Heat exchanger

Abstract

A heat exchanger, comprising at least a double shell, wherein the lower portion of the inner space of the inner shell is filled with liquid phase change medium, and at least one coiler is provided in the upper portion. The heated fluid flows in the coiler. After the downstream side pipe of the coiler is pierced through the inner shell, at least one surrounding pipe is formed in the cavity between the double shells. The bottom heat exchange plate of heat exchanger of the inner shell is located above the heat source. The cavity between the two shells forms the flue gas passage. After bottom heat exchange plate of the inner shell is heated by the heat source, the flue gas rises from the bottom of perimeter of the inner shell along the flue gas passage and the heat is transferred to the heated fluid in the surrounding pipe. The heat device using the heat exchanger according to the present invention can significantly improve the efficiency of heat utilization.

Claims

1. A heat exchanger comprising: a boiling-condensing heat transfer, which comprises a closed container having at least two layers of shells, a lower portion of the container is filled with a liquid phase change medium, at least one first heat exchange tube is provided at the upper portion of the container fluid being heated flows in the first heat exchange tube; at least one second heat exchange tube, which is a downstream side pipe of the at least one first heat exchange tube formed in a cavity between the double shells; a heater, which comprises a heat source and a bottom heat exchange plate of the container located above the heat source; a flue gas passage, which comprises a cavity between the two shells; after the bottom heat exchange plate of the container is heated by the heat source, in the boiling-condensing heat transfer the vaporized liquid phase change medium is condensed by the first exchange tube to heat the fluid therein by a boiling-condensing heat exchange; in the flue gas passage the fluid in the second heat exchange tube is heated by heat exchange with flue gas.

2. The heat exchanger according to claim 1, wherein the outer shell of the double-shell is made of a heat-insulating material, or the outer shell is wrapped around by a heat-insulating material.

3. The heat exchanger according to claim 1, wherein the first heat exchange tube and the second heat exchange tube are integrally formed by one tube.

4. The heat exchanger according to claim 1, wherein the first heat exchange tube is subjected to a hydrophobic treatment.

5. The heat exchanger according to claim 1, wherein connection parts between the first heat exchange tube and the second heat exchange tube with the closed container are sealed.

6. The heat exchanger according to claim 1, wherein a central portion of the inner space of the closed container is provided with a filter screen for liquid-resistant vapor-through adjacent to the boiling side of the liquid phase change medium.

7. The heat exchanger according to claim 1, wherein a top of the outer shell of the double shell is provided with an induced draft fan for pumping the flue gas in the flue gas passage.

8. The heat exchanger according to claim 1 wherein the second heat exchange tube is surrounded within a cavity between the double shells, and a fin is provided on the wall of the second heat exchange tube.

9. A water heater comprising the heat exchanger according to claim 1.

10. A three-heating core phase change gas water heater comprising: a three-layer heating cores, a first heating core is a remaining flue gas heat exchange section, a second heating core is a vacuum phase change heat exchange section of an inner closed shell, a third heating core is a flue gas swept around the pipeline heat exchange part around the heat exchange chamber; the three-layer heating cores comprises three layer of shells, which are a first, a second and a third shells from outside to inside, respectively; a third heating core area is located between the second and the third layer of the shell; the first shell is the outermost shell, a heat exchange tube is provided at the left top, the first heating core area is located in a gap between the first shell and second shell, a burner is arranged at a bottom of the second shell, the third shell is located above the burner, and a spiral heat exchange tube is arranged outside the third shell, the heat exchange tube is finned to strengthen the heat exchange, this area is the third heating core area, inside the third shell is the second heating core area, that is, the phase change heat exchanger, an upper part of the phase change heat exchanger is arranged with a heat exchange water pipe and a lower part is a phase change medium, the heat exchange tube enters the first, second and third heating core area for heat exchange, successively; the water pipe is one pipe from beginning to end, and the burner is arranged below the lower plate of the phase change heat exchanger, the flue gas flows upward along the gap between the second and third shells and finally discharged from the upper part of the water heater.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view of the structure of the heat exchanger according to the present invention;

(2) FIG. 2 is a cross-section left view of the heat exchanger according to the present invention;

(3) FIG. 3 is a schematic structural view of a gas water heater using the heat exchanger according to the present invention.

