| 摘要 |
A variable capacity refrigeration system which does not require a costly inverter compressor and does not exhibit low energy efficiency at high capacity. The system employs a constant speed compressor that operates continuously when the system is energized, irrespective of the heat load, and a refrigerant bypass path including a secondary expansion device, a heat exchanger, and a flow control device which is operable to permit a portion of the refrigerant exiting from the condenser to flow through the bypass path to an inlet of the compressor when the heat load is below a predetermined threshold, whereby the heat exchanger operates as a secondary evaporator, and to prevent refrigerant exiting from the condenser from flowing through the bypass path to the compressor inlet when the heat load is not below the predetermined threshold. In one embodiment, the flow control device is further operable to permit a portion of the refrigerant exiting from the compressor to flow through the bypass path to the primary evaporator through the primary expansion device when the heat load is not below the predetermined threshold, whereby the heat exchanger operates as a secondary condenser. In several embodiments, a pressure differential is maintained between the refrigerant in the heat exchanger and the evaporator. The pressure differential is accommodated by a vacuum generating device such as a vortex generator, a venturi or the like, or by a flow restrictor such as a capillary tube. In several embodiments, the heat exchanger is thermally coupled to the compressor to remove heat from the refrigerant as it flows through the compressor.
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