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Heat exchanger for a vehicle

Heat exchanger for a vehicle description/claims

The present invention relates to a heat exchanger for a vehicle, and more particularly, to a highly efficient thin radiator for reducing production costs by decreasing the weight of a heat exchanger, reducing energy loss due to a pressure drop of a coolant-side in a case of being mounted in a real vehicle, and enhancing heat radiation performance.

FIG. 1 is a conceptual view showing a cooling system of a general vehicle. Since an engine 1 for a vehicle always ignites and burns high-temperature and high-pressure gas, the engine 1 is overheated in a case where it is left as it is, so that cylinders and pistons may be seriously damaged due to the melt of a metallic material constituting the engine 1. In order to prevent this, as shown in FIG. 1, a water jacket (not shown), in which a coolant is stored, is mounted around the cylinder of the engine 1 for a vehicle, the engine is circularly cooled by allowing the coolant to pass through a radiator 2 or a heater core 3 using a water pump 5, and the coolant may not pass through the heater core 3 but be immediately returned through a bypass circuit 6 depending on a use of cooling or heating. At this time, the thermostat 4 is mounted in a path through which the coolant flows so as to function as an adjusting mechanism for preventing the engine 1 from being overheated by adjusting a degree of opening and shutting depending on a temperature of the coolant passing through the engine 1.

(a) and (b) of FIG. 2 are a perspective view and an exploded perspective view of a general radiator, respectively. The radiator is a kind of heat exchanger for allowing heat of the coolant to be radiated when the coolant receiving heat of the engine transferred while circulating to the engine flows. The radiator is mounted to an engine room, and a cooling fan for blowing wind into the core of the engine is mounted to a central portion of the engine room.

The radiator is generally made of aluminum with a superior heat conduction effect, and has a characteristic in that heat radiation performance depends on elements of heat exchanging tubes and fins. That is, if the heights of the tube and the fin are reduced even in a radiator with the same core, the heat radiation performance is theoretically enhanced. However, if the height of the fin becomes too low, a foreign substance is stuck or stacked between the fins so that it interferes with ventilation, and since a foreign substance produced due to an antifreezing solution or a reactant is stacked inside the tube if the height of the tube becomes too small, there occurs a phenomenon in that a flow channel is blocked so that the deterioration of heat transfer performance may be rather caused. In this case, since the number of tubes and fins become large, there may be caused a problem in that this is very disadvantageous in a view of stability of a radiator structure and productivity in manufacturing.

In a case of U.S. Pat. No. 4,332,293 (1982. 6. 1) as a prior art, there is suggested a numerical range in that the length of a fin in a direction of air flow should be 12 to 23 mm, the pitch of the fin should be 1.5 to 3.3 mm, and the pitch of a tube should be 8.5 to 14 mm as elements of a radiator mounted within a range of a limited core mounting space so as to overcome air resistance generated as the length of the fin is lengthened in the direction of air flow in the radiator with a tube arrangement of 2 or 3 rows and reduction of heat transfer performance according thereto.

However, the conventional radiator is focused on heat radiation performance of an outer side of the tube through which air passes. Further, in order to prevent a coolant-side pressure drop, the caliber of the tube is set not to be small, and the height of the fin is simultaneously set to be relatively high considering an air-side pressure drop amount. In a case of a general radiator, there is a case where it is overlooked that, although a heat transfer rate due to heat conduction is frequently caused due to air-side convection, a variation of a heat transfer rate is not so large as compared with a structure modification degree of its components, while, although a heat transfer rate due to heat convection in a heat exchange tube has a low ratio occupying in a total heat transfer rate, it is sensitively changed depending on the structure modification degree of its component and a variation thereof is relatively large. Further, there is no detailed understanding of an effect of pressure loss due to surface shear stress occurring on a wall surface of the tube, which is accompanied in a case where the flow of a coolant in the heat exchange tube is developed into a turbulent flow region.

In such conventional radiators, coolant-side pressure drop amount is not simultaneously considered together with air-side heat radiation performance. Particularly, there are some limitations in suggesting a preferred design object of exchanger tubes in a critical operation condition such as alpine regions with many inclines or cold or arctic regions.

This requires more thorough observation on flow of a coolant in a radiator tube and the heat transfer characteristic to the inside thereof, and more researches and experiments on radiators with more effective heat radiating performance.

It is an object of the present invention to provide a heat exchanger, i.e., a highly efficient thin radiator for reducing production costs by decreasing the weight of a heat exchanger, reducing energy loss due to a pressure drop of a coolant-side in a case of being mounted in a real vehicle, and enhancing heat radiation performance.

It is another object of the present invention to provide an optimal design condition for enhancing heat radiation performance of a radiator in a coolant flow rate region corresponding to a hill-climbing mode that is a critical driving mode of a vehicle and reducing a coolant-side pressure drop amount.

It is a further object of the present invention to provide a preferred a design condition of a lightweight thin radiator, wherein heat radiation performance of a conventional radiator with a broad width and a heavy weight can be maintained, and a coolant-side pressure drop amount almost identical with that of the conventional radiator can also be maintained when comparing the heat radiation performance and coolant-side pressure drop amount of the conventional radiator.

It is a still further object of the present invention to provide a preferred design range of each main component of the radiator, which can meet the optimal design range.

To achieve these objects of the present invention, there is provided a heat exchanger for a vehicle for exchanging heat between a coolant heated by an engine and air flowed into the front of the vehicle to cool the engine, including: a pair of tanks for supplying a coolant supplied from the engine through a thermostat for adjusting opening/shutting depending on the temperature of the coolant and a water pump, and discharging the cooled coolant to an engine side; a core portion including a header at one side coupled with the tank at one side, to which the coolant is supplied, heat exchange tubes which is structurally fastened to communicate with the heater at one end portion thereof, and arranged in parallel to a direction of driving wind, a header at the other side coupled with the tank at the other side, which is structurally fastened at the other end portion of the heat exchange tube to communicate therewith so as to discharge the coolant into the engine, and fins fixedly brazed between the heat exchange tubes; wherein Td the width of a core of the heat exchanger is in the range of 12 to 15 mm, the distance between outermost tubes of the core portion is in the range of 300 to 600 mm, the flow of the coolant flowing through the core portion is a completely developed turbulent flow region when the composition of an antifreezing solution and water is 1:1 and the flow rate is in the range of 60 to 80 L/min, and a transition from laminar flow to turbulent flow occurs at a flow rate of 40 L/min or less.

Preferably, when the flow rate of the coolant is in the range of 60 to 80 L/min and the temperature thereof is 100° C., the flow of the coolant has a Reynolds number of 2,100 or more, a transition from laminar flow to turbulent flow occurs at a flow rate of 40 L/min or less.

Preferably, when the flow rate of the coolant is in the range of 60 to 80 L/min and the temperature thereof is 100° C., the pressure drop amount of the coolant at an exit side of the heat exchanger is 150 mmHg.

Preferably, Th the outer width of the tube is in the range of 1.60 to 2.10 mm, and more preferably, 1.70 to 1.90 mm.

Preferably, Tth the material thickness of the tube is in the range of 0.15 to 0.24 mm for the purpose of reducing a weight and a pressure drop amount.

Preferably, Fh the height of the fin is in the range of 5.3 to 5.8 mm, and the thickness of the fin is in the range of 0.05 to 0.06 mm for the purpose of reducing a weight and maximizing a heat transfer rate.

Preferably, the heat exchange tube is a flat type with no dimple in an interior thereof, and the heat exchanger is a cross flow type.