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NEW QUESTION # 18
You can buy air compressor A for $15,000 or air compressor B for $6,000. Compressor A will cost $10,000 per year to operate. Compressor B will cost $11,500 per year to operate. If both air compressors have a 10- year life and your required return on investment is 12%, which air compressor has the lowest total life-cycle cost?
- A. Compressor B
- B. Both air compressors have the same life-cycle cost
- C. Compressor A
Answer: A
NEW QUESTION # 19
A gas-fired boiler is operating with 31.9% excess air. A feedwater economizer is used to reduce the stack temperature rise from 310°C to 160°C. Using the natural gas combustion efficiency tables in your workbook, find the energy savings from the economizer as a percentage of historical fuel consumption.
- A. 5.8%
- B. 3.1%
- C. 7.1%
- D. 9.3%
- E. 1.2%
Answer: A
NEW QUESTION # 20
Which of the following controls can optimize the operation of lighting systems?
- A. Occupancy sensors
- B. Photocells
- C. Timer
- D. All of the above
- E. Dimming ballasts
Answer: D
NEW QUESTION # 21
Electricity costs SO. 10 per kWh. if an electric water heater has an efficiency of 95*6. what is the equivalent price of natural gas per Gigajoule for a natural gas water heater? The natural gas water heater has an efficiency of 95*t based on lower-heating value.
[Natural gas has an energy content of 36.400 K|/m3 (higher-heating value) and 32-760 K/m3 (lower-heating value).] SELECT THE CORRECT ANSWER
- A. $25 / GJ
- B. $21 / GJ
- C. $33 / GJ
- D. $15/GJ
Answer: B
Explanation:
To determine the equivalent price of natural gas per gigajoule (GJ) for a natural gas water heater, we compare the cost of electricity and natural gas on an energy-equivalent basis.
Step 1: Convert Electricity Cost to Cost per GJ
* Electricity cost: $0.10/kWh
* 1 GJ = 277.8 kWh
NEW QUESTION # 22
A three phase, 380-volt system, has the following voltage measurements:
Va = 375 volts
Vb = 380 volts
Vc = 391 volts
Calculate the percent voltage imbalance.
- A. 1.1%
- B. 5.5%
- C. 6.2%
- D. 2.4%
- E. 3.4%
Answer: D
NEW QUESTION # 23
An air conditioning unit cools make-up air from 25°C (dry bulb temperature) and 50% relative humidity down to 13°C. What type of heat has been removed from the air?
- A. No heat energy has been removed
- B. Both sensible and latent heat
- C. Latent heat
- D. Sensible heat
Answer: B
NEW QUESTION # 24
Natural gas costs $4.80/GJ. How much does it cost to heat 500 liters of water from 18°C to 50°C using a natural gas water heater with an efficiency of 85%? [The efficiency and fuel price are both based on HHV.
The specific heat of water (C) is 4.2 kJ/kg-°C.]
- A. $0.38
- B. $0.25
- C. $1.44
- D. $0.76
- E. $1.25
Answer: D
Explanation:
To calculate the cost of heating water using natural gas:
Step 1: Compute Energy Required to Heat the Water
Given:
* Mass of water = 500 L = 500 kg
* Temperature rise (#T) = 50°C - 18°C = 32°C
* Specific heat of water (Cp) = 4.2 kJ/kg-°C
Energy Required (Q)=m×Cp×#T
=500×4.2×32
=67,200 kJ=67.2 MJ
NEW QUESTION # 25
Which is the best application for variable-speed drives?
- A. Waste-water sewer lift pump
- B. Reciprocating air compressor
- C. Centrifugal fan motor in a multi-zone air conditioning system
- D. Centrifugal fan motor in a variable-air volume air-conditioning system
Answer: D
NEW QUESTION # 26
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 > 15%
- C. IRR < 0%
- D. IRR = 15%
Answer: B
NEW QUESTION # 27
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. Yes
- B. No
Answer: A
Explanation:
The Energy Utilization Index (EUI) is measured as total 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
NEW QUESTION # 28
Which type of lighting control technique operates in "manual on" and "auto-off mode, and can be used in situations where there is brief occupancy that do not need lights on?
- A. Microphonics technology
- B. PIR/Microphonics dual technology
- C. Vacancy sensor
- D. Occupancy sensor
- E. Photocell control
Answer: D
NEW QUESTION # 29
In a PID control system, what is the purpose of the Proportional Gain?
- A. Senses high load rate
- B. Control point
- C. Reduces/eliminates offset
- D. Reacts to change
Answer: D
NEW QUESTION # 30
A 100-kW packaged engine-generator combined heat and power (CHP) system has the specifications listed below. What is the annual purchased fuel cost for the CHP system, assuming that the CHP is electrical output limited and operates at full electrical load all year?
SELECT THE CORRECT ANSWER
- A. $28,900/yr
- B. $32,668/yr
- C. $43,776/yr
- D. $52,222/yr
- E. $58,300/yr
Answer: C
NEW QUESTION # 31
Which type of single-phase alternating-current motor has the highest efficiency?
- A. Permanent split-capacitor motor
- B. Electronic-commutated motor
- C. Shaded-pole motor
Answer: B
NEW QUESTION # 32
Exhaust gases from an industrial furnace flow through a heat-recovery steam generator, which generates medium-pressure steam. This steam is used in a steam turbine to generate shaft power driving a fan. Which type of combined heat and power (CHP) cycle does this process describe?
- A. Topping cycle
- B. Bottoming cycle
- C. Combined cycle
- D. This cycle is not a combined heat and power system
Answer: B
NEW QUESTION # 33
Which of the following is the primary benefit of integrating energy management with a Building Automation System (BAS) in a commercial facility?
SELECT THE CORRECT ANSWER
- A. Reduced initial installation costs compared to traditional control systems
- B. Enhanced tenant satisfaction through manual lighting control in individual zones
- C. Simplified maintenance by eliminating the need for system diagnostics and fault detection
- D. Increased energy efficiency by enabling real-time monitoring and automated adjustments to HVAC, lighting, and other systems
Answer: D
NEW QUESTION # 34
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