37201096
Descrição
FlashCards por Kara Biczykowski, atualizado more than 1 year ago
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Criado por Kara Biczykowski
mais de 2 anos atrás
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| Questão | Responda |
| NOMENCALTURE E = energy (W-hr) I = electrical current (A) P = electrical power (W) pf = power factor | R = resistance (Ω) t = time (hr) V = voltage (V) Z = impedance (Ω) |
| 1) what is a net zero structure? 2) which fossil fuel is the most efficient? 3) what is natural gas's heating value? 4) what gas can be used when natural gas is not available & what is it's heating value? | 1) a bldg that consume only as much energy as it produces on site thru renewable means 2) natural gas, it's clean burning & low in cost, but not always available in areas 3) 1050 Btu/ft3 4) propane / heating value = 2500Btu/ft3 |
| 1) b/c oil is a petroleum product, what are the disadvantages? 2) what are the 6 grades of oil for resi & commercial heating? 3) ^ which grades are for resi/ light commercial & what is the heating value? 4) & grade used for large commercial? | 1) cost & availability depend on world & local market cond.'s, needs to be stored near the bldg, & equip for burning it req.'s more maintenance than gas boilers 2) no. 1 (most refined & $$$), 2, 3, 4, 5 light, 5 heavy, & 6 3) No. 2 / 137,000 - 141,000 Btu/gal 4) No. 4 & 5 / 146,800 - 152,000 Btu/gal |
| 1) what are the advg's of using electricity? 2) the disadvantages? | 1) easy & inexpensive to install, simple to operate, easy to ctrl, flexible in zoning, doesn't req storage facilities, exhaust flues, or supply air 2) cost compared to oth fuels, esp. during "peak use" when public consumption is high, but on-site photovoltaics can reduce reliance on utility co. |
| 1) what type of heating is electricity ideal for? 2) what is one of the most common uses w/ electric heating? 3) what is electricity's heating value? | 1) radiant heating via clg panels, baseboard units, operate elec furnaces for forced air systems, heat water circulated in hydronic systems 2) supplemental space heating 3) 3413 Btu/kW |
| 1) steam is used as a bi-product in urban locations & campuses from generating electricity & is typ used for: 1) what is a heat pump? | 1) not direct heating, but to heat water for water or air heating systems & drive absorption-type water chillers for A/C 2) device that can absorb heat from cooler locations & transfer it to warmer ones = prvd heat in winter & cooling in summer |
| SUMMER CYCLE OF HEAT PUMP 1) acts as a std. air conditioner 2) refrigerant circulates inside the heat pump thru a cycle that includes an evaporator & condenser 3) in the evaporator, the refrigerant absorbs heat from the inside air | 4) this warmed refrigerant then flows to the condenser where it releases heat that is sent to the outside air 5) the cooled refrigerant then flows back to the evaporator to absorb more heat to cont. cycle |
| 1) how is the winter cycle different than summer in a heat pump? 2) what is the disadvantage of a heat pump when the outside temp is 40F or less? 3) to increase efficiency for a heat pump, it can be connected to: | 1) refrigerant flow is reversed so the heat pump absorbs heat from the outside air & releases it to the inside 2) efficiency decreases & it's not economically competitive w/ oil or gas heat - so better for climates w/ mild winters 3) a solar energy system |
| 1) how does a solar energy system work w/ a heat pump? 2) if system set up to use heat pump & solar energy, heat pump only turns on at what temp after too cold for solar 3) what else can supplement a heat pump when temp is very cold | 1) heat pump 1st preheats the air, then the solar energy further heats air so temp is high enough for space heating 2) lower than 47F, & then when really cold both systems work together ^ 3) electrical resistance heating or use a ground source heat pump (earth's heat) |
| 1) best sources of natural energy are: 2) the fuel needed for heating can be estimated w/ "degree days," what is this? 3) how "heating degree days" calc'd? | 1) solar, photovoltaic, geothermal, wind, & tidal energy (ch12) 2) rough measure of how much heating is needed for human comfort in a particular location over a year, using 65F as a base 3) 65F - XF which is less than 65F, then add up daily values to get total degree days for the year |
| 1) how are "cooling degree days" calc'd? 2) natural gas efficiency (__)% : 3) propane efficiency 4) no. 2 oil efficiency 5) anthracite coal efficiency 6) electricity efficiency | 1) same as heating days, but when the temp is over 65F 2) 70-80 3) 70-90 4) 65-85 5) 65-75 6) 95-100 |
| 1) any type of fuel must be converted to: 2) distribution of fuel thru a bldg typ req.'s 3) 2 of the most common devices for converting fuel to heat are: 4) what are the 3 types furnaces come in? | 1) a useful form like heated or chilled air for distribution thru a bldg 2) an add'l energy source like electricity to operate fans, motors, system components 3) the furnace and boiler 4) upflow, downflow, & horizontal |
| 1) how to furnaces heat air? | 1) they burn fuel inside a combustion chamber, here air is circulated in chamber by a fan, & as cool air from return air ducts pass over chamber it is heated for distribution, meanwhile hot exhaust gases pass thru a flue that's vented to the outside |
| 1) what occurs in an "upflow furnace?" 2) in a "downflow furnace?" 3) in a "horizontal furnace?" | 1) the return air is supplied at the btm of the unit & heated air is delivered to the bonnet abv the furnace where it's distributed thru ductwork 2) ^operates in opposite way, typ used where ducts located in basement & furnace is on 1st flr 3) it's designed to be used in areas w/ limited headroom like crawl spaces |
| 1) a boiler uses fuel to create: 2) what can fuel source of boiler be? 3) how is heat created in boiler? 4) if fuel for boiler is electricity or steam, then there is no need for: | 1) hot water or steam 2) gas, oil, electricity, or steam 3) tubes containing water to be heated are in the combustion chamber where heat exchange takes place & then gases/ products of combustion are carried away thru breeching into the flue or chimney 4) an exhaust flue |
| 1) what are the 2 refrigeration processes that can produce chilled air or water? 2) in some climates, what is a 3rd option? | 1) compressive refrigeration & absorption 2) evaporative cooling |
| 1) what is "compressive refrigeration?" 2) ^ how does it work? | 1) based on the transfer of heat during the liquefaction & evaporation of a refrigerant 2) as a refrigerant in a gaseous form is compressed, it liquefies & releases latent heat as it changes state, & as same liquid vaporized back to a gas, it absorbs latent heat from the surroundings Fig17.1 |
| 1) refrigerant that was banned 2) common refrigerant now used 3) friendlier environment options for refrigerant | 1) freon b/c it contains chlorofluorocarbons (CFCs) that contribute to ozone depletion 2) (HFCs) hydrofluorocarbons, don't harm ozone but are threat to atmosphere b/c of their global warming potential 3) ammonia, sulfur dioxide, propane, but concerns of toxicity & flammability |
| 1) what are the 3 fundamental components of a compressive refrigeration system? 2) describe the process of a compressive refrigeration system: | 1) the compressor, condenser, evaporator 2) 1st compressor receives the refrigerant as a gas & compresses it into a liquid, then liquid flows into condenser where it's latent heat is released (typ condenser is outside of bldg), then refrigerant enters evaporator & draws heat from surroundings, expands, becomes a gas again, process repeats |
