Plate heat exchanger

Abstract

A plate heat exchanger includes a heat-transfer plate stack including a plurality of heat-transfer plates in which first fluid and second fluid exchange heat each other, a first cover allowing the first and second fluids to flow therethrough, and a second cover having a cover hole defined therein. Each heat-transfer plate has a dead zone, and at least one dead zone hole is defined in the dead zone. Inspection gas may be injected into the cover hole, and the injected gas may be introduced into the dead zone through the dead zone hole to conduct fluid-tightness inspection of the dead zone. Accordingly, a brazing defect is detected before product shipment, and thus, freezing and breakage of the plate heat exchanger is prevented.

What is claimed is: 
     
         1 . A plate heat exchanger comprising:
 a heat-transfer plate stack comprising a plurality of heat-transfer plates that are stacked, each of the plurality of heat-transfer plates configured to carry first fluid and second fluid such that the first and second fluids exchange heat with each other;   a first cover coupled to a first surface of the heat-transfer plate stack and configured to allow each of the first and second fluids (i) to flow into the heat-transfer plate stack from an outside of the plate heat exchanger therethrough and (ii) to discharge from the heat-transfer plate stack to the outside therethrough; and   a second cover coupled to a second surface of the heat-transfer plate stack opposite to the first surface of the heat-transfer plate stack,   wherein the plurality of heat-transfer plates comprise:
 at least one first heat-transfer plate having (i) a first heat-transfer area that defines a first fluid channel configured to carry the first fluid and (ii) a first dead zone disposed away from flow of the first fluid and the second fluid, and 
 at least one second heat-transfer plate having (i) a second heat-transfer area that defines a second fluid channel configured to carry the second fluid and (ii) a second dead zone disposed away from flow of the first fluid and the second fluid, 
   wherein the at least one second heat-transfer plate and the at least one first heat-transfer plate are stacked on and joined to each other,   wherein the second cover defines a cover hole configured to provide gas injected from the outside into at least one of the first dead zone or the second dead zone, and   wherein the at least one of the first dead zone or the second dead zone defines a dead zone hole configured to receive the gas injected into the cover hole.   
     
     
         2 . The plate heat exchanger of  claim 1 , wherein the first cover is configured to provide each of the first and second fluids from the outside into the heat-transfer plate stack therethrough and to discharge each of the first and second fluids to the outside therethrough after heat exchange between the first fluid and the second fluid. 
     
     
         3 . The plate heat exchanger of  claim 1 , wherein the cover hole extends through the second cover in a thickness direction of the second cover, and
 wherein the cover hole and the dead zone hole are fluidly connected with each other and overlap with each other in a stacking direction of the plurality of heat-transfer plates and the first and second covers.   
     
     
         4 . The plate heat exchanger of  claim 1 , wherein the cover hole and the dead zone hole have a circular shape, have a same diameter, and are concentric. 
     
     
         5 . The plate heat exchanger of  claim 1 , wherein the cover hole and the dead zone hole are concentric, and
 wherein a diameter of the cover hole is larger than a diameter of the dead zone hole.   
     
     
         6 . The plate heat exchanger of  claim 1 , wherein the at least one first heat-transfer plate and the at least one second heat-transfer plate are made of a first material,
 wherein the second cover is made of a second material different from the first material, and   wherein a strength of the second material is greater than a strength of the first material.   
     
     
         7 . The plate heat exchanger of  claim 1 , wherein each of the at least one first heat-transfer plate and the at least one second heat-transfer plate has a first thickness, and
 wherein the second cover has a second thickness greater than the first thickness.   
     
     
         8 . The plate heat exchanger of  claim 1 , wherein the at least one first heat-transfer plate and the at least one second heat-transfer plate are made of a SUS316L material,
 wherein the second cover is made of a SUS304 material, and   wherein a thickness of the second cover is 5 to 7 times greater than a thickness of each of the at least one first heat-transfer plate and the at least one second heat-transfer plate.   
     
