| 摘要 |
<p>A vapor control system (10) utilizes a variable speed compressor (11) driven by a motor (12) or the like. A condenser (13) is provided downstream of the compressor (11). Multiple evaporators (14, 15, etc.) are arranged in parallel with stepper motor controlled thermal expansion valves (16, 17, etc.) located upstream thereof. Refrigerant exit temperatures (Tr1, Tr2, etc.) are sensed at the exits of the evaporators (14, 15, etc.) and source exit temperatures (Ts1, Ts2, etc.) are also sensed. A function generator (18) calculates refrigerant dewpoint temperature (Tdew) is substracted from each of the refrigerant exit temperatures (Tr1, Tr2, etc.) to determine a minimum superheat temperature which is used to calculate an error signal for providing a speed signal (Nc). The loads on the evaporators (14, 15, etc.) are individually controlled with the thermal expansion valves (16, 17, etc.) whose positions are responsive to signals (Xc1, Xc2, etc.) which are generated by calculating an error signal based upon comparisons of the individual source exit temperatures (Ts1, Ts2, etc.) with preselected setpoint temperatures (T¿s1 SETPOINT, Ts2, SETPOINT?, etc.).</p> |
