RETA INDUSTRIAL REFRIGERATION BOOK 2 (2013 Revision) NEWEST 2024 ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT DETAILED ANSWERS (VERIFIED ANSWERS)

B) Consume more hp per CFM of air moved C) Are quieter D) Have fewer components to maintain - ANSWERS,C) Are quieter The operating engineer? (pg. 1-7) A) Cannot change the 'k' factor of the metal but has some control of the overall 'U' factor for the evaporator as a unit B) Can increase 'k' factor by increasing the air velocity over the evaporator and has some control of the overall 'U' factor for the evaporator as a unit C) Should allow frost to collect on the evaporator increase 'k' factor D) Can increase 'k' factor by starting another compressor - ANSWERS,A) Cannot change the 'k' factor of the metal but has some control of the overall 'U' factor for the evaporator as a unit The limiting factor of an evaporator's capacity that the operator cannot control is? (pg. 1-7) A) Suction Temperature B) Suction Pressure C) Evaporator Size D) Refrigerant Liquid Feed Flow - ANSWERS,C) Evaporator Size The best way to keep an evaporator from being affected by oil build-up is to? (pg. 1-8) A) Operate the system at the correct evaporator temperature B) Periodically remove oil from the oil collection points C) Set hot gas defrost cycle for a minimum of 30 minutes D) Increase air flow across the evaporators - ANSWERS,B) Periodically remove oil from the oil collection points The effectiveness of a heat transfer surface depends on several factors. One factor the operator has control over is? (pg. 1-8) A) Evaporator surface area B) Material the evaporator is made of C) Type of fans used D) Cleanliness of the evaporator - ANSWERS,D) Cleanliness of the evaporator One advantage of using axial type fans is? (pg. 1-12) A) Quieter operation B) They require less motor horsepower per CFM C) They can move air further across the space to be cooled D) They can work against a higher static pressure - ANSWERS,B) They require less motor horsepower per CFM Which of the following is NOT a result of scale build-up on a condenser coil? (pg. 1-13) A) Reduced heat transfer B) Increased operating cost C) Increased 'U' value D) Increased condensing temperatures - ANSWERS,C) Increased 'U' value If 'R' value is doubled, what will happen to the heat transfer rate (assuming the temperature difference and the area do not change)? (pg. 1-13) A) The rate of heat that is transferred will be double B) The rate of heat that is transferred will be cut in half C) The rate of heat that is transferred does not change D) The conductance is doubled so that heat transfer rate is increased - ANSWERS,B) The rate of heat that is transferred will be cut in half What happens to the theoretical capacity of an evaporator in a 0°F freezer if the ammonia evaporating pressure is dropped from 8.96 PSIG to 6.11 PSIG? (pg. A) The capacity of the evaporator is reduced by 50% B) The capacity of the evaporator is doubled C) The capacity of the evaporator is not changed D) The capacity of the evaporator is increased by 50% - ANSWERS,C) The capacity of the evaporator is not changed Damaged insulation on the suction line in an ammonia refrigeration system will? (pg. 1-14) A) Not change the efficiency of the system because suction pressure will not change B) Cause efficiency loss and potential damage to the suction line C) Look bad but will not cause any major problems D) Cause an efficiency loss but will not cause any other problems - ANSWERS,B) Cause efficiency loss and potential damage to the suction line Enthalpy is? (pg. 2-2) A) A measure of total energy (heat content) per pound of refrigerant measured in BTU's B) The net heat absorbing capacity of the refrigerant after the point of expansion C) The amount of cooling effect that can be obtained from a refrigeration system D) Heat that cannot be measured through a change in temperature - ANSWERS,A) A measure of total energy (heat content) per pound of refrigerant measured in BTU's The enthalpy diagram? (pg. 2-6) A) Illustrates the changes of condition and heat content of a pound of refrigerant at different points of the refrigeration cycle B) Illustrates the total heat transfer capacity of the system from evaporators through condensers in tons of refrigeration C) Utilizes two scales, pressure and tons of refrigeration D) Does not take into account the effect of flash gas - ANSWERS,A) Illustrates the changes of condition and heat content of a pound of refrigerant at different points of the refrigeration cycle The enthalpy diagram has three regions of refrigerant condition which are? (pg. 2-10) A) Solid, Liquid and Gas B) Subcooled Liquid, SAT Liquid and Vapor, and Superheated Vapor C) Hot, Medium, and Cold D) Flash Gas, Subcooled Liquid, Subcooled Liquid and Flash Gas - ANSWERS,B) Subcooled Liquid, SAT Liquid and Vapor, and Superheated Vapor The pressure scale on an enthalpy diagram typically used in the U.S. is expressed in? (pg. 2-8) A) Kilopascals B) PSIG C) PSIA D) Newtons - ANSWERS,C) PSIA In a refrigeration system (at normal refrigeration pressures), how does the heat content of a pound of saturated vapor compare to the heat content of a pound of saturated liquid? (pg. 2-10) A) The heat quantity in a pound of saturated vapor is greater than the heat quantity in a pound of saturated liquid at the same pressure B) The heat quantity in a pound of saturated vapor is less than the heat quantity in a pound of saturated liquid at the same pressure C) The heat quantity in a pound of saturated vapor is equal to the heat quantity in a pound of saturated liquid at the same pressure D) It is not possible to measure heat content in a pound of saturated vapor - ANSWERS,A) The heat quantity in a pound of saturated vapor is greater than the heat quantity in a pound of saturated liquid at the same pressur