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MAE 576 Final T/F Questions with answers
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The two compressor types are positive displacement and variable. - Solution False, the two types are positive displacement and dynamic. In the Annual Energy Outlook's Reference case, by 2050 industrial energy consumption is projected to increase to more than 40 quads. (1 quad is 10^15 BTU) - Solution False In 2020, the southwest region (including Texas) produced the most onshore oil among the lower 48 states. - Solution True In general, electricity for residential buildings costs more than electricity for commercial buildings. - Solution True Energy consumption fell faster than gross domestic product in 2020. - Solution True In all cases, electricity demand is projected to decrease from 2020 to 2050.
- Solution False For residential central air conditioners in the south (hot-dry and hot-humid), in 2009 the average SEER value for the installed base was 13.0. True - Solution False The total installed cost for a residential air source heat pump is $3,500 for an Energy Star unit in 2017. - Solution False The total installed cost for a residential Energy Star ground-source heat pump is between $12,000 and $21,000 in 2017. - Solution True The water consumption for a high-efficiency top-loading residential clothes washer is 17 gal/cycle in 2020. - Solution True In 2016, more front-loading residential clothes washers were shipped than top-loading residential clothes washers. - Solution False
In the USA, privately owned utility companies are regulated by agencies usually called Public Utility Commissions or Public Service Commissions. - Solution True (Example: Arizona Corporation Commission, ACC) Electrical energy and demand are both charged on a per kW basis. - Solution False (energy: kWh, demand: kW) For electricity, the kW in Demand Charge is typically determined based on a 15-minute period of maximum use for commercial customers. - Solution True For electricity, summer peak energy charges are higher than the winter energy charges for commercial customers. - Solution True Electric utilities have to incur the cost of remedial equipment if an industry has a leading power factor. - Solution False For natural gas, a service fee is not charged if you have a connection but don't consume natural gas. - Solution False. You are charged if it is connected. You are also charged for: customer accounts, revenue cycle, system benefits, transmission, delivery, and generation. For natural gas, rate adjustment charges can never be negative, only positive. - Solution False. Similar to solar! The per Therm cost of natural gas increases with an increase in consumption. - Solution False No electricity is required for an absorption air conditioning system. - Solution False For residential customers, natural gas consumption is generally higher in the winter than in the summer. - Solution True The Coefficient of Performance (COP) is defined as the energy used by the AC unit divided by the rate of heat removal. - Solution False. Sought over Bought. SEER is usually greater than EER because the outside temperature is often less than 95 degrees Fahrenheit. - Solution True
Using a counter-flow heat exchanger for an evaporator increases the performance of a positive temperature glide system. - Solution True Hydrofluorocarbons (HFCs) do not deplete the ozone layer, and have a relatively low Global Warming Potential (GWP). - Solution False. R134a, R410a. They have a high GWP. Mostly used for AC and refrigeration. by 2050, they can contribute to about 20% of GHG from CO2. Hydrochlorofluorocarbons (HCFCs) are being substituted under the Montreal Protocol because of concerns over their flammability. - Solution False Refrigerant R1234ze is an attractive substitute for R134a because of its lower GWP, while having other similar properties. - Solution True Transitioning to low-GWP refrigerants could eliminate a majority of direct emissions from A/C systems. - Solution True R410A has a higher value of GWP than does R32. Correct! True - Solution True Multiple compressors are useful to accommodate cyclic or periodic loads in a compressed air system. - Solution True A compressor running at peak load is generally more efficient than a compressor running at partial load, when producing the same output. - Solution True To operate a 1-hp air motor requires less than 1 hp of electrical energy. - Solution False For each 1 psi reduction in system pressure above 100 psi, the corresponding energy savings is approximately 0.5%. - Solution True Two types of compressed air dryers are refrigerated and regenerative desiccant. - Solution True The purpose of an air receiver is to store compressed air. - Solution True
The most common types of positive displacement air compressors are rotary screw and centrifugal. - Solution False. It is reciprocating and rotary. Single-stage rotary screw compressors come in two configurations: lubricant-injected or lubricant-free. - Solution True In compressed air systems, air filters are always installed downstream of the compressor. - Solution False In order to improve the efficiency of multiple-compressor systems, the use of a sequencer is recommended. - Solution True The lower heating value of fuel assumes that all H2O in the stack gas remains in the vapor state. - Solution True An insufficient amount of air during combustion results in a decrease in efficiency, while excess air has no effect on the efficiency of a boiler. - Solution False An estimate on the amount of steam lost from an orifice per hour can be obtained from Grashof's formula. - Solution True Scaling on heat exchanger surfaces has a favorable effect on heat transfer.
