Refrigeration – Intermediate fluid container transferring heat to heat... – With indirect fluid pump or agitator
Reexamination Certificate
2002-08-13
2003-11-04
Jiang, Chen Wen (Department: 3743)
Refrigeration
Intermediate fluid container transferring heat to heat...
With indirect fluid pump or agitator
C165S157000
Reexamination Certificate
active
06640579
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a laminated heat exchanger and a refrigeration cycle. More particularly, it relates to a plate-type laminated heat exchanger used for an evaporator or a condenser forming a refrigeration cycle, and a refrigeration cycle itself.
Generally, in a plate-type heat exchanger, flow paths are formed between a plurality of laminated plates, and fluids having a different temperature are caused to flow alternately in these flow paths, by which heat exchange is effected. Therefore, the heat exchanger of this type offers an advantage that the size thereof can be decreased to a large extent as compared with the conventional heat exchanger such as a shell-and-tube heat exchanger.
A herringbone type plate for the plate-type heat exchanger has a herringbone wavelike heat transfer surface disposed slantwise downward from a longitudinal centerline of the plate toward both directions, and is manufactured usually by pressing a thin metal sheet such as a stainless steel sheet. These plates are laminated by being vertically reversed alternately, by which the plate-type heat exchanger is formed.
When the plate-type heat exchanger is used as an evaporator or a condenser for a refrigeration cycle, a high-pressure refrigerant and low-pressure water flow alternately in the flow paths formed by the plates. In the plate-type heat exchanger of a herringbone type, the pressure resisting strength is improved by contact between peaks of the wavelike heat transfer surfaces. However, it is difficult to completely prevent leakage of the refrigerant. Also, it is indispensable to use a highly rigid metal such as stainless steel as a material for the plate, which imposes a restriction on fabrication. Further, in order to prevent leakage of the refrigerant, the whole of the laminated plates are fixed usually by brazing. The brazing of the plates requires highly sophisticated production technology and equipment, which results in a higher cost.
Further, the upper limit value of working pressure is kept at about 3.1 MPa because of the pressure resistance, it is difficult to use the heat exchanger of this type for a refrigeration cycle using a high-pressure refrigerant such as R410A and carbon dioxide. Since the plate is manufactured by pressing a thin metal sheet, a ratio of molds to initial cost is high, so that it is difficult, in terms of cost, to freely set pattern and dimensions of heat transfer surface so as to meet specification of heat exchanger needed for the refrigeration cycle.
Conventionally, a plate-type heat exchanger constructed by laminating a plurality of heat transfer plates, in which an inflow opening for a refrigerant is provided in a central portion in a widthwise direction of the heat transfer plates to prevent deflected flow of fluid in a flow path between the plates, is known and has been disclosed, for example, in JP-A-2000-292079 specification. Also, a plate-type heat exchanger in which vertical orifices communicating with flow paths between plates are provided at the inflow opening portion to promote turbulent flow of refrigerant flowing in the flow paths to uniformize the refrigerant has been disclosed, for example, in JP-A-2001-50611 specification.
In the above-described prior arts, it is difficult to improve both prevention of the deflected flow of the fluid in the flow path between the plates and uniform distribution of the fluid among the flow paths. Also, when the laminated heat exchanger is used as an evaporator or a condenser, distribution performance of water and refrigerant must be made especially high to promote downsizing and improvement in performance of the heat exchanger or to avoid a danger of freezing. Further, if the plates are fixed completely to each other by brazing to enhance the pressure resistance of a refrigerant-side flow path, the plates cannot be detached, so that dirt adhered to the plate surface of a water-side flow path cannot be removed.
Also, in the plate-type heat exchanger, in the ordinary service condition, since the fluid flows vigorously in a narrow and flat flow path, a pressure loss is generally high. For example, in a chiller unit, the pressure loss in the water-side flow path must be kept at a certain value or lower in connection with a water pump. However, the pressure loss in the water-side flow path being made too small leads to an increase in size of the heat exchanger.
An object of the present invention is to solve the above problems and to provide a laminated heat exchanger and a refrigeration cycle which are suitable for a high-pressure refrigerant also, the size thereof are small, the pressure loss are low, the degree of freedom of design is high, the heat exchanger is capable of being disassembled, the distribution of water and refrigerant is good, and the refrigerant does not leak. Also, another object thereof is to enable dirt adhered to the plate surface of a water-side flow path to be removed easily from the viewpoint of energy saving of refrigeration cycle.
SUMMARY OF THE INVENTION
To attain the above objects, the present invention provides a laminated heat exchanger including a plurality of laminated plates, in which a plurality of heat transfer tubes bent into a zigzag form are arranged in contact with each surface of each of the plates, and the plates are laminated so that the heat transfer tubes on one of adjacent plates intersect with the heat transfer tubes on the other of the adjacent plates.
Also, it is preferable that headers should be provided to bundle the heat transfer tubes for each plate, and collecting headers should be provided to bundle the headers.
Further, it is preferable that there should be provided headers for bundling the heat transfer tubes for each plate; collecting headers for bundling the headers; refrigerant pipes respectively connected to the collecting headers; and a sealed casing having a water inlet and a water outlet and containing the plates, the headers, and the collecting headers.
Further, it is preferable that there should be provided headers for bundling the heat transfer tubes for each plate; collecting headers for bundling the headers; refrigerant pipes connected to the collecting headers; water scattering plates which are formed with holes; and a sealed casing having a water inlet and a water outlet and containing the plates, the headers, the collecting headers, and the water scattering plates, the water scattering plates being inclined slantwise with respect to the water inlet and the water outlet.
Further, it is preferable that there should be provided headers for bundling the heat transfer tubes for each plate; collecting headers for bundling the headers; refrigerant pipes connected to the collecting headers; and a casing having a water inlet and a water outlet, containing the plates, the headers, and the collecting headers, and provided with flanges in end portions thereof, the casing being sealed by fastening end face covers to the flanges.
Further, it is preferable that the heat transfer tubes should be bent into a sinusoidal wave form.
Further, it is preferable that the heat transfer tubes should be bent into an S-shape.
Further, the present invention provides a refrigeration cycle having a primary loop in which a primary refrigerant circulates through a compressor, an outdoor heat exchanger, an expansion valve, and an intermediate heat exchanger and a secondary loop in which a secondary refrigerant circulates through the intermediate heat exchanger, a pump, and an indoor heat exchanger, in which the intermediate heat exchanger has a plurality of plates and a plurality of heat transfer tubes which are bent into a zigzag form and are arranged in contact with each surface of each plate, the plates being laminated so that the heat transfer tubes in contact with one surface of each plate intersect with the heat transfer tubes in contact with the other surface of each plate.
Further, it is preferable that a natural refrigerant should be used as the primary refrigerant, and water should be used as the secondary refrigerant.
REFERENCE
Aoyama Mitsugu
Matsushima Hitoshi
Uchida Mari
Antonelli Terry Stout & Kraus LLP
Hitachi, Ltd. for the Benefit of Hitachi Air Conditioning System
Jiang Chen Wen
LandOfFree
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