RETA Industrial Refrigeration Book I Exams Study Guide, Exams of Refrigeration and Air Conditioning

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RETA Industrial Refrigeration Book I Exams Study Guide

As defined in Chapter one of this text, the primary purpose of a refrigeration system it Lo? (pg. 1-3) A) To freeze food B) To cool buildings C) To preserve food D) To maintain a lemperature - © ‘K-D) To maintain a Lomporature ich of the following best describes the areas of required knowledge for this to be possible? (pg. 14) Operators must keep refrigeration systems operating safely and efficiently. /\) Basic physical principles, interpretation of informalion from temperature and pr ure gauges, basic operating principles B) Basic physical principles, interpretation of information from temperature and pressure gauges, manufacturer of the equipment C) Interpretation of information from temperature and pressure gauges, basic operating principles, company quality control policies and procedures D) Interpretation of information from Lempcralure and pressure gauges, mamafacturer of the equipment, company quality control policies and procedures - CORRECT ANSWER- /\) Basic physical principles, interpretation of information from temp: gauges, basic operating principles Mechanical refrigeration is a scries of sleps thal? (pg. 1-2) A) Moves heat energy from a space or object to an area where it can do no harm B) Adds cold Lo a space or obicct. C) Transforms heat energy into cold energy to reduce the temperature of the area to be cooled D) Utilizes the cooling effect of compressing a gas to reduce the temperature in a space or object - ‘ ANSWER-A) Moves heat energy from a space or object to an area where it can do no harm Heat energy always flows? (pg. 1-23) A) From a substance with more heat energy [measured in BTUs] to a substance with less heat energy [ measured in BTUs] B) Regardless of temperature C) From an object at a higher temperature to an object at a lower temperature D) From a liquid to a vapor - C) From an object at a higher temperature to an object at a lov Sensible heat? (pg. 1-22) A\) Is measured using a pressure gauge B) Is always between 32° F and 212° F C)Is heal energy that causes a change of slatc but docs not cause a change in temperature Dy Is heat cnergy that causcs a change in Lemperature but does not cause a change of CORRECT ANSWER_D) Is heat energy that causes a change in temperature but does not cause a change of state sta Latent heat? (pg. 1-22) A)Is measured using a pressure gauge B) Can be sensed by using a thermometer C) By removing heat energy from an object or area D) By increasing the molecular vibration of an object - CORRECT ANSWER-C) By removing heat energy from an object or area Which of the following is used to measure the quantity of heat energy? (pg. 1-21) A) British Thermal Units (BTUs) or Calories B) Pascals and Kilopascals C) Degrees Kelvin D) Degrees Celsius or Fahrenheit - CORRECT ANSWER-A) British Thermal Units (BTUs) or Calories Which of the following are used in heat calculations? (pg. 1-40 -A) Mass, sensible heat, temperature, specific heat. B) Mass, latent heat, temperature, specific heat C) Mass, sensible heat, heat of cooling, change of state D) Mass, latent heat, temperature. heat of refrigeration - CORR. ANSWER-B) Mass, latent heal, lomperauurc, specilic heal. Latent heat of vaporization? (pg. 1-22) Ajls calculated using temperature B) Is always going to raise the temperature of the liquid it is trying to bail CyIs the heat energy required Lo cause a liquid Lo become a vapor D) Is the same for all liquids cause a liquid Lo became a vapor Pressure is a measure of? (pg. 1-11) A) The action seen from the attraction of gravity B) Weight C) The relationship of a force being applied over a given area D) The distance between the top of the piston and the dischar: compressor - C' given area The relationship between temperature difference and heat flow is? (pg. 1-23) A) There is no relationship between temperature and heat flow he slower heat flows B) The greater the temperature differenc: C) The greater the temperature difference, the more rapid heat flows D) The more rapidly the heat flows the greater the temperature increases - CORRECT Specific heat? (pg. 1-29) A\) Is groaler as the substanee requircs more heal energy Lo increase Lempcralure B) Is less as the substance requires more heat energy to increase temperature C)Is 1 BTU/Ib/degree Fahrenheit for all substances D) Is related to change of state, not temperature change of a substance - CORRECT ANSWER-A) Is groalor as ihe subslance requires more heal energy Lo inercase Temperature is a measure of? (pg. 1-18) A) The latent heat of an object B) Heat of fusion that has been absorbed