Brazed Plate Heat Exchanger
Unlike traditional heat exchangers, the brazed plate heat exchanger consists solely of surfaces that make an active contribution to heat transfer. The plates are welded or brazed together to prevent the fluids from mixing or leaking. The advantage of this style is that the heat exchanger can be designed for higher pressures and temperatures or in cases where readily available gaskets may not be compatible with the fluids.
Brazed plate heat exchangers are widely used in refrigeration plants.
- How It Works
- Copper Brazed
Units in the Alfa Laval AC series of copper-brazed heat exchangers are mainly used as:
- Evaporators for dry expansion and cooling water
- Condensers for rejecting or recovering heat to water
- De-superheaters for partial heat recovery to water
- Economizers for cooling liquid refrigerant and super-heating vapour refrigerant.
They can also be used as:
- Sub-coolers to cool liquid refrigerants using well water
- Intermediate heat exchangers in the absorption cycle, to preheat the diluted solution or to pre-cool the concentrated solution.
How It Works
Brazed heat exchangers used for HVAC applications normally use a parallel flow to achieve the most efficient heat transfer. In a single-pass design, all the connections are located on one side of the heat exchanger, making installation very easy.
Alternate channel pattern
When used as an evaporator, the channels formed between the corrugated plates and corners are arranged so the two media flow through alternate channels, always in opposite directions (counter-current flow). The two-phase refrigerant (vapour + liquid) enters at the bottom left of the unit. The vapour quality depends on operating conditions in the refrigeration plant.
Evaporation of the liquid phase takes place inside the channels. Some degree of superheating is always required – hence the process being called "dry expansion". The dark blue and light blue arrows show the location of the refrigerant connections. The water (brine) to be cooled flows counter-currently in the opposite channel; the dark and light red arrows show where the water (brine) connections are.
AC Series as condenser
When used as a condenser, the main components are still the same as for the evaporator. The refrigerant enters at the top left as a hot gas and starts to condense on the surface of the channels. Once fully condensed, it is then subcooled slightly, in a process called "free condensation". The dark and light blue arrows show the location of the brine connections. The refrigerant flows counter-currently in the opposite channel and is cooled. The dark and light red arrows show where the refrigerant connections are.
CB - Copper-Brazed Heat Exchanger
The CB range of brazed plate heat exchangers feature efficient heat transfer with an extremely small footprint, making them ideal for demanding installations where space is at a premium.
The thin, corrugated stainless steel plates used in the CB design are brazed together with copper. This forms a self-contained unit that can handle both high pressures and high temperatures. And unlike traditional designs, the brazed plate heat exchanger consists solely of surfaces that actively contribute to heat transfer, resulting in significant increases in overall efficiency.
The CB range of brazed plate heat exchangers has numerous advantages over traditional heat exchangers in both Industrial and HVAC&R installations. The exceptional heat transfer efficiency makes all CB units very compact. As a result, they can tackle large-capacity duties even though there is only limited installation space available.
The brazed construction also does away with gaskets, making CB units ideal in applications where temperatures and/or pressures are high. Examples include district heating and a wide range of heating, cooling and tap water solutions.
Units in the CB range are available in many different sizes and capacities, with varying plate patterns and connections for particular duties and performance specifications. CB units can be configured as single-pass, dual-pass or multi-pass installations, according to project requirements.