Heat transfer principles Flashcards
The driving force that causes heat transfer is ___.
Temperature differential
A tank contains 100 pounds of oil. The specific enthalpy (h) of the oil is 100 BTU/lb. the oil contains ___ total enthalpy (H).
10,000 BTU
___ is the type of heat transfer that involves molecular action.
Conduction
___heat transfer involves fluid or gas flow.
Convention
___ heat transfer does not require flow or a medium.
Radiation
Describe Energy
Energy can’t be created nor destroyed, but only converted from one form to another.
The units of enthalpy are:
BTU/lb
The ___ is the amount of heat that will transfer through each square foot of heat transfer surface area for each degree Fahrenheit (°F) of temperature differential.
Heat transfer coefficient (U)
What is the theoretical temperature at which all molecular movements stops?
Absolute zero
What describes energy?
Cannot be created not destroyed, only converted from one form to another.
The units of specific heat are:
BTU/lb/°F
Heat transfer is:
Movement is heat energy from one material or liquid to another.
Cooling water flowing in a heat exchanger has a temperature in of 70°F; temperature out of 80°F; flow rate of 100lb/min; and a specific heat of 1 btu/lb/°F. Calculate the heat transfer.
1000 BTU/min
The units for enthalpy are:
BTU/lb
The type of heat transfer that involves molecular action is:
Conduction
What substance has the highest specific heat capacity?
Hydrogen 3.45btu/lb°f
Water 1btu//lb/°f
Stainless steel .12btu/lb/°f
Iron .11btu/lb/°f
___ heat transfer involves fluid flow.
Convection
The general heat transfer equation is commonly used for all these purposes except:
- establishing maintenance schedule
- heat exchanger troubleshooting
- heat transfer problem investigation
X heat exchange design consideration
Unknown
If the tubes get dirty in a lube oil cooler but the heat load, heat transfer surface area, the cooling water flow and temperature remains constant, the lube oil temperature will:
Increase?
What is another name for natural convection?
Natural draft
___ Heat transfer does NOT require flow or a medium.
Radiation
If the temperature difference between the hot and cold substance triples, the rate of heat transfer between them:
Triples
___ is the amount of heat energy a substance contains.
Enthalpy