| 1) for small cooling units, how is air cooled that's to be circulated thru rooms? 2) what is a more efficient medium than air for carrying heat? 3) in large bldg's, air is typ cooled when water is pumped over the (__) coils & then this chilled water is pumped to: 4) to release heat, water in the pipes draw heat from the: | 1) air is forced over the evaporator coils by a fan 2) water 3) evaporator coils / remote cooling units where air is circulated over the chilled water pipes 4) condenser pipes & flows to remote cooling towers to release heat into air |
| 1) refrigeration by "absorption" produced chilled water thru: 2) evaporation by absorption is produced in a: 3) what is used to draw water vapor from the evaporator? | 1) the loss of heat when water evaporates Fig17.2 2) closed system 3) a salt solution, & as it absorbs water & becomes diluted it must be regenerated by boiling off the water & returning the strong salt solution to the absorber |
| 1) water that is boiled off is returned to a liquid state in: 2) what removes the waste heat & carries it to cooling towers? 3) compared to compressive systems, absorption systems are: | 1) the condenser & then returned to the evaporator 2) both the condenser & absorber 3) less efficient, so they're mostly used when waste heat is available for energy input to the generator part of the system |
| 1) "evaporative cooling" occurs when water is dropped over: 2) as the free water evaporates (as vapor), heat is: 3) why does this only work in hot-arid climates? | 1) pads or fin tubes where outdoor air or water is circulated 2) drawn from the air or water circulating & cooled air is distributed to indoor spaces 3) b/c outdoor air has a low enough humidity level to allow moistened air to evaporate |
| 1) why can evaporative cooling be more economical than refrigeration cooling? 2) a "ton of refrigeration" aka a ton of cooling, is a unit to describe: 3) needed capacity of a refrigeration machine in tons can be calc's by: | 1) it only used 1 motor, not 3, & has a simpler const. w/ fewer parts & no refrigerant line 2) capacity of refrigeration system - effect when 1 ton of 32F ice melts to water in 24hrs = 12,000Btu/hr 3) dividing the calc'd total heat gain in Btu/hr by 12,000 |
| HVAC: ALL AIR SYSTEMS 1) what is a "direct expansion (DX) system" aka an incremental unit? 2) can a DX system also provide heat? 3) what is an "all-air system?" | 1) most simple type of HVAC, it's a self-contained unit that passes non-ducted air (OSA) over an evaporator which cools the air & is then discharged into room 2) yes, if a heating coil is included w/ unit 3) it cools or heats a space using conditioned air only |
| 1) all-air systems move heat to & from a space w/ supply & return ducts, & the most basic type of all-air systems is the: 2) where are these systems typ used? 3) describe the process of this system type | 1) "constant volume single-duct system" 2) resi & small commercial 3) air is heated (or cooled) in a central furnace (or A/C) & is distributed thru bldg in ducts at constant volume, one central thermostat ctrl's operation of furnace, then return ducts collect cool air & return it to furnace for reheating |
| 1) what is the disadvantage of this system? 2) what are the 4 main types of all-air systems used in larger bldg's? | 1) need for individual zone or rm ctrl is not possible, only way to ctrl air flow is to adjust dampers on supply registers in ea. room 2) - variable air volume (VAV) system - high-velocity dual-duct system - reheat (constant volume) system - multizone system |
| 1) in a variable air volume system, air is: 2) a thermostat ctrls a damper that varies the: 3) when outdoor cond's make it unnecessary to mech cond. the air, dampers on the return air side allow: | 1) heated or cooled as needed in a central plant & distributed to the bldg at a constant temp thru a single duct 2) vol. of conditioned air that enters the space to meet user's needs 3) variable amts of fresh air to be let into the bldg for ventilation & cooling |
| 1) a VAV system is limited in its ability to compensate for: 2) a VAV system offers an efficient means of: 3) how is a high-velocity dual-duct system set up? | 1) extremes in simultaneous heating & cooling demands in a bldg 2) air conditioning large internal load dominated bldgs 3) 2 parallel ducts run to ea. space, one w/ hot air & one w/ cool air & enter a mixing box to create proper mixture that's ctrl'd by pneumatic valves |
| 1) why can ducts be smaller in this system & therefore better for space saving? 2) why can the dual-duct system respond to varying req.'s thru the bldg? 3) what are the disadvantages of a dual-duct system? | 1) air travels at a high velocity 3000ft/min 2) b/c both hot & cool air are available at ea. location in a bldg 3) inefficient b/c hot & cool air have to be supplied at all times (cooled air may need heating or vice versa), high velocities take larger powerful fans using more energy & noise, & initial cost is high b/c of quantity of ductwork needed |
| 1) in a reheat (constant vol.) system: 2) how do individual spaces receive air? | 1) return air & fresh outdoor air are mixed, the system cools & dehumidifies the mixture & is then distributed in a constant vol. at low temp thru the bldg 2) air near space is cond'd, air is reheated as needed based on cooling load of ea. space Fig17.3 |
| 1) how is reheating air accomplished? 2) if the reheat equip. is located near the conditioned space, the unit is called: 3) if the reheating coils are located in the ductwork that serves an entire zone, the unit is called: 4) ^ how is temp regulated in #3 5) what is an economizer cycle & when is it used? | 1) typ w/ water, but electricity works too 2) a terminal reheat system 3) a zone reheat system 4) thermostats are used to ctrl valves in the water supply line 5) it allows outdoor air to be used for cooling when temps are low enough, it adjusts dampers on the return air ducts & fresh air intakes |
| 1) what are the advg's of the reheat system? 2) what is the disadvantage? | 1) humidity & temp can be carefully ctrl'd & that the low supply temp equates to smaller duct sizes & lower fan horsepower 2) it uses more energy than oth types of systems, b/c the primary air vol. must be cooled most of the time & then reheated |
| 1) in a "multizone system" air is supplied to a central mixing unit where: 2) just like in a dual-duct system, the advantage of a multizone system is: 3) the main disadvantage is that the amt of duct space: 4) this type of system is only used for (__) sized bldgs, or where: | 1) separate heating & cooling coils produce separate hot & cold airstreams & these are then mixed w/ dampers ctrl'd by zone thermostats & the resulting tempered air is delivered to the zones 2) simultaneous cooling & heating of different zones can be accommodated 3) increases rapidly as more zones are added 4) medium sized bldgs / central mixing unit can be located on ea. floor |
| HVAC: ALL WATER SYSTEMS 1) an "all-water system" uses 2) ventilation is provided by: 3) in a two-pipe system hot or chilled water is pumped thru: 4) in a four-pipe system (Fig17.4): | 1) a fan coil unit in ea. conditioned space, & these are connected to 1 or 2 water circuits 2) openings thru the wall at the location of the fan coil unit from int. zone air heating or simple infiltration 3) one pipe & returned in another 4) one circuit is provided for chilled water & one for hot (2 supply, 2 returns) |
