Test chamber and a method for its control

A test chamber comprising a temperature-insulated test space, which is sealable against an environment and serves for receiving test material, and a temperature control device for controlling the temperature of the test space, a temperature ranging from −20° C. to +180° C. being produced within the test space by means of the temperature control device, the temperature control device comprising a cooling device having a cooling circuit with carbon dioxide (CO2) as a cooling agent, a heat exchanger in the test space, a low-pressure compressor and a high-pressure compressor downstream of the low-pressure compressor, a gas cooler, a storage container for the cooling agent and an expansion valve, the test chamber comprising a control device for controlling and/or regulating the temperature in the test space,

• wherein
• the cooling circuit comprises a high-pressure valve downstream of the gas cooler, the gaseous and/or liquid cooling agent being dosed in the storage means by means of the high-pressure valve, the storage means being connected to a medium-pressure side of the cooling circuit upstream of the high-pressure compressor and downstream of the low-pressure compressor via a medium-pressure bypass of the cooling circuit, the gaseous cooling agent being dosed in the medium-pressure side from the storage means by means of a medium-pressure valve when the low-pressure compressor is switched off.