Refrigeration System
The original coolant was R-12 refrigerant. Liquid refrigerant is held in a low-pressure surge tank. The pressure in this tank is maintained at the saturation pressure for the desired temperature for the cooling coils. Vapor from this tank is compressed to a gage pressure of 20 psi (138 kPa) by the first-stage compressor. The compressed vapor is expanded into an intermediate, desuperheater tank. Liquid condensed in this expansion is drained back the to the surge tank. The remaining vapor is compressed in a high-stage compressor to a gage pressure of about 150 psi (1 MPa). Heat is transferred from the hot vapor to cooling water. Any condensed liquid is returned to the intermediate tank, the surge tank, or the supply tank. Liquid refrigerant from the surge tank is pumped through the cooling coils at sufficient pressure to avoid vaporization. Warmed liquid is returned to the surge tank. As its pressure is reduced, a portion of this liquid will flash into vapor.
There are three such refrigeration systems. Each low-stage compressor is powered by a 1,000 horsepower (746 kW) motor and each high-stage compressor is powered by a 1,250 horsepower (932 kW) motor. The system was built by York Corporation. The original motors were Allis-Chalmers induction motors. They have been replaced by variable frequency, synchronous motors manufactured by EMICC that operate between 350 and 1800 rpm. Recent efforts have been made to change from ozone-depleting refrigerants.
For engine tests, there is need for makeup air. The system originally could cool 200 pounds (91 kg) per second of humid air. In 1966, this was increased to 450 pounds (204 kg) per second. Air is also cooled by a two-stage heat exchanger. The first stage uses 110,000 US gallons (416 m3) of 20% calcium chloride brine pre-cooled to 24 °F (−4 °C). The second stage uses 137,500 US gallons (520 m3) of methylene chloride pre-cooled to −97 °F (−72 °C). This can cool 450 pounds (204 kg) per second of humid air from 80 °F (27 °C) to −65 °F (−54 °C) for 40 minutes.
Read more about this topic: Mc Kinley Climatic Laboratory
Famous quotes containing the word system:
“When the finishing stroke was put to his work, it suddenly expanded before the eyes of the astonished artist into the fairest of all the creations of Brahma. He had made a new system in making a staff, a world with full and fair proportions; in which, though the old cities and dynasties had passed away, fairer and more glorious ones had taken their places.”
—Henry David Thoreau (1817–1862)