| 1) in a three-pipe system: 2) is an all-water system an efficient way to transfer heat? 3) how/why is it easily ctrl'd? 4) it's not possible to ctrl what at the central unit? | 1) uses a single return pipe for both hot & cold water 2) yes 3) b/c the thermostat in ea. room regulates how much water flows thru the coils 4) humidity ctrl |
| HVAC: AIR-WATER SYSTEMS 1) this system relies on a central air system to provide: 2) when/where are these systems typ used? | 1) humidity ctrl & ventilation air to conditioned spaces, but majority of heating & cooling is from fan coil units in ea. space 2) where return air can't be recirculated b/c of potential contamination (hospital) -so 100% outside air is supplied & return air is completely exhausted to exterior |
| 1) in an "induction system" Fig17.5a, air is supplied thru the bldg how? 2) how is the water supply system for induction delivered? 3) another air-water system uses a fan coil for primary heating & cooling, but has a separate air supply to prvd: | 1) under high pressure & velocity to ea. induction unit, velocity & noise are attenuated before air passes over the coils & is heated or cooled as needed 2) heated or chilled water delivered to coils in either a 2 or 4 pipe system w/ thermostatic ctrl of water amt & temp flowing thru the coils 3) humidity ctrl & ventilation |
| HVAC: ELECTRIC SYSTEMS 1) the most common method of electric heating uses a: 2) advg's to electric heating are: 3) the biggest disadvantage of electric heat is that: 4) typ electric heat is used for supplemental heating in: | 1) grid of wires in the clg of a room to prvd radiant heating 2) it's a uniform, clean, inconspicuous form of heating that can be ctrl'd w/ a separate thermostat in ea. room, no space needed for piping or ductwork 3) it's not economical except in areas where electricity is inexpensive 4) localized radiant panels or to boost temp for water or air systems |
| GREAT TABLE 17.2 -selecting an appropriate HVAC system for a bldg depends on: 1) use profile of the bldg (occupancies) 2) bldg scale | 3) control needs 4) fuels available 5) climatic zone 6) flexibility 7) economics 8) integration w/ bldg systems |
| 1) some occupancies need flexible systems for different req's of multiple tenants; VAV & induction systems satisfy this req., a bldg w/ multi uses of simultaneous variations in heating & cooling loads may need dual-duct or multizone sytems; hospitals & labs need induction or fan coil systems w/ supplementary air so supply is 100% OSA w/ complete exhaust to outside | 2) bldg size helps determine if a central sytem is needed or individual units -if A/C load 25 tons < direct expansion units or heat pumps can be used (rooftop mtd or thru-wall type), but for large cooling needs a central station is more economical |
| 3) some bldg's like hotels, apt's, offices need thermostatic ctrl over individual spaces, oth's like theaters need less 4) selecting an HVAC system according to which fuel is readily & economically available | 5) climates like dry-hot ones req. little dehumidification so an all-water system could work vs a location w/ temp swings may need a dual-duct or four-pipe system to prvd response to change outside |
| 6) flexibility for bldgs that may change occ. or added onto would benefit from an all-water or all-air system that can be size to accommodate end capacity 7) the initial cost of an HVAC system, long-term maintenance, & cost of operating the system must be considered; needs life-cycle cost analysis | 8) the structural system in a bldg may suggest using one type of system over another - like in a cast-in-place conc struct w/ low flr-flr ht, all-water systems offer smaller piping rather than trying to fit large ductwork |
| -per IMC, req's for exhaust systems are distinct from ventilation req's; dedicated systems may be needed for: 1) equip that produce or throw off dust or particles sufficiently light to float in the air 2) equip that emit heat, odors, fumes, spray, gas, or smoke in quantities irritating or injurious to health/ safety | 3) hazardous mat.'s used in production 4) garages & motor vehicle repair facilities 5) clothes dryers 6) domestic kitchen exhaust 7) commercial kitchen hoods & grease ducts 8) laboratories 9) dust, stock, & refuse conveying systems 10) sub-slab soil exhaust systems 11) smoke ctrl systems 12) energy recovery ventilation systems |
| 1) exhaust air must be discharged where? 2) exhaust air cannot be discharged into: 3) determination of exact distances from general HVAC exhaust outlets & air intake is left up to: *see table 17.3 for distances of things to exhaust outlets | 1) outdoors where it won't cause a "nuisance," a legal term meaning dangerous to human life or health, & where it can't be drawn back into the bldg by an intake for ventilating system 2) attic or crawl space 3) local code official, not IMC |
| 1) how much energy is typ used by HVAC systems in overall consumption of bldg 2) what was enacted to est. min efficiency std.'s for heating & cooling equip? 3) performance of this equip ^ is rated based on: | 1) 40% - 60% 2) National Appliance Energy Conservation Act of 1987 3) annual fuel utilization efficiency, coefficient of performance, energy efficiency ratio, integrated part load value IPLV, seasonal energy efficiency ratio SEER |
| MECH TECH. TO CONSERVE ENERGY 1) an "economizer cycle" uses outdoor air when: 2) in "dual-condenser cooling," refrigeration equip uses: 3) ^(2) when heat is needed in the bldg (__) is used, & when it is not: | 1) it's cool enough to mix w/ recirculated indoor air; reduces energy needed to cool, esp when 60F & for large bldgs w/ large internal loads & heat gain in winter 2) 2 condensers instead of 1 3) the heat recovery condenser is used which sends waste heat to fan coil units / heat rejection condenser sends heat to cooling towers; auto system ctrls which condenser to be active |
| 1) what is a sim. alt. that can be used like a dual-condenser cooling system? 2) "absorption chillers" compared to A/C chillers, don't rely on: | 1) using multi chillers w/ units of varying sizes, not 1 big one, for efficiency 2) electricity & ozone depleting refrigerants they're powered by natural gas, a more economical fuel, but aren't as efficient unless it's a large bldg located where electricity costs are high & low cost heat sources from steam are available |
| 1) absorption chillers can be more efficient when using "solar-powered absorption cooling" b/c: 2) alt type of solar-powered cooling is the "solar-powered desiccant cooling" that uses: | 1) they're powered by hot water from solar collectors, std. flat-plate collectors can supply water at 175F to 195F or higher w/ parabolic concentrating collectors 2) desiccants (mat. that absorbs water) to dehumidify & cool air by means of evaporative cooling |
| 1) "direct contact water heaters" operate by 2) to improve efficiency, what is added? 3) when inlet water temp is blw 59F, what is efficiency of system? 4) b/c it's a high cost alt, it's best used where there's a continuous demand for: | 1) passing hot gases directly thru water to heat it, natural gas is burned to prvd flue gases that transfer heat to water (safe for human consumption) 2) heat exchanger on combustion chamber to reclaim heat lost from chamber 3) 99% 4) hot water, like at laundries |
