Heat exchanger

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.