Heat exchanger and refrigeration system and method

A refrigeration system comprising:

• a compressor for compressing a gaseous refrigerant, such that a temperature and a pressure of the gaseous refrigerant increases, wherein a boiling point of the gaseous refrigerant 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 gaseous refrigerant condensing to a liquid refrigerant;
• an expansion valve reducing a pressure of the liquid refrigerant from the condenser, hence reducing the boiling point of the refrigerant;
• an evaporator, in which the liquid refrigerant exchanges heat with a low temperature heat carrier, such that the refrigerant vaporizes;
• a suction gas heat exchanger exchanging heat between the liquid refrigerant from the condenser and the gaseous refrigerant from the evaporator,
• wherein the evaporator is formed by a plate heat exchanger comprising first heat exchanger plates formed with a first pattern of ridges and grooves, and second heat exchanger plates 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,
• wherein the ridges and grooves are formed such that the interplate flow channels between different plate pairs have a first volume and a second volume, wherein the first volume is greater than the second volume;
• wherein brazing joints are provided at the contact points, and the brazing joints are elongated, wherein the elongated brazing joints comprise first elongated brazing joints extending in a first orientation and second elongated brazing joints extending in a second orientation, and wherein the first orientation and the second orientation are different,
• wherein the first elongated brazing joints extend at a first brazing joint angle and are located in the interplate flow channels having the first volume, the second elongated brazing joints extend at a second brazing joint angle and are located in the interplate flow channels having the second volume,
• wherein the 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 the 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, wherein a difference between the first angle and the second angle is 2° to 35°, and
• wherein the grooves of the first heat exchanger plates are formed with identical corrugation depth, wherein first grooves of the second heat exchanger plates are formed with a first depth, and second grooves of the second heat exchanger plates are formed with a second depth different from the first depth.

A refrigeration method comprising the steps of:

• a) compressing a gaseous refrigerant by a compressor, such that a temperature and a pressure of the gaseous refrigerant increases, wherein a boiling point of the gaseous refrigerant increases;
• b) conducting the gaseous refrigerant from the compressor to a condenser;
• c) in the condenser, exchanging heat between the gaseous refrigerant from the compressor and a high temperature heat carrier, said heat exchange resulting in the gaseous refrigerant condensing to liquid refrigerant;
• d) reducing the pressure of the liquid refrigerant from the condenser in an expansion valve, hence reducing the boiling point of the refrigerant;
• e) conducting the refrigerant with reduced boiling point to an evaporator;
• f) in the evaporator, exchanging heat between the refrigerant and a low temperature heat carrier, such that the refrigerant vaporizes;
• and
• g) exchanging heat between high temperature liquid refrigerant from the condenser and high temperature gaseous refrigerant from the evaporator by means of a suction gas heat exchanger,
• wherein the method further comprises:
• in step f), conducting the refrigerant through interplate flow channels formed by first heat exchanger plates formed with a first pattern of ridges and grooves, and second heat exchanger plates 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 the interplate flow channels for fluids to exchange heat, wherein the ridges and grooves are formed such that the interplate flow channels between different plate pairs have a first volume and a second volume, wherein the first volume is greater than the second volume, wherein brazing joints are provided at the contact points, and the brazing joints are elongated, wherein the elongated brazing joints comprise first elongated brazing joints extending in a first orientation and second elongated brazing joints extending in a second orientation, and wherein the first orientation and the second orientation are different,
• wherein the first elongated brazing joints extend at a first brazing joint angle and are located in the interplate flow channels having the first volume, the second elongated brazing joints extend at a second brazing joint angle and are located in the interplate flow channels having the second volume,
• wherein the 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 the 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, wherein a difference between the first angle and the second angle is 2° to 35°, and
• wherein the grooves of the first heat exchanger plates are formed with identical corrugation depth, wherein first grooves of the second heat exchanger plates are formed with a first depth, and second grooves of the second heat exchanger plates are formed with a second depth different from the first depth.