Question 1 Remove Topic Question Text Which thermodynamic diagram is specifically highlighted as a learning objective for refrigeration cycle analysis? Explanation The Day 3 objectives specifically mention learning to identify and interpret Mollier or pressure-enthalpy diagrams. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 2 Remove Topic Question Text What is the primary function of the reliquefaction plant during normal voyage? Explanation The reliquefaction plant continuously condenses boil-off gas to maintain cargo tank pressure within design limits. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 3 Remove Topic Question Text Which of the following is listed as an additional auxiliary function of the reliquefaction plant? Explanation Additional reliquefaction plant functions listed include hot gas line clearing, vapor purging ashore, and inter-tank vapor transfer. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 4 Remove Topic Question Text On a Mollier diagram, what does the vertical axis represent? Explanation The vertical axis on the Mollier diagram is absolute pressure, shown on a logarithmic scale. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 5 Remove Topic Question Text What does the horizontal axis on a Mollier diagram represent? Explanation The horizontal axis on the pressure-enthalpy or Mollier diagram is enthalpy, measured in kJ/kg. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 6 Remove Topic Question Text In a direct reliquefaction system, what is used as the primary cooling medium for the cargo condenser? Explanation Direct system reliquefaction plants use seawater as the primary cooling medium in the cargo condenser. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 7 Remove Topic Question Text Why do warmer seas reduce direct-system efficiency? Explanation Warmer seawater raises condensing pressure, reducing efficiency and increasing the compressor work required. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 8 Remove Topic Question Text What is a key benefit of intercooling between compression stages? Explanation Intercooling between compression stages reduces discharge temperatures and reduces throttling losses. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 9 Remove Topic Question Text Why are cascade systems essential for fully refrigerated Ethane/Ethylene cargoes? Explanation The presentation states that fully refrigerated Ethane/Ethylene cargoes require cascade systems because direct seawater cooling is not suitable. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 10 Remove Topic Question Text Indirect reliquefaction systems are essential for cargoes that cannot be mechanically compressed for what reason? Explanation Indirect systems are needed for chemically sensitive cargoes such as ethylene oxide and propylene oxide. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 11 Remove Topic Question Text Why is a liquid separator or knockout drum fitted ahead of the cargo compressor? Explanation Liquids are incompressible and can cause catastrophic liquid knock if they enter the compressor cylinder. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 12 Remove Topic Question Text During starting, why should the suction valve be throttled? Explanation The operational note states that the suction valve should be throttled during starting to avoid condensation within piping and compressor. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 13 Remove Topic Question Text What is a typical example of 3rd-stage ethane hot gas discharge conditions mentioned in the presentation? Explanation The presentation gives ethane 3rd-stage discharge as an example at about 28 bar and +135C. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 14 Remove Topic Question Text What is the usual temperature relationship between condensate leaving the condenser and the cooling medium? Explanation The condenser outlet condensate is typically around 5-8C warmer than the seawater or refrigerant temperature. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 15 Remove Topic Question Text What is the function of the condenser accumulator or receiver? Explanation The receiver collects condensed liquid so the condenser remains free of accumulated liquid and maintains maximum heat transfer area. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 16 Remove Topic Question Text Which factor will generally lower condensing pressure? Explanation Lower seawater or refrigerant temperature reduces condensing pressure. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 17 Remove Topic Question Text What is one major purpose of the economizer or intercooler? Explanation The economizer provides suction gas cooling between compression stages and also sub-cools condensate. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 18 Remove Topic Question Text What does NIC mean in reliquefaction operating modes? Explanation NIC means no inter-cooling in a two-stage compression mode. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 19 Remove Topic Question Text Where do foreign or incondensable gases collect if they do not condense? Explanation Non-condensables collect in the condenser accumulator above the liquid level because they do not condense at cargo conditions. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 20 Remove Topic Question Text What is a likely consequence of excessive non-condensables collecting in the system? Explanation As foreign gases accumulate, condenser accumulator pressure rises and compressors may trip on high pressure. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 21 Remove Topic Question Text Which vent gas disposal method is described as the preferred option for most operations? Explanation The vent gas cooler is preferred because it recovers condensable vapors before venting and minimizes cargo loss. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 22 Remove Topic Question Text What type of cargo compressor is used in the presentation's cargo system overview? Explanation The cargo compressor is described as a reciprocating, oil-free piston type with dry cylinders. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 23 Remove Topic Question Text What glycol mixture is recommended for compressor cooling? Explanation The presentation recommends a 50/50 weight mixture of nonethylene glycol and freshwater, with corrosion inhibitor. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 24 Remove Topic Question Text At what abnormal high discharge temperature is the cargo compressor listed to trip? Explanation One of the listed compressor trip conditions is abnormal high discharge temperature of 175C. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 25 Remove Topic Question Text How long should the oil separator heating element be activated before starting refrigerant compressors? Explanation The start-up sequence specifies heating the oil separator for approximately 2 hours before start. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 26 Remove Topic Question Text Before starting a cargo compressor, to what temperature should the compressor be warmed by glycol circulation? Explanation The normal starting procedure says not to start until the compressor temperature reaches 35C. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 27 Remove Topic Question Text What suction-side condition must be maintained to avoid liquid knock during continuous operation? Explanation The suction-side gas temperature must remain above the corresponding dew point to avoid condensation and liquid knock. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 28 Remove Topic Question Text What can happen if cold cargo is introduced into the cargo system without prior cooldown? Explanation Without cooldown, cold cargo can vaporize rapidly causing pressure rise and severe thermal stresses that may damage the tank. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 29 Remove Topic Question Text What is the stated target at the tank bottom during initial cooldown? Explanation The primary objective is to reduce steel temperature to as close as practical to cargo temperature, within 10C at the tank bottom. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
Question 30 Remove Topic Question Text If IBS pressure decreases too fast during cooldown, what action is recommended? Explanation When IBS pressure drops too quickly, manual control using the bypass may be necessary to maintain adequate pressure. Option 1 Remove Option 2 Remove Option 3 Remove Option 4 Remove Add Option
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