Modern Ref. Chapter 4 Flashcards
What is the purpose of a refrigeration system?
To transfer heat from one location to another.
_____ is the ability to effect change in matter
Energy
Potential energy is _______ energy
stored
Name 5 types of energy
Chemical Thermal Light Electrical Mechanical
What is the law of conservation of energy?
Energy can neither be created or destroyed, it is simply changed from one form to another
What is density?
A substances mass per unit of volume (lb/ft^3)
What is Avogadro’s law?
Different gases at equal temperatures, pressures, and volumes contain equal numbers of molecules.
What is force?
Energy applied to matter that, unless counteracted y opposing forces, causes a change in the matters velocity.
Si unit of force?
Newton (N)
What is work?
Work is force multiplied by the distance through which it travels.
Si unit of work?
joule (J)
What is power?
the rate at which work is performed
Si unit of power?
Watts (W)
The temperature of melting ice in Fahrenheit and Celsius?
32 degrees Fahrenheit
0 degrees celsius
The temperature of boiling water in Fahrenheit and Celsius?
212 degrees Fahrenheit
100 degrees Celsius
What does absolute zero mean?
This is the temperature at which molecular motion stops. it is the lowest temperature possible.
What are the Rankine and Kelvin scale?
These are two absolute zero temperature scales. One in Fahrenheit and one in Celsius
What is ambient temperature?
The temperature of the air surrounding an object
Radiation is the transfer of heat by ____
rays
Three methods of heat transfer commonly used in comfort heating and cooling are:
Radiation, Conduction, and Convection
Light generates more heat when striking through ____ coloured rough objects than when striking _____ coloured polished surfaces
dark, light
Superheat is the difference in temperature between a vapour and its _________ _____
condensation point
To calculate a vapours superheat, subtract its _______ ____ from its measured temperature.
condensation point
Heat always flows from a ______ substance to a _____ substance
warmer to cooler
The ____ system is the modern version of the metric system?
Si system?
The two main classifications of energy are?
potential and kinetic energy
The law of conservation of energy states that:
Energy can neither be created or destroyed
The weight of a substance is defined as the:
force of gravity acting on a substance
The density of a substance is defined as the mass of the substance
divided by its volume
If a substance has a specific gravity less than 1.0, it means that the substance is _____
less dense than water
Objects that float on water have a specific gravity ____ ____ one
less than
Relative density is defined as the ratio of the mass of a certain volume of a gas compared to the mass of an equal volume of hydrogen. Knowing this concept and that density is mass per volume, a heavy gas would then have a density _______
greater than 1
____ is the rate at which work is performed
power
Temperatures measured on the ____ scale can be converted to Fahrenheit temperatures by subtracting 460F
Rankine
The ___ of a substance is the amount of heat added or released to change the temperature of 1lb of the substance by 1 degree F or 1kg of the substance by 1 k.
specific heat capacity
Enthalpy is the ______
total amount of heat in a substance calculated from an accepted reference temp.
______ is the method by which heat is transferred from one substance to another through a circulating medium such as air or water
Convection
Heat energy can be categorized as latent heat and ____heat.
sensible
Latent heat is added to the substance that _____
causes the substance to change state
A ton of refrigeration effect is defined as the:
Amount of heat energy absorbed when a ton of ice melts during one 24-hour day.
