Thermal, Environmental, And Comfort Concepts Flashcards
True/false: heat always flows from substance of higher temperature to substance of lower temperature.
True
What is heat?
Agitation of atoms and molecules
Quantity of heat is measured in what?
BTUs British thermal units
As a rule of thumb, one BTU is given off by one what?
One wooden match
In scientific terms, a BTU is the amount of heat, at constant and standard atmospheric pressure, required to do what?
Raise the temperature of one pound of water from 59.5 degrees to 60.5 degrees
One BTU is equivalent to how many joules?
1055 joules
MBtu or kBtu is how many Btus?
1,000 Btus
MMBtu is how many Btus?
1,000,000 Btus
1 therm is equal to how many Btus?
100,000 Btus
The heating value of a fuel is the quantity of what produced by its combustion?
Heat
Temperature is a measure of the average of what?
Kinetic energy associated with the movement of atoms Andmolecules in a substance
What is specific heat?
The amount of heat that must be added to one pound of any given substance to raise its temperature by one degree.
Specific heat capacity is the amount of heat required to change the temperature of a (blank) of a substance by (blank) degrees.
Volume. One.
(Blank) is the heat associated with change in temperature of a substance
Sensible heat
True or false: the addition or removal of heat from a substance changes it’s temperature disproportionately to the heat added or removed.
False. In direct proportion.
What I enthalpy?
Thermal energy
Power is defined as the measure of (blank) consumed over a (blank)
Energy. Period of TIme.
The unit used to defined power is…
Btu/hour
Psychometrics is the study of the thermodynamic properties of (blank) mixtures under varying (blank) and (blank).
Gas-water vapor. Temperatures. Pressures.
By definition, dry air is air that contains no (blank).
Water vapor
Saturated air is air that contains the maximum amount of moisture the air can hold at (blank)
That temperature
Dry bulb temperature is the temperature of the mixture of (blank) and (blank) at (blank)
Air. Moisture. Rest.
Dry bulb temperature is not affected by the amount of (blank) in the air or the (blank) from the surroundings
Moisture. Thermal radiation.
Wet bulb temperature is the temperature measured with a thermometer with a (blank) covering its bulb as fast moving (blank) passes across it.
Wet cloth. Air.
Wet bulb and dry bulb temperatures are equal only when the air is (blank)
Fully saturated
(Blank) is the temperature of the air/moisture mixture when it is fully saturated (100%) relative humidity.
Dew point temperature.
Frost point temperature is where the dew point temperature (blank)
Falls below freezing
What is partial pressure as it relates to humidity?
It is the amount of pressure that moisture contributes to the total pressure of the air/moisture mixtures.
Relative humidity is measure by what instrument?
A hydrometer
Humidity Ratio is the mass of (blank) to the mass of (blank) contained In a sample of air.
Water vapor. Dry air.
Specific humidity is the ratio of (blank) to the total mass of (blank).
Water vapor. Moist air.
Absolute humidity is the ratio of the (blank) of water vapor to the total (blank) of the sample.
Mass. Volume.
Specific volume is the ratio of the (blank) of dry air per (weight) of dry air. Example cubic feet per pound.
Volume. Weight.
Specif volume is the opposite of what?
Density.
THe sensible heating process involves adding (blank) to air without changing its (blank) content.
Heat. Moisture.
The two basic mechanisms that the body uses to regulate temperature are change of (blank) and change of (blank).
Metabolism. Blood circulation near the skin.
Convection moves heat away from the body by what?
Air movement around the body and a difference in temperature between skin and air.
1 kilocalorie is approximately equivalent to (blank) Btus.
4
Ashrae standard 55-2004 specifies combinations of indoor space environmental and personal factors that will produce thermal environmental conditions where (blank) % of occupants do not express dissatisfaction with room conditions.
80%
For design of heating systems, the lower temperature in the winter design temperature range is (blank) degrees. In the summer the upper limit for the cooling and air conditioning design temperature is (blank) degrees
- 79.
An indoor relative humidity range of between (blank) and (blank) percent is optimal.
30% and 60%
Increases in indoor humidity between the range of 30% to 60% increases the temperature sensation by about (blank) degrees for every 10% to 15% increase in humidity.
1
True or false: adding humidity to an indoor environment is a more efficient way of increasing temperature sensation than heating the ambient air.
False. It is more efficient to heat the air.
Mean radiant temperature is a measure of the combined effects of the temperatures of (blank) within that space..
Surfaces.
What has a greater impact on thermal comfort: mean radiant temperature or dry bulb temperature?
Mean radiant temperature.
The unit used to describe the metabolic activity level of a person is what?
A met
1 met is equal to the metabolic rated of a (blank)
A quietly seated male.
What does a black globe thermometer measure?
Mean radiant temperature
What instrument is used to measure relative humidity in the room?
Hydrometer.
The heat index is a measure of the contribution of (blank) and (blank) make in reducing the bodies ability to cool itself.
High ambient temperature. High humidity.