     
         9 . The plate heat exchanger of  claim 1 , wherein the cover hole is one of a plurality of cover holes that are defined at different positions of the second cover,
 wherein the dead zone hole is one of:
 a plurality of first dead zone holes defined at the at least one first heat-transfer plate, wherein a number of the plurality of first dead zone holes is equal to a number of the plurality of cover holes, 
 a plurality of second dead zone holes defined at the at least one second heat-transfer plate, wherein a number of the plurality of second dead zone holes is equal to the number of the plurality of cover holes, and 
   wherein a corresponding one of the plurality of cover holes, a corresponding one of the plurality of first dead zone holes, and a corresponding one of the plurality of second dead zone holes are fluidly connected with one another and overlap with one another in a stacking direction of the plurality of heat-transfer plates and the first and second covers.   
     
     
         10 . The plate heat exchanger of  claim 1 , wherein the first cover defines:
 a first fluid outside-communicating inlet that is configured to receive the first fluid from the outside into the heat-transfer plate stack;   a first fluid outside-communicating outlet that is configured to discharge the first fluid from the heat-transfer plate stack to the outside after heat exchange with the second fluid;   a second fluid outside-communicating inlet that is configured to receive the second fluid from the outside into the heat-transfer plate stack; and   a second fluid outside-communicating outlet that is configured to discharge the second fluid from the heat-transfer plate stack to the outside after heat exchange with the first fluid.   
     
     
         11 . The plate heat exchanger of  claim 1 , wherein the at least one first heat-transfer plate defines:
 a first heat-transfer plate first fluid inlet that is provided at a first end in a longitudinal direction of the first heat-transfer area, that is connected to the first fluid channel, and that is configured to provide the first fluid into the first heat-transfer area;   a first heat-transfer plate first fluid outlet that is provided at a second end in the longitudinal direction of the first heat-transfer area, that is connected to the first fluid channel, and that is configured to discharge the first fluid from the first heat-transfer area;   a first heat-transfer plate second fluid inlet that is spaced apart from the first heat-transfer plate first fluid outlet in a width direction of the first heat-transfer area, that is fluidly separated from the first fluid channel, and that is configured to provide the second fluid into the first heat-transfer area; and   a first heat-transfer plate second fluid outlet that is spaced apart from the first heat-transfer plate first fluid inlet in the width direction of the first heat-transfer area, that is fluidly separated from the first fluid channel, and that is configured to discharge the second fluid from the first heat-transfer area,   wherein the first dead zone is one of a pair of first dead zones that are disposed adjacent to the first heat-transfer plate second fluid inlet and the first heat-transfer plate second fluid outlet, respectively, and   wherein the dead zone hole is one of a plurality of dead zone holes comprising a pair of first dead zone holes that extend through the pair of first dead zones, respectively, in a thickness direction of the at least one first heat-transfer plate.   
     
     
         12 . The plate heat exchanger of  claim 11 , wherein the second heat-transfer plate defines:
 a second heat-transfer plate second fluid inlet that is provided at a first end in a longitudinal direction of the second heat-transfer area, that is connected to the second fluid channel, and that is configured to provide the second fluid into the second heat-transfer area;   a second heat-transfer plate second fluid outlet that is provided at a second end in the longitudinal direction of the second heat-transfer area, that is connected to the second fluid channel, and that is configured to discharge the second fluid from the second heat-transfer area;   a second heat-transfer plate first fluid inlet that is spaced apart from the second heat-transfer plate second fluid outlet in a width direction of the second heat-transfer area, that is fluidly separated from the second fluid channel, and that is configured to provide the first fluid into the second heat-transfer area; and   a second heat-transfer plate first fluid outlet that is spaced apart from the second heat-transfer plate second fluid inlet in the width direction of the second heat-transfer area, that is fluidly separated from the second fluid channel, and that is configured to discharge the first fluid from the second heat-transfer area,   wherein the second dead zone is one of a pair of second dead zones that are disposed adjacent to the second heat-transfer plate second fluid inlet and the second heat-transfer plate second fluid outlet, respectively, and   wherein the plurality of dead zone holes further comprise a pair of second dead zone holes that extend through the pair of second dead zones, respectively, in a thickness direction of the second heat-transfer plate.   
     
     
         13 . The plate heat exchanger of  claim 12 , wherein each of the pair of first dead zones overlaps with one of the pair of second dead zones in a stacking direction, and
 wherein each of the pair of first dead zone holes is fluidly connected with and overlap with one of the pair of second dead zone holes in the stacking direction.   
     
