Brazed Plate Heat Exchangers (BPHE) is a special type of liquid to liquid plate heat exchanger that combines the qualities of compactness, high efficiency and durability. These heat exchangers are fabricated from stacked plates that are brazed and corrugated together to increase surface area and promote greater heat transfer.
Alfa Laval AC line of brazed plate heat exchangers provide efficient heat transfer with a small footprint. They are specifically developed to work in air conditioning, refrigeration, chillers and heat pump applications.
Brazed plate heat exchangers are widely used in refrigeration plants. They are normally used to transfer heat from the refrigerant – the primary fluid – and from water or brine as the secondary fluid.
Units in the Alfa Laval AC line of copper-brazed heat exchangers are mainly used as:
They can also be used as:
In a Brazed Plate Heat exchanger, a standard plate arrangement is provided which creates two independent circuits that run in alternate layers. The two fluids have a flow direction that is opposite to each other. Since brazed heat exchangers are made in a vacuum furnace and are helium pressure tested, they ensure highly leak-free performance.
Following are the key benefits of BPHE:
Brazed plate 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 line 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 sub cooled 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.