An air-conditioning system at full load is rated at 70-kW (thermal cooling) and has a coefficient of performance (COP) of 4.1. What is the electrical load at full load?
Which of the following statements regarding refrigerants is NOT correct?
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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 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 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.
What instrument is NOT used to measure temperature?
Insulation has a thermal conductivity of 0.04 Watt/(m-°C). What is the R-value for this insulation when it is 5-cm thick?
In a warehouse, lights are mounted 4 meters above the floor. This provides an average light level of 150 lux. To increase the light level without installing more lights or higher Wattage lights, you lower the light fixtures with pendants so that the lights are located 3.25 meters above the floor. Calculate the new average light level on the floor.
Which of the following is NOT a renewable-energy resource?
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What does a manometer measure?
A desk lamp is located inside a windowless office. The office is heated during the winter and cooled during the summer. When the lamp is switched on, how much of the energy consumed by the lamp becomes heat in the office space?
In a typical compressed air system, energy can be saved by which of the following actions?
What instrument determines flow rate by measuring pressure differential?
Using a degree-day base of 18°C, calculate the number of cooling degree days (CDD) if the outside temperature is a uniform 25°C throughout the year (365 days/year).
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 55-kW motor at full load is used to drive a pump that generates 50 meters of head while pumping water at a rate of 5,000 liters per minute. Calculate the pump efficiency.
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?
What is the definition of lamp life for a fluorescent lamp?
If a boiler cycles on and off too frequently, what control can you adjust to reduce the number of times a boiler cycles on and off?
At the end of a performance contract, who owns the equipment installed by the project?
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 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?
An energy project implemented today saves $10,000 per year for the next 20 years. Using the 5% interest table, determine the total value of savings at the end of the 20th year?
When comparing two similar facilities, you see that the facility with newer, higher-efficiency equipment has a higher energy-use index [EUI] (kJ/m²-yr). What might be the cause?
Why do electric utility companies transmit power at high voltages?
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How can commissioning reduce the life-cycle cost to owners and operators?
Calculate the monthly electric bill for a customer that used 400 kW and 75,000 kwh during one month. Use the following declining block structure for a monthly bill:
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Air is heated from 10°C (dry bulb temperature) and 80% relative humidity to 32°C (dry bulb temperature). What is the new relative humidity?
Thermal scans of electrical equipment are useful for:
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.)
If the temperature difference across an external wall is 20°C and the heat flow across the wall is 2.5 Watts/m², calculate the insulation value of the wall (including inside and outside air films)?
What is the purpose of top (or skimming) blowdown in a steam boiler?
Which pump system listed below is most likely the best application for converting to variable-speed drive?
A new energy-efficient boiler costs $60,890 to buy and install. The new energy-efficient boiler will save $15,400 per year and last for 20 years. What is the internal rate of return (IRR) of the project?
The International Performance Measurement and Verification Protocol (IPMVP) has how many categories (method options) to determine the performance of an energy- or water-consuming system?
A 75-kW induction motor operates at 80% partial load and 88% efficiency. A new high-efficiency 75-kW motor can be installed that will operate at 95% efficiency (also at 80% partial load). What is the reduction in electric power demand?
Which of the following is NOT included in commissioning documentation?
How can you tell if steam traps in a steam distribution system may NOT be working correctly?
Some international electric utilities use 'net metering" for customers with renewable energy equipment, such as photovoltaic power panels. Which of the following best describes net metering with regard to excess power generation and utility billing practices?
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