Chapter 4 commercial ref. R Q – 2342 with Complete Questions and Answers
4 views 0 purchase
Course
Chapter 4 commercial
Institution
Chapter 4 Commercial
Chapter 4 commercial ref. R Q – 2342 with Complete Questions and AnswersChapter 4 commercial ref. R Q – 2342 with Complete Questions and AnswersChapter 4 commercial ref. R Q – 2342 with Complete Questions and Answers
The discharged vapor picks up which of the following two additional sources...
Chapter 4 commercial ref. R Q –
2342 with Complete Questions
and Answers
The discharged vapor picks up which of the following two additional sources of
sensible heat as the suction vapor is processed through the compressor ?
a. motor heat and the heat of compression
b. evaporators superheat and motor heat
c. motor heat and condensing heat - ANSWER - motor heat and the heat of
compression
What is "clearance volume " and how does it affect compressor efficiency ? -
ANSWER - The clearance volume is the space between the closed discharge valve in
the piston when it is at the top of its stroke. The higher the pressure, the lower the
piston must fall before the suction valve opens and the less suction vapor will be
pulled into the cylinder. The less suction vapor in the cylinder, the less efficient the
compressor.
What is " volumetric efficiency " ?
a. The size of the cylinder in relation to the clearance volume.
b. How well a compressor is operating compared to its design capacity.
c. The head pressure divided by the suction pressure. - ANSWER - How well a
compressor is operating compared to its design capacity.
If an R404A commercial freezer has design conditions of -20 degrees and +125
degrees condensing, what is the compression ratio ? - ANSWER - 11.2:1
If an R404A commercial freezer has design conditions of -30 degrees evaporator
and + 125 degrees condensing, what is the compression ratio ? - ANSWER - 14.1: 1
If an R-404A freezer has an evaporator design temperature of -20 degrees, but the
condenser is designed for 25 degrees condenser split and the condensing
, temperature drops to 120 degrees. What is the compression ratio ? - ANSWER - 10.
5:1
If the suction valves are broken, what is the cause ?
a. flooding
b. slugging
c. flooded start - ANSWER - slugging
What causes flooding and slugging ?
a. too much refrigerant returning to the compressor.
b. too little refrigerant in the system
c. compressor running too slow to pump vapor - ANSWER - Too much refrigerant
returning to the compressor.
What is the difference between an air- cooled compressor and a suction cooled
compressor ? - ANSWER - An air cooled compressor receives its motor cooling from
outside of the compressor. Either condenser air is blown across the compressor
body or corals of water tubing are wrapped around the compressor in the area of
the motor. Also, the suction service valve is mounted closer to the valve plate and
cylinder. A suction cooled compressor receives its motor cooling from the suction
vapor flowing over the windings before moving on to cylinder. Also, the suction
service valve is mounted close to the motor area.
As the compression ratio of compressor is increased.....
a. less heat produced in the head of the compressor
b. more refrigerant is pumped through the system
c. less refrigerant is pumped through the system - ANSWER - Less refrigerant is
pumped through the system .
What is the inter-stage on a two-stage system ?
a. Where the discharge of one enters the suction of the other.
b. Where the suction of one enters the discharge of the other.
c. where the refrigerant is added to increase suction pressure. - ANSWER - Where
the discharge of one enters the suction of the other.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller NursingTutor1. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.99. You're not tied to anything after your purchase.
