BRIEF DESCRIPTION OF THE DRAWINGS
Many aspects of the present invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views:
FIG. 1 is a pulsating heat pipe in accordance with a preferred embodiment of the present invention;
FIG. 2 is an enlarged view of a circled portion II of the pulsating heat pipe of FIG. 1 ;
FIG. 3 is an enlarged transverse cross-sectional view of the pulsating heat pipe of FIG. 1, taken along line III-III thereof;
FIG. 4 is a front view of a mesh of the pulsating heat pipe of FIG. 1;
FIG. 5 a transverse cross-sectional view of the mesh of FIG. 4, taken along line V-V thereof; and
FIG. 6 is a pulsating heat pipe in accordance with another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates a pulsating heat pipe 10 in accordance with a preferred embodiment of the present invention. The pulsating heat pipe 10 includes a serpentine, elongate capillary tube 11, a flexible interwoven artery mesh 13 disposed within the elongate capillary tube 11, and a predetermined quantity of condensable bi-phase working fluid 15 (FIG. 2) filled in the elongate capillary tube 11 and the artery mesh 13.
The elongate capillary tube 11 is made of deformable metallic materials, such as copper or aluminum, so it can be bent into a required shape by a suitable bending machine (not shown). Alternatively, the elongate capillary tube 11 may be made of other deformable materials such as polymer or macro-molecular material. The elongate capillary tube 11 is bent into a hand-like shape, having a plurality of heat receiving and heat radiating portions 112, 114 formed on predetermined parts thereof, and a plurality of adiabatic portions 116 formed between the heat receiving and heat radiating portions 112, 114. The heat receiving portions 112 are alternately arranged with the heat radiating portions 114. It is noted that the heat receiving portions 112 are disposed in a heating region H and the heat radiating portions 114 are disposed in a cooling region C. The heating region H is located at fingertips of the hand, while the cooling region C is located near a wrist of the hand. Terminal ends (not labeled) of the metallic elongate capillary tube 11 are hermetically connected with each other to form a close looped flow passage of the working fluid 15. Alternatively, shown in FIG. 6, the terminal ends of the elongate capillary tube 11 may be heretically sealed and separated from each other to form an un-looped flow passage of the working fluid 15. In addition, a filling tube 17 is formed at the cooling region C of the elongate capillary tube 11 for filling and supplying the working fluid 15 into the elongate capillary tube 11.
Referring to FIGS. 2 to 5, the artery mesh 13 is an elongate hollow tube, which is attached to an inner wall of the elongate capillary tube 11 and extends along the entire length of the capillary tube 11. Alternatively, the elongate artery mesh 13 may be divided into a plurality of spaced segments (shown in FIG. 6), which are equidistantly disposed in the elongate capillary tube 11. Further alternatively, the spaced segments may also be not equidistant from each other in some parts of the elongate capillary tube 11. The artery mesh 13 is formed by weaving a plurality of metal wires 131 (FIG. 4), such as copper, or stainless steel wires together. Alternatively, the artery mesh 13 can be formed by weaving a plurality of non-metal threads such as fiber together. A first channel 132 is defined in an inner space of the artery mesh 13, whilst a second channel 133 is defined between an outer wall of the artery mesh 13 and the inner wall of the elongate capillary tube 11. Both first and second channels 132, 133 are for passages of vaporized working fluid 15. A plurality of pores (not shown) is formed in a peripheral wall of the artery mesh 13, which provides a first strong circulation propelling force (capillary action) to the working fluid 15 and communicates the first channel 132 with the second channel 133. The artery mesh 13 has a ring-like transverse cross section, a diameter of which is smaller than a diameter of the elongate capillary tube 11. The artery mesh 13 has a linear contact with the inner wall of the elongate capillary tube 11 thereby defining an adjacent portion 134 contacting with the inner wall of the elongate capillary tube 11 and a distal portion 135 spaced a distance from the inner wall of the elongate capillary tube 11 along a radial direction of the pulsating heat pipe 10. In the present pulsating heat pipe 10, the artery mesh 13 may be loosely inserted into the elongate capillary tube 11 with some portions thereof separating from the inner wall of the elongate capillary tube 11.