DESCRIPTION OF COMPONENT REFERENCE NUMERALS

(4) 1: inner shell. 2: outer shell. 3: phase change medium. 4: coiler. 5: heat exchanger inlet pipe section. 6: heat source. 7: bottom heat exchange plate. 8: filter screen. 9: surrounding pipe. 10: induced draft fan. 11: water heater shell. 12: burner. 13: water inlet pipe. 14: first heating core area. 15: second heating core area. 16: third heating core area. 17: water outlet pipe. 18: fin.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) FIGS. 1 and 2 are schematic views of the structure of a heat exchanger provided by the present invention.

(6) The heat exchanger comprises a double shell. The lower portion of the inner space of the inner shell 1 is filled with the liquid phase change medium 3, the first heat transfer tube is provided in the upper portion, and the first heat transfer tube may be designed as a coiler 4. The heated fluid flows within the coiler 4, and the coiler 4 may be made of material having a high thermal conductivity, and the outer wall of the coiler 4 may be subjected to a hydrophobic treatment to promote bead-like coagulation. The phase change temperature of the liquid phase change medium 3 should be higher than the operating temperature of the heated fluid. The upstream side of the coiler 4 is an inlet pipe section 5 of the heat exchanger which penetrates from the outside of the double-shell. A downstream side of the coil 4 pierces through the inner shell and threads out after surrounding around the cavity between the double shells. High temperature flame or high temperature flue gas provides heat source 6 for the heat exchanger, a bottom heat exchanger plate 7 of heat exchanger inner shell 1 is provided above the heat source 6. The inside of the inner shell 1 is subjected to a vacuum treatment, and the connection between the pipe and the shell are sealed to remove the influence of the non-condensable gas and prevent leakage.

(7) The liquid phase change medium 3 in the lower portion of the inner space of the inner shell 1 is heated and vaporized, and then flows to the upper portion of the inner space of the inner shell 1. The vaporized phase change medium 3 contacts with the upper coiler 4 and is condensed into liquid, and then falls into the lower portion of the inner space of the inner shell 1 and will be vaporized again, thereby forming the self-circulation of the phase change medium 3. As a result, the fluid in the coiler 4 is heated.

(8) Preferably, a filter screen 8 for liquid-resistance and gas-through is provided at the middle of the inner space of the inner shell 1 near to the boiling side of the liquid phase change medium 3 so as to prevent the condensate from directly falling to the vapor-liquid interface and suppressing the rapid generation of the vapor, which results in reducing heat transfer efficiency. The filter screen 8 is inclined, or the center of the filter screen is slightly higher than that of the perimeter so that the liquid phase change medium 3 can flow to the lower portion of the filter screen 8 in the vertical direction after the condensation and return to the liquid surface of the liquid phase change medium 3.

(9) The cavity between the double shells forms a flue gas passage. After the heat source 6 heats the bottom heat exchange plate 7 of the inner shell of the heat exchanger, the flue gas rises vertically along the flue gas passage, the heat is transferred to the heated fluid in the second heat transfer tube. The second heat transfer tube may be designed as surrounding pipe 9. Due to the chimney effect of the flue gas passage, the high temperature flue gas passes over the surrounding pipe 9 at a faster rate, and the heat is absorbed by the heated fluid in the surrounding pipe 9 to achieve a better heat transfer effect.

(10) Preferably, the induced draft fan 10 is provided at the top of the outer shell 2 to pump the flue gas to further increase the flue gas flow rate and increase the heat transfer amount. Further, in order to reduce the heat of the high-temperature flue gas dissipating through the outer shell 2 as far as possible, a heat insulating material may be wrapped around the outer shell 2, or the outer shell 2 may be made of a heat insulating material such as ceramic. Fins may be provided on the walls of the surrounding pipe 9 to increase the heat supply area of the high temperature flue gas.