| 1) a "recuperative gas boiler" aka fuel or boiler economizer, recovers the heat in: 2) the reclaimed heat is used to preheat: 3) std. gas boilers max efficiency = 83%, what is the economizer one? | 1) the flue gases that would normally be discharged to the atmosphere, it cools the gas to condensate so sensible & latent heat are recovered 2) the cold water entering the boiler 3) 95% |
| 1) "displacement ventilation" is an air distribution system in which supply air is: 2) this system is only good for new const., why? | 1) dispensed at flr level & rises to return air grilles in clg as it warms Fig17.6, air doesn't need as much cooling since it's delivered closer to users at flr level = energy savings 2) space for underfloor ducting needs to be provided, 12" or more is needed, so flr-flr ht needs to be pre-established |
| 1) a "water-loop heat pump system" uses: 2) why does no additional energy need to be added or removed when heating & cooling modes are balanced? | 1) a series of heat pumps for different zones of a bldg; they're all connected to the same piping system of circulating water Fig17.7 that's a temp of 60F-90F 2) if some zones are in cooling mode & dumping heat into loop, oth's are in heating mode & extracting that heat; a cooling tower & boiler are there if most of units are in same mode |
| 1) when is it good to use this type of system? 2) what is advg over 2 & 4-pipe systems? 3) "thermal energy storage" uses (__) to store excess heat or coolness for use at a later time | 1) efficient where there is a simultaneous need for heating & cooling in different areas, not good for bldgs w/ small cooling loads 2) reduces piping costs 3) water, ice, or rock beds |
| 1) what does thermal storage make possible? 2) ex, in summer chillers cool water at night when: 3) what medium can absorb & give off more heat, both sensible & latent? | 1) manage a bldg's energy needs over climatic temp swings thru day/week, allow use of less $$ off-peak energy costs to cool 2) utility rates are lower & cooling needs less than at day, & next day the stored coolness can be used to min. energy needed for cooling 3) ice, & it occupies 1/8 space as water |
| HEAT TRANSFER 1) in order to better IAQ, more OSA is needed, but that causes a need for: 2) "energy recovery ventilators" aka air-to-air heat exchangers, reclaim: 3) ^these can reduce energy needed to cond. incoming air by: | 1) energy use in conditioning the air, which is at odds w/ energy conservation, so selection of heat transfer method needed 2) waste energy from the exhaust air stream & use it to cond. incoming fresh air 3) 60% - 70% |
| 1) why are these efficient in very cold, hot, or humid climates? 2) what type of bldgs are they most efficient in? | 1) b/c the temp differential btwn indoor & outdoor air is high 2) those w/ cont. occ. like hotels/hospitals |
| 3 Cond's req'd for recovery ventilators: 1) fresh air intake must be kept far away from exhaust outlet as possible to avoid sucking exhaust back into bldg 2) exhaust air that contains excessive moisture, grease, oth contaminant should be separated from heat exchanger air | 3) in cold winter cond.'s, a defroser in the device may be needed to prevent the condensate in the exhaust air from freezing |
| 1) what 3 common devices are used to facilitate air-to-air heat exchange? 2) a "flat-plate heat recovery unit" is: | 1) flat-plate heat recovery units, energy transfer wheels, & heat pipes 2) device w/ 2 separate ducts, one for incoming air & oth for exhaust, separated by thin wall to facilitate heat transfer (sensible heat only), but offer no humidity ctrl |
| 1) an "energy transfer wheel" aka enthalpy heat exchanger, transfers heat btwn: 2) what is the advg of the wheel exchanger over others? 3) some units have a transfer efficiency of: | 1) 2 airstreams thru the use of a heat exchanger wheel, air passes thru small openings in wheel that have substance to absorb moisture & transfer it to oth airstream 2) it can transfer latent & sensible heat 3) 80% |
| 1) how does the energy transfer wheel exchange heat? | 1) in winter heat from warm, humidified exhaust air is transferred to cool, dry incoming air, & in summer, cool exhaust air removes some of the heat & excess humidity from the hot incoming air Fig17.8 |
| 1) a "heat pipe" is a self-contained device that: * to work, pipes need incoming & outgoing airstreams to be adjacent | 1) transfers sensible heat energy from hot exhaust air to cool outdoor air, as hot exhaust air passes over heat pipe it vaporized a refrigerant inside the pipe which then moves to a section of the pipe that is exposed to cool incoming air; as the refrigerant condenses, it releases heat to the incoming air, warming it, then a wick inside the pipe carries refrigerant back to hot side thru capillary action |
| 1) "water-to-water heat exchangers" aka runaround coils, use water or oth liquid to exchange heat by: 2) do incoming & exhaust airstreams need to be adjacent? 3) the efficiency of water-to-water heat exchangers is: | 1) in winter, hot exhaust air passes over coils that contain a heat transfer fluid, fluid then pumped into coils that cool incoming air passing over; in summer the cooled indoor air being exhausted is used to reduce the temp of the hot incoming air 2) no 3) 50% - 70% |
| 1) an "extract-air window" uses a double-paned insulated glass unit, w/ another pane placed inside the bldg, so air can be: | 1) drawn up btwn the int. pane & the main wndw unit & it's extracted into the return air system; this warms the glass in winter & cools it in summer to maintain a comfortable radiant temp & eliminate need for a separate perimeter heating system |
| 1) "ground-coupled heat exchangers" heat or cool outside air by: 2) in the summer, the air can be used directly if: 3) in the winter, the system can preheat air for: 4) they're suitable only for what bldg type | 1) circulating it thru pipes buried in the ground 2) the outdoor air temp is higher than the ground temp 3) an energy recovery ventilator (to prevent frosting) or for a std. fan-coil heating unit 4) low-rise bldgs |
| 1) their disadvantage is that: 2) an alt to this type of system is the ground-source heat pump that uses: 3) a "chilled beam" is a clg mtd unit that uses (__) to prvd: 4) a "passive chilled beam system" relies on | 1) long runs of pipes are needed for efficient operation 2) geothermal energy 3) water to prvd cooling & heating 4) natural convection & can prvd only cooling, temp of water must be slightly higher than room's dew pt to avoid condensation |
| 1) explain how passive chilled beams cool air: 2) separate ventilation ducts are req.'d b/c no ventilation air is used, but this separation allows for: | 1) installed abv suspended clg, warm room air rises by natural convection, enters the unit and comes in contact w/ fin tubes that cool water is circulated thru, air is cooled on contact & sinks naturally back down 2) smaller air ducts & fans, so reduced energy consumption |
| 1) why does this system allow a bldg's central chillers to be small than usual which saves energy? 2) in an "active chilled beam system" a ventilation system is integrated so it can prvd: 3) explain how an active system works | 1) b/c the water temp is higher than the std. temp of chilled water supplied to HVAC units 2) both heating & cooling 3) fresh air is drawn into unit where it's cooled or warmed by water, air is then forced out of the unit & into the room |
| 1) what is a "multiservice chilled beam system?" 2) chilled beams have a high initial cost, but what are the advg's? | 1) combines an active system w/ oth bldg services like lighting, sprinklers, data cabling, bldg mgmt system sensors 2) they offer much energy savings over all-air & air-water HVAC systems, lower maintenance b/c of fewer parts, compact design, quieter operation |
