Unit 29 Assign
For each 12,000 Btu/h capacity, a wastewater-cooled condensing unit uses approzimately __ GPM.
1.5
For each 12,000 Btu/h capacity, a water-cooled condensing unit and cooling tower combination will circulate approzimately __ GPM through the condenser.
3
Most water-cooling towers can cool the water that supplies the condenser to a temperature within __ degrees F of the wet-bulb temperature of the ambient air.
7
In a high-temperture refrigeration unit, the boiling point of the refrigerant in the coil is normally __ lower than the cabinet temperature.
A. 10 - 20 degrees F
In a wastewater cooled system, the difference between the condensing temperature of the refrigerant and the leaving water temperature is approximately __.
A. 10 degrees F
In a water-cooled condensing unit/cooling tower combination, the temperature difference of the water through the condenser will be approximately __.
A. 10 degrees F
In a wastewater systems, the water entering the condenser is 85 degree F and the water leaving the condenser is 105 degree F. Which of the following statements is a logical explanation for the above conditions?
A. reduced water flow through the condenser
The process of ice making usualy occurs in which temperature range?
B. 5 - 20 degress F
The refrigerated cabinet temperature of a high-temperature refrigeration unit ranges from __.
C. 45 - 60 degress F
The approach of a cooling tower is the __.
C. difference in temperature between the entering air wet-bulb temperature and the sump water temperature.
With the entering air to the condenser above 70 degree F, the temperature difference between the outdoor air and the condensing temperature on standard will be __.
D. 25 to 30
Medium-temperature refrigerated cabinet temperatures range from __.
D. 30 - 45 degrees F
If an air-cooled condenser is located on a 95 degree F roof and the condenser saturation temperature is 150 degree F, which of the following is a possible scenario?
D. The system is overcharged and the condenser is clogged.
Condensing units located outside that are required to operate year-round must have __.
D. head pressure control
An air-cooled R-12 refrigeration system is operating normally with a suction pressure of 25 psig and a head pressure of 136 psig. Which of the follwing represents a possible set of operating pressures if the condenser fan motor burns out?
D. high side 180 psig, low side 35 psig
When the comperssor in a system using capillary tubes is sweating, it is a sign of __.
D. refrigerant overcharge, dirty evaporator, and evaporator blower motor problem.
In a wastewater systems, the water entering the condenser is 85 degree F and the water leaving the condenser is 90 degree F. Which of the following statements is a logical explanation for the above conditions?
D. water regulating valve stuck in the wide-open position, excess water flow through the condenser
T/F: A thermostatic expansion valve's capacity will drop if the pressure drop across the valve increases.
FALSE
T/F: Bubbles in the sight glass always indicate refrigerant shortage.
FALSE
T/F: High compression ratios will lead to lower compressor discharge temperatures.
FALSE
For a low-temperature refrigeration system with an evaporator saturation temperature of -40 degrees F, why might R-502 be used instead of R-12?
R-502 will keep the pressure positve. R--12 will will operate in a vacuum
T/F: Becuase of the low refrigerant flow rate through the compressor and the system being undercharged, the 100% satured vapor point in the condenser will be very low in the condenser, causing low condenser subcooling.
TRUE
T/F: Dirty condenser coils are often the cause for inefficient condensers.
TRUE
T/F: If the evaporator and compressor are starved of refrigerant, the condenser will also be starved.
TRUE
T/F: Low density vapors entering the compressor will mean low refrigerant flow through the compressor.
TRUE
T/F: Since many new replacement refrigerants are being used throughout the industry, a techician should rely on system temperatures to ease the troubleshooting process.
TRUE
T/F: The best place for a liquid line sight glass is at the inlet of the expansion device.
TRUE
If a system has a __ for a metering device, the __ will try to maintain evaporator superheat even with an excessive overcharge.
TXV, TXV
In a 2-ton TX valve system, the unit does not develop full capacity. Head pressure is high, suction pressure is slightly above normal, and subcooling is superheat is normal, and subcooling is above normal. What is the problem?
dirty condenser
In a 2-ton capillary tube system, the unit does not develop full capacity. Head pressure is low, and suction pressure is high. What is the problem?
inefficient compressor
Will the gauge readings be high or low with a system using a capillary tube that has a low refrigerant charge?
low
A low refrigerant charge will cause a __ suction pressure, which will __ the compression ratio.
low suction and increase compression
The water quality required to maintain the water level in the sump is called __.
make-up
In a 2-ton TX valve system, the unit does not develop full capacity. Head pressure is high, suction pressure is slightly above normal, superheat is normal, and subcooling is above normal. What is the problem?
overcharged
In a 2-ton capillary tube system, the unit does not develop full capacity. Head pressure is high, suction pressure is high, and there is no superheat. What is the problem?
overcharged
In a 2-ton capillary tube system, the unit does not develop full capacity. Head pressure is low and suction pressure is low. What is the problem?
under charged
Why is it that many products that require medium - temperature refrigeration will not freeze at 30 degree F?
water freezes at 32 degrees F any other addtives will lower the freezing put
