| 摘要 |
<p>A controlled space is maintained at a desired set point temperature by adjusting the evaporator boiling pressure in a refrigeration system, thereby controlling the evaporator capacity (namely, the amount of cooling imparted to the air supplied to the space) which is inversely proportional to the evaporator boiling pressure. When the space temperature tends to vary from the desired set point due, for example, to a changing heat load, the control system automatically changes the refrigerant flow through the evaporator to establish the evaporator boiling pressure (and hence the boiling temperature) at the control point required to cool the air sufficiently to maintain the controlled space at the desired temperature. More specifically, in response to a space temperature increase, the flow rate of the refrigerant increases to decrease the evaporator boiling pressure; and in response to a drop below the set point, the refrigerant flow decreases to increase the evaporator boiling pressure. Such control of the flow rate, and consequently the evaporator boiling pressure, is achieved by varying the displacement of a controlled displacement compressor included in the refrigeration system. When the heat load on the evaporator is constant, the refrigerant flow is automatically controlled in order to hold the evaporator boiling pressure fixed at the required control point.</p> |
