| 摘要 |
<p>HEAD PRESSURE CONTROL INCLUDING MEANS FOR SENSING CONDITION OF REFRIGERANT A sensing device detects "flashing" in a refrigerant liquid line, upstream from the expansion valves of the evaporators of a refrigeration system. In response, a valve opens in a line extending between the compressor discharge line and a receiver, to bypass discharge vapor into the receiver, thus raising the head pressure to an extent sufficient to satisfy the requirement for a steady liquid refrigerant flow at the expansion valve. The head pressure is raised only to the minimal extent necessary to satisfy this requirement. Disclosed is a sensor of the type incorporating a sight glass in the path of a beam extending between photoelectric cells, though other sensing devices of an equivalent nature can be used. The invention can comprise a single sensing device in the liquid line extending to one or more evaporators connected in parallel. Alternatively, one may utilize separate sensing devices, one for each of several evaporators connected in parallel, with each sensing device having the capability of operating the valve, thus to assure a minimal but sufficient head pressure within the liquid line sufficient to maintain a liquid refrigerant seal at the expansion valve where flashing has been detected by its associated sensor.</p> |