by an object e of a reciprocating WER-C) The relationship of a force being applied over a B) 7.35 PSIG €) 7.35 in. Hg D)0 in. Hg- CORRECT ANSWER-A) 7.35 PSIA Which of the answers below is an example of heat transfer by conduction? (pg. 1-35) A) The sun’s rays B) Arod heated on one end becoming warm at the other end C) Product being frozen in a blast freezer heated on one end becoming warm at the other end Which answer below represents the two most common forms of heat transfer in refrigeration? (pg. 1-36) A) Conduction and radiation B) Conduction and convection C) Convection and radiation D) Conduction and sensible heat - CORRECT. WER-B) Conduction and convection If specific heat for air is 0.24 BTUAb/*? F and the specific volume is 12.7 cubic feet/lb., how much heat energy must be removed to cool the air in a room that is 16’ x 12’ x 8’ from 70° Fito 40° F? (pg. 1-40) A) 121 BTUs B) 1536 BTUs C) 29 BTUs D) 871 BTUs - CORRECT ANSWER-Room Volume: (16 x 12 x 8) = 1536 cubic feet Total pounds of air: (total room volume/specific volume of air Total pounds of air: (1536 / 12.7) = 121 pounds of air Sensible Heat Equation: M x Cp x Temp. Change Sensible Heat Equation: 121 x 0.24 x (70-40) = 871 BTUs D) 871 BTUs The condition of boiling liqnid is? (pg. 1-30) A) Always hot B) Always superheated C) Subcooled D) Saturated - CORRECT. WER-D) Saturated Agallon of milk weights 8 pounds. If it leaves the cow at 90° F and must be cooled to 35° F. how many BTUs must be removed in the cooling process? (pg. 1-40) A) 409 BTUs B) 40. BTUs €) 440 BTUs D) 51.15 BTUs - CORRECT ANSWER-Q =M x Cp x Change in Temp. Q=8 x 0.93 x55 = 409 BTUs A) 409 BTUs A meat plant process 100 animals a day with an average processed weight of 730 pounds of beef per animal. The meat must be cooled to 45° F from 85° F. How many BTUs must be removed in the cooling process? (pg. 1-40) A) 3,000,000 BTUs Fahrenheit = (9 x -6.7)/3) + 32 =20 B) 20° F The condition of a liquid that exists at a temperature below its boiling point is? (pg. 2-12) A) Superheated B) Subcooled C) Saturated D) Permeated - CORRECT ANSWER-B) Subcooled Why does the refrigerant in the condenser change state from vapor to liquid? (pg. 2-4) /\) The pressure is decreased by the compressor B) The refrigerant runs down into the receiver C) The refrigerant loses heat energy to the surrounding environment D) The fans increase the pressure to above saturation - CORRECT ANSWER-C) The refrigerant loses heat energy to the surrounding environm The expansion valve controls only one of the items below. Which is it? (pg. 2-2) A) The flow of liquid into the evaporator B) The pressure in the evaporator C) The pressure in the receiver evaporator Which of the following is a true statement? (pg. 2-16/17) A) 10PSIA is greater than 10 PSIG B) 10 PSIG is equal to 10 PSIA C) 10 PSIG is a greater pressure than 10 PSIA D) 10 PSIG and 10 PSIA use different scales and therefore cannot be compared in this ANSWERC) 10 PSIG is a greater pressure than 10 PSIA way - C Flash gas is? (pg. 2-2) A) Only the gas created at the expansion device B) The gas used to defrost evaporators that use gas defrost systems C) The gas created anytime liquid refrigerant evaporates ‘RLA) Only the gas created at the expansion device Which of the answers below is an example of a pressure drop? (pg. 2-21) A) The difference in pressure due to refrigerant “dropping” in a vertical pipe riser B) Ina compressor, the difference in pressure when the piston is at top dead center and bottom dead center C) The loss of pressure as a fluid moves down the pipe duc to the interaction of the fhiid and the inner walls of the pipe D) The change in pressure between the condenser outlet and the high pressure receiver - € interaction of the fluid and the inner walls of the pipe ‘-C) The loss of pressure as a fluid moves down the pipe due to the Refrigerant absorbs the most heat when? (pg. 2-6) A) Superheated B) Subcooled C) Changing from liquid to vapor (pg. 2-2) A) Evaporator, condenser, receiver, compressor B) King valve, gauges, thermometers, amp meter C) Expansion device, evaporator, compressor, condenser D) Evaporator, condenser, king valve, compressor - CORRECT ANSWER-C) Expansion device, evaporator, compressor, condenser Aconventional mechanical refrigeration system is considered? (pg. 2-1) A) An expendable refrigerant system B) A closed loop system ©) An open loop system D) A multi-loop system - CORRECT. Superheat is found at which points of a typical system? (pg. 2-13) A) The compressor suction and the liquid line B) The compressor suction and the high-pressure receiver inlet C) The condenser outlet (CD) line D) The compressor suction and compressor discharge line - CORRECT ANSWER-D) The compressor suction and compressor