Application
Soldered plate heat exchangers are primarily used as evaporators, condensers and oil coolers. In multi-step systems or complex refrigeration circuits they also excel as desuperheaters, super-coolers and economiser. Plate heat exchangers can also be used in reversible refrigeration circuits as well as in indirect systems. This wide range of possible applications means that different heat exchanger versions are needed.
Structure
The stainless steel plates are soldered, thus avoiding the need to use seals and large frame. The solder creates a connection between contact points on the plates and seals the package. Soldered Alfa Laval plate heat exchangers are soldered at all contact points to ensure optimal heat transfer and high pressure resistance. The heat exchangers are designed for a long service life. By using almost all of the material for heat transfer, the soldered plate heat exchanger is very compact and lightweight with minimal refrigerant content. Alfa Laval is able to produce custom equipment for specific customer requirements.
Materials
The heat exchangers are manufactured in accordance with the European Pressure Equipment Directive 2014/68/EU. The soldered plate heat exchangers consist of a package of copper and stainless steel 1.4401 plates and connections made from 1.4404. The package is vacuum soldered with copper solder (99.9%).
Function
Soldered plate heat exchangers are generally used in reverse flow refrigeration application in order to achieve maximum heat transfer. All connections are located on one side of the equipment without the need for any special connections being created, thus ensuring simple installation.
Function of the evaporator
The channels produced by the profiles plates are arranged such that flow is the opposite direction to the medium (counter flow principle). The two-phase refrigerant (vapour and liquid) enter the heat exchange at the bottom left. The proportion of gas depends on the operating conditions of the refrigeration system. The liquid evaporates in the channels before the vapours are then superheated (dry evaporation). The refrigerant connections are labelled as S3/S4 in the diagram. The water (brine) flows in the opposite direction in the next channel. The water (brine) connections are labelled as S1/S2.
Function of the condenser
The design is the same as the evaporator. Hot gas enters the device at the top left. It condenses on the surface of the channels until fully liquified and is then slightly subcooled. This process is known as “free condensation”. The refrigerant connections are labelled as S3/S4 in the diagram. The water (brine) flows in the opposite direction in the next channel. The water (brine) connections are labelled as S1/S2.
X-distributor and Equalancer SystemTM
The distribution systems developed by Alfa Laval ensure excellent cooling performance figures, stable control and good oil return. The two-phase mixture is mixed together by the patented “X” distribution system as it enters the evaporator. This stabilises the flow and increases performance.
