Abstract: A fuel cell system includes a branch anode gas supply pipe in which hydrogen before supplied to a fuel cell flows; and a branch cathode gas supply pipe in which air before supplied to the fuel cell flows. One end on the upstream side of the branch anode gas supply pipe is connected to the upstream side of a regulator in an anode gas supply pipe, and the other end thereof is connected to the branch cathode gas supply pipe via a hydrogen injector. The branch anode gas supply pipe is provided with a hydrogen regulator, which detects a pressure in the branch cathode gas supply pipe as a signal pressure.

Abstract: A heat exchanger has a heat exchange part that includes a heat supply medium channel with at least one heat supply passage and a heat recovery medium channel surrounding the heat supply medium channel. The heat exchange part is arranged such that, during operation, a heat supply medium passing through the heat supply medium channel exchanges heat with a heat recovery medium passing through the heat recovery medium channel. Cross-sectional space available to accommodate heat recovery medium flow in different sections of the heat recovery medium channel varies according to an amount of heat to be transferred from the heat supply medium to the heat recovery medium in each of the different sections.

Abstract: A fuel cell system includes a branch anode gas supply pipe in which hydrogen before supplied to a fuel cell flows; and a branch cathode gas supply pipe in which air before supplied to the fuel cell flows. One end on the upstream side of the branch anode gas supply pipe is connected to the upstream side of a regulator in an anode gas supply pipe, and the other end thereof is connected to the branch cathode gas supply pipe via a hydrogen injector. The branch anode gas supply pipe is provided with a hydrogen regulator, which detects a pressure in the branch cathode gas supply pipe as a signal pressure.

Abstract: A heat exchanger exhibiting excellent heat exchange efficiency has a heat exchange part including a group of heat supply pipes, through which a heat supply medium flows, and a heat recovery pipe part, through which a heat recovery medium flows, surrounding the heat supply pipes. Each heat supply pipe has a vertically elongated cross section and a predetermined width. The heat supply pipes are arranged so that the heat supply pipe having cross-sectional area is located farther from the center of the heat exchange part. Spacings between the heat supply pipes and an inner wall are made stepwise narrower in the direction from the center to the periphery of the heat exchange part.