 Evaporators
by Alfa Laval
Using the brazed
heat exchanger as an evaporator provides a low cost alternative
to the conventional shell & tube heat exchangers. Channels are formed
between the corrugated plates and corner are arranged so that the
two media flow through alternate channels, always in counter current
flow.
The two phase
refrigerant (vapour+liquid) enters the bottom left of the exchanger
with a vapour quality depending on the operating condition of the
plant. Inside the channels the evaporation of the liquid phase takes
place and some degrees of superheat are always requested. The process
is called "dry expansion", see the blue and arrow for the inlet
and outlet ref. connections location.
The water (brine) to be cooled flows counter current in the opposite
channel side, see the dark and light red arrow for the water (brine)
connection location.
Advantages of using a brazed heat exchanger as an evaporator:
- Special Built in distributor allows for a more even flow performance
eliminating performance fluctuations
- Lower refrigeration charge results in cost savings for the
operator of the system
- The possibility of freezing is lessened with a turbulent flow
with a short retention time in the heat exchanger
- Proven performance with thorough testing done at Alfa Laval's
refrigeration labs in Sweden and the United States
- Large capacity ranges for evaporators from ¼-55 refrigeration
tons in brazed units and higher tonnages in other types of heat
exchangers
- Most units available from stock
|
