Deck 8: Cooling Towers

Question 1

The measurement of how much water the air has absorbed at a given temperature.

A) relative humidity
B) standard humidity
C) wet bulb
D) approach to the tower

Answer 1

relative humidity

Question 2

Devices used in a cooling tower to keep water from blowing out.

A) louvers
B) drift eliminators
C) columns
D) splash bars

Answer 2

drift eliminators

Question 3

_______________ is a term applied to the horizontal direction that air takes in relationship to the downward flow of water in a cooling tower. _______________ is a term applied to the vertical flow of air as it moves through a cooling tower in relationship to the downward flow of water.

A) induced and forced
B) horizontal and counterflow
C) cross and vertical
D) cross and counterflow

Answer 3

cross and counterflow

Question 4

The objective of water treatment is to reduce or minimize all of the following except:

A) Scale formation- suspended solids form deposits
B) Corrosion- electrochemical reactions with metal surfaces
C) Fouling- silt, debris, algae plug exchanger tubes
D) Wood decay- fungi
E) pH increase or decrease
F) water deionization

Question 5

Heat that can be measured or sensed is referred to as:

A) latent heat of vaporization
B) latent heat of condensation
C) sensible heat
D) latent heat of fusion

Question 6

The approach to tower is the:

A) Relative humidity minus the dry bulb
B) Wet-bulb minus the dry-bulb
C) temperature delta ∆ that exists between the relative humidity and the wet-bulb temperature of the air leaving the tower.
D) temperature delta ∆ that exists between the water leaving the tower and the wet bulb temperature of the air entering the tower.

Question 7

Dry bulb temperature is the:

A) the air temperature as measured by a bulb thermometer covered by a water saturated wick. Takes into account the relative humidity.
B) combination of dry and wet-bulb temperature
C) air temperature as measured by a dry-bulb thermometer
D) wet-bulb temperature minus the relative humidity

Question 8

The wet bulb temperature is the:

A) the air temperature as measured by a bulb thermometer covered by a water saturated wick. Takes into account the relative humidity.
B) combination of dry and wet-bulb temperature
C) air temperature as measured by a dry-bulb thermometer
D) wet-bulb temperature minus the relative humidity

Question 9

Identify the following components:

Question 10

A cooling tower has a(n):

A) box shaped collection of multi-layered wooden slats and louvers that direct air flow and breaks up water as it falls from the top of the tower or water distribution header.
B) internal design of the tower ensures good air and water contact.
C) chimney design used to move air flow by buoyancy forces.
D) a & b

Question 11

A cooling tower is classified by:

A) How it produces air flow; mechanical or natural.
B) How the air flows in relation to the downward flow of water; cross or counter current.
C) How the water flows in relation to the downward flow of air, cross or counter.
D) a & b

Question 12

The temperature delta that exists between the water leaving the tower and the wet bulb temperature of the air entering the tower.

A) wet bulb ÷ dry bulb
B) relative humidity ÷ dry bulb
C) approach to tower
D) temperature delta

Question 13

A device used in a cooling tower to break up and redirect the flow of falling water.

A) louvers
B) drift eliminators
C) columns
D) splash bars

Question 14

Vents located on the side of a cooling tower.

A) louvers
B) drift eliminators
C) columns
D) splash bars

Question 15

Mechanical draft towers use fans to force air in (_______draft) or pull air out (_________draft.)

A) forced draft and induced draft
B) induced draft and forced draft
C) cross and counterflow
D) counterflow and cross

Question 16

Air moves through a (forced draft or induced draft) at a higher rate. What happens to the flow rate at the discharge point?

A) forced, speeds-up, 10% efficiency increase
B) forced, slows-down, 20% efficiency decrease
C) induced, speeds-up, 10% efficiency increase
D) induced, slows-down, 20% efficiency decrease

Question 17

The measure of how much water the air has absorbed at a given temperature.

A) humidity
B) wet bulb
C) relative humidity
D) dry bulb

Question 18

Identify the following components.

Question 19

A term applied to fluid flow that is directed into one piece of equipment before exiting and entering another. Example heat exchanger

A) parallel flow
B) series flow
C) cross flow
D) counter-current flow

Question 20

A pipe that evenly disperses hot water over the fill of a cooling tower.

A) water distribution header
B) tower water discharge line
C) hot water inlet to cooling tower
D) a & c

Question 21

Draw a simple hyperbolic cooling tower. Identify basic components.

Question 22

Draw a simple induced-draft cooling tower with counter-flow.

Question 23

A post used to support the framework of a cooling tower.

A) treated wood column
B) white pine column
C) plastic column
D) a & c

Question 24

Hyperbolic towers are primarily designed for service in what industry?

A) chemical plants
B) power plants
C) refineries
D) fertilizer plants

Question 25

A common term used to describe the internal buildup on the surface area of a heat exchanger that results in restricted flow .

A) corrosion
B) plugging
C) fouling
D) scale

Question 26

Draw a simple flow diagram of a cooling tower, pump, valves and three heat exchangers in series service.

Question 27

Draw a simple atmospheric cooling tower. Identify basic components.

Question 28

Results when electrochemical reactions occur between metal surfaces and surrounding hot water that results in the gradual wearing away of metal.

A) corrosion
B) plugging
C) fouling
D) scale

Question 29

Sensible heat transfer accounts for __________ to ___________ of the cooling effect in a cooling tower.

A) 10% to 20%
B) 40% to 70%
C) 80% to 90%
D) 90% to 100%

Question 30

Which tower is most efficient, forced or induced? What happens to the flow rate at the discharge point?

A) forced, speeds-up, efficiency increase
B) forced, slows-down, efficiency decrease
C) induced, speeds-up, efficiency increase
D) induced, slows-down, efficiency decrease

Question 31

The efficiency of a tower is tied to all of the following factors except:

A) relative humidity
B) temperature
C) wind velocity
D) personnel
E) equipment condition
F) tower design
G) water contamination

Question 32

Hot water has all of the following characteristics except:

A) Hot water dissolves a little bit of everything it comes in contact with. By the time the hot water returns to the tower it is full of suspended solids.
B) Hot water also has a tendency to become corrosive and deposit forming.
C) When hot water enters the cooling tower laced with suspended solids it undergoes evaporation. This process removes water and leaves the solids. The remaining fluid concentrates in the basin. Over time this concentration will build up to levels that must be controlled.
D) Increases oxygen level in the water raising pH levels.

Question 33

A term applied to fluid flow that is equally distributed to multiple pieces of equipment. Example heat exchanger

A) parallel flow
B) series flow
C) cross flow
D) counter-current flow

Question 34

____________ draft cooling towers use natural forces to bring air into a cooling tower while ____________ draft towers use fans to induce or force air into a tower.

A) natural & mechanical
B) cross and counter-current flow
C) vertical and horizontal
D) normal and modern

Question 35

Which hyperbolic tower gets higher air flow; counter-flow, cross-flow?

A) counterflow
B) cross-flow

Question 36

Which hyperbolic tower is more efficient; counter-flow, cross-flow?

A) counterflow
B) cross-flow

Question 37

Evaporative cooling accounts for ___________ to __________ of the cooling effect in a tower.

A) 10% to 20%
B) 40% to 70%
C) 80% to 90%
D) 90% to 100%

Question 38

The rate of air flow in a natural draft cooling tower depends primarily on _________________.

A) wind velocity
B) temperature
C) air intake louver position
D) a & b

Question 39

Draw a simple flow diagram of a cooling tower, centrifugal pump, valves, and two heat exchangers in parallel service.