NOVELTY - A heat-pipe electric power generating device, suitable for converting a heat energy or a heat source energy into an electrical energy, comprises: a heat-pipe (100), having a sealed internal chamber, and generating an airflow from an evaporating end (104) to a condensing end (108) due to a pressure difference between two ends of the heat-pipe; a magnetic field change generating device (114); a hollow case (118); a bearing (124); and a stator coil of a generator (112).    USE - The heat-pipe electric power generating device is useful for converting a heat energy or a heat source energy into an electrical energy; used in hydrogen/oxygen gas generating apparatus; and in an internal combustion engine system (all claimed).    ADVANTAGE - The heat-pipe electric power generating device efficiently and effectively converts a heat energy or a heat source energy into an electrical energy.    DETAILED DESCRIPTION - A heat-pipe electric power generating device, suitable for converting a heat energy or a heat source energy into an electrical energy, comprises: a heat-pipe, having a sealed internal chamber, and generating an airflow from an evaporating end to a condensing end due to a pressure difference between two ends of the heat-pipe; a magnetic field change generating device, disposed within the internal chamber of the heat-pipe, comprising: at least a fan, where a permanent magnetic substance is disposed on the fan to generate a magnetic field; a hollow case, aligned with an inner wall of the heat-pipe, where a first end of the hollow case contacts with the evaporating end of the heat-pipe, and at least an opening is disposed so that a vapor generated at the inner wall of the heat-pipe enters the hollow case through the opening; a bearing, disposed on a second end corresponding to the first end of the hollow case to install a shaft of the fan; at least an airflow passage, directing the vapor inside the hollow case to the fan; and a stator coil of a generator, disposed on a position corresponding to the fan at an outer of the heat-pipe. INDEPENDENT CLAIMS are:    (1) a hydrogen/oxygen gas generating apparatus having the heat-pipe electric power generating device, comprising: the heat-pipe electric power generating device; a container, containing an electrolytic solution and having a gas outlet; and a set of positive and negative electrodes, disposed within the electrolytic solution in the container, where the set of positive and negative electrodes and a power output end of a stator coil of a generator of the heat-pipe electric power generating device are electrically connected; and    (2) an internal combustion engine system having the heat-pipe electric power generating device, comprising: the heat-pipe electric power generating device; a container, containing an electrolytic solution and having a gas outlet; a set of positive and negative electrodes, disposed within the electrolytic solution in the container, where the set of positive and negative electrodes and an power output end of a stator coil of a generator of the heat-pipe electric power generating device are electrically connected; and an internal combustion engine, connected to the gas outlet, where a gas product directed from the gas outlet is used as a fuel of the internal combustion engine.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic cross-sectional view of the heat pipe electric power generating device.    Heap pipe (100)    Capillary structure (102)    Evaporating end (104)    Middle region (106)    Condensing end (108)    Generator (112)    Magnetic field change generating apparatus (114)    Fan (116)    Hollow case (118)    Opening (122)    Bearing (124)    Shaft (126)    Airflow passage (128)