Chapter 11 Flashcards
A procedure in which the direction of flow through the exchanger is reversed to remove solids that, for example, have accumulated in the inlet tubes of a heat exchanger.
Backwashing
A metal plate that is placed inside a vessel or tank and is used to alter the flow of chemicals, facilitate mixing, or cause turbulent flow.
Baffle
A measure of energy in the English system, referring to the heat required to raise the temperature of 1 pound of water 1°F at sea level.
British thermal unit (BTU)
The amount of heat energy required to raise the temperature of 1 g of water by 1°C at sea level.
Calorie
Flow that occurs when two fluids are flowing in the same direction.
Co-current flow
An exchanger used to convert a substance from a vapor to a liquid.
Condenser
The transfer of heat from one substance to another by direct contact.
Conduction
The transfer of heat as a result of fluid movement.
Convection
Occurs when two streams flow perpendicular (at 90° angles) to each other.
Cross flow
Located on the end of a heat exchanger, it directs the flow of fluids into and out of the tubes.
Exchanger head
Accumulation of deposits (such as sand, silt, scale, sludge, fungi, and algae) built up on the surfaces of processing equipment.
Fouling
The transfer of energy from one object to another as a result of a temperature difference between the two objects.
Heat transfer
A process to process heat exchanger. Interchangers use hot process fluids on the tube side and cooler process fluids on the shell side. Also known as cross exchanger.
Interchanger
A streamline flow that occurs when the Reynolds number is low (at very low fluid velocities).
Laminar flow
Occurs in a heat exchanger when the shell flow and the tube flow are parallel to one another.
Parallel flow
A heat exchanger that adds heat to some substance prior to a process operation.
Preheater
The transfer of heat through electromagnetic waves (example warmth emitted from the sun).
Radiation
A tubular heat exchanger, placed at the bottom of a distillation column or stripper, that is used to supply the necessary column heat.
Reboiler
A number used in fluid mechanics to indicate whether a fluid flow in a particular situation will be smooth or turbulent.
Reynolds number
The outer casing, or external covering of a heat exchanger.
Shell
The measure of the thermal energy of a substance (example the “hotness” or “coldness”) that can be determined using a thermometer.
Temperature
A group of fixed, parallel tubes though which process fluids are circulated.
Tube bundle
A formed metal plate with drilled holes that allows process fluids to enter the tube bundle.
Tube sheet
flow that occurs when a dimensionless number (Reynolds number) is above 10,000 (at high velocities).
Turbulent flow
Devices that are used to transfer (exchange) heat from one substance to another without the two process fluids physically contacting each other. Without this many processes could not occur properly.
Heat exchangers
Heat can be transferred through conduction, convection, or radiation. However, the primary modes of heat transfer in the process industries are:
conduction and convection
1BTU is equivalent to:
252 calories
The term calorie, with a capital C found on food labels and in diet books is really 1,000 of the calories referred to in this chapter. That means one BTU is actually equivalent to:
252,000 of the calories we eat!
Heat is commonly transferred by three methods:
conduction, convection, and radiation
Example of conduction
frying pan
Example of convection
hair dryer
Example of radiation
sunlight
consist of a series of thin plates that are mounted on a frame with alternating hot and cold fluids.
Plate and frame heat exchangers
a group of fixed or parallel tubes through which process fluids are circulated.
Tube bundle
is a flat plate to which the tubes in a heat exchanger are fixed.
Tube sheet
consists of a group of fixed or parallel tubes, a tube sheet, baffles, and tie rods.
Tube bundle
Heat exchangers are used to transfer heat between:
hot and cold streams
Which of the following is the flow characteristic that occurs when the tube side stream and the shell side stream flow in the opposite directions?
Parallel flow
Components that are found in a heat exchanger:
channel cover, baffle/divider, and tube sheet
A ________________ is the piece of equipment that is bolted to the outside end of the channel to retain exchanger fluid and provide access for cleaning.
channel cover
Which of the following pieces of equipment is used to convert a vapor to a liquid?
condenser
Which of the following is not a potential problem in heat exchangers?
chemical balance
Provides circulation based on density differences.
Thermosiphon reboiler
Used to cool hot liquids.
Cooler
Used to cool gas from a furnace.
Transfer line exchanger
Uses cooling to convert a substance from a vapor to a liquid.
Condenser
