Abstract: Provided is a refrigeration apparatus capable of appropriately supplying oil separated by oil separators to compressors according to the situation. The refrigeration apparatus includes N refrigeration units each including a compressor, an oil separator, an oil return pipe, and a heat dissipation heat exchanger; N pressure reducing valves each connected to the heat dissipation heat exchanger of a corresponding one of the N refrigeration units; and an oil return control mechanism that controls a return destination of the oil separated by the oil separators of the N refrigeration units. The oil return control mechanism includes an oil supply pipe that connects the oil return pipes of the N refrigeration units to each other, and a flow control mechanism, which controls a flowing condition of oil in the oil supply pipe, disposed in the oil supply pipe.

Abstract: There is disclosed a projector which supplies air cooled by a cooling unit to an optical element group, whereby the occurrence of dew condensation is prevented. The projector includes a cooling apparatus 11 disposed in a main body 1 and functioning as the cooling unit; a sealed or substantially sealed duct 30 through which cold air cooled by a cooler 18 of the cooling apparatus 11 is circulated and supplied to an optical element group 5 to cool the optical element group; an outside air introduction port 32 and an air discharge port 33 which function as a ventilation unit for introducing outside air into this duct 30 to discharge the air from the duct 30, dampers 34 and 35 for opening and closing these ports; and a controller C functioning as a control unit for controlling the dampers 34 and 35 to execute a ventilating operation in the duct 30.

Abstract: An object is to provide a two-stage expansion refrigerating device capable of performing control with low cost so that a pressure of a refrigerant which has flowed through a high-pressure-side expansion unit is an optimum pressure, the device comprises a control unit (a controller) which controls a compressor (a low-stage-side compression element and a high-stage-side compression element) and each expansion unit (a high-pressure-side expansion valve as a high-pressure-side expansion unit and a low-pressure-side expansion valve as a low-pressure-side expansion unit), and a temperature sensor (a temperature detection unit) which detects a temperature of the refrigerant which has flowed through the high-pressure-side expansion valve, and the controller estimates a pressure of the refrigerant which has flowed through the high-pressure-side expansion valve based on a temperature detected by the temperature sensor, and controls one of the high-pressure-side expansion valve and the low-pressure-side expansion valve