The Dark Energy Survey (DES) project will study the accelerated expansion of the universe. In order to further study this phenomenon,... Show moreThe Dark Energy Survey (DES) project will study the accelerated expansion of the universe. In order to further study this phenomenon, scientists have devised a method of creating an array of charged couple devices (CCD) to capture images that will be studied. These CCDs must be cooled and remain at 173K to eliminate thermal gradients and dark current. Therefore, a two-phase CCD liquid nitrogen (LN2) cooling system was designed to maintain the array of CCDs at a constant temperature. However, the centrifugal pump used to supply LN2 has a mean time between failure (MTBF) of approximately two thousand-eight hundred hours (116 days). Because of the low MTBF of the centrifugal pump, a new pump is being considered to replace the existing one. This positive displacement pump is a simpler design that is expected to have a MTBF that will exceed 116 days (2800hrs). This positive displacement reciprocating pump, also known as, the cryogenic over-pressure pump (OPP), was tested in February 2012 and successfully cooled the CCD array to 173K. Though un t for service for DES CCD cooling system, the overall concept of this pump has been proven. Typical ow rates, pressures, and temperatures trends have been captured via instrumentation and are speci c to the operation of future over-pressure pumps. M.S. in Mechanical and Aerospace Engineering, July 2012 Show less
