Heat exchanger and refrigeration system and method

A refrigeration system comprising

• a compressor for compressing a gaseous refrigerant, such that the temperature, pressure and boiling point thereof increases;
• a condenser, in which the gaseous refrigerant from the compressor exchanges heat with a high temperature heat carrier, said heat exchange resulting in the refrigerant condensing;
• an expansion valve reducing the pressure of liquid refrigerant from the condenser, hence reducing the boiling point of the refrigerant;
• an evaporator, in which the low boiling point refrigerant exchanges heat with a low temperature heat carrier, such that the refrigerant vaporizes;
• and
• a retrofit port heat exchanger exchanging heat between high temperature liquid refrigerant from the condenser and high temperature gaseous refrigerant from the evaporator, wherein
• the evaporator is formed by a brazed plate heat exchanger comprising a plurality of first and second heat exchanger plates, wherein the first heat exchanger plates are formed with a first pattern of ridges and grooves, and the second heat exchanger plates are formed with a second pattern of ridges and grooves providing contact points between at least some crossing ridges and grooves of neighbouring plates under formation of interplate flow channels for fluids to exchange heat, said interplate flow channels being in selective fluid communication with port openings, wherein the first pattern of ridges and grooves is different from the second pattern of ridges and grooves, so that an interplate flow channel volume on one side of the first heat exchanger plates is different from an interplate flow channel volume on an opposite side of the first heat exchanger plates, the second pattern of ridges and grooves has first and second grooves, wherein the first grooves are formed with a first depth and the second grooves are formed with a second depth different from the first depth, brazing joints are formed at said contact points between crossing ridges and grooves of the first and second heat exchanger plates, and said brazing joints are elongated,
• wherein the first and second heat exchanger plates are arranged alternatingly so that every other of the heat exchanger plates are the first heat exchanger plates, and the remaining heat exchanger plates are the second heat exchanger plates,
• wherein ridges and grooves of the first heat exchanger plates, at least in a central main heat exchanging section of the first heat exchanger plates, extend in a first angle and ridges and grooves of the second heat exchanger plates, at least in a central main heat exchanging section of the second heat exchanger plates, extend in a second angle different from the first angle,
• wherein a difference between the first angle and the second angle is 2° to 35°,
• wherein the elongated brazing joints are arranged in a first orientation in the interplate flow channel volume on the one side of the first heat exchanger plates, and in a second orientation in the interplate flow channels on the opposite side of first heat exchanger plates,
• wherein the first orientation and the second orientation are different, and
• wherein the interplate flow channel volume on the one side of the first heat exchanger plates is larger than the interplate flow channel volume on the opposite side of the first heat exchanger plates.