     
         14 . The plate heat exchanger of  claim 12 , wherein the at least one first heat-transfer plate comprises a first flange that is disposed along and surrounds an edge of the at least one first heat-transfer plate,
 wherein each corner of the at least one first heat-transfer plate has a round shape,   wherein one of the pair of first dead zone holes is defined at a position adjacent to the first flange at one of the corners of the at least one first heat-transfer plate,   wherein the at least one second heat-transfer plate comprises a second flange that is disposed along and surrounds an edge of the at least one second heat-transfer plate,   wherein each corner of the at least one second heat-transfer plate has a round shape, and   wherein one of the pair of second dead zone holes is defined at a position adjacent to the second flange at one of the corners of the at least one second heat-transfer plate.   
     
     
         15 . The plate heat exchanger of  claim 1 , wherein the cover hole is configured to receive the gas in a fluid-tightness inspection in which the gas received through the cover hole is provided into the first or second dead zone through the dead zone hole to thereby determine a fluid-tightness of the first or second dead zone based on whether the gas flows between the first or second dead zone and the first fluid channel, and
 wherein the fluid-tightness inspection determines whether a brazing joining of the plurality of heat-transfer plates around the first or second dead zone is defective.   
     
     
         16 . The plate heat exchanger of  claim 1 , further comprising a plug configured to be inserted into and block the cover hole after a fluid-tightness inspection of the first or second dead zone. 
     
     
         17 . The plate heat exchanger of  claim 1 , further comprising a welding sealing that is configured to be provided at the cover hole after a fluid-tightness inspection of the first or second dead zone, the welding sealing comprising a welding material configured to block the cover hole. 
     
     
         18 . The plate heat exchanger of  claim 1 , further comprising a sealing material that is injected to the cover hole after a fluid-tightness inspection of the first or second dead zone, the sealing material being configured to block the cover hole. 
     
     
         19 . A plate heat exchanger comprising:
 a heat-transfer plate stack comprising a plurality of heat-transfer plates that are stacked, each of the plurality of heat-transfer plates being configured to carry first fluid and second fluid such that the first and second fluids exchange heat with each other; and   a cover coupled to an outside of the heat-transfer plate stack,   wherein the plurality of heat-transfer plates comprise:
 at least one first heat-transfer plate having (i) a first heat-transfer area that defines a first fluid channel configured to carry the first fluid and (ii) first dead zones that are disposed at ends of the at least one first heat-transfer plate in a longitudinal direction, that are spaced apart from the first heat-transfer area, and that are disposed away from flow of the first fluid and the second fluid, and 
 at least one second heat-transfer plate having (i) a second heat-transfer area that defines a second fluid channel configured to carry the second fluid and (ii) second dead zones that are disposed at ends of the at least one second heat-transfer plate in the longitudinal direction, that are spaced apart from the second heat-transfer area, and that are disposed away from flow of the first fluid and the second fluid, 
   wherein the at least one second heat-transfer plate and the at least one first heat-transfer plate are stacked on and joined to each other,   wherein the cover defines a cover hole configured to receive gas injected from the outside into at least one of the first dead zones or the second dead zones, and   wherein the at least one of the first dead zones or the second dead zones defines at least one dead zone hole configured to receive the gas injected into the cover hole.   
     
     
         20 . The plate heat exchanger of  claim 19 , wherein the cover is one of a plurality of covers that cover and seal opposing surfaces of the heat-transfer plate stack, the plurality of covers comprising:
 a first cover coupled to a first surface of the heat-transfer plate stack, the first cover being configured to allow each of the first and second fluids (i) to flow into the heat-transfer plate stack from the outside therethrough and (ii) to discharge from the heat-transfer plate stack to the outside therethrough,   a second cover coupled to a second surface of the heat-transfer plate stack opposite to first surface of the heat-transfer plate stack, the second cover having the cover hole and covering the heat-transfer plate stack outside the cover hole, and   wherein the plate heat exchanger further comprises a sealing that is configured to be inserted into and block the cover hole after a fluid-tightness inspection of at least one of the first dead zones or the second dead zones.