discharge line Which of the following is not a true statement about heat of compression? (pg. 2-14) A) It happens to all refrigerants in mechanical refrigeration systems Bj It is the energy that is applied to vapor by the compressor reducing the volume C)It is one reason why a condenser must be sized larger than the evaporator load D) It improves the operating efficiency of most systems by improving condensing rate - CORRECT ANSWERD) It improves the operating efficiency of most systems by improving cond In an operating ammonia refrigeration system, subcooled refrigerant can only be? (pg. 2- 13) A) Solid B) Liquid C) Vapor D) Combination of liquid and vapar - CORR: ANSWER-B) Liquid Superheated refrigerant can only be? (pg. 2-14) AN) Solid B) Liquid C) Vapor D) Combination and liquid and vapor - CORRECT ANSWER-C) Vapor Saturated refrigerant can? (pg. 2-12) A) Only be a liguid B) Only be a vapor C) Only be a combination of liquid and vapor vapor, or combination of the two Calculate the compression ratio for the R22 system: (pg. 2-16) R307 is a/n? (pg. 3-2) A) HCFC refrigerant B) Azeotrope C) CFC refr D) Water based refrigerant - CORRE: ‘-B) Azeotrope Which of the following statements is NOT true concerning high discharge temperatures? (pg. 3-4) A) High discharge temperatures can cause refrigerant breakdown B) High discharge temperatures insure no liquid is drawn inlo the compressor C) High discharge temperatures may be an indication of compressor distress T ANSWE! D) High discharge temperatures can break down lubricating oil - CORREC B) High discharge temperatures insure no liquid is drawn into the compressor What do you multiply times ta mass flow rate to determine the vapor flow rate through the compressor? (pg. 3-9) A) Density [Ibs. / cubic foot] B) Specific volume [cubic feet / Ib.J C) Capacity [BTUs / minute] D) Velocity [feet / minute]- CORRECT ANSWER-B) Specific volume [cubic feet / Ib] Three factors to consider when choosing a refrigerant are? (pg. 3-9/10) A\) Molecular weight, availability, and safely B) Refrigeration effect, cost, and viscosity C) Cost, availability, and safety D) Cost, availability, and refrigeration coefficient - CORRECT ANSWER-C) Cost. availability, and safety According to this text, “trapped” ammonia liquid results in how much pressure change? (pg. 3-12) A) 1 psi per 100 to 150 degree Fahrenheit increase B) 100 to 150 psi per degree Fahrenheit increase C) 1 psi per 100 to 150 degree Fahrenheit decrease D) 100 to 150 psi per degree Fahrenheit decrease - CORRECT ANSWER-B) 100 to 150 psi per degree Fahrenheit increase One positive characteristic of Halocarbon refrigerants is? (pg. 3-21) A) They are always non-toxic and safe B) They are usually nal explosive C) They are odorless D) They have a much higher latent heat of boiling than ammonia - CORRECT B) They are usually not explosive Which refrigerant in table 3-2 would operate at the lowest suction pressure with an evaporator Lomperalure of 10° F? (pe. 34) A)R717 B) R507 C) R-40da D) R-134a - CORRECT ANSWER-D) R-134a D) Turn red - C ICT ANSWER) Turn green Ifa reciprocating system's evaporator temperature is decreased, what happens to the compressor theoretical discharge temperature? (pg. 3-6) A) Discharge temperature rises B) Discharge temperature is unaffected C) Discharge temperature falls D) Depends on type of condenser - C NSWER-A) Discharge temperature rises At 93° F condensing and 0° F evaporating temperature, the theoretical discharge temperature for ammonia Is? (pg. 3-7) A}312° F B) 255° F C)318° F D) 242° F- CORRECT ANSWER-D) 242° F Which refrigerant requires the largest compressor displacement per ton? (pg. 3-4) A)R717 B) Ra07 C) R-134a D) HCFC-22 - CO, ANSWER-C) R-134a Which is NOT a direct symptom of air in an ammonia system? (pg. 3-3) A) Increased discharge temperature B) Increased power consumption C) Decreased compressor capacity D) Decreased evaporating temperature - CORRECT A. temperature Of the refrigerant listed below, which refrigerant has the highest mass flow rate requirement at the same evaporator and condensing temperature? (pg. 3-4) A)R717 B) R-404a €) HCFC-22 D) R-134a - CORRECT ANSWER-B) R-404a Which refrigerant was first phased out by the Montreal Protocol? (pg. 3-24) A) Ammonia B) CFC-12 C) HCFC-22 D) Sulfur Dioxide - CORRECT ANS As the ratio between the evaporator and condensing pressure increases? (pg. 3-6) A) The theoretical discharge temperature decreases B) The theoretical discharge temperature stays the same C) The theoretical discharge temperature increases D) The theoretical discharge and evaporating temperature increase - CORRECT ANSWER C) The theoretical discharge temperature increases Under the Clean Air and Montreal Protocol? (pg. 3-24) NSWEI_D) Decreased evaporating