Heat exchanger and air conditioner

Patent metadata

Field	Value
Publication number	US-11828477-B2
Application number	US-201816494360-A
Country	US
Kind code	B2
Filing date	Mar 30, 2018
Priority date	Mar 31, 2017
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

A heat exchanger includes: a surface with a water-repellent coating. The surface has a surface structure that includes protrusions. Condensed water droplets, each having a droplet diameter that allows a subcooled state to be maintained even under a predetermined freezing condition, combine with one other on the surface and generate an energy. The surface structure uses the energy to remove the combined condensed water droplets from the surface.

First claim

The invention claimed is:

1. A heat exchanger comprising:
a surface with a water-repellent coating, wherein
the surface has a surface structure that includes protrusions,
the surface structure causes condensed water droplets, each having a droplet diameter that allows a subcooled state to be maintained even under a predetermined freezing condition, to combine with one another on the surface and generate energy,
the surface structure uses the energy to remove the combined condensed water droplets from the surface,
each of the protrusions protrudes in a protruding direction,
each of the protrusions has a constricted shape whose cross-sectional area in a plane perpendicular to the protruding direction decreases to a minimum cross-sectional area at a height along the protruding direction that is less than the height of each protrusion and then increases in the protruding direction toward the end of each protrusion,
the height of the minimum cross-sectional area is within 30% from the end of each protrusion in the protruding direction,
the shape of each protrusion has a maximum cross-sectional area in the plane perpendicular to the protruding direction, and
a ratio of the maximum cross-sectional area to the minimum cross-sectional area is greater than or equal to 1.5 and less than or equal to 4.0.

2. The heat exchanger according to claim 1 , further comprising:
heat transfer fins; and
a heat transfer pipe that is fixed to the heat transfer fins and in which refrigerant flows, wherein
a surface of each of the heat transfer fins has the surface structure.

3. An air conditioner comprising:
a refrigerant circuit including the heat exchanger according to claim 1 ;
a compressor; and
a controller that causes the refrigerant circuit to switch between:
a normal operation in which the heat exchanger functions as a refrigerant evaporator, and
a defrosting operation for melting frost adhered to the heat exchanger, wherein

the controller switches from the normal operation to the defrosting operation when a predetermined frosting condition is satisfied during the normal operation.

4. An air conditioner comprising:
the heat exchanger according to claim 1 ; and
a fan that supplies air to the heat exchanger, wherein
the air flows in a horizontal direction of the heat exchanger.

5. The heat exchanger according to claim 1 , wherein
the ratio of the maximum cross-sectional area to the minimum cross-sectional area is greater than or equal to 2.0 and less than or equal to 3.0.

6. A heat exchanger comprising:
a surface with a water-repellent coating, wherein
the surface has a surface structure that includes protrusions,
each of the protrusions protrudes in a protruding direction,
each of the protrusions has a constricted shape whose cross-sectional area in a plane perpendicular to the protruding direction decreases to a minimum cross-sectional area at a height along the protruding direction that is less than the height of each protrusion and then increases in the protruding direction toward the end of each protrusion,
the height of the minimum cross-sectional area is within 30% from the end of each protrusion in the protruding direction,
the shape of each protrusion has a maximum cross-sectional area in the plane perpendicular to the protruding direction, and
a ratio of the maximum cross-sectional area to the minimum cross-sectional area is greater than or equal to 1.5 and less than or equal to 4.0, and
the surface structure satisfies:
rw (entirety)>0.6/|cos θ w|,

rw (protrusion)>0.6/|cos θ w|,

0.1 <d/L< 0.8,
L< 3.0 μm, and

90°<θ w< 120°, where

L is an average pitch of the protrusions,
d is an average diameter of the protrusions,
rw(entirety) is an average area-enlargement ratio of an entire surface of a heat transfer fin of the heat exchanger,
rw(protrusion) is an average area-enlargement ratio of a protrusion among the protrusions, and
θw is a contact angle of water on a flat surface of the water-repellent coating.

7. The heat exchanger according to claim 6 , further comprising:
heat transfer fins; and
a heat transfer pipe that is fixed to the heat transfer fins and in which refrigerant flows, wherein
a surface of each of the heat transfer fins has the surface structure.

8. An air conditioner comprising:
a refrigerant circuit including the heat exchanger according to claim 6 ;
a compressor; and
a controller that causes the refrigerant circuit to switch between:
a normal operation in which the heat exchanger functions as a refrigerant evaporator, and
a defrosting operation for melting frost adhered to the heat exchanger, wherein

the controller switches from the normal operation to the defrosting operation when a predetermined frosting condition is satisfied during the normal operation.

9. An air conditioner comprising:
the heat exchanger according to claim 6 ; and
a fan that supplies air to the heat exchanger, wherein
the air flows in a horizontal direction of the heat exchanger.

10. The heat exchanger according to claim 6 , wherein
the ratio of the maximum cross-sectional area to the minimum cross-sectional area is greater than or equal to 2.0 and less than or equal to 3.0.

Assignees

• Daikin Ind Ltd

Inventors

• Nagano Tomohiro
• Fujino Hirokazu
• Yoshida Kaori
• Fujinami Isao
• Mondal Deb Kumar
• Yamaguchi Hiroki

Classifications

• F24F11/43 Primary

  of indoor units · CPC title

• F24F1/48

  characterised by air airflow, e.g. inlet or outlet airflow · CPC title

• F25B39/02

  Evaporators · CPC title

• F25B47/02

  Defrosting cycles · CPC title

• F28D1/047 Primary

  the conduits being bent, e.g. in a serpentine or zig-zag · CPC title