AEE CEM試験問題集にはPDF問題とテストエンジンを試せ！ [Q21-Q45]

AEE CEM試験問題集にはPDF問題とテストエンジンを試せ！

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質問 # 21
A 7 bar (gauge pressure) compressed air system has 5 leaks that are 3 mm in diameter and 3 leaks that are 6 mm in diameter. The compressed-air system is pressurized 8,760 hours per year. Electricity cost is $0.10
/kWh. What is the annual cost of the leaks in the compressed air system?

A. $25,220/yr
B. $56,500/yr
C. $30,910/yr
D. $18,150/yr
E. $48,480/yr

正解：C

質問 # 22
A facility replaces a natural gas heating system rated at 10,000 kJ/h and 80% efficiency with an electric heat pump rated at 10,000 kJ/h and a coefficient of performance (COP) of 2.3. Will this project also reduce the annual energy utilization index (EUI) for the facility?

A. No
B. Yes

正解：B

解説：
The Energy Utilization Index (EUI) is measured astotal energy consumption per unit area.
Step 1: Compare Energy Inputs for Both Systems
* Existing Natural Gas System:
* Heating output:10,000 kJ/h
* Efficiency:80%
* Required input energy
A screenshot of a math test AI-generated content may be incorrect.

質問 # 23
What is the best type of heat exchanger to recover and transfer latent heat energy from one air stream to another?

A. Desiccant heat wheel
B. Heat pipe
C. Shell and tube
D. Run-around system
E. Ceramic recuperator

正解：A

質問 # 24
According to the institute of Electrical and Electronic Engineers (IEEE) standard 519. "Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems." the maximum total harmonic distortion (THD) for general low voltage systems less than 600 votts) should be:
SELECT THE CORRECT ANSWER

A. Less than 1%
B. Less than 10%
C. Less than 5%
D. Less than 20%
E. Greater than 1%

正解：C

解説：
The Institute of Electrical and Electronics Engineers (IEEE) Standard 519, titled "Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems," sets forth guidelines to maintain the quality of electrical power by limiting harmonic distortions. According to IEEE 519, for general low-voltage systems (defined as systems with a voltage less than 600 volts), the Total Harmonic Distortion (THD) of the voltage waveform should not exceed 5%. This threshold ensures the reliable operation of electrical equipment and minimizes potential issues such as overheating or malfunctioning caused by excessive harmonics.
Therefore, the correct answer is C. Less than 5%.

質問 # 25
A heat pump water heater has an annual average coefficient of performance (COP) of 2.1 and heats water from 15°C to 50°C. Hot water use is 100 liters per day, 365 days/yr. The electricity cost is $0.10/kWh. What is the annual water heating cost? (The specific heat of water (C) is 4.2 kJ/kg-°C.)

A. $52.20/year
B. $44.88/year
C. $64.66/year
D. $70.97/year
E. $88.29/year

正解：C

質問 # 26
At the end of a performance contract, who owns the equipment installed by the project?

A. The company that paid the contract payments
B. The equipment manufacturer
C. The bank
D. The energy service company

正解：A

質問 # 27
A hot-water boiler has a cut-in set point of 65°C on the hot water supply temperature and a differential set point of 10°C. What is the hot-water supply temperature that causes the boiler to turn off?

A. 55°C
B. It depends on the return water temperature
C. 75°C
D. 65°C

正解：C

質問 # 28
Which of the following is a closed-loop controller?

A. Thermostat for an air conditioning unit
B. Manual dimmer for a light switch
C. Accelerator pedal in an automobile
D. Time clock schedule controller

正解：A

質問 # 29
Which of the following instruments is most useful for tracking long-term boiler performance?

A. The exhaust stack temperature sensor
B. The feedwater temperature sensor
C. The drum water level gauge
D. The boiler room ambient temperature sensor
E. The pressure gauge

正解：A

質問 # 30
Which heat recovery device listed below can be used to preheat boiler make-up water using the heat energy from skimming blowdown?

A. Shell and tube heat exchanger
B. Heat pipe
C. Desiccant heat wheel
D. Regenerative recouperator

正解：A

質問 # 31
Which is the best application for variable-speed drives?

A. Reciprocating air compressor
B. Centrifugal fan motor in a variable-air volume air-conditioning system
C. Waste-water sewer lift pump
D. Centrifugal fan motor in a multi-zone air conditioning system

正解：B

質問 # 32
How does an enthalpy-based economizer control operate?

A. Using a constant mixed air proportion control sequence
B. Comparing the difference in dry-bulb air temperature measurements of the return air and the outdoor air
C. Using the dry-bulb temperature and relative humidity of both the outdoor-air and return-air
D. Measuring the outdoor air dry-bulb temperature and relative humidity

正解：C

質問 # 33
A compressed air system has a total volume of 247,500 liters. During a 30-minute break in production (air compressor system turned off and no production demand for compressed air), the system pressure drops from
7 bar, gauge (700 kPa, gauge) to 5 bar, gauge (500 kPa, gauge). Calculate the leakage rate in the compressed air system.

