23 terms

Unit 22 quiz #1

Unit 22 quiz #1
1.Why do some condenser have to be
cleaned with brushes and others with chemicals
Answer: So the condenser can properly reject heat without going into a high system pressure,
The types that have to be clean with chemicals are types that are not excusable
2.What are 3 materials condensers are
normally made of ?
Answer: Stainless steel, copper and nickel
3.Who should be consulted when
condenser cleaning is needed ?
Answer : The manufacturer
When is the most heat removed from the refrigerant in the condensing process.
The greatest amount of heat that is given up from the refrigerant is while the condensing
process is taking place, de superheating
5.After heat is absorbed into a
condenser medium in a water cooled condenser,the heat can be deposited in one of two places.What are they?
Answer : The water can be used once, then wasted down the drain or where large amounts
of water are being used, it is more economical to save water, cool it in an outside water tower and reuse it.
6.A water cooling tower capacity is
governed by what aspect of the ambient air?
Answer : The wet bulb temperature of the air
7.When a standard efficiency air cooled
condenser is used the condensing refrigerant will normally be....F higher in temperature than the entering air temp .
Answer : 30F higher than the outside air temp
8.Four methods of controlling head
pressure in an air cooled condenser are?
Answer : Fan cycling controls, variable speed fans, shutters and condenser flooding controls
9.The prevailing winds can affect which
of the air cooled condensers?
Answer : The cooling tower
10.Air-cooled condensers are much
more efficient than water-cooled condensers.
Answer : (False) Water cooled condensers are much more efficient than air cooled condensers
11.The type of condenser that has the
lowest operating head pressure is the------ cooled condenser.
Answer : The water cooled condenser
12.Compare the standard conditions of
high efficiency and standard air cooled condensers.
Answer : High efficiency would be to have the condenser head pressure as close to the
ambient air as possible.
13.Name 2 ways in which the heat from
an air cooled condenser can be used for heat reclaim?
Answer : The discharge gas can be passed to the rooftop condenser or to a coil mounted in
the duct work that supplies heat to the store.
14.Briefly describe what is meant by
floating head pressure and tell why it is used in refrigeration and AC system
Answer : An industry term for attaining the lowest possible condensing pressure is called
Floating head pressure. Floating head pressure systems simply let the condensing pressure follow the ambient temperature as the seasons swing from summer to winter.
15.Explain how to flush impurities from
a water regulating valve that is on a water cooled condenser.
Answer : Water cooled condensers can be cleaned by brush or chemically
16.Explain the basic operations of a
combination ORI and ORD low ambient head pressure control valve.
Answer : ORD valve sense a factory preset pressure difference of 20 psi between the
receiver and compressor discharge , It will start to open and bypass hot compressor discharge gas to the receivers inlet The ORI valve stows refrigerant in the condenser to maintain the correct head pressure. Both the ORI and the ORD will work in conjunction of one another to maintain proper receiver pressure, regardless of outside temperature.
17.Name two problems a refrigeration
system may have if the condensing unit is exposed to low ambient condition when it is not using a low ambient head pressure control valve
Answer : When the condensing medium is cold enough to reduce the head pressure to
the point that the expansion device will starve the evaporator. And less head pressure cause less heat to be available for the heat reclaim coils to heat buildings
18. Name 3 types of cooling towers?
Answer : Natural Draft, Forced Draft, and Evaporative
19.How much higher does a water
cooled condenser condense at when using a cooling tower?
Answer : 10F
20.What must be added to the system
to help water when it is evaporating from over concentrating minerals ?
Answer : Water must be added to the system to keep this from happening
21.Name the 3 types of water cooled
Answer : Tube within a tube, Shell & coil, Shell & tube
22.What is the component that rejects
heat from the refrigeration system ?
Answer : The Condenser
Recirculating water uses what ? to help
the cooling process.
Answer : Evaporation