Abstract: A projection device includes a housing and a light engine, a circuit board, and a fan that are arranged in the housing. The bottom wall of the housing is provided with an air inlet hole facing the light engine and an air outlet hole. A first gap is formed between a bottom side of the light engine and the bottom wall of the housing, and in communication with the air inlet hole. The circuit board is arranged on a top side of the light engine. A second gap is formed between the circuit board and the light engine, and in communication with the air inlet hole. The fan is configured to drive cooling airflow entering the housing from the air inlet hole to respectively flow through the first gap and the second gap and then flow towards the first radiator, and to be discharged from the air outlet hole.

Abstract: A method is provided for operating a fuel cell stack with improved performance recovery from sub-saturated conditions, the method comprising setting an alert for the performance recovery of the fuel cell stack, performing at least one oxidant starvation by supplying oxidant at a stoichiometric ratio below 1 to the fuel cell stack in at least one pulse for a preset amount of time and at low current while the fuel cell stack does not generate power. The fuel cell system with an improved performance recovery comprises a shorting circuit which is connected to the fuel cell stack at predetermined times (startup, shutdown or standby mode) and an air compressor powered by a DC-DC converter which supplies a predetermined number of oxidant pulses of a predetermined duration to the fuel cell stack.

Abstract: A method is provided for operating a fuel cell stack with improved performance recovery from sub-saturated conditions, the method comprising setting an alert for the performance recovery of the fuel cell stack, performing at least one oxidant starvation by supplying oxidant at a stoichiometric ratio below 1 to the fuel cell stack in at least one pulse for a preset amount of time and at low current while the fuel cell stack does not generate power. The fuel cell system with an improved performance recovery comprises a shorting circuit which is connected to the fuel cell stack at predetermined times (startup, shutdown or standby mode) and an air compressor powered by a DC-DC converter which supplies a predetermined number of oxidant pulses of a predetermined duration to the fuel cell stack.