston of the refrigeration compressor capacity control mechanism is obtained from the discharge of the compressor lube oil pump. This pump circulates lubricating oil throughout the compressor, and a portion of this pressurized oil is diverted to provide the necessary hydraulic force to actuate the unloader mechanism and control the compressor capacity.
The other options are incorrect because: A) the gas discharge from the compressor would not provide the necessary hydraulic power; C) the high side liquid receiver does not contain a pressurized fluid source; and D) a secondary hydraulic pump is not typically used for this purpose in standard refrigeration compressor capacity control systems.
Related Questions
#1 Capacity control of a centrifugal refrigeration compressor can be accomplished by what means? #3 During operating periods of a multi-box refrigeration system using a capacity controlled compressor, when all of the evaporators of a four box plant are actively being fed with liquid refrigerant, the control oil pressure acting on the hydraulic relay piston will be at what value? Illustration GS-RA-13 #4 On a modern refrigerated container unit employing suction modulation for the purposes of capacity control and capacity limitation, what happens when the applied voltage and current draw associated with the normally open (NO) suction modulation valve located in the suction line both increase? #5 A refrigeration compressor used in a multi-box refrigeration system is designed with six of its eight cylinders able to be controlled for variable load conditions. If all of the reefer boxes are currently feeding, what percentage of the total number of compressor cylinders will be loaded after start up?