Disclosed is a heat exchange device for effecting a heat exchange between a heat transfer fluid of a first network of capillary heat pipes and a heat transfer fluid of a second network of capillary heat pipes. The heat exchange device includes a solid block provided with a first channel and a second channel which are independent of one another, the first channel having at least one opening intended to be connected to a capillary heat pipe of the first network, the second channel having at least one opening intended to be connected to a capillary heat pipe of the second network, the first channel having a portion which lies near a portion of the second channel such that the heat transfer fluid of the first network is able to exchange heat with the heat transfer fluid of the second network via the heat exchanging portions.