- Solution False The purpose of a steam tracer line is to maintain the hot temperature of the liquid inside the pipe or vessel around which the tracer line is wrapped. - Solution True One of the functions of a steam trap is to return condensate to the boiler. - Solution True The efficiency of a boiler is not related to the stack temperature. - Solution False If a steam trap "fails closed," its effect and cost are the same as a steam leak. - Solution False One of the software tools provided by the US Department of Energy is the Steam System Modeler. - Solution true
Induction motors are physically the same as synchronous motors. - Solution False If a motor fails, one generally has the option to "rewind" the motor rather than to replace it with a new motor. - Solution true Larger motors generally have higher efficiencies than smaller motors. - Solution true Larger motors usually have higher power factors than smaller motors. - Solution true One of the "Tip Sheets" available from the US Department of Energy is entitled "When to Purchase Premium Efficiency Motors." - Solution True The more electrical power a motor is able to convert to mechanical power, the higher is its efficiency. - Solution True Electrical capacitors can sometimes be installed on motors to provide power factor correction. - Solution true The "Service Factor" of a motor tells us how much overload the motor can safely handle on a long-term basis. - Solution False. It is the percentage multiplier that a motor can handle for short periods of time when operating within its normal voltage and frequency tolerance. The synchronous speed of a motor depends on the number of poles. - Solution True Incandescent lamps have a relatively short life span compared with LEDs. - Solution True "A lamps" project light out in all directions. - Solution true The beam of Ellipsoidal Reflector (ER) lamps is wider than that of R lamps. True - Solution False Incandescent lamps have a higher efficacy than metal halide lamps. - Solution False
A T12 fluorescent bulb has a larger diameter than a T8 fluorescent bulb. - Solution True The luminous efficacy of a lamp is an estimate of the light output divided by the electrical power input under test conditions. - Solution True. It is the total luminous flux emitted divided by the total lamp power input. A high CRI indicates good color rendering. - Solution True. CRI: color rendering index: a measure of how colors of a surface will appear when illuminated by a light source. Max: 100 The color temperature of a lamp describes the appearance of the light generated compared to the perceived color of a blackbody radiator at that temperature. - Solution True The DOE Solid-State Lighting Program leads the USA's efforts to drive research and development of innovative LED and OLED technologies. - Solution True Resources provided by the DOE Solid-State Lighting program include CALiPER reports that evaluate commercially available LED products. - Solution True Waste heat goes into the environment without providing any appreciable benefit to the user. - Solution true Heat wheels cannot be used to transfer both latent heat and sensible heat.
- Solution false Waste heat boilers are employed when there is sufficient waste heat to vaporize working fluid. - Solution true The purpose of the fins in a finned-tube heat exchanger is to enlarge the heat transfer surface area. - Solution true An "economizer" is another word for a "run-around coil." - Solution false. draws outdoor air and mixes it with return air from indoors. a run-around coil is a type of recovery HX.
The operating temperature of a phosphoric acid fuel cell is less than that of a proton exchange membrane fuel cell. - Solution false A solid oxide fuel cell can operate at temperatures as high as 1000 C. - Solution true A programmable controller is a control device that has logic potential. - Solution true A Building Automation System (BAS) needs to at least control functions of a heating, ventilating, and air conditioning (HVAC) system. - Solution true There are two main parts to an EIS: (1) data removal, and (2) web publishing. - Solution false TCP/IP is the communications protocol followed by the Internet. - Solution true XML, or Extensible Markup Language, is an internet standard that organizes data into a predefined format for the main purpose of sharing between or within computer systems. - Solution true BAS stands for Building Addition System. True - Solution false. It stands for Building Automation Systems. This uses computer based monitoring to coordinate, organize and optimize building control subsystesms. BACnet is a standard communication protocol developed by ASHRAE. - Solution true For submetering, an Energy Information System (EIS) that continuously collects the sub-meter data and displays it in easy-to-understand charts and graphs is the key for making the information useful. - Solution true. it allows for energy use to be attributed to specific pieces of equipment or tenant. The Utility Reporting System (URS) is an example of a web-based system that allows utility customers to view library account data. - Solution false
Sub-metering utility usage is the most direct method for energy saving measurement. - Solution true The energy audit process starts with an examination of the historical and descriptive energy data for the facility - Solution true A thorough knowledge of the facility's rate structures is a must to analyze the energy bills. - Solution true The building envelope includes all building components that are directly exposed to the outside environment. - Solution true The number of heating degree days (HDD) is the same across the USA, regardless of location. - Solution false An ultrasonic leak detector is used primarily to identify leaks in water pipes.
- Solution false A successful energy audit should include audit interviews, thereby knowing the expectations of the client. - Solution true The Executive Summary of an energy audit report should be tailored to engineering personnel who are familiar with technical jargon. - Solution false Within the Industrial Assessment Center program, ARC stands for "Assessment Recommendation Criterion." - Solution false Assessment Recommendations (ARs) from Industrial Assessment Center (IAC) audits are uploaded to a nationwide database that is publicly available. - Solution true Energy monitoring is never needed once the energy audit is complete. - Solution false The ISO 50001 program is mandatory for all medium- to large-scale industries. - Solution false
The power factor is consisted of the real power (kW) and reactive power (kVAR). - Solution True To increase the power factor, three-phase power can be used. - Solution True, more power can be delivered over the same conductor. Better and smoother operation for motors. Energy is also known as demand. - Solution False, it is the usage. Demand is power. Power factor is for commercial, industrial, and residential for natural gas. - Solution False, it is only for general service and not residential. What is a RPS? - Solution Renewable Portfolio Standard: a regulatory mandate to increase production of energy from renewable resources. What is 1 therm? - Solution 100,000 BTU What does a delivery charge for NG cover? - Solution Local gas transportation to house maintenance, administrative costs, etc What is a net load? - Solution The difference between a forecasted load and expected electricity generation from variable resources like solar and wind. Duck curve! How can utilities meet the new load? - Solution Demand response, energy storage, real-time pricing, sell/buy power from a larger network. A linear compressor has a piston that moves along a linear track, similar to a solenoid valve. - Solution true Dynamic compressors convert angular momentum to pressure rise. - Solution True. requires high angular speeds The most popular compressors for HVAC is centrifugal. - Solution true All refrigeration compressors require lubricant to be added to the refrigerant. - Solution True, either natural or synthetic. (mineral or POE oil)
Synthetic lubricants cost more, but deliver more efficient performance for refrigeration compressors. - Solution True To control the capacity of a compressor, it can be run at part-load coniditions. - Solution true: on/off, unloading (valve), VFD (variable frequency drive) also called Variable speed drive SNAP stands for Standard New Alternative Powers - Solution False, it stands for Significant New Alternatives Policy. It regulates ozone-depleting chemicals that are being phased out under the Clean Air Act. identifies and publishes a list of acceptable and unacceptable substitutes Ozone is a gas that is naturally present in the atmosphere. - Solution true. it is distributed in three parts of the atmosphere. The Montreal Protocol establishes a schedule to reduce the production and consumption of CFCs and Halons. - Solution True. phase it out An aftercooler is installed to reduce the temperature of the compressed air leaving the compressor. - Solution True A separator captures the water vapor that condenses the air when it is cooled by the aftercooler. - Solution True A steam boiler is necessary when you need temperatures above 500 deg C. - Solution False, it is 100 deg C. Efficient motors have to use permanent magnets made from rare earth metals. - Solution False LED lighting shines in a straight line. - Solution true Rejected energy accounts for about 68.4% of total energy - Solution true Regenerators separates heat transfer fluids - Solution False. They store heat in a medium. 1 ton = 30,000 BTU/hr - Solution False, it is 12,000 BTU /hr SEER stands for Seasonal Energy Efficiency Ratio - Solution True
Positive displacement compressors squeezes the refrigerant vapor - Solution true! The two positive displacement types of compressors are reciprocating and rotary. - Solution true. blower, screw, scroll, single acting, double acting A dynamic compressor is a centrifugal compressor. - Solution true, think of the angular momentum. a centrifugal pump spins with an impeller. it is the most popular type for an HVAC system Variable speed control increases the SEER, HSPF, IEER, and IPLV. - Solution true. HSPF: heating seasonal performance factor, and IPLV: integrated part load valve. HCFCs are to be phased out for developed countries completely by 2020. - Solution true. allowing 0.5% for servicing HFC consumption is mainly mobile air conditioning - Solution false, it is refrigeration and stationary AC Boilers can only have liquid and solid fuel. - Solution False. they can have solid, liquid, and gas fuels. The HHV is the total energy provided by the fuel that is obtained after water vapor in the flue gas stream is condensed back to its natural state - Solution true. also known as the gross heating value The LHV is the total energy provided by the fuel that is obtained without the condensation of the water vapor in the flue gas stream. - Solution true. also known as the net heating value The higher the exhaust gas temperature, the greater the stack losses - Solution true There are two contributions to stack loss: flue gas temperature and combustion - Solution true Combustion zone oxygen content must be minimized to reduce energy losses. - Solution true
Positioning control is where the flue gas oxygen content is monitored continuously and inlet air flow is adjusted accordingly to stay within limits - Solution False, it is automatic control that is described. The two types of pumps are positive displacement and dynamic - Solution true A DC motor uses an induction motor - Solution false. an AC motor does Incandescent and halogen lamps are considered to be thermal radiation types. - Solution true Fluorescent and metal halide lamps are considered gas discharge - Solution true LEDS use semiconductors for electroluminescence. - Solution true LEDS and OLEDs are considered to be solid-state lighting - Solution true. the material that gives off light is in solid form (no moving parts, glass, filament to break) OLEDs have a point source like an LED - Solution false. they have a planar source of light. but efficacy (lm/W) is lower than LEDs North and South facing windows are generally considered to be more desirable than east and west, since they have no disadvantages - Solution true. Electrochromic windows cannot change transparency on demand - Solution false. they can. something with electrons and only permitting some through Combustion efficiency increases with increasing combustion inlet air temperature - Solution true. recover the waste heat to preheat the combustion air A HRV system only exchanges latent heat between indoor and outdoor air.
- Solution false. it only exchanges latent heat.
