Refrigeration and Air Conditioning Technology (MindTap Course List)
8th Edition
ISBN: 9781305578296
Author: John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson
Publisher: Cengage Learning
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Chapter 50, Problem 14RQ
To determine
The economizer mode of operation that uses the system compressor(s) and has the outside air dampers at their minimum position.
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_controls
on/off of the motor, when the
air compressor tank reaches
the specified bar.
O a. Electric Motor.
O b. Auto drain.
O C. Compressor.
d. Pressure Switch.
8. What would be done to increase the compressor speed
on a belt-driven compressor?
A. Decrease drive pulley size
B. Increase drive pulley size
C. Increase driven pulley size
13. What lubricates the refrigeration compressor?
A. Refrigerant
B. Moisture
C. Desiccants
D. Oil
D. Both A andC
9. Describe the reciprocating compressor piston, rod,
crankshaft, valves, valve plate, head, shaft seal, internal
motor overload device, pilot-duty motor overload de-
vice, and coupling.
10. Name two things in the design of a reciprocating com-
pressor that control the efficiency of the compressor.
А.
14. What can the service technician do to keep the refrig-
eration system operating at peak efficiency?
15. List the main advantage that a discus compressor's
valve plate design has over a conventional piston-type
В.
11. At what speeds in rpm does a hermetic compressor nor-
mally turn?
A. 1750
В. 3450
C. 4500
D. Both A and B
12. What effect does a slight amount of liquid refrigerant
have on a compressor…
1. (a) List out the classification of air-conditioning system.
(b) With the aid of following sketch diagram(s) Fig.1, explain the working principle and
details of the loops involved in the centralized HVAC building system. .
Fresh Air
Necessary
considering
IAQ
Water 12°C
137°C
Water
Return Air
24°C
Pump
Air-handling Supply
Unit
Air
Chiller
Fan
7°C
Cooling Tower
14°C
Produce
chilled
water (7°C)
32°C
Supply
Air
Pump
Heat Gain
or
24°C
Return
Air Heat Gain
Room
Chiller
Fan
Air cool chiller
Heat rejected to the
environment
Fig.1 Systematic diagram of an air-conditioning system
Chapter 50 Solutions
Refrigeration and Air Conditioning Technology (MindTap Course List)
Ch. 50 - Which of the following is true regarding the...Ch. 50 - Which process would best represent the opposite of...Ch. 50 - Mixed air is best described as the combination of...Ch. 50 - Which of the following should be taken into...Ch. 50 - A bonded roof is one that has A. reinforced steel...Ch. 50 - Properly installed roof curbs will reduce the...Ch. 50 - When rigging a unit to the roof, what minimum...Ch. 50 - What is the acceptable method for communicating...Ch. 50 - Prob. 9RQCh. 50 - Prob. 10RQ
Ch. 50 - The most efficient way to establish the best...Ch. 50 - Free-cooling can be accomplished if the
A....Ch. 50 - Prob. 13RQCh. 50 - Prob. 14RQCh. 50 - Explain why the outside air damper is typically...Ch. 50 - Briefly explain the purpose of ASHRAE Standard 62.Ch. 50 - Explain the concept of demand control ventilation.Ch. 50 - Explain how carbon dioxide levels can be used to...Ch. 50 - Describe the blowers used on VAV systems.Ch. 50 - A cooling-only VAV box has all of the following...Ch. 50 - Which of the following is true regarding a reheat...Ch. 50 - Variable refrigerant flow systems sense the...Ch. 50 - The acronym PID stands for ______, _____, and...Ch. 50 - Explain the main benefit of a heat-recovery VRF...Ch. 50 - The pump on a dry cooler can direct water to...Ch. 50 - During low ambient conditions, the space cooling...
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- Explain why the outside air damper is typically nevercompletely closed, even when the outside air conditionsare not adequate to provide free-cooling.arrow_forwardto run d. both a and b 44. Ifa thermostatic expansion valve's thermal bulb came loose from the suction line at the outlet of the evaporator, whích of the following could result? The bulb pressure would increase and the c. thermostatic expansion valve would open. b. The superheat in the evaporator would decrease. a. Liquid refrigerant would flow back to the compressor. d. All of the above are correct. 45. If the thermal bulb assembly develops a leak, what will occur? All of the system's refrigerant will leak a. The valve will open to allow more c. refrigerant to flow. d. It will have no effect on system operation. out. b. The bulb pressure will reduce and the valve will close. 46. The purpose of an externally equalized thermostatic expansion valve is to compensate for excessive evaporator pressure drop b. allow system to equalize faster a. prevent the expansion valve from frosting up d. c. allow refrigerant to expand in the compressor 47. The primary function of an expansion device is…arrow_forwardThe capacity control for a screw compressor is accomplished with cylinder unloading true or falsearrow_forward
- Why does a system need to be maintained?arrow_forward- Industrial Motor Controls, 12.a. What is the purpose of thermostat number 2, IN7, in the mixing vat machine?A. This thermostat is used to monitor the temperature of the incoming fluids.B. This thermostat is used to prevent an over-temperature condition in the event thermostat one sticks open.C. This thermostat is used to turn off the mixing motor after the mixture reaches temperature.D. This thermostat is used to shut off the heater when the chemical mix reaches setpoint.12.b. Why are motor current readings from a frequency inverter not exact readings of motor current?A. Because the output of a frequency inverter is not a sinewaveB. Because a frequency inverter adds a DC voltage level to the AC waveformC. Because a frequency inverter uses a lower voltage sinewaveD. Because the inverter pulses the motor with various sinewave frequenciesarrow_forwardWhich list states the correct order of components for the absorption refrigeration? A) Evaporator, then absorber, then concentrator, then condenser. B) Absorber, then condenser, then evaporator, then concentrator. C) Condenser, then absorber, then concentrator, then evaporator.arrow_forward
- What does a 1 ton refrigerant represent: a. The weight of the air conditione r b. The amount heat required to cool 1 ton of air in 1 hour c. The amount of heat required to melt 1 ton of ice at 0 degree in 24 hours d. The weight of the refrigerant used.arrow_forwardDraw and label the parts of the following: 1. Central AC Compressor 2. Window air conditioning system 3. the parts of a hydraulic elevatorarrow_forward1. An air-source heat pump is a heat-pump system that uses air: a. as the system refrigerant. b. as the heat source when operating in the cooling mode. c. as the heat sink when operating in the heating mode. d. as the heat source when operating in the heating mode. 2. According to the Department of Energy, duct leakage can result in a energy loss? a. 10% b. 20% c. 30% d. 40% 3. As the outside ambient temperature drops, the efficiency of a heat-pump system operating in the mode will: a. heating, drop b. heating, rise c. cooling, rise d. Both a and c are correct.arrow_forward
- Which of the following components are common to most automatic control systems for residential split air conditioners? a. Thermostat, contactor, transformer b. Thermostat, magnetic starter, contactor c. Thermostat, diode, contactor d. Thermostat, time-delay relay, contactorarrow_forwardWhich process would best represent the opposite ofexhausting air from a system?A. CoolingB. VentilatingC. HeatingD. Filteringarrow_forwardAn overheating vehicle is being discussed. Technician A states that coolant in a normal flow cooling system flows from the radiator to the heater core to warm up the passenger compartment quickly. Technician B states that in a reverse flow cooling system, coolant flows to the cylinder heads first, which keeps engine components at a more uniform temperature. Who is correct? Select one: a. Technician A only b. Technician B only c. Both Technicians A andB d. Neither Technician A nor Barrow_forward
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