A. 22,750 liters/minute
B. 48,250 liters/minute
C. 16,500 liters/minute
D. 32,000 liters/minute
E. 8,250 liters/minute

正解：C

質問 # 34
What is the main cause of low power factor?

A. Low-load induction motors
B. Solar flares
C. Computers and electronic equipment
D. Harmonics
E. Fluorescent lighting

正解：A

質問 # 35
A 1OO-kW packaged engine-generate combined heat and power (CHP) system has the specifications listed below. The CHP equipment operates fully loaded for 8.000 h/yr. What isthe annual fuel cost for the ChP equipment?
CMP equipment specifications: Electrical output 100kw Electrical efficiency: 25% Thermal recovery efficiency: 50*6 Total CMP efficiency: 75% Additional information: Fuel cost: S3.S0/GJ Electricity cost S0.06/kWh Previous water heating efficiency:
8046 Mot water usage: 75,700 liters/day (21 *C temperature rise)
[The question from the previous image, which was about calculating the annual cost of heat loss through a wall, but had a discrepancy between the calculated cost and the provided answer choices]

A. $43,776/yr
B. $58,300/yr
C. $52,222/yr
D. $32,668/yr
E. $28,900/yr

正解：A

質問 # 36
How can commissioning reduce the life-cycle cost to owners and operators?

A. Improve the effectiveness of operations and maintenance
B. Improve the satisfaction of building occupants
C. Improve the performance of energy systems
D. All of the above
E. Reduce the cost of change orders during construction

正解：D

質問 # 37
An outdoor parking area has 25 light poles. Each pole has a 420 Watt (ballast included) high-pressure sodium (HPS) luminaire. The parking area lights are illuminated 4,500 hours per year and the electricity cost is $0.08
/kWh. What is the annual energy cost reduction if each luminaire is replaced with a 220-Watt (driver included) LED luminaire?

A. $1,800/yr
B. $2,200/yr
C. $1,500/yr
D. $1,200/yr
E. $2,600/yr

正解：A

解説：
To determine the annual energy cost savings from switching to LED luminaires:
A table with numbers and symbols AI-generated content may be incorrect.

質問 # 38
Using an interest rate of 15%, an energy project has a net-present value (NPV) of $3,500. Which statement is true about the project's internal rate of return (IRR)?

A. IRR = 15%
B. IRR < 0%
C. IRR > 15%
D. IRR < 15%

正解：C

質問 # 39
A high-pressure steam system passes 180°C condensate (saturated liquid) through a steam trap to an atmospherically vented condensate receiver tank. If the steam trap is working properly, how much of the condensate mass can be lost out the vent of the receiver tank in the form of flash steam?

A. 6%
B. 25%
C. 66%
D. 15%
E. 100%

正解：B

質問 # 40
A 50-kW induction motor (1,500 rpm synchronous speed) has a nameplate full-load rotational speed of 1,455 rpm. Field measurements show the actual rotational speed is 1,475 rpm. Using the slip method, calculate the partial load factor of the motor.

A. 98%
B. 80%
C. 56%
D. 101%
E. 46%

正解：B

質問 # 41
A facility has the thermal cooling load profile shown in the table below. The utility rate traffic has an no-peak time-of-use period that begins at 10:00 a.m ends at 7:00 p.m. What chiller capacity (output) is required for a load-leveling operating strategy?

[Question from the previous image, which was about chiller capacity for load leveling, but the table was missing]

A. 7.0 GJ/h
B. 8.0 GJ/h
C. 5.0 GJ/h
D. 4.0 GJ/h

正解：B

質問 # 42
A compressed-air distribution system has one section that frequently has low pressure when demand for compressed air is high. How can you resolve the problem without increasing energy consumption?

A. Install a receiver tank near the remote load experiencing low pressure
B. Decrease the distribution pipe size to the remote load experiencing low pressure
C. Answers B and C
D. Raise the supply air pressure

正解：A

質問 # 43
In a chilled water thermal energy storage system, chilled water is stored at 4°C and used for supply water.
Chilled water return is 14°C. Calculate the storage capacity required to hold 50 GJ of thermal cooling. (The specific heat of water (C) is 4.2 kJ/kg-°C. Assume no system losses.)

A. 2,618 m³
B. 1,356 m³
C. 766 m³
D. 4,180 m³
E. 1,191 m³

正解：E

質問 # 44
For general indoor residential lighting applications, which light source can provide the most appropriate illumination with the highest efficacy?