Study sets, textbooks, questions
Upgrade to remove ads
Commercial Refrigeration Ch. 3
Chapter 3 Condensers
Terms in this set (37)
What is the primary function of the condenser?
Reject heat from the refrigerated space
Why does the suction vapor have to be increased in temperature before it can be condensed?
So the condensing temperature is above ambient
How can the temperature of refrigerant be increased without adding excessive heat?
Raise the pressure of the refrigerant
What are the three phases of the condenser?
De-superheat, condense, and subcool
Where does the superheat in discharge gas come from?
Suction vapor heat, compressor motor heat, and heat of compression
When does condensing start?
When the discharge gas is cooled to its condensing temperature
What is subcooling and what does it indicate?
Subcooling is cooling the liquid refrigerant below its condensing temperature
After the vapor has been condensed to a liquid, what are two causes for the liquid to flash back into vapor before it reaches the metering device?
A rise in temperature or a fall in pressure
If a ⅜" liquid line has a vertical lift of 40 feet, how much pressure drop is there?
Based on the pressure drop in the question above and a design condensing temperature of 125° for R22, what is the minimum subcooling required?
5 degrees Fahrenheit
What is "condenser split"?
The difference between ambient air and the condensing temperature
If the condenser split of a unit is 30° what should the condensing temperature be with an ambient air temperature of 70° entering the condenser?
100 degrees Fahrenheit
Based on the previous question, if the system is using R22 what should the head pressure be?
What, or who, determines the condenser split of a unit?
The condensing unit manufacturer
What are the approximate condenser splits of the following units and why?
a. Standard medium temperature refrigeration condensing unit?
b. Commercial freezer?
c. Remote refrigeration condenser?
a. 30 degrees b. 20 to 25 degrees c. 10 to 30 degrees
How does a technician make sure a condenser is clean?
The technician thoroughly cleans it himself
Why is it necessary to make sure the condenser fan blades are clean?
Dirty blades provide less airflow than clean ones
The term "low ambient" usually describes ambient temperatures below __ degrees.
60 degrees Fahrenheit
What is the minimum condensing temperature for standard refrigeration units?
125 degrees Fahrenheit
What are three common methods of head pressure control during low ambient?
Dampers, fan cycle controls, and condenser flooding
Fan cycle controls can respond to what two conditions?
Head pressure and ambient temperature
What problems can occur if the condenser fan stays off too long?
Air-cooled compressor motor overheating and erratic TEV operation result
What problem occurs when the condenser fan short cycles?
The fan motor can be damaged
What region of the United States is best suited for fan cycle controls?
How do "prevailing winds" affect a condensers operation?
They lower head pressure even when the fan stops
How does "condenser flooding" maintain head pressure in low ambients?
The refrigerant takes up space in the condenser tubing, forcing head pressure up
What four things must a technician know before diagnosing an HPR valve?
Ambient temperature, head pressure, liquid line temperature, and valve rating
What is "floating head pressure"?
Allowing the head pressure to drop along with the ambient
What does "tube-in-tube" mean when referring to water cooled condensers?
Water is circulating through an inner tube, which is surrounded by an outer pipe that contains the refrigerant.
What is a "shell-and-tube" water-cooled condenser?
This is a water cooled condenser that utilizes a large tank, or shell, for the purpose of condensing and holding the refrigerant. The hot discharge gas enters the shell or tank coming into contact with the cool water pipes, or tubes that run through the tank.
Waste water condensers use how much water per minute at incoming water temperatures of 75°?
1.5 GPM per ton
If the compressor in the previous question is rated at 6,000 btuh, what should be the leaving water flow rate in gallons per minute (gpm)?
What is the approximate condensing temperature of a water cooled condenser?
105 degrees Fahrenheit
The water leaving the water cooled condenser should be how many degrees below the condensing temperature?
10 degrees Fahrenheit
If the head pressure is correct, do you need to measure the flow rate of the outlet water? Justify your answer.
Yes, mineral deposits inside the tube increase the water flow not the head pressure.
If the head pressure is high and the flow rate is high, what is the condition of the water-cooled condenser?
There is too much mineral buildup in the condenser
Is cleaning a water cooled condenser always successful? Why?
No. The cleaner may not be able to remove enough material to lower the head pressure
Recommended textbook explanations
Mechanics of Materials
Fundamentals of Electric Circuits
Charles Alexander, Matthew Sadiku
Thermodynamics: An Engineering Approach
Yunus A. Cengel
Adel S. Sedra, Kenneth C. Smith
Sets found in the same folder
Commercial Refrigeration Ch 6
Commercial Refrigeration Ch. 4
Commercial Refrigeration Ch.7
Commercial Refrigeration Ch.1
Sets with similar terms
Commercial Refrigeration Final Study Guide
Unit 22 (Condensers)
Unit 22 Condensers Exam
Other sets by this creator
Commercial Refrigeration TS
Low Pressure Boilers Ch.9
Low Pressure Boilers Ch. 11
Commercial Refrigeration Final Study Guide
Other Quizlet sets
Ethics Exam 3
18.12: The Effect of Substituents on Reactivity
Sales - Assignment #1
Political Ideology Review