Absa 4B Power Engineering Exam Questions With Correct Verified Answers | 100% Pass (A+ Certified)

ABSA 4B POWER ENGINEERING EXAM QUESTIONS WITH CORRECT VERIFIED ANSWERS | 100% PASS (A+ CERTIFIED)The type of brine used for skating and hockey rink refrigeration systems is usually a) calcium sulphate b) calcium chloride c) calcium carbide d) calcium nitrate e) sodium chloride Answer B Refrigerant evaporators a) always have the refrigerant on the shell side b) are located between the expansion valve and the receiver c) may have brine pumped past the coils in an indirect system d) may be of the walk-in type e) are usually oil cooled Answer C Which of the following is NOT an advantage of a factory assembled packaged refrigerant? a) Components are designed to match each other. b) Parts can be ordered and installed separately. c) The unit is more compact. d) Space requirements are minimized. e) The unit is equipped with all the required auxiliary equipment. Answer B Which of the following statements about the economisers is false? a) It controls the flow of liquid refrigerant from the low pressure evaporator to the high pressure condenser. b) It is composed of two chambers. c) The upper float chamber is connected to the bottom of the condenser. d) The economiser float chamber is connected via the motor to the second stage inlet of the compressor. e) Liquid refrigerant levels in each chamber are controlled by a float operated valve in the evaporator. Answer A Which of the following is a result of an economiser on the refrigeration system? a) an intercooling effect on the compressor b) reduction of the power required for compression in the second stage compressor c) reduction of flash vapour in the evaporator d) increase in the refrigerating capacity of a system e) all of the above Answer E In actual systems there will be a gradual pressure drop through each side of the system due to a) the economiser b) friction in the evaporator, condenser, and piping c) decomposition of refrigerants d) coefficients of expansion of system components e) superheating effects Refrigeration Compressors Answer B Which of the following is not a function of the compressor in a refrigeration system? a) draw low pressure refrigerant out of the evaporator b) draw low temperature refrigerant out of the evaporator c) lower the temperature of the refrigerant d) maintain sufficiently low pressure in the evaporator e) raise the pressure of the refrigerant Answer C Which of the following is the compressor responsible for doing? i) Maintains a high pressure in the condenser ii) Maintains a low pressure in the evaporator iii) Raises the pressure of the refrigerant a) i only b) both i and iii c) both ii and iii d) iii only e) i, ii, and iii Answer E In a refrigeration system, the purpose of the compressor is to a) establish two pressure levels b) reject the heat from the system c) absorb the heat into the system d) regulate the flow of the refrigerant e) heat the refrigerant Answer A Which of the following compressor types uses impellers to draw in vapour? a) Centrifugal compressors b) Rotary compressors c) Reciprocating Compressors d) None of the above e) All of the above Answer A One negative factor of Hermetic type reciprocating compressors is a) the compressor and motor are mounted within the same housing b) the motor is cooled by the low pressure, low temperature vapour being drawn into the housing c) it does not have or require shaft sealing d) field servicing is not possible e) the compressor is driven by an electric motor Answer D In a rotating vane design rotary compressor, a good seal is maintained between the vanes and the cylinder by a) centrifugal force b) the oil c) high pressure refrigerant vapour d) low pressure suction e) the eccentric rotor size Answer A