Particularly referring to FIG. 1, the working fluid 15 is filled in the artery mesh 13 and the elongate capillary tube 11. The working fluid 15 is usually selected from a liquid such as water, methanol, or alcohol, which has a low boiling point and is compatible with the artery mesh 13. Thus, the working fluid 15 can easily evaporate to vapor when it receives heat at the heating region H of the pulsating heat pipe 10. The elongate capillary tube 11 of the pulsating heat pipe 10 is evacuated and hermetically sealed after the working fluid 15 is injected into the elongate capillary tube 11 and fills the capillary tube 11 and the artery mesh 13. Before operation, capillary effect causes the working fluid 15 to form as piece-wise liquid segments 151 distributed along the elongate capillary tube 11, and vapor bubbles 152 existed between the liquid segments 151. During operation, the heating region H is heated to vaporize the working fluid 15 which generates a vapor pressure thereat, whilst the cooling region C is cooled to condense the vaporized working fluid 15 which generates a negative vapor pressure (attracting force) thereat. Mutual actions between the vapor pressure and the attracting force cooperatively cause the liquid segments 151 and the vapor bubbles 152 to pulsate in and finally generate a second strong circulation propelling force to propel the working fluid 15 to circulate in the capillary tube 11.
In addition, one or a plurality of pressure sensitive small-sized check valves 19 (shown in FIG. 6) may be disposed in the circulation passage of the working fluid 15 for limiting flowing direction of the working fluid 15. Mutual distances between the check valves 19 are balanced. It is noted that as the number of the check valves 19 increases, the circulation of the working fluid 15 becomes strong and fast.
In operation, the heat receiving portions 112 generate the vapor pressure due to the vaporization of the working fluid 15 thereat and the heat radiating portions 114 generate the attracting force due to the condensation of the vapor. The artery mesh 13, and the vapor pressure and attracting force generate the respective first and second strong propelling actions toward a predetermined circulation direction for the working fluid 15 and its vapor. These mutual actions cause the working fluid 15 and its vapor to continue circulation at a high speed in the looped elongate capillary tube 11. The circulating working fluid 15 is vaporized by an amount of heat supplied at the heat receiving portions 112 to form the vapor. The amount of heat is absorbed as a latent heat in the vaporization, and the vapor streams in the first channel 132 of the artery mesh 13 and the second channel 133 between the artery mesh 13 and the looped elongate capillary tube 11. When the stream of vapor reaches the heat radiating portions 114, the stream of vapor is cooled and liquefied to the working fluid 15. During the liquefication, the vapor supplies the amount of heat for the heat radiating portions 114 as the latent heat in condensation to radiate heat externally. In this way, the working fluid 15 circulates within the looped elongate capillary tube 11 and the artery mesh 13 and repeats the vaporization and condensation, i.e., the heat reception and the heat radiation.
In the pulsating heat pipe 10, the first propelling action, i.e., the capillary action generated by the artery mesh 13 helps to conquer the gravity of and propel the working fluid 15 to circulate in the elongate capillary tube 11, so that the required start up pressure generated by heating the heating region H of the pulsating heat pipe 10 is decreased. The required start up temperature of the pulsating heat pipe 10 is accordingly decreased, which results in the pulsating heat pipe 10 being easy to be operated under a lower temperature. In addition, the artery mesh 13 helps to prevent the working fluid 15 from accumulating in some portions of the elongate capillary tube 11, which further decreases the required start up pressure of the pulsating heat pipe 10. Therefore, the pulsating heat pipe 10 is capable of being used for dissipating heat generated by heat sensitive electronic components.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Patent Application
20080073066
