CH 14 Active Climate Control Systems

The absorption refrigeration cycle needs about ___ times the heat-rejection capacity of the vapor compression refrigeration cycle.

2

The common sizing procedure for wood-burning heating devices assumes a ___ moisture content of the wood fuel.

20%

A central HVAC system with the following classification would require the largest distribution tree:

all-air

Even though no change in total heat content occurs, evaporative cooling is accompanied by:

an increase in relative humidity

A ground-source heat pump system may be difficult to deploy in an urban area because:

city infrastructure systems, such as water and electricity mains, must be circumvented

Locating a heat source below a window:

evens out the temperature in a room but increases heat loss through the window

The acronym "HVAC" stands for

heating, ventilating, and air conditioning

Which air-water HVAC system functions by mixing incoming supply air with room air by way of high-pressure jets?

induction systems

One of the attractions of dispersing large building HVAC systems into smaller elements is that:

large equipment rooms are not required

The procedure for sizing cooling equipment is more complicated than for heating equipment because:

latent as well as sensible heat must be considered for cooling equipment

What is a disadvantage of using refrigerants that contain no chlorofluorocarbons and thus constitute a low threat to the environment?

machines that use these refrigerants may be less efficient and thus involve higher energy consumption some of these refrigerants may contain harmful chemicals natural hydrocarbon refrigerants are flammable and explosive

Which boiler type is preferred for energy conservation?

modular boiler

The following are disadvantages of a local HVAC system (choose three):

noise with the potential to disturb space activities air quality is more difficult to maintain than in a central system there is little opportunity to reuse equipment waste heat

A distribution tree approach that flows from a rooftop central air-handling unit will:

reduce duct size on lower building floors

Control of which thermal comfort determinant can usually not be accomplished (in many climates) without mechanical assistance?

relative humidity

In the HVAC design process, component sizing typically occurs before which process?

resolving conflicts with other building systems

Integrating vertical distribution trees with structure can bring the advantage of:

saving prime floor space

Which of the all-air HVAC systems has the smallest distribution tree?

single-duct

Which type of HVAC system makes the most sense for an interior zone of a large-floor-plate building?

single-duct VAV

A skin-load dominated building tends to be best suited for a local, room-by-room HVAC scheme because:

the building may have differing but simultaneously occurring needs across short distances

One ton of cooling capacity is equivalent to:

the useful cooling effect of one ton (12,000 Btu/h [3.5 kW]) of ice

Which of the following materials has the highest emittance?

white granular-surface bitumen