Toyota Jidosha Kabushiki Kaisha

Shoji Hirose

Shigeru Ogino

Tomoji Yamada

Mitsuo Inagaki

A catalytic combustion heater having, in a fuel gas flow passage in which an inflammable gas- and combustion support gas-containing fuel gas flows, tubes in which an object fluid to be heater flows, and an oxidation catalyst provided on outer surfaces of the tubes and contacting the fuel gas to generate an oxidation reaction, comprising a catalyst-carrying heat exchanger adapted to heat the object fluid with the oxidation reaction heat of the fuel gas, a detecting member adapted to detect the temperature of a combustion exhaust gas in the fuel gas flow passage to check whether the temperature is at the level of a dew point thereof or not, and a control unit adapted to control at least one of a feed rate of the combustion support gas, which is supplied to the fuel gas flow passage, and a feed rate of the inflammable gas.

Catalytic combustion heat exchanger

Catalytic combustion heater

A catalytic combustion heat exchanger includes a fuel gas passage and a number of tubes, which are located in the fuel gas passage. Fuel gas flows in the fuel gas passage. An object fluid, which is heated by the heat exchanger, flows in the tubes. Fins, which carry a catalyst, are fixed to the outer surfaces of the tubes. The fluid is heated by an oxidation reaction of the fuel gas that occurs on the surface of the fins. When the heat exchanger is initially activated, the controller maintains the flow rate of the object fluid at a relatively low rate until a temperature detector detects that the temperature of the object fluid is higher than a certain level to limit heat transfer from the fins to the object fluid. This increases the fin temperatures throughout the heat exchanger. The controller increases the flow rate of the object fluid when the temperature of the object fluid exceeds a certain level, to increase heat transfer to the object fluid. The control method prevents the fins from overheating and speeds up the initial activation of the heat exchanger.

Multiple heat-receiving fluid passages, through which heat-receiving fluid flows, are arranged in layers in a fuel gas passage provided in a container. Multiple fins, on which an oxidation catalyst is carried, are provided on outer peripheries of the heat-receiving fluid passages. A feed port for combustion support gas is provided at one end of the fuel gas passage, and multiple combustible gas feed ports are provided in a wall of the fuel gas passage. Combustible gas is separately supplied to the respective layers of the heat-receiving fluid passages in accordance with a state of the heat-receiving fluid so as to suitably control a heat release value. Especially in the intermediate layer where the heat-receiving fluid is at its boiling point and thus exhibits a low heat transfer resistance, more combustible gas feed ports are provided than in the other layers. As a result, more fuel is supplied, the heat release value is increased, and the heat exchange efficiency is enhanced.

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Nissin, Japan

Shoji Hirose