Heat exchanging tube and heat exchanger

1. A heat exchanging tube comprising:

a flat tube main body having a predetermined length; and

a plurality of refrigerant passages extending in a tube longitudinal direction and arranged in a tube widthwise direction,

wherein the following relational equations (a) to (c) are satisfied:

W=6 to 18 mm  (a),

Ac/At× 100=50 to 70%  (b) and

P/L× 100=350 to 450%  (c),

where “W” is a width of the tube main body, “Ac” is a total cross-sectional area of the refrigerant passages, “At” is a total cross-sectional area of the tube main body and the refrigerant passages, and “L” is an external perimeter of the tube main body and “P” is a total inner perimeter of the refrigerant passages.

2. The heat exchanging tube as recited in claim 1 , wherein the following relational equation (d) is satisfied:

P/W× 100=750 to 850%  (d).

3. The heat exchanging tube as recited in claim 1 , wherein the following relational equation (e) is satisfied:

N/W=3 to 4  (e),

where “N” is the number of refrigerant passages.

4. The heat exchanging tube as recited in claim 1 , wherein the following relational equation is satisfied:

H=0.5 to 1.5 mm  (f),

where “H” is a height of the tube main body.

5. The heat exchanging tube as recited in claim 1 , wherein the following relational equation (g) is satisfied:

Ta=50 to 80 μm  (g),

where “Ta” is a thickness of the partitioning wall partitioning adjacent refrigerant passages in the tube main body.

6. The heat exchanging tube as recited in claim 1 , wherein the following relational equation (h):

Tb=80 to 250 μm  (h),

where “Tb” is the thickness of the external peripheral wall in the tube main body.

7. The heat exchanging tube as recited in claim 1 , wherein the refrigerant passage is approximately rectangular in cross-section.

8. The heat exchanging tube as recited in claim 1 , wherein the width W of the tube main body is set to be 6 to 14 mm.

9. The heat exchanging tube as recited in claim 1 , wherein the width W of the tube main body is set to be 7 to 12 mm.

10. The heat exchanging tube as recited in claim 1 , wherein the following relational equation is satisfied:

Ac/At× 100=55 to 65%.

11. The heat exchanging tube as recited in claim 1 , wherein the following relational equation is satisfied:

P/L× 100=360 to 420%.

12. A heat exchanger comprising:

a pair of headers; and

a plurality of heat exchanging tubes arranged in parallel in a header length direction, opposite ends of the heat exchanging tube being connected to the headers in fluid communication,

wherein the heat exchanging tube is provided with a flat tube main body having a predetermined length and a plurality of the refrigerant passages extending in a tube longitudinal direction and arranged in a tube widthwise direction, and the following relational equations (a) to (c) are satisfied:

W=6 to 18 mm  (a),

Ac/At ×100=50 to 70%  (b) and

P/L ×100=350 to 450%  (c),

where “W” is a width of the tube main body, “Ac” is a total cross-sectional area of the refrigerant passages, “At” is a total cross-sectional area of the tube main body and the refrigerant passages, and “L” is an external perimeter of the tube main body and “P” is a total inner perimeter of the refrigerant passages.

13. The heat exchanger as recited in claim 12 , wherein the width W of the tube main body is set to be 6 to 14 mm.

14. The heat exchanger as recited in claim 12 , wherein the width W of the tube main body is set to be 7 to 12 mm.

15. The heat exchanger as recited in claim 12 , wherein the following relational equation is satisfied:

Ac/At× 100=55 to 65%.

16. The heat exchanger as recited in claim 12 , wherein the following relational equation is satisfied:

P/L× 100=360 to 420%.