REF UNIT 22 Flashcards
what are the end caps of the shell of tube and shell condensers called?
water boxes (that’s where water circulates)
what is the typical flow rate in a wastewater system with 75F entering water?
1.5 GPM/ton
what is the typical flow rate in a recirculating water system with a cooling tower?
3 GPM/ton
what valve controls water flow rate in wastewater system?
water-regulating valve
what is the typical DTD Inca recirculated water system?
about 10F
(12.1) why are condensers sized at 15,000 BTU/ton?
because the condenser has to reject extra heat caused by HOC.
(22.4) can coiled tube-in-tube condenser’s be mechanically cleaned?
no
(22.6) how does a shell-and-coil condenser work?
refrigerant is in the shell, water flows through coil inside shell.
(22.7) can you mechanically clean a shell-and-tube condenser?
yes.
(22.8) a standard cooling tower can only cool water within ___ to ___ degrees of the ambient wet bulb temperature.
7 to 8.
(22.11) what are the 3 different types of cooling towers?
natural draft, forced draft, evaporative.
(22.12) define makeup water
water added to cooling tower to make up for evaporated water.
(22.14) how are evaporative condensers different from cooling towers?
evaporative condensers are inside the cooling tower, and other condensers are outside of the cooling tower.
(22.14) define blowdown
the water dumped by a cooling tower to prevent mineral deposits.
(22.18) what does flooding the compressor accomplish?
raises head pressure under low ambient conditions.
(22.18) what is a LAC valve?
low ambient control valve. Floods the condenser under low ambient conditions.
(22.18) if all the refrigerant in a system is pumped into the receiver, how full should that receiver be?
80%
(22.18) what does splitting the condenser accomplish?
reduces the amount of extra refrigerant charge needed for changing outdoor conditions.
(22.21) what does floating head pressure mean?
letting the head pressure fluctuate with ambient temperature for lower compression ratios for better efficiency.
