4Th Class Power Engineering B2 C124

Front 1

Which statement is false for a typical absorption chiller start up sequence?A) A dilution cycle and system shutdown is initiated if the chilled water temperature drops below the control rangeB) Automatic controls ensure that each step is completed before the next step is initiatedC) The chilled water pump is started after the absorption unitD) The cooling tower fan is controlled by the cooling water temperature controllerE) The condenser cooling water pump is started before the absorption unit

Back 1

C

Front 2

What is the direct connection between the generator and the absorber in a lithium bromide absorption chiller called?A) the heat exchanger bypassB) the absorber inletC) the generator feedD) the precipitatorE) the level equalizer

Back 2

A

Front 3

During seasonal start-up, when should the purge pump be started?A) Simultaneously with the absorption unitB) One half hour before the absorption unit is startedC) At least 24 hours after the compressor is startedD) About one half hour after the absorption unit is startedE) Only when noncondensables are detected in the system

Back 3

D

Front 4

How many pumps are there in a lithium bromide absorption chiller?A) 1B) 2C) 3D) 4E) 5

Back 4

C

Front 5

The heat exchanger bypass, in a lithium bromide refrigeration system, is a direct connection between what two system components?A) concentrator, generatorB) concentrator, evaporatorC) concentrator, absorberD) evaporator, absorberE) evaporator, condenser

Back 5

C

Front 6

In a lithium bromide absorption chiller, why is the concentrated solution mixed with diluted solution?A) to raise the saturation temperatureB) to prevent crystallizationC) to lower the vapour pressureD) the achieve equilibriumE) the reduce the concentration

Back 6

B

Front 7

When the concentration of a saltwater solution decreases, which of the following statements is true?A) The vapour pressure increasesB) Less water molecules leave the solutionC) The vapour pressure decreasedD) The vapour pressure is not affectedE) Less water molecules are absorbed back into the solution

Back 7

A

Front 8

A ________ cycle is performed during the shut-down of an absorption refrigeration system to prevent ________ .A) condensation, vapourizationB) vapourization, condensationC) dilution, condensationD) dilution, crysallizationE) concentration, dilution

Back 8

D

Front 9

Which of these statements are true for a closed tank, partially filled with a saltwater solution, at a temperature well below the boiling point of the solution? 1. Some molecules of water vapour will excape from the solution2. There will be a steady stream of water vapour molecules leaving and entering the solution3. No molecules of water vapour will excape from the solution4. No molecules of water vapour will be absorbed into the solution5. Some molecules of water vapour will be absorbed back into the solutionA) 1, 2, 5B) 2, 3, 4C) 1, 2, 4D) 2, 3, 5E) 3, 4

Back 9

A

Front 10

When the temperature of a solution increases, which of the following statements is true?A) The vapour pressure is higherB) Less water molecules leave the solutionC) The solubility of the salt decreasesD) The concentration decreasesE) The equilibrium constant decreases

Back 10

A

Front 11

Regardings hermetically sealed motors, the stator electrical windings are sealed to prevent what?A) contact with bearing greaseB) contact with the fluid being pumpedC) overlubricationD) subcoolingE) contact with steam

Back 11

B

Front 12

The concentration of Lithium Bromide in an absorption refrigerating system will change during which of the following steps?A) Going through the expansion valveB) Going through the suction valveC) Cooling through the heat exchangerD) Absorbing water vapour in the absorberE) None of the above

Back 12

D

Front 13

The low pressure side of a lithium bromide absorption chiller consists of which parts? 1. the generator2. the evaporator3. the condenser4. the absorberA) 1, 2B) 2, 3C) 3, 4D) 1, 3E) 2, 4

Back 13

E

Front 14

Octyl alcohol is added to the lithium bromide solution to:A) act as a drying agentB) act as a wetting agentC) help the lithium bromide solution absorb ammoniaD) help the lithium bromide solution absorb non-condensable gasesE) act as a dispersing agent

Back 14

B

Front 15

Which statement is true for the heat exchanger bypass on a lithium bromide absorption system?A) The upper loop of the bypass tube forms a loop sealB) The lower loop of the bypass tube forms a loop sealC) The bypass valve is closed on start upD) The bypass allows non-condensable gases to escapeE) The bypass prevents the return of hot solution from the absorber.

Back 15

B

Front 16

This occurs when the temperature of a strong but still unsaturated solution is lowered so far that its salt concentration exceeds the maximum concentration possible at the lower temperature.A) IonisationB) DissociationC) CrystallisationD) VaporisationE) Neutralisation

Back 16

C

Front 17

What types of purge systems are there in lithium bromide absorption chillers? 1. hermetic2. saturated3. mechanical4. automaticA) 1, 2B) 2, 3C) 3, 4D) 1, 3E) 2, 4

Back 17

C

Front 18

What will happen if you try to add more salt to a salt/water solution which is saturated?A) the solution's temperature will dropB) the solution's pressure will decreaseC) the water will crystallizeD) the solution will thickenE) the salt will precipitate, not mix

Back 18

E

Front 19

If a saturated water/salt solution is heated, what will happen?A) the salt will crystallizeB) the solution will become unsaturatedC) the salt will precipitate out of solutionD) the vapour pressure will dropE) the solution will separate

Back 19

B

Front 20

Which statement is false for a typical absorption chiller start up sequence?A) The unit is controlled by the chilled water temperatureB) The start up sequience is initiated by a manual pushbuttonC) The condenser cooling water pump is started after the chiller pumpD) The cooling tower fan is started firstE) The absorber and generator pumps are started automatically after the absorber unit start is initiated

Back 20

D

Front 21

Which of the following is NOT a result of having noncondensable gases in the absorption systems?A) CorrosionB) Oxidation of Lithium BromideC) Lower than normal temperatures of the chilled water leaving the evaporatorD) Reduction in capacity of the systemE) Crystallisation in the heat exchanger

Back 21

C

Front 22

Which of the following is a daily check for an absorption refrigeration system?A) lubricate the mechanical purge pump motorB) clean the strainers onthe steam and condensate systemC) clean the magnetic strainersD) check the oil level in the circulating pumpsE) check the pH and TDS of the cooling water

Back 22

E

Front 23

If there is a crystallisation upon shutdown a possible corrective action is to:A) add octyl alcohol chargeB) purge the systemC) adjust cooling tower controlD) check pump operationE) reduce steam pressure

Back 23

D

Front 24

What are the two purposes of the heat exchanger bypass in a lithium bromide absorption chiller? 1. to limit the level in the generator2. to lower the concentration of the concentrated solution3. to pass crystals directly to waste4. to direct heated concentrated solution back to the absorber 5. to dilute the solution upon shutdownA) 1, 5B) 2, 3C) 3, 4D) 1, 4E) 3, 5

Back 24

D