| 摘要 |
A vapor compression refrigeration and freezer system (10) includes a compressor (12), a condenser (14), an expansion device and an evaporator (16 ) which includes an evaporator coil having an inlet and an outlet which coil i s in heat exchange relation with an air medium along substantially the entire coil length. The inlet to the evaporator coil is in flow communication with an outlet of the expansion device via an evaporator feedline (28). The expansio n device can include a multifunctional valve (18) that cooperates with the evaporator feedline (28) to supply the evaporator coil inlet with a mixture of refrigerant vapor and liquid at a linear velocity and with relative amounts of vapor and liquid which are sufficient to provide efficient heat transfer alo ng substantially the entire length of the coil, substantially reducing the buil d- up of frost on the evaporator coil and enabling the system to be operated without requiring a defrosting cycle over a substantially increased number o f operating cycles compared to conventional refrigeration and freezer systems operating at the same cooling load and evaporating temperature conditions.</ SDOAB>
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