| 1) a "variable refrigerant flow system" uses a single compressor & condenser unit outside, connected to: 2) refrigerant is supplied to: 3) each evaporator is: 4) how is power consumption reduced? | 1) multiple evaporators located in different zones of the bldg 2) each zone, amt varies based on zone needs 3) individually controlled 4) both the compressor & all evaporators operate at varying speeds to meet load in each zone |
| 1) VRF systems can be designed to incorporate oth systems like: 2) VRF is ideal for bldg types: 3) it's not ideal for bldg types: | 1) heat pump technology or heat recovery for simultaneous zone heating & cooling, also ea. unit can accept ductwork for ventilation 2) offices, hotels, schools, multi resi, bldgs w/ varying loads & diff zones, also renovations b/c of small pipe/equip sizes 3) w/ large open volumes like theaters, gyms, arenas |
| 1) what are the advg's of VRF? 2) what is a "building automation system" (BAS)? | 1) saves energy, zone & equip location flexibility, quick installation, quiet operation ,reduced piping, central ctrl, monitor energy use for bldg mgmt system 2) computer-based integrated system used to monitor & ctrl bldg systems |
| 1) BAS can manage systems for: 2) the energy conservation component of a BAS is: 3) ^it detects enviro cond.'s in & out of bldg, monitors status of all equip like (__), & optimizes ctrl of equip by: | 1) HVAC, energy mgmt, lighting, life safety, security, vert. transportation, communications, mat. handling, irrigation 2) "energy mgmt system" (EMS) 3) temp, humidity, flow rates / start & stop times & operational adjustments (CH51) |
| ELECTRICAL FUNDAMENTALS 1) "ampere" (amp or A) = unit flow of electrons in a conductor = 6.241 x10^18 electrons passing a given section in 1 sec 2) "energy" = product of power & time, aka "work" 3) "impedance" = resistance in an alternating current (AC) circuit in ohms | 4) "ohm" Ω = unit of resistance in an electrical circuit 5) "power factor" = phase diff. btwn voltage & current in an alternating current circuit |
| 6) "reactance" = part of the electrical resistance in an alternating current circuit, caused by inductance & capacitance | 7) "volt" V = unit of electromotive force or potential diff., 1V is amt of force or potential diff. that will cause a current of 1A to flow thru a conductor whose resistance is 1Ω 8) "watt" W = unit of electrical power |
| 1) what is electricity? 2) a basic electric circuit consists of a: 3) what is used to interrupt a circuit? | 1) the energy generated by the flow of electrons 2) conductor, the actual flow of electrons (current), an electric potential difference to cause the electrons to move (voltage), & some type of resistance to the low of electrons Fig17.9 3) a switch |
| 1) Ohm's law for DC circuits states the current in a circuit is directly proportional to the voltage & inversely proportional to the resistance, what is the equation? *DC (direct current) | I = V / R |
| 1) "power" is the rate at which work is done or at which energy is used (expressed in watts), what is the equation? | 1) P = V I * in DC circuits wattage is the product of voltage & current * a watt is amt of power in a circuit when V = 1 volt & I = 1 amp |
| 1) a useful mnemonic is PIE which stands for: 2) AC (alternating currents) circuits operate when a: | 1) power (P) equals current (I) times electromotive force (E) *(E) is another term for voltage 2) conductor is moved in a magnetic field so a voltage is induced; the direction of movement determines the polarity of the voltage to be positive or negative |
| 1) how is a voltage of alternating polarity produced w/ a conductor? 2) how is AC voltage represented graphically? 3) ^amplitude of wave represents: 4) distance btwn peaks represents: 5) frequency is measured in: | 1) when a coil of a conductor (typ a wire) is rotated w/in a magnetic field, or when the magnetic field is rotated around a fixed coil 2) w/ a sine wave Fig17.10 3) voltage 4) one cycle 5) units of hertz (Hz) or cycles per sec. -in US AC is produced at 60Hz, Euro & oth countries = 50Hz |
| 1) in AC circuits, resistance is known as: 2) the difference in voltage & current is represented by the: | 1) impedance which comprises both resistance & reactance & causes a phase change difference btwn voltage & current 2) "power factor" (pf) & is a significant factor in calc'g power in an AC circuit |
| 1) Ohm's law for AC circuits, what is the equation? | 1) I = V / Z *remember Z is impedance which is resistance in an AC circuit measured in Ω * & remember impedance is difference btwn voltage & current |
| 1) what is the equation for power in an AC circuit? (remember it's sim to DC circuits) 2) what is the power factor for circuits w/ only resistive loads like incandescent lights or electric heating elements? | 1) P = V I (pf) *so same as for DC circuits but w/ the power factor included 2) 1.0 |
| 1) energy can be measured in (__) but is more commonly measured in: 2) what is the equation for calc'g the energy used in a system? | 1) watt-hours (W-hr) / thousands of watt-hours or kilowatt-hours (kw-hr) 2) E = Pt *so multiply power by time |
| 1) what are the 2 basic types of electric circuits? 2) describe how a series circuit works | 1) series & parallel Fig17.11 2) the loads (zigzag lines in diagram) are placed in the circuit one after another & current (I) remains constant thru circuit but voltage potential changes (drops) across each load |
| 1) describe how a parallel circuit works 2) adding up the individual currents in a parallel circuit results in: 3) why are series circuits not used in bldg const.? | 1) the loads are placed btwn the same 2 pts, the voltage remains the same, but the current is different across each load 2) a total current that is applied to the circuit as a whole 3) b/c of voltage drops across individual loads & if one load is removed the entire circuit is opened (ex light bulb burns out in a string of lights) |
| MATERIALS 1) what is the basic mat. of an electrical system? 2) when the AWG number designation decreases, the conductor: 3) what is considered "cable?" 4) what is considered "wire?" | 1) the conductor, sizes are based on American Wire Gauge (AWG) & thousand circular mil (MCM) designations 2) size increases 3) single insulated conductor no. 6AWG/+ or multi conductors assembled into a single unit 4) conductors no. 8AWG or smaller |
| 1) how is the cable diameter represented? 2) the current-carrying capacity or a conductor's "ampacity" depends on: 3) what are the 2 most common conductors? 4) why are specialists req.'d to install aluminum conductors? | 1) as a "circular mil" which is an area of measurement in thousandths of an inch sizes 250, 300, 400, 500 MCM's 2) its size, type of insulation around it, & the surrounding temp 3) aluminum $ & copper $$$, alum must be larger to carry same amperage as copper but are lighter 4) to avoid loose joints & oxidation that causes overheating & resistance |
| 1) what is conduit & what is the purpose 2) what type of cable is used in wood-frame resi bldgs of 3 or less stories? 3) what is the most common type of wire & cable? | 1) it supports & protects the wiring, serves as a system ground, & protects surrounding const. from fire if wire overheats or shorts 2) nonmetallic sheathed cable, 2/+ plastic insulated conductors & ground wire 3) a single conductor covered w/ thermoplastic or rubber insulation, needs a conduit |
