A fluid reactor device, in particular a fluid purification device, comprising:
- a heat-transfer bed comprising heat storage material configured to heat fluid flowing through the heat storage material such that the fluid heats up and reacts while flowing through the heat storage material;
- a heat source configured to heat the heat storage material to a predefined temperature;
- and
- one or more hollow body arranged in the heat storage material wherein a respective interior of the one or more hollow body is accessible from outside the heat-transfer bed, wherein at least part of the heat source is arranged in the one or more hollow body.