Closed loop air conditioning system having automatic pressurizing means

Abstract

An air conditioning system for an enclosed space including a jointly driven compressor and expander of the positive displacement type each having an inlet port and an outlet port with a primary heat exchanger connected between the compressor outlet port and expander inlet port and a secondary heat exchanger connected between the expander outlet port and the compressor inlet port to complete a closed loop having a charge of air and with one of the heat exchangers being thermally coupled to the enclosed space. Ambient air is injected into the closed loop to raise the pressure in the secondary heat exchanger to substantially above the atmospheric level to increase the heat rate of the system. Alternatively air is bled from the loop to reduce the pressure in the secondary heat exchanger thereby to decrease the heat rate of the system. In an alternate embodiment a source of pressurized air is provided, preferably in the form of an accumulator, with valving to feed air from the accumulator into the loop. While the system may be manually controlled, it is one of the features of the invention that injection and bleeding are under the automatic and corrective control of a temperature pressure sensing device so that the heat rate of the system is varied automatically in accordance with the requirements of an enclosed space for automatic maintenance of a present condition.