| 1) when tapping into high currents is involved, what is used to avoid high $$? 2) what is req.'d for commercial & large resi const.? 3) what are the 3 types of metal conduit? | 1) a "busbar" or a rectangular bar of copper, & when several are used it's called a "busduct" or "busway" 2) individual conductors must be placed in mtl conduit or oth approved carrier 3) rigid steel conduit, intermediate mtl conduit, electric metallic tubing |
| 1) what is "rigid steel conduit?" 2) what is "intermediate mtl conduit?" IMC 3) what is "electric metallic tubing?" EMT | 1) heaviest type, connected to junction boxes & devices w/ threaded fittings 2) same as abv, but thinner walls, same dia., same purpose 3) lightest of all, uses special pressure fittings b/c too thin to thread, easier & faster install, more flexible so good where rigid can't be used |
| 1) # of conductors in single conduit is limited to ctrl heat build up & depends on: 2) the (NEC) National Electrical Code sets limits on: 3) when would underfloor raceways or undercarpet cable be used? 4) what are the 2 types of raceways? | 1) conductor type & size & size of conduit 2) length, number, radius of bends permitted in conduit btwn pull boxes, typ max (4) 90deg bends 3) like in office bldgs when locations of receptacles must be changed a lot 4) underfloor ducts & cellular mtl floors |
| 1) "underfloor ducts" are steel raceways that are: | 1) cast into concrete floor at regular spacing of 4', 5', 6', feeder ducts run perp. to distribution ducts carrying power & signal wiring from main elec. closet - preset inserts placed at intervals of distribution ducts to be tapped when needed |
| 1) "cellular mtl floors" use sim concept but 2) the most common form of elec. energy used in bldgs is "alternating current" AC, so when is "direct current" DC used? 2) utility companies prvd power to property lines, it's the owner's responsibility to then: | 1) are actually part of the struct. floor, aka mtl decking designed for use as cable raceways 2) some types of elevator motors, low-voltage applications like w/ signal systems, ctrls, sim equip. 3) pay for wiring, metering, transformers, & distribution to bldg's service entry |
| 1) service to a bldg may be underground (more $) or overhead, when it's overhead: 2) when might it be more cost effective for the owner of a bldg to purchase a transformer? | 1) service cable is connected to a weatherhead mtd min 12ft abv ground, this is part of conduit that leads to the meter & distribution panel 2) buy power from utility co. at higher voltages & use transformer to bring volts down than pay more for lower voltages |
| 1) what electrical wiring system is most commonly used for residences & small bldgs? 2) systems common for larger bldgs? 3) for larger bldgs typ w/ fluorescent lights which can use smaller wiring & currents 4) very large bldgs & factories w/ much machinery | 1) 120/240V, single-phase, 3-wire system Fig. 17.12a 2) 120/208V, three-phase, 4-wire system Fig17.12b 3) 277/480V, three-phase, 4-wire system (same as abv but w/ higher voltage) 4) 2400/4160V, three-phase, 4-wire system |
| 1) what are "transformers" used for? 2) what is a transformer's unit of measure? 3) for cooling, transformers can be: 4) if possibility of fire like w/ oil-filled transformers, equip must be placed in: | 1) to change alternating current voltages up or down, typ owner needs to bring it down to a service described on previous card^ 2) kilovolt-amperes (kVa) 3) dry, oil-filled, or silicone-filled 4) fire-resistive vault room at an exterior wall & vented to the outside |
| 1) what must be prvd'd at a bldg's service entrance? 2) in add. to total energy used, energy co.'s levy energy charges also based on: 3) most utility co.'s charge based on | 1) meter so utility co. can charge for energy used, it encourages conservation 2) "peak demand" b/c they must be able to supply power at max amt even if actual amt of energy used is low 3) "maximum interval demand" or avg amt of energy used in a time period of for ex 15 or 30 min |
| 1) what is "load factor?" 2) what does a low load factor mean? 3) what do all these terms mean: load ctrl, load shedding, peak demand ctrl, peak load regulation | 1) ratio of power used to max power demand 2) an inefficient use of energy & a high demand charge 3) that a bldg's elec system should be designed to avoid peak electricity use |
| 1) how does load ctrl work? esp w/ automatic systems 2) how does load scheduling work & help? | 1) device monitor's energy use & when certain pt is reached, nonessential electrical loads are shut off like lighting, water heating, space heating 2) diff. elec loads are auto. sch'd to operate at diff. times to ctrl peak demand |
| 1) large bldgs need a: 2) equip like transformers, meters, switchgears may req. a room that is: 3) power that comes thru the meter & transformer is: | 1) switchgear, or central electrical distribution center, to distribute power to oth parts of bldg 2) secure & have fire-rated walls & doors w/ panic hdwr on the exits 3) split into separate circuits, ea. w/ a master switch & breaker to protect from overload & short circuits |
| 1) b/c power from utility co. isn't always a steady, regulated voltage, what is used to help? 2) what is a "harmonic current" & why are they a problem for bldgs w/ computers & electronic equip? | 1) voltage regulators, surge suppressors, & filters, or "power conditioning units" for rooms w/ sensitive electronic equip. 2) it's a voltage or current at a frequency that's a multiple of the fundamental frequency, so in US typ 60Hz, so harmonic can be 120Hz, 180Hz, etc - they can cause overheating of the neutral conductor wiring & transformers, trip breakers, tele interference |
| 1) where do harmonic currents come from? 2) what can prevent them? 3) in "active line cond.'g" a comp. analyzing the harmonics of a line voltage adds a: | 1) produced from nonlinear electric loads like computers, copiers, variable-speed motors, etc, not simple resistive loads like incandescent lights for ex. 2) oversizing the neutral conductor, adding passive harmonic filters to the distribution system, "active line cond.'g" 3) equal but out-of-phase voltage to cancel out harmonics |
| 1) secondary distribution is when power from main switchgear is distributed to individual panelboards where it's further: 2) how is a circuit protected? 3) how many amperes is typ for gen. lighting & power vs for large loads? | 1) split into individual branch circuits used for power, lighting, motors, etc involving lower voltages of 120V, 240V, 277V 2) w/ circuit breakers in the panelboard, which are rated for amperage circuit is expected to carry 3) 15A - 20A vs 100A for large loads |
| 1) what are the 3 kinds of protection for electric circuits? 2) what is "grounding?" 3) to achieve grounding, the ground & neutral wire are both grounded at bldg's service entrance to a: | 1) grounding, ground-fault protection, arc-fault protection 2) it prvd's a path for a fault 3) grounding electrode buried in earth or fnd. or cold water pipe to prevent a dangerous shock is someone simultaneously touches an appliance w/ a short circuit & a ground path like a water pipe |
| 1) what are "ground fault circuit interrupters (GFCIs)" or "ground fault interrupters (GFIs)?" 2) where are GFI's req.'d? | 1) devices that can detect small current leaks, if it does it disconnects the power to the circuit or appliance 2) in dwelling units: bathrooms, garages, accessory bldgs at or blw grade, crawl spaces, unfinished basements, countertop outlets in kitchens, laundry rm, outdoors w/in 6ft of outside edge of wet bar, bathrooms of commercial occ. |