(11) In the fore-mentioned heat exchanger structure, the high temperature flame or high temperature flue gas is used for heating the phase change medium 3 inside the closed inner shell 1 first and then flows through the surrounding pipe 9 between the double shells, and the temperature is successively lowered to achieve cascade utilization of the heat of high temperature flame or high temperature gas.

(12) The heat exchanger of the present invention described above can be used in various heating equipments which use high temperature flame or high temperature flue gas as the main heat source for improving the thermal efficiency of the heating equipments. The following embodiments illustrate the use of the heat exchanger according to the present invention in a heating device, taking gas water heater as an example.

(13) The gas water heater structure provided by the present invention is shown in FIG. 3, and the core part is the above mentioned heat exchanger. The water inlet pipe 13 enters the first layer of the shell (i.e., the water heater shell 11) from the lower portion of the water heater and reaches the first heating core 14, the first heating core 14 performs heat exchange of the remaining flue gas pumped from the heat exchanger by the induced draft fan 10. The water pipes in the first heating core 14 are arranged in a coiler-like manner and the pipes at the coiler outlet pass through the second and third shells (i.e., double shells 1, 2 of the heat exchanger) into the second heating core area 15 (i.e., the interior of the inner shell of the heat exchanger), and then threads out the third shell into the third heating core area 16 (i.e., the cavity between the two shells of the heat exchanger), surrounding the outside of the heat exchanger between the second layer and third layer of shell, and finally become the lower water outlet pipe 17 of the water heater. The burner 12 is disposed below the bottom heat exchange plate 7 of the heat exchanger inner shell 1. Thus a three-thermonuclear phase change gas water heater is constituted.

(14) After the gas water heater is started, the water in the inlet pipe 13 enters the first heating core 14 from the lower portion of the water heater and burns in the burner 12 and passes through the second and third heating core area 15, 16 (i.e., the heat exchange of the present invention). The remaining flue gas is used for a first heat exchange that takes condensation of water vapor as major heat transfer. The water is preheated through the first heating core area 14 and flows along the inlet section 5 of the heat exchanger, passes through the second and third shells, and enters the second heating core area 15.

(15) The second heating area 15 is mainly composed of condensing heat exchange containing phase change. The phase change temperature of the phase change medium 3 is higher than the leaving water temperature of the hot water, and optional medium can be deionized water. In the second heating core area 15, the liquid phase change medium 3 is boiled and vaporized. The heat of the boiling vaporization of the liquid phase change medium 3 is derived from the high temperature flame produced by the burner. And the vapor meets the upper water coiler 4 and condensation heat exchange occurs, the self-cycle of phase change medium is formed and the water in the water pipe is sufficiently heated.

(16) After the heat exchange in the second heating core area 15 is completed, the water in the water pipe flows to the surrounding pipe 9 at the downstream side and radiative heat exchange and heat convection with the flue gas in the third heating core area 16 occur. Thereafter, hot water flows out of the outlet pipe 17.

(17) The gas water heater achieves the efficient gradient utilization of flue gas heat through the three-heating core heat transfer mode. And temperature of exhaust gas discharged is significantly reduced. In order to reduce the flow resistance as much as possible, the water pipe in the gas water heater can be a pipe from beginning to end, or can be multiple pipes arranged in the parallel with single inlet and single outlet and no branch. Of course, some pipelines are also allowed to be connected there between in other ways to form one pipe. In addition, in order to increase the heat exchange area, enhance the heat exchange effect, fin structure can be arranged outside the water pipe of the water heater in different degrees, and bottom heat exchange plate 7 of the heat exchanger can be designed as curved surface.

(18) The present invention does not describe the burner, the water-gas linkage valve, and the automatic control circuit conventionally disposed in the gas water heater in detail.

(19) The embodiments of the present invention are merely illustrative of the present invention and are not intended to limit the scope of the invention, and those skilled in the technology may also make changes to them, the changes are within the scope of this invention as long as they do not exceed the spirit of the invention.

INDUSTRIAL APPLICABILITY

(20) The heat exchanger according to the present invention is applicable to various heating device using high temperature flame or high temperature flue gas as the main heat source.