HVAC 1-4

अब Quizwiz के साथ अपने होमवर्क और परीक्षाओं को एस करें!

A latent heat change always causes a change in molecular spacing. True of False

True

A sensible heat change always causes a change in temperature True or False

True

There is a change of state in a substance whenever latent heat is added to it or removed from it. True or False

True

Heat produced by human bodies is an example of

chemical

A gas-fired furnace relies upon ...to take the heat of the flame through a metal of its heat exchanger to the air passing over it.

conduction

The three ways heat is transferred are called

conduction, convection, radiation

Materials that help heat move by conduction are called

conductors

The air which is circulated through an air conditioned space moves heat by

convection

The currents you see in a cup of hot coffee, tea or chocolate are caused by

convection

Heat is a form of

energy

As the temperature of any substance increases, the molecules which make it up vibrate

faster

Heat flows downhill. This means

it naturally flows from a warmer to a colder substance

List four forms of energy that turn into heat energy in air conditioned (cooled) spaces.

light, electrical, chemical, mechanical

Since man cannot destroy heat, when we say refrigeration "removes" heat, we are really saying it ......heat

moves/transfers

Sunlight is an example of

radiation

List two examples where mechanical refrigeration is used

refrigerator/ AC

Total heat is the sum of

sensible heat and latent heat

When we compare "heat content" to "heat transfer" which things are true?

-Heat content tells how much heat is contained in a substance -Heat transfer tells how much heat is moved from one substance to another

Mechanical refrigeration systems have all the components listed below except one.

A low side float value

One pound of refrigerant will take up the most space.

As a gas because it has the lowest density

Using the word "molecule" give a simple definition of density.

Density is a measurement of how packed molecules are from any substance

When heat is moved, the temperature of the substance it moved from:

Drops

Define latent heat

Energy of molecular separation/arrangement

Name two scales most commonly used to measure temperature

Fahrenheit and Centigrade

A thermometer can be used to measure a latent heat change. True or False

False

A livingroom in a house is kept at 70 F. When it is 20 F outdoors, which items below demonstrate heat flowing downhill?

Heat flows from the indoor air to the outside wall Heat flows from the outside wall to the outdoor air

Define sensible heat

Heat of molecular motion

When a substance changes state from a liquid to a gas, the spacing of its molecules.

Increase greatly

Hot food brought into space (Latent or Sensible)

Latent

Outside air brought in for ventilation (Latent or Sensible)

Latent

People perspiring and breathing in a space (Latent or Sensible)

Latent

To the refrigerant mechanic the most important type of heat

Latent, because the machinery moves most of its heat that way.

Which one of these is a good insulator and, therefore, a poor conductor?

Polystyrene

Define refrigeration

Refrigeration is cooling by the removal of heat.

There are 4 basic categories for the use of mechanical refrigeration. Which of these in NOT one of them?

Room air conditioner

Heat coming in through a hot roof (Latent or Sensible)

Sensible

Heat from electric appliances and motors (Latent or Sensible)

Sensible

Heat from lights (Latent or Sensible)

Sensible

Sun shinning in through a window (Latent or Sensible)

Sensible

What does temperature measure?

Sensible heat/ Speed of vibration of molecules in a substance

air conditioning is a form or refrigeration T or F

T

A cooling coil has 40 F refrigerant inside its tubes while 80 F air passes over it. Because heat flow "down hill" it will move from

The air into the coil surface

A cooling coil has 40 F refrigerant inside its tubes while 80 F air passes over it. Because heat flows "downhill" it will move from

The air into the coil surface

Define temperature

The density of heat in a substance

Define heat transfer

The movement of heat from one place to another


संबंधित स्टडी सेट्स

Chapter 19: Fossil fuels, their impacts and energy conservation

View Set

Anatomy Session 17: Shoulder and Brachial Plexus

View Set

CMB Chapter 6 DNA Replication, Repair, Recombination

View Set

Week 3 Package Managers & Background

View Set

Security Awareness - Unit 12 Quiz

View Set

J3OP-US261-HB Emergency Preparedness Response Course (EPRC) - Basic Awareness Course (2 hrs)

View Set