| 1) what is an "arc-fault circuit interrupter" (AFCI)? 2) where are AFCIs req.'d? | 1) helps protect against effects of arc faults from "arcing" & de-energizing the circuit when one is detected 2) in bedroom branch circuits serving both outlets & lighting (must run separate from all oth circuits in dwelling), also on 15A & 20A branch circuits on outlets in oth rooms |
| 1) the most common receptacle for normal distribution is the: 2) special outlets are req.'d for objects like: 3) what does it mean to be "hardwired?" 4) duplex outlets have holes to supply power, but also a 3rd hole for: | 1) duplex receptacle (outlet) aka "convenience outlet" since it's for use by occupants for portable objects at 120V 2) electric ranges, dryers, large copiers 3) electrical devices are connected to the bldg circuits in junction boxes 4) a grounding pole |
| 1) what is a "split-wired receptacle?" 2) outlets are typ mtd vert how high abv flr 3) ^but what is the min mtg ht req.'d for forward & side reach accessibility (ADA)? 4) in resi const. outlets must be a min (__) apart | 1) one outlet is energized but the oth is ctrl'd from a wall switch 2) 12" - 18" 3) 15" 4) 12ft w/ no pt more than 6ft from outlet & if space is 6ft< but >2ft & unbroken by openings it must also have an outlet |
| 1) most resi duplex outlets are (__) amps 2) outlets serving kitchen countertops must 3) on counters, how far apart are outlets? 4) do outlets in kitchen need to be GFIs? | 1) 15A, but min (2) 20A appliance circuits must be prvd for kitchen/dining 2) be on 2 diff circuits w/ no more than 4 outlets per 20A circuit 3) 24in w/ min one btwn appliances & sink so cords aren't draped across 4) yes |
| 1) what is a "two-way" switch? 2) what is a "three-way" switch? 3) a "four-way" switch? | 1) when one switch ctrls a light or oth device b/c it needs 2 conductors (non including the ground) to function 2) req.'s 3 conductors to make ctrl'g a light from 2 diff switches possible 3) can ctrl the same device from 3 or more locations |
| 1) switches can also be made low-voltage operated on 24V instead of line-voltage on 120V, the 4 advantages are: | 1) 1st same device can be ctrl'd from many spots that are remote from ea. oth, 2nd a central ctrl station can be set up to monitor the entire system & override local ctrl, 3rd ctrl devices like timers & energy mgmt can be wired to override local ctrl, 4th good for large installations req.'g flexible ctrl & less $ |
| 1) what is a "power line carrier system" (PLC)? 2) what is req.'d by model & energy conservation codes to ctrl lighting? | 1) can remotely ctrl line-voltage lighting & outlets by using power lines to carry low-voltage, high frequency code signals - ex a light can respond to it's unique code w/out add.'l wiring 2) individual area switching, so lights can be turned off when not needed vs one switch for a whole area |
| 1) what are some methods used to prvd multiple levels of illuminance? 2) specific req.'s for switching can vary by jurisdiction, but most req.'s are sim to ANSI/ASHRAE/IES Std. 90.1 Energy Std. for Bldgs Except Low-Rise Resi Bldgs which req.'s: | 1) multilevel lighting ctrl, dimmers (aren't effective for conservation), time-of-day controller, infrared or ultrasonic occupant sensors, a daylight compensation ctrl (this can reduce energy up to 60%) 2) auto shutoff be used in most bldgs larger than 5000SF |
| 1-3) methods to accomplish auto shutoff: *exceptions include areas w/ 24hr operations, spaces w/ patient care needed, or it would endanger safety/ security of room or occupants | 1) time-of-day controllers programmed to shut off lighting at specific times, ea. ctrl per 25,000SF but 1/floor 2) occ. sensors turn off lighting after occ. left area for 30min 3) separate ctrl or alarm system, like bldg security, set up to send signal to lighting ctrl device when area is unoccupied |
| 1) Std. 90.1 req.'s every space enclosed by clg ht walls have at least: 2) where is a manual switch not req.'d? 3) when a manual switch for override is req.'d, it must: 4) device must not ctrl area more than (_)SF | 1) one device to ctrl gen lighting in space, device must turn off 30min after last occ. 2) classrooms, conf./meeting rm, employee break rm 3) not override for more than 4 hrs 4) 2500sf if space is 10,000sf or less, OR 10,000sf if space is more than 10,000sf |
| 1) add.'l ctrls are req.'d for uses: 2) why must fluorescent & incandescent lights not be on a single circuit together? | 1) display lighting req. separate ctrl, hotel rooms need master ctrl device at room entry, supplemental task lighting, nonvisual lighting like for food warming, lighting equip. for sale/ used in demonstrations 2) 277V circuit is best for fluorescent while 120V is good for incandescent |
| 1) emergency power is supplied by generators or batteries for electrical systems that relate to: 2) standby power provides electricity for functions that: | 1) the safety of occupants like exit lighting, alarms, elevators, tele's, fire pumps, life threatening equip in hospitals 2) the bldg owner needs to avoid an interruption in business like computer operations or industrial processes |
| 1) 2 of the most common sources of large water supplies for cities are: 2) to treat water, its pH level must be known, what are the types? | 1) surface water from rain & snow that runs off into rivers & lakes AND groundwater that seeps down to the water table (large ones are called aquifers) 2) 7 is neutral, anything less is acidic & can be "acid rain," esp around industrial areas, & rust iron & steel pipes, & anything 7-14 is alkaline |
| 1) what is "hardness" of water & what is the problem with it? 2) what is "turbidity" in water? 3) how are odor problems in water treated? 4) how are water color problems treated? 5) color & odor problems are caused from: | 1) caused by calcium & magnesium salts in water, & if untreated can clog pipes & corrode boilers, inhibits cleaning power of soap in laundry or bathing 2) suspension of mat. in water like silt, clay, organic mat., treated w/ filtration 3) w/ filtration thru activated carbon 4) w/ fine filtration or chlorination 5) organic matter, inorganic salts, gases |
| 1) biological contamination in water can be caused by: 2) chemical contamination comes from: 3) water treatment methods are categorized into what 4 groups? | 1) bacteria, viruses, protozoa 2) industrial processes, mining, pesticides, some can be deadly & treatment can be expensive & complex 3) pretreatment, filtration, demineralization, disinfection |
| 1) pretreatment is typ necessary before oth methods & used to: 2) 1st "sedimentation" uses gravity & still water to allow particles to sink before: 3) "coagulation" is the process of getting particles in water to stick together by: 4) "flocculation" is last where water & alum mix is sent to still water so: | 1) remove suspended matter & large particles from water 2) clear water is piped into 2nd filtration system (can be done w/ or w/out coagulation & flocculation) 3) adding alum or oth chemicals 4) particles & alum form aggregated mass call floc which is heavy enough for sedimentation to occur |
| FILTRATION 1) "slow sand filtration" allows water to seep thru a bed of fine sand 3-4ft deep to: 2) "direct filtration" passes water under pressure thru a filter medium, this process always includes: | 1) allow a biological slime to form on sand where organic matter degrades, great for filterning out Giardia bacteria, not good for water w/ high turbidity, coagulation or flocculation not req.'d 2) coagulation & filtration, great for eliminating Giardia & most viruses |
| 1) "packaged filtration" is same as direct filtration except all elements are: 2) "diatomaceous earth filtration" uses a thin layer of diatomaceous earth on septum or filter element to: 3) "membrane filtration" forces water at high pressure thru a thin membrane that: | 1) placed in a single unit for direct hookup to a water supply 2) remove cysts, algae, asbestos, but not bacteria & turbidity (this is sedimentary rock formed from siliceous shells of phytoplankton) 3) removes particles 0.2mm? & larger, Giardia, oth bacteria, viruses, & microorganisms |
| 1) "cartridge filtration" uses self-contained units placed along the water supply line to: DEMINERALIZATION 2) what does demineralization remove? 3) "ion exchange" is used in water softeners to treat hard water & to remove: | 1) filter out particles 0.2mm? & larger, cartridges must be replaced once fouled 2) dissolved solids & chemicals that cause hard water 3) cadmium, chromium silver, radium, oth chemicals, water is piped into softener which contains zeolite where calcium or magnesium ions are exchanged for the sodium ions in zeolite |
| 1) "reverse osmosis" removes contaminants by using a semipermeable embrane that allows only: 2) "electrodialysis" places charged membranes at the inflow stream of water to: | 1) water to pass thru & not dissolved ions, good for removing inorganic chemicals, bacteria, suspended particles 2) attract counterions, can remove barium, cadmium, selenium, fluoride, nirates, but are expensive & need high water pressure & direct current power |
| DISINFECTION 1) disinfection destroys what in water? 2) "chlorination" is most common treatment to kill organisms by: 3) "chloramine" is sim to chlorination but: | 1) microorganisms that can cause disease, EPA req.'s it of water supply from surface water or groundwater created by surface 2) introducing chlorine gas, liquid, or solid into water 3) includes ammonia, gen used as 2nd disinfectant b/c it's weaker |
| 1) "ozonation" disinfects water thru the use of: 2) "ultraviolet light" destroys a cell's ability to reproduce & is effective against: 3) "nanofiltration" uses filter membranes that are capable of trapping particles: | 1) ozone, it req.'s a 2nd disinfectant after, typ used for cooling tower water 2) bacteria & viruses, but not Giardia or Cryptosporidium, suspended solids, turbidity, & needs 2nd disinfectant 3) one nanometer in size, can remove bacteria, viruses, pesticides, organic mat., needs high pressure to force water thru |
| 1) "distillation" is treated by: 2) "aeration" or "oxidation" is used to improve: 3) process of aeration works by expsing as much of waer as possible to air thru: | 1) boiling it & condensing the vapors, very clean, all solids, bacteria, salts removed, often used to treat seawater 2) taste & color of water, aids in removal of iron & manganese by oxidizing them 3) sprays, fountains, waterfalls |
| 1) if you want a private water supply in the form of a well, two important considerations in drilling are: 2) what yield is needed for a private residence 3) what protects well water from seepage of surface contamination? | 1) depth and yield, depth is impossible to know until drilling begins, yield is the # of gallons per min. it prvd.'s 2) 5gpm to 10gmp, otherwise a storage tank may be needed to collect during off peak hours 3) steel pipe casing that's 4-6in in dia. w/ perforations at base to allow well water in |
| 1) pump systems used in wells have 3 fundamental components: 2) "suction pumps" are only good for water tables (__)ft 3) "jet pumps" can operate at depths from: 4) "turbine pumps" are used for: 5) common pump for residences is: | 1) a well, a pump, a storage tank 2) less than 25ft 3) 25ft to over 100ft 4) high capacity sytems w/ deep wells 5) submersible pump w/ a motor that pumps water up to pressure tank |
| 1) "jet pumps" have pump & motor abv grd to: 2) "pressure tanks" are used to maintain a constant water pressure for use in: | 1) lift water using the "venturi effect" - a jet stream is created in another pipe, low pressure sucks up well water to surface & pumped to a pressure tank 2) the bldg & to compensate for brief peak use demand that exceeds pump capacity, it also reduces amt pump needs to run thru sensors of tank depletion |
| 1) once municipal water supply has been treated, it's: 2) one of the 1st tasks in bldg a project is to determine the location of: 3) ^ where can this information be found? | 1) pumped thru water mains on avg at a pressure of 50psi, a pressure-reducing valve may be needed at bldg meter 2) the public water main, its size, its pressure, & cost for tapping it which can be significant if owner must extend line to site 3) the local water company |
| 1) why does the designer need to know the pressure in the line? SOLAR WATER HEATING 2) how is an "open-loop system" aka a direct system defined? 3) in a "closed-loop system" aka an indirect system: | 1) to determine what kind of supply system can be used 2) water used in the bldg is the same that's heated in the solar collectors 3) a separate fluid for collecting heat, is then transferred to the domestic hot water |
| 1) what is the adv vs disadvantage btwn the 2 systems? 2) "passive circulation systems" rely on what? 3) passive systems are simple & low cost, but their storage tanks must be placed: | 1) direct systems are simple & efficient but can freeze, indirect can avoid freezing w/ anti-freeze heating medium but needs a heat exchanger so efficiency goes down 2) gravity & thermosiphoning action of heated water 3) abv solar collectors & pt of use needs to be close to storage tanks |
| 1) "active circulation systems" use: 2) how can freezing be avoided in systems? 3) a "bach system" heats water directly in a: | 1) pumps to circulate the heat-collecting fluid, more flexible but w/ added cost of equip. 2) anti-freeze medium, or if not possible drain liquid at night or when cloudy 3) black-painted tank inside a glazed box - simple but can freeze & lose heat at night |
| 1) a "thermosiphon system" relies on the: 2) in this system ^ where are storage tanks located? 3) ^ how does this system avoid freezing? | 1) natural movement of heated water to circulate the water in a passive, open-loop system 2) abv the solar collectors 3) a variation of it in a closed-loop form uses anti-freeze medium |
| 1) in a "closed-loop active system" a separate, nonfreezing fluid is circulated by pumps thru the solar collectors &: 2) a sensor is included to track temp when: 3) a "drain-down system" is a direct, active system that solves the freezing problem by: | 1) into a heat exchanger where the dometic hot water is heated 2) the collector is lower than stored water so it turns off pump 3) automatically drains water from collectors when outside temp is near freezing, should only be used w/ mild winters to avoid draining water often |
| 1) a "drain-back system" is an indirect, active system that uses water as the heat-collector fluid, so heated water is pumped to a heat exchanger where: 2) a "phase change system" uses a phase change mat. as collector fluid b/c: | 1) a coil of domestic hot water is heated & when the ctrl senses too low a temp it turns off the pump & the collector water drains back into the solar storage tank 2) they can store large amts of latent & sensible heat CH51 *definitions